Table of contents :

• iatrophysics : the physics of medicine or of medical and surgical treatment
• orinotherapy : treatment by living in high, mountainous regions
• antidecubitus mattress :
• irrigation : washing by a stream of water or other fluid. A liquid used for irrigation.
• acetic acid irrigation : a sterile aqueous solution of glacial acetic acid; used to irrigate the bladder in the treatment of urinary infections with cystitis.
• glycine irrigation : a sterile solution of glycine in water for injection, used to irrigate the bladder during urogenital surgical procedures.
• Ringer's irrigation, mixture or solution : a sterile solution containing, in each 100 mL, 820–900 mg of sodium chloride, 25–35 mg of potassium chloride, and 30–36 mg of calcium chloride in water for injection; used as a topical physiological salt solution
• sodium chloride irrigation or solution : a sterile aqueous solution of sodium chloride; used to irrigate wounds and body cavities and as an enema to flush the colon and promote evacuation
• lavage : the irrigation or washing out of an organ, such as the stomach or bowel
• bronchoalveolar lavage : a technique by which cells and fluid from bronchioles and lung alveoli are removed for diagnosis of disease or evaluation of treatment; a bronchoscope is wedged into a bronchus and sterile saline is pumped in and then removed along with the fluid and cells to be analyzed.
• peritoneal lavage : dialysis by instillation into the peritoneal cavity and subsequent withdrawal of dialysis fluid, for the removal of elements not being excreted by the kidneys.
• pleural lavage : irrigation of the pleural cavity to assess for presence of malignant or otherwise abnormal cells
• pressure gradients
• constant pressure gradient
• pneumatic antishock garment / medical anti-shock trousers (MAST) : an inflatable garment used to combat shock, stabilize fractures, promote hemostasis, increase peripheral vascular resistance (PVR), and permit autotransfusion of small amounts of blood. The Shock Sheet is an inflatable plastic bag which squeezes blood from the legs to the head, is designed to minimize brain damage after a heart attack
• Sengstaken-Blakemore tube
• variable pressure gradients
• counterpulsation : a technique for assisting the circulation and decreasing the work of the heart, by synchronizing the force of an external pumping device with cardiac systole and diastole
• intra-aortic balloon (IAB) counterpulsation : circulatory support provided by a balloon (intra-aortic balloon pump (IABP)) inserted into the thoracic aorta via the femoral artery, which is inflated during diastole (enhancing coronary perfusion pressure) and deflated during systole, resulting in a decrease in afterload and improvement in cardiac function. Indicated in cardiogenic shock. Contraindicated in aortic valve failure (would cause ventricular enlargement during diastole when the IAB is inflated). Complications : thrombosis, embolism or dissection of femoral, renal, mesenteric arteries or aorta


• enhanced external counterpulsation (EECP) (source : Vasomedical Inc.) is responsible for:
• augmented diastolic pressure and retrograde aortic flow that increase myocardial perfusion
• systolic unloading reduces cardiac workload and oxygen requirements
• increased venous return, coupled with enhanced systolic flow, increases cardiac output.

• massage therapy / massotherapy : the treatment of disease by massage, i.e. the use of specific gliding and kneading strokes and friction to achieve muscle relaxation. A general term for a range of therapeutic approaches with roots in both Eastern and Western cultures. It involves the practice of kneading or otherwise manipulating a person's muscles and other soft tissue with the intent of improving a person's well-being or health. Aggressive massage can cause soft tissue injuries. Drawing upon millennia of empirical knowledge, some 80 American schools instruct students in an array of the soft tissue manipulative approaches that constitute massage. 31 states and the District of Columbia license trainees to perform therapeutic massage.
• cardiac or heart massage : rhythmic compression of the ventricles of the heart against the vertebral bodies by pressure applied manually over the sternum (closed cardiac massage) or directly to the heart through an opening in the chest wall (open cardiac massage) with a rate = 80-90 per minute; done to reinstate and maintain circulation in patients with mydriasis, cyanosis and lack of central arterial pulse. When properly performed it allows 25% of normal cardiac output, 20% of normal cerebral blood flow, and 5% of normal coronary perfusion.
• thumpversion : delivery of 1 or 2 blows to the chest in initiating CPR, in order to initiate a pulse or to convert ventricular fibrillation to a normal rhythm.
• only rhythmic abdominal compression (OAC-CPR) : a new technique is desperately needed because conventional CPR has a success rate of 5% to 10%, depending on how fast rescuers are able to respond and how well the procedure is performed. For every one minute of delay, the resuscitation rate decreases by 10%. In other words, at 10 minutes, the resuscitation is absolutely ineffective. Any medical procedure that had that low a success rate would be abandoned right away. But the alternative is not very good, either: Don't do CPR and the person is going to die. Geddes has developed the first new CPR alternative, which works by pushing on the abdomen instead of the chest. "There are major problems with standard CPR. One is the risk of breaking ribs if you push too hard, but if you don't push hard you won't save the person. Another problem is the risk of transferring infection with mouth-to-mouth breathing. The new CPR method eliminates both risks. Findings will be detailed in a research paper appearing this month in the American Journal of Emergency Medicine, published by Elsevier Inc. The paper was authored by Geddes and his Purdue colleagues Ann E. Rundell, assistant professor of biomedical engineering, biomedical engineering doctoral student Aaron Lottes, and basic medical sciences graduate students Andre Kemeny and Michael Otlewski. In standard chest-compression CPR, which has been in practice since the 1960s, the rescuer pushes on the chest and blows into the subject's mouth twice for every 30 chest compressions. However, the risk of infection is so grave that many doctors and nurses often refuse to administer mouth-to-mouth resuscitation. In one 1993 study of 433 doctors and 152 nurses, 45% of doctors and 80% of nurses said they would refuse to administer mouth-to-mouth resuscitation on a stranger. This is the real world that nobody knows about, and it's a sobering thought. OAC-CPR eliminates the need to perform mouth-to-mouth resuscitation. The American Heart Association requires that rescuers administering CPR push with enough force to depress the chest 1 and a half to 2 inches at a rate of 100 times per minute. To depress the chest 1.5 to 2 inches takes 100 to 125 pounds of force. So you have to push pretty hard and pretty fast, and two people are needed to perform it properly. One blows up the lungs and the other compresses the chest. And when the one who's compressing the chest gets tired, they change positions. OAC-CPR requires only one rescuer. Instead of two breaths for every 30 chest compressions, the new procedure provides a breath for every abdominal compression because pushing on the abdomen depresses the diaphragm toward the head, expelling air from the lungs. The release of force causes inhalation. Researchers have known since the 1980s that pushing on the abdomen circulates blood through the heart. The idea was originated by Purdue nursing doctoral student Sandra Ralston. She made the remarkable observation that if you pushed on the abdomen after each chest compression you could double the CPR blood flow," he said. "So I started thinking, what would happen if you just pushed on the abdomen and eliminated chest compression entirely? The procedure provides a new way to effectively perform "coronary perfusion," or pumping blood through the heart muscle, which is critical for successful resuscitation because the heart muscle is nourished by oxygenated blood. Unfortunately, in standard chest-compression CPR, blood sometimes flows in the wrong direction, which means the coronary blood flow goes backward, bringing de-oxygenated blood back into the heart muscle," Geddes said. "This retrograde flow reduces the likelihood of resuscitation. Findings showed that OAC-CPR eliminates this backward flow. The Purdue researchers compared coronary artery blood flow during standard chest-compression CPR with the flow resulting from only abdominal compression CPR. Findings showed that using the new method and pushing with the same force recommended for standard CPR provided 25% more blood flow through the heart muscle without retrograde flow in the coronary arteries. The researchers followed the standard recommended by the American Heart Association, pushing with 100 pounds of pressure 100 times per minute. With OAC-CPR, you really don't have to press as hard or as often, but we followed the American Heart Association standard to avoid possible criticism from people who could have said we didn't observe the standard. Another benefit of OAC-CPR is that it eliminates rib fractures, which are commonly caused by compressing the chest. Rib fractures cause the chest to recoil more slowly, but effective CPR requires that rescuers wait until the chest recoils fully before compressing. Geddes created a wooden "pressure applicator" that resembles a scaled-down version of a baseball home plate. It is contoured so that it can be used to compress the abdomen without pushing on the ribs. However, a rescuer could push with the hands to perform the procedure if no applicator were available. Abdominal organs contain about 25% of the total blood volume in the body. You can squeeze all of that into the central circulation when you press on the abdomen. Whether the procedure gains widespread acceptance depends on whether other researchers can duplicate the results. In research, you publish data and then the scientific community looks at the data and tries to duplicate it to verify that it works," said Geddes, who was awarded the National Medal of Technology from President George W. Bush in a White House ceremony on July 27. It is the nation's highest honor for technological innovation^ref
• carotid sinus massage : firm rotatory pressure applied to one side of the neck over the carotid sinus of the supine patient; it causes vagal stimulation, increasing vagal inhibition of sinus and atrioventricular nodes, and it can slow or terminate tachycardia. It is contraindicated if a carotid murmur is detected (risk of mobilization of atheroembolism)
Indications :
• paroxysmal atrial tachycardia
• atrial flutter
• supraventricular tachycardia with aberrant ventricular conduction
• sinusal tachycardia
• eyeball massage : attenuation of sinusal tachycardia
• hydromassage : massage by means of moving water.
• electrovibratory or vibratory massage : massage by means of an electric vibrator
• gingival massage : the systematic application of frictional rubbing and stroking to the gingiva
• ice massage : massage in which ice is rubbed over the body surface for local analgesic effects and relief of muscle spasms
• pneumomassage / pneumatic massage : air massage of the tympanum by the alternate compression and rarefaction of the air in the external auditory canal
• pneumothermomassage : the application to the body of hot condensed air to produce an effect resembling massage
• infant massage : taught to new parents by trained instructors, infant massage practices are designed to enhance the bonding between parent and baby. As preventive therapy, infant massage can help strengthen and regulate a baby's respiratory, circulatory, and gastrointestinal functions, often relieving gas and colic while relaxing both parent and child.
• geriatric massage : the practitioners listed in this category use a variety of hands-on techniques to address health problems associated with aging.
• on-site massage : these practitioners perform a range of bodywork techniques at the client's location, typically the workplace. Generally, the client remains fully clothed while sitting in a specially designed massage chair brought by the practitioner.
• pregnancy massage : the practitioners listed in this category use or teach a variety of bodywork techniques to relieve common complaints of pregnancy and to ease the labor process.
• Swedish massage : the most commonly practiced form of massage in Western countries, Swedish massage integrates ancient oriental techniques with modern principles of anatomy and physiology. Practitioners rub, knead, pummel, brush, and tap the muscles. Swedish massage is widely practiced; thus, practitioners will range greatly in training, technique, and length of session.
• artificial respiration / artificial or assisted ventilation : any artificial method of ventilation in which air is forced into and out of the lungs of a person who has stopped breathing.
Indications : hypercapnia
It may be either :
• nonmechanical ventilation (positive pressure)
• mouth-to-mouth method (the most effective) : with victim supine, the rescuer places one hand under the nape of the victim's neck and the other hand on the victim's forehead and presses the victim's nostrils closed; rescuer takes a deep breath and breathes out directly between victim's lips (2 pairs of lips must form an airtight seal); repeat 4 times quickly to inflate victim's lungs before allowing the first exhalation.
• other less used techniques are :
• Holger Nielsen method / back pressure–arm lift method : with victim prone, rescuer alternately extends victim's arms to aid inspiration and presses down on victim's scapulae to aid expiration
• Schafer method : patient is prone with forehead on one arm; rescuer's knees are on either side of patient's hips; pressure is exerted on patient's back using 2 hands over the lower ribs; rescuer rises up slowly and simultaneously relaxes the pressure on patient's back; procedure is repeated every 5 seconds.
• Silvester method / chest pressure–arm lift method : with patient supine, rescuer pulls patient's arms firmly over head to raise the ribs and aid inspiration; the arms are then brought down and pressed against the chest to aid expiration; procedure is repeated 16 times per minute
• mechanical ventilation : ventilation accomplished by a ventilator / inhaler / respirator
• automatically triggered ventilators (ATV)
• manually triggered ventilators (MTV)
• negative pressure ventilation / negative pressure body ventilation (NBV) : a type of mechanical ventilation in which negative pressure is generated on the outside of the patient's chest and transmitted to the interior of the thorax in order to expand the lungs and allow air to flow in; used primarily with patients having extreme weakness or paralysis of the chest muscles. It is practiced in a stiff wall chamber
• pancho
• cuirass respirator or ventilator : a type of negative pressure ventilator in which a cuirasslike apparatus either completely surrounds the trunk or is applied only to the front of the chest and abdomen, and allows intermittent negative pressure by evacuation of air to force the chest to expand
• Drinker respirator / tank ventilator / iron lung : a type of negative-pressure ventilator consisting of a metal tank enclosing the body of the patient with the head outside. It was formerly in wide use, but its use has now decreased in favor of less cumbersome cuirass and jacket ventilators
• Engström respirator : a volume-controlled, piston-operated respirator with a sine wave airflow pattern.
• pulsator : an apparatus for maintaining respiration.
• Bragg-Paul pulsator : a pulsator consisting of an air bag placed around the patient's chest and abdomen and rhythmically inflated and deflated by an electric pump.
• exsufflation : the act of removing the air from a cavity by artificial or mechanical means, especially such action upon the lungs by means of an exsufflator.
• exsufflator : an apparatus that produces sudden negative pressure in order to reproduce in the bronchial tree the effects of a natural, vigorous cough
• positive pressure ventilation : any of numerous types of mechanical ventilation in which gas is delivered into the airways and lungs under positive pressure, producing positive airway pressure during inspiration; it may be done via either an endotracheal tube or a nasal mask.
• invasive mechanical ventilation (IMV) : muscle curarization,
• tracheostomy : local anaesthesia in chronic patients, general anaesthesia in emergency situations
• laryngeal mask airway (LMA)
• endotracheal intubation
• one lung ventilation (OLV)
Advantages : it allows aspiration of secretions and hence avoid ab ingestis pneumonia.
Indications : consciousless (coma, respiratory or cardiac standstill), in postoperatory complications (hemorrhages, infections), MOF, ARDS (nowadays NMVI is preferred), shock, sepsis, polytrauma, severe neurological disorders (stroke, cerebral hemorrhage), severe respiratory failure (Weitzemblum criteria : P_{O2, artery} < 30 mmHg, P_{CO2, artery} > 80 mmHg, 7.2 < pH < 7.25)
Risks : infections and health-care workers requirement.
• noninvasive positive-pressure ventilation (NPPV) / noninvasive mechanical ventilation (NIV / NIMV)
• pressometric
• bilevel positive airway pressure (BiPAP / Bi-PAP)
• continuous positive pressure ventilation using continuous positive airway pressure (CPAP) : used with patients who are breathing spontaneously. Pressure in the airway is maintained above the level of atmospheric pressure throughout the respiratory cycle. The purpose is to keep the alveoli open at the end of expiration and thus increase oxygenation and reduce the work of breathing in an effort to improve oxygenation by recruiting underventilated alveoli.
• nasal continuous positive airway pressure (nCPAP) with Boussignac –Vygon mask CPAP system

 
• hermetic plastic helmet CPAP (Castar, Starmed, Italy)


• noninvasive intermittent positive pressure ventilation (NIPPV / IPPV)
• continuous
• discontinuous
• proportional assist ventilation : positive pressure ventilation in which the ventilator can sense the patient's level of inspiratory flow and deliver pressure support to achieve a given tidal volume.
• respiratory mechanical unloading (RMU) of spontaneous breathing
• volumetric
• intrinsic positive end-expiratory pressure (PEEPi) : used in conjunction with mechanical ventilation; pressure is maintained above the level of atmospheric pressure at the end of exhalation. This is achieved by preventing the complete release of gas during exhalation, usually by means of a valve within the circuit. The purpose is to increase the volume of gas remaining in the lungs at the end of expiration, thus recruiting alveoli when lung volumes are reduced and reducing the shunting of blood through the lungs and improving gas exchange; done in acute respiratory failure to allow reduction of inspired O₂ concentrations
• open lung ventilation
Devices :
• nose mask (mouth has to be forcedly closed)
• face mask
• bag-valve-mask (BVM)
• Boothby-Lovelace-Bulbulian (BLB) mask : a face mask that has a combined inspiratory and expiratory valve and a bag for rebreathing, used mainly with oxygen delivery systems at high altitudes, and occasionally for clinical administration of oxygen.
• Venturi mask : a face mask used in oxygen therapy, delivering a controlled mixture of oxygen and air according to color codes


• Adam circuit (nasal ogives)
• nozzle
Risks : air exhaled from oxygen masks at the peak of simulated exhalation reached a distance of approximately 0.40 m, possibly representing a source of aerosolized infectious pathogens^ref
Risks : mechanical ventilation with high peak inspiratory pressure (PIP), with or without prolonged inspiratory time, induces lung injury and bacterial translocation from the lung into the systemic circulation. PEEP prevented bacterial translocation in the high PIP group. However, the protective effect of PEEP was lost when inspiratory time was prolonged^ref
Ventilatory modes :
• assist mode ventilation : 25 ms inspiratory triggers
• assist/control mode ventilation (ACMV) : positive pressure ventilation in the assist-control mode; if the spontaneous ventilation rate falls below a preset level, the ventilator enters the control mode and provides a minimum number of mandatory breaths. A TV is triggered by the patient’s own inspiratory efforts, minimising airway pressures and reducing the risk of pulmonary barotrauma
• control mode or controlled mechanical ventilation (CMV) : positive pressure ventilation in which the ventilator is in control mode, with its cycle entirely controlled by the apparatus (preset frequency, inspiration/expiration duration (I/E ratio : similar to invasive mechanical ventilation), TV and RR (usually according to the patient’s weight)) and not influenced by the patient's efforts at spontaneous ventilation
• intermittent mandatory ventilation (IMV) : a type of CMV in which the patient breathes spontaneously while the ventilator delivers a positive-pressure breath at preset intervals
• synchronized IMV (SIMV) : positive pressure ventilation in which the patient breathes spontaneously while the ventilator delivers a positive-pressure breath at intervals that are predetermined but synchronized with the patient's breathing. A a preset tidal volume is provided at a preset rate. Spontaneous breaths are allowed but the timing of mandatory breaths is coordinated with the spontaneous breaths to avoid stacking.
• intermittent positive pressure breathing or ventilation (IPPV)
• mandatory minute ventilation :  a type of IPPV designed to maintain a constant minute ventilation
• pressure control ventilation (PCV) : positive pressure ventilation in which breaths are augmented by air at a fixed rate and amount of pressure, with tidal volume not being fixed; used particularly for patients with acute respiratory distress syndrome
• pressure support ventilation (PSV) : positive pressure ventilation in which the patient breathes spontaneously and breathing is augmented with air at a preset amount of pressure, with tidal volume not being fixed.
• I/E ratio : a ratio <1:1 (commonly 1:2) is usually employed to allow complete exhalation. In (tracheo)bronchial asthma patients, for example, a prolonged expiratory phase may be needed to allow lung deflation
• high-frequency ventilation : mechanical ventilation in which small tidal volumes are delivered at a high respiration rate; it may either be positive pressure ventilation or be delivered in the form of frequent jets of air.
• inverse ratio ventilation : a type of assisted ventilation in which inspiratory time is artificially increased until it is longer than expiratory time; believed to improve distribution of ventilation at lower airway-inflating pressures and to decrease intrapulmonary shunting. Used for patients with acute lung injury or acute respiratory distress syndrome that is refractory to other methods.
Advantages : intermitting, allows oral feeding, swallowing, talking, physiological warming and humidification of inspired air, physiological coughing, easier weaning
Indications :
• breath rate > 35
• [HbO₂%]_plasma < 90%
• 15-20 mmHg variation in P_{CO2, artery}
• pH_plasma < 7.35
• distress signs
• mild sensory impairment
Monitoring :
• transcutaneous pulse oxymetry to monitor P_{O2, artery}
• respiratory rate (RR)
• EKG
• radial arterial catheterization to monitor P_{CO2, artery}
• neurological scales
• hydroelectrolyte balance
Suspend if :
• hemodynamic instability (atrial fibrillation, atrial flutter, ...)
• fibrobronchoscopic aspiration
• claustrophobia
• facial deformities
• untolerable pain at nose root
• no neurological improvement within 30'
• no recovery in ABG analysis
• pulmonary barotrauma
• volutrauma : damage to the lung caused by overdistension by a mechanical ventilator set for an excessively high tidal volume
weaning : gradual removal of mechanical ventilation, as patient's lung strength and vital capacity increases.
• sparing therapy : treatment directed to the protecting and sparing of an organ by allowing it to rest as much as possible.
• collapse therapy : a treatment for pulmonary tuberculosis (PTB), formerly widely used, in which the diseased lung was collapsed in order to immobilize it and allow it to rest. Common methods were :
• oleothorax : a method of collapse therapy in which oil or paraffin was inserted into part of the thoracic cavity.
• plombage : a former method of collapse therapy in which part of the thoracic cavity was surgically filled with inert material
• pneumonolysis / pneumolysis : division of the tissues attaching the lung to the wall of the chest cavity so that the lung collapses inward; it was formerly a common method of collapse therapy (q.v.) and is still sometimes done to allow access during thoracic surgery
• artificial, induced, or therapeutic pneumothorax : pneumothorax induced intentionally by artificial means; formerly used as a method of collapse therapy in treatment of pulmonary tuberculosis (PTB) with Forlanini's or Morelli's device (no longer used). At the end of surgery, 2 drainings are placed to allow air (pleural cupole) and pleural fluid (posterior costophrenic sinus) to exit.
• thoracoplasty
Pneumonolysis and thoracoplasty are still sometimes done to collapse a lung and allow access during thoracic surgery.
• acupressure
• acupuncture
• thermal therapy
• cryotherapy / crymotherapy / frigotherapy : the therapeutic use of cold
• cryosurgery : destruction of tissue by the application of extreme cold, used in some forms of intracranial and cutaneous surgery.
• cryoablation : the removal of tissue by destroying it with extreme cold
• prostate cryosurgery with Endocare Cryocare^®
• cryothalamectomy / cryothalamotomy : destruction of a portion of the thalamus by application of extreme cold.
Web resources : National Cancer Institute Page on Cryosurgery
• ethyl chloride : a colorless, extremely volatile, flammable liquid, C₂H₅Cl, sprayed on skin to produce local anesthesia by superficial freezing caused by its rapid evaporation; formerly used as an inhalational anesthetic.
• ice bag : a bag filled with ice, for applying cold to the body.
• thermal ablative therapy (including thermoablative tumor therapy) is used to kill tumors by heating them : temperatures = 42-45°C can cause irreversible change; temperatures >50°C  for an extended period of time cause instant protein denaturation; > 70°C cause thermal coagulation; > 100°C cause cell necrosis and vaporization. The combination with MRI allows an exact definition of the target volume and a safe guidance : non-invasive temperature measurement using real time MRI is based on the analysis of changes in longitudinal relaxation time (T₁) and water proton resonance frequency (PRF) > diffusion coefficient (D)
• metal nanoshells are a class of nanoparticles (about 20 times smaller than a RBC) of electrically inert silica coated with a thin layer of gold with tunable optical resonances : the blood vessels inside tumors develop poorly, allowing small particles like nanoshells to leak out and accumulate inside tumors. Whether the particles absorb or reflect light, and the wavelength of that light, depends on the diameter of the particles and the depth of the gold coating : nanoshells with 100-nm diameter spherical dielectric (silica) core and a 10-nm shell preferentially absorb near infrared (NIR) light (820 nm), a region of the spectrum where optical absorption in soft tissue is minimal and optical transmission through tissue is optimal. In the treatment, NIR induces collective oscillations of conductive metal electrons at the nanoshell surface, resultinùf in the production of heat that destroys nearby tumor cells. Despite the local injection of nanoshells only 5 mm into the tumour, they are found to diffuse throughout the tumour volume. The heating is very localized and does not affect healthy tissue adjacent to the tumor. A distribution of nanoshells at depth in tissue can be used to deliver a therapeutic dose of heat by using moderately low exposures of extracorporeally applied NIR light. Irradiating the tumors for 6' raise the temperature of the tissue about 38°C at 2.5-mm depth and 37°C at 6-mm depth (but data show that it can induce heating to at least 2 cm), while irradiation of control tumors without nanospheres, in contrast, raised the tissue temperature < 10°, a temperature that does not cause irreversible tissue damage. Histological analysis revealed coagulation, cell shrinkage and loss of nuclear staining in NIR-exposed regions. Deeper masses can be successfully targeted by using either conjugated antibodies or by taking advantage of leaky vascularization around tumors, which causes small particles to accumulate. The method could potentially be used proactively : e.g. a patient with a family history of breast cancer could receive a routine prophylactic thermal treatment every few years, so if any very, very small lesions were starting, you could knock them out before they turned into anything. Similarly, during removal of cancerous ovaries, surgeons could inject the shells and irradiate the peritoneal wall^ref. Another animal trial involved 25 mice with tumors ranging in size from 3-5.5 mm. The mice were divided into 3 groups : the first group was given no treatment, the second received saline injections, followed by 3 minutes exposure to near-infrared laser light and the final group received nanoshell injections and laser treatments. In the test, researchers injected nanoshells into the mice, waited 6 hours to give the nanoshells time to accumulate in the tumors and then applied a 5 mm wide laser on the skin above each tumor. Surface temperature measurements taken on the skin above the tumors during the laser treatments showed a marked increase that averaged about 46°F for the nanoshells group. There was no measurable temperature increase at the site of laser treatments in the saline group. Likewise, sections of laser-treated skin located apart from the tumor sites in the nanoshells group also showed no increase in temperature, indicating that the nanoshells had accumulated as expected within the tumors. All signs of tumors disappeared in the nanoshells group within 10 days. These mice remained cancer-free after treatment. Tumors in the other 2 test groups continued to grow rapidly. All mice in these groups were euthanized when the tumors reached 10 mm in size. The mean survival time of the mice receiving no treatment was 10.1 days; the mean survival time for the group receiving saline injections and laser treatments was 12.5 days.
• minimally invasive thermocoagulation
• hot saline injection
• microwave coagulation therapy (MCT) : microwave antennas. This type of cell death caused by microwave treatment is morphologically different from previously known types of cell death, either oncosis or apoptosis.

Indications : percutaneous : non-resectable primary liver cancers and liver metastases
• laser-induced thermotherapy (LITT) or interstitial thermal therapy is a minimally invasive technique for local tumor destruction within solid organs using optical fibers to deliver a high-energy laser to the target lesion

Indications :
• non-resectable primary liver cancers and liver metastases
• lung metastases
• radiofrequency ablation (RFA) with expandible active electrode needles and large dispersive radiofrequency electrodes (e.g. on thighs). Alternating current at high frequency (200-1200 KHz) is applied => tissue ions are agitated as they attempt to follow the changes in direction of AC => frictional heat => at 50°C proteins are permanently damaged and cell membrane fuse => coagulation necrosis
• 15G 4-9 hooks (each hook has a thermistor) (Rita Medical System) : 50-100 W


• 15 G 10 hooks LeVeen (Radiotherapeutics) 100 W


• 17G cooled tip needle (Radionics) : 100-200 W



Guidance :
• echography
• CT
Indications :
• liver cancers > non-resectable liver metastases (< 4 lesions < 4 cm each, > 1 cm from hepatic hilum or gallbladder, not adjacent to GI tract, and liver only site of metastasis). In HCC lymphocyte infiltrations creates a pseudocapsule (absent in liver metastases) which allows an oven effect.
• painful bone metastases
• lung tumors
• renal tumors
• varices
Some issues :
• temperature > 95°C may cause charring of tissue closer to needle that prevents transfer of heat to tissue further away
• blood vessels near the tissue causes the conduction of thermal energy away from the target tissue into the cooler blood
During operations echography detects gas microbullae from parenchymal necrosis. Killed tumor cells are replaced by fibrosis and scar tissue, seen as a non-contrasted area at control CT after 1 months.
• non-invasive thermocoagulation
• high-intensity focused ultrasound (HIFU) / focused ultrasound surgery (FUS) allows high-precision, non-invasive thermocoagulation of tissues by ultrasound transducers within seconds, with sparing of surrounding areas  and increases access to tumour cells by the immune system. A threshold exposure time always exists under a certain acoustic intensity. Temperature rise is slow when exposure time exceeds the threshold exposure time. The greater the acoustic intensity is, the earlier the threshold time appears. The focal temperature rise and the relative cumulative thermal dose (RCTD) increase with the increasement of acoustic intensity and exposure time. For a certain therapeutic dose, the effects of acoustic intensity on focal temperature rise are more distinct than the effects of exposure time on focal temperature rise. Therefore, the optimal HIFU therapeutic dose should meet the need, i.e. moderate acoustic intensity, and the exposure time be the threshold exposure time under this acoustic intensity.
• extracorporeal percutaneous : hepatocellular carcinoma (HCC), breast cancers, bladder cancers, renal tumors, brain cancers
• transrectal : benign prostatic hypertrophy (BPH) and prostate cancers (for patients for whom surgical removal of the prostate is considered too risky : 65% of the patients remain disease-free for 5-years, a similar success rate to surgery, but rates of incontinence, the major side effect of surgery, are cut from 80% to 8%)
• intraductal during ERCP : cholangiocarcinoma and carcinoma of the duodenal papilla
• magnetic resonance guided focused ultrasound (MRgFUS) (ExAblate 2000^®; source : InSightec Image Guided Treatment Ltd. of Tirat Carmel, Israel)



• If HSP expression induced by hyperthermia is involved in tumor immunity, novel cancer immunotherapy based on this novel concept can be developed. In such a strategy, a tumor-specific hyperthermia system, which can heat the local tumor region to the intended temperature without damaging normal tissue, would be highly advantageous. To achieve tumor-specific hyperthermia, an intracellular hyperthermia system using magnetite nanoparticles was developed. This novel hyperthermia system can induce necrotic cell death via HSP expression, which induces antitumor immunity^ref
PMNs may play a crucial role in mediating the anti-tumor effects of a mild, fever-range whole-body hyperthermia (FR-WBH) protocol, where core body temperatures are raised to 39.5-40°C for 8 hrs. Indeed, in BALB/c mice bearing the colon tumor CT26, the anti-tumor effect of WBH correlates with increased granulocytic infiltrate at the tumor site as determined using immunohistochemical analysis for Gr-1⁺ cells. In both BALB/c mice bearing CT26 and SCID mice bearing human colon tumors, PMN depletion in vivo using anti-Gr-1 ascites ablated the anti-tumor effect of mild WBH. Because mild thermal stress is also found to enhance the respiratory burst of granulocytes, these data collectively suggest that the thermal stimulation of granulocytes may help to prevent tumor establishment.^ref
• shock waves
• extracorporeal shock wave lithotripsy (ESWL) : a procedure for treating upper urinary tract stones and gallstones: the patient is immersed in a large tub of water or placed in contact with a water cushion; a high-energy shock wave generated by
• high-voltage spark (HM3, TechnoMed, ...)
• electromagnetic impulse
• piezoelectric generator
... in a focus of a copper ellipsoid reflector is reflexed to the other focus centered on the stone, which disintegrates into particles small enough to be expelled from the organ. Calcification (calcified aneurysms, bones) don't crash as they are immersed in an organic matrix.
Indications :
• 95% of urolithiasis
• nephrolithiasis : 14 => 23 kV
• ureterolithasis : 14 => 18 kV
• cholelithiasis
• vas deferens calculi
• prostatolithiasis
• calcifying insertion tendinitis
• avascular necrosis of the head of femur and other necrotic bone alterations^ref
• treatment of tendons, ligaments and bones on horses in veterinary medicine
Contraindications :
• pregnancy
• back obesity
• pacemaker users (even it may be temporarily disactivated)
• antiplatelet drugs
Side effects :
• hemorrhages => hematomas
• subcapsular hematomas
• 80% are self-limiting
• 20% require surgery
• extracapsular hematomas
• renal colic (18-25%)
• urinary tract infections
• renal fracture
• spleen fracture
• extracorporeal shock wave therapy (ESWT) for stroke-related hypertonia in the upper limbs^ref
• hyperbaric medicine : the treatment of disease in an environment of higher than atmospheric pressure.
• preoxygenation : the prolonged breathing of oxygen before exposure to low atmospheric pressure at high altitudes, as prophylaxis against decompression syndrome
• altitude chamber : a vacuum chamber used to simulate the effects of high altitude and low atmospheric pressure (hence low oxygen partial pressure). It is considered by some a form of doping to increase hematocrit
• hyperbaric oxygen therapy (HBOT) consists of intermittently administering 100% oxygen at pressures > 1 atmosphere in a pressure vessel
Indications :
• decompression syndrome
• acute ischemic stroke^ref
• haemorrhagic stroke^ref
• traumatic brain injury (TBI)^ref
• radiation-induced brain injury^ref
• influenza-associated encephalopathy^ref
• limit the growth of cerebral contusions (dynamic cortical deformation (DCD) induced by negative pressure applied to the cortex)^ref
• multiple sclerosis^ref
• unilateral idiopathic sudden deafness^ref
• sustained thermal burns^ref
• chronic wound^ref (topical HBO (THBO) therapy, also referred to as topical oxygen therapy, is used for the treatment of diabetic wounds of the lower extremities)
• treatment of clostridial myonecrosis / gas gangrene and other anaerobic infections
• descending necrotizing mediastinitis (DNM)^ref
• perineal Crohn's disease^ref
• rattlesnake-venom-induced myonecrosis^ref
• acute myocardial infarction^ref.
• hemorrhagic cystitis
  
Contraindications :
• hypercapnia in COPD patients (raising PO₂ would depress the respiratory rate and hence lead to CO₂ retention)
• acute lung injury
• retinopathy of prematurity (ROP)
• irritation of airway mucosa
The use of increased atmosphere pressure for medical therapy has intrigued many physicians, scientists, and lay persons for hundreds of years. Vague accounts of increased atmosphere pressures used on humans date to the fifth century BC. Henshaw, a British clergyman, built the first sealed chamber, termed the Domicilium, in 1662. This chamber compressed air (21% oxygen) for numerous ailments such as inflammation, scurvy, arthritis, and rickets but likely had too little compression to do any physical good. Following Priestley's discovery of oxygen in the late 1700s, Beddoes developed a pneumatic laboratory enriched with oxygen to treat chronic conditions such as leprosy. In the early 1930s, the Junod reported improvement in patients with cardiorespiratory disorders when treated in 2 atm of pressure in a copper compression chamber. These early reports spawned the creation of a number of "pneumatic institutes" in Europe. These chambers were able to treat up to 10 people at once and reached pressures of 2 or more atm. Compression therapy became the "in vogue" spas of the day. Pneumatic spas came to North America in 1860, with the first compression chamber built in Oshawa, Ontario, Canada. The French surgeon Fontaine built a mobile compressorized operating suite in 1879. Patients reportedly had better outcomes because of improved oxygenation and decreased postoperative vomiting and cyanosis. Easier reduction of hernias was noted. Corning introduced the therapeutic compression chamber to the US in 1891 to treat nervous and mental afflictions. This chamber was the first operated by electric power. Orville Cunningham noted 25 years later that patients with certain cardiovascular disorders improved when moved from high altitudes to sea-level altitudes. He discovered this during the Spanish flu epidemic in 1918, which resulted in more than 500,000 deaths. Many of these victims died in a cyanotic state. Under the care of Dr Cunningham, a rather sick resident physician was treated in the compression chamber and recovered completely. Cunningham subsequently built an 88-ft long and 10-ft wide chamber to treat numerous patients, with remarkable success. The credibility of the compression chamber was reinforced during treatment of flu patients. One night when the chamber's power accidentally was shut off, all patients died. At the time, the interpretation credited hyperbaric therapy with keeping the patients alive. When the compression stopped, these patients died. However, the deaths were likely the result of rapid ascent from the compression rather than the secondary effects of the Spanish flu. In 1928, Mr Timkin, an appreciative patient whose uremic state was resolved after receiving hyperbaric therapies, constructed for Cunningham an enormous 60-ft tall, 6-story hyperbaric hospital that looked like a steel sphere. Conditions such as hypertension, diabetes, syphilis, and cancer were treated here until 1930, when the local medical society closed the hyperbaric hospital for lack of scientific evidence or merit. After 1930, much of the medical or scientific community did not look favorably upon the use of hyperbaric medicine. Supplemental use of oxygen increased with availability after this time. The military soon had an increased interest in underwater activities, and this promoted the use of oxygen and hyperbaric medicine for diving and decompression sickness. Hyperbaric medicine treatments had sound physiologic principles based on known physics of mixed gas when treating decompression sickness. A flurry of interest in therapeutic hyperbaric medicine was fostered by Dr I. Boerema, who, while in Amsterdam in 1956, reported hyperbaric oxygen (HBO) as an aid in cardiopulmonary surgery, particularly for congenital conditions such as tetralogy of Fallot, transposition of great vessels, and pulmonic stenosis. A colleague of Boerema's, W. H. Brummelkamp, also interested in hyperbaric medicine, discovered in 1959 (and subsequently published in 1961) that anaerobic infections were inhibited by hyperbaric therapy. Meanwhile, Boerema had published an article, "Life without blood," a report of fatally anemic pigs treated successfully with volume expansion and pressurized hyperoxygenation. Boerema often is credited as the father of modern-day hyperbaric medicine. In 1962, Smith and Sharp reported the enormous benefits of HBO in carbon monoxide poisoning. International interest thus was rekindled, and HBO therapy was thrust into the modern era. Hyperbaric units subsequently were built at Duke University, New York Mount Sinai Hospital, Presbyterian Hospital and Edgeworth Hospital in Chicago, Good Samaritan in Los Angeles, St. Barnaby Hospital in New Jersey, Harvard Children's Hospital, and St. Luke's Hospital in Milwaukee. Further chambers were installed in numerous international sites. The benefits of hyperbaric medicine subsequently were observed for split-thickness skin graft acceptance, flap survival and salvage, wound re-epithelization, and acute thermal burns. These studies lent credibility to the therapeutic employment of HBO therapy. This fostered the establishment of organized scientific congresses and societies such as the International Congress on Hyperbaric Oxygen and the Undersea Medical Society. Unfortunately, as the availability of hyperbaric medicine chambers increased, the indiscriminate and inappropriate use of the chamber for a variety of medical conditions by practitioners searching for a "cure-all" therapy resulted in a backlash from the scientific society, once again tarnishing the credibility of hyperbaric medicine. As a result, by the late 1970s, the Undersea Medical Society had formulated guidelines for the use of hyperbaric therapy. Researchers conducting wound-healing studies continued to try to take advantage of the angiogenic properties of increasing oxygen gradients resulting from hyperbaric therapy. Foot wounds from diabetes, radiation ulcers, and other ischemic wounds have been manipulated and successfully treated with HBO. Prospective blinded randomized trials and well-executed laboratory studies continue to further define the role of hyperbaric therapy in medical therapeutics. In 1989, in recognition of advances in hyperbaric treatments, the American Board of Medical Specialists approved a certification of added competency in Undersea Medicine. The National Board of Hyperbaric Medicine Technology gave its first certification to hyperbaric technicians in 1991. In 1986, the Undersea Medical Society changed its name to the Undersea and Hyperbaric Medical Society.
Comparison of types of hyperbaric oxygen therapy chambers :

	advantages	disadvantages
monoplace chambers	relatively low purchase price  requires little space and relatively minor facility renovations  modest program capitalization treatment protocol specific to patient and/or condition modest staffing requirements patient does not wear mask/hood/head tent for oxygen delivery relatively mobile chamber for possible relocation no risk of iatrogenic decompression sickness in patient or staff add-on capability for ease of program expansion	patient isolated during treatment inability to suction patient limited pressure capability (3 atmosphere absolute (ATA)) pure oxygen environment; associated fire hazard inability to use certain diagnostic and/or therapeutic equipment (transcutaneous oxygen assessment now available [radiometer - transcutaneous monitor -3]) increased risk of complications from pneumothorax and/or tension pneumothorax and arterial air embolism developing during decompression
multiplace chambers	greater working pressure constant patient attendance ability to use a variety of electrically generated signals during therapy attendants able to enter and exit during therapy ability to manage complications such as pneumothorax without releasing pressure ability to conduct intensive care activities during treatment	higher capitalization requirements major space requirements; basement and/or ground floor level limitations higher operating costs larger and experienced staffing requirements risk of decompression sickness in internal personnel all patients on same protocol uncertain oxygen delivery tension at patient with face mask severe maxillofacial and/or head and neck involvement possibly making effective delivery of oxygen difficult facility fire-associated decompression requirements significant equipment maintenance and system upkeep requirements

Effects of hyperbaric treatments on cardiovascular system :
• heart rate - decreased
• contractility - no effect
• stoke volume - no effect
• cardiac output - decreased
• blood pressure - possible minimal increase
• systemic vascular resistance - after load increases, arterial vasoconstriction
Primary effects of hyperbaric oxygen :

mechanism	effect	clinical utility
hyperoxygenation	greater oxygen carrying capacity increased oxygen defusion in tissue fluid diffusion distance proportional to the square root of dissolved oxygen	severe blood loss anemia (unable to carry oxygen) crush injury, compartment syndrome graft, and flap salvage (decreased perfusion) edema (increased diffusion barrier)
decrease gas bubble size	Boyle law - Gas volume inversely proportional to pressure hyperbaric diffusion gradient favors gas leaving the bubble and oxygen moving in, metabolizing oxygen in the bubble law of Laplace p-4t/r bubbles unstable as they decrease in size	decompression sickness air embolus syndrome

Secondary effects of hyperbaric medicine :

mechanism	effect	clinical application
vasoconstriction	decreased inflow into tissues decreased edema	crush injuries acute burns compartment syndrome
angiogenesis	increased oxygen gradient between wound and surrounding environment increased fibroblast proliferation leading to increased collagen deposition and increased fibronectin, which aids in neovascularization	graft and flap salvage osteoradionecrosis radiation endarteritis obliterans chronic wounds
fibroblast proliferation	oxygen-dependent proliferation	chronic wounds radiation-induced injury
leukocyte oxidative killing	increased oxygen free radicals anaerobes lack superoxide dismutase to control oxygen free radicals	necrotizing soft-tissue infections chronic osteomyelitis
toxin inhibition	decreased clostridial alpha toxins	clostridial gas gangrene decreased cardio toxins
antibiotic synergy	fluoroquinolones, amphotericin B, and aminoglycosides - Use oxygen to transport across cell membranes	sepsis necrotizing infections

Signs and symptoms of oxygen toxicity :
• CNS
• nausea and vomiting
• seizures
• sweating
• pallor
• muscle twitching
• anxiety and/or respiratory changes
• visual changes
• tinnitus
• hallucinations
• vertigo
• hiccups
• decreased level of consciousness
• pulmonary
• dry cough
• substernal chest pain
• bronchitis
• shortness of breath
• pulmonary edema
• pulmonary fibrosis
Contraindications to hyperbaric oxygen :

	rationale
claustrophobia	anxiety
pneumothorax	gas emboli, pneumomediastinum  pneumoperitoneum  tension (pneumothorax) subcutaneous emphysema
history of spontaneous pneumothorax	increased lung bleb incidence (pneumothorax)
chronic obstructive pulmonary disease	increased oxygen intolerance increased risk of seizures
Pneumocystic carinii pneumonia	questionable fetal teratogen
seizure disorders	barotrauma to sinus/ear/lung
pregnancy (HBO may be required in pregnancy in situations of carbon monoxide poisoning, cerebral gas embolus, decompression sickness, or clostridial myonecrosis)	decreased threshold for oxygen-induced seizures
upper respiratory infection	increased hemolysis
hyperthermia
hereditary spherocytosis
optic neuritis	questionable - Increased optic nerve pathology
malignant tumors	questionable - Increased vascularity for tumors
acidosis	decreased threshold for oxygen seizures
drugs : cis-platinum doxorubicin bleomycin  steroids alcohol  aromatic hydrocarbons disulfiram nicotine	decreased wound healing increased free oxygen radicals pulmonary fibrosis leading to pneumothorax decreased threshold for oxygen seizure dehydration (increased risk of decompression sickness) spontaneous combustion inhibits superoxide dismutase decreased seizure threshold

Organs affected by barotrauma :

organ	pathology	presentation
sinuses	congestion and/or occlusion	pain, bloody discharge
middle ear	Eustachian tube occluded failure to equalize pressure within middle ear space	edema, rupture, or retraction of tympanic membrane  hemorrhage
external ear	wax build-up or ear plugs occlude canal	pain, bleeding
inner ear	oval or round window rupture	ataxia, vertigo, tinnitus, hearing loss
GI tract	gas in bowels, distention on ascent	vomiting, nausea, flatulence, colicky pain
teeth	infected or restored teeth (may harbor gas)	tooth pain  tooth implosion or explosion
gas embolus	emergent decompression with blocked glottis (extremely rare)	sudden decreased level of consciousness; hemiplegia, blown pupil

Teed scale : middle-ear barotrauma of descent
• grade 0 : symptoms without signs
• grade I : injection of the tympanic membrane, especially along the handle of the malleus
• grade II : injection plus slight hemorrhage within the substance of the tympanic membrane
• grade III : gross hemorrhage within the substance of the tympanic membrane
• grade IV : free blood in the middle ear as evidenced by blueness and bulging
• grade V : perforation of the tympanic membrane
Clinical application of hyperbaric oxygen :
• primary therapy :
• carbon monoxide poisoning
• cerebral arterial gas embolus
• decompression sickness
• osteoradionecrosis
• clostridial gas gangrene
• adjunctive therapy
• radiation tissue damage
• osteoradionecrosis prophylaxis
• acute ischemia and/or crush injuries
• necrotizing infections
• acute exceptional blood loss
• acute thermal burns
• compromised skin grafts or flaps
• selected problem wounds
• refractory osteomyelitis
Treatment protocols may vary to a limited degree between institutions :

dosage	indications
2.0 ATA* oxygen X 90 min	wound healing compromised skin grafts and/or flaps thermal burns osteomyelitis crush injury and/or compartment syndrome mucormycosis
2.0 ATA oxygen X 90 min with 10 min air break (high seizure risk)	wound healing compromised skin graft and/or flaps thermal burns osteomyelitis crush injury and/or compartment syndrome mucormycosis
2.5 ATA oxygen X 90 min	nonclostridial gas gangrene necrotizing infections osteomyelitis (Escherichia coli or Pseudomonas species isolated) late radiation tissue injury (osteoradionecrosis, soft tissue radionecrosis)
3.0 ATA oxygen X 90 min	carbon monoxide poisoning clostridial gas gangrene

Delivery of hyperbaric pressures generally is accepted through one of two different chambers. Monoplace chambers house one individual placed in the supine position. Current chambers have an acrylic shell, which allows the patient to observe his or her surroundings. Communication devices located within the chamber allow direct conversation between the patient and the hyperbaric medicine technician or physician. Conversely, multiplace chambers can accommodate 2-10 patients. Table 1 illustrates and compares the advantages and disadvantages of the monoplace and multiplace chambers. Gas is piped directly from its source to the chamber. Humidification and heat exchange gases are present in all modern chambers. The application of HBO depends on the physical properties of gases under pressure, specifically, oxygen at pressure greater than 1 atm. Oxygen is essential in a variety of enzymatic, biochemical, and physiologic interactions that promote normal cellular respiration and tissue function. Mono-oxygenase, intradioxygenase, and interdioxygenase are specific enzymes that recruit oxygen as a cofactor to perform required biologic processes. Collagen deposition and synthesis depend on an oxygen-dependent prolyl-hydroxylase hydroxylation of proline. Angiogenesis and epithelization also are oxygen dependent. Under normal conditions, 97.5% of oxygen is carried in the bloodstream bound to hemoglobin. The remaining 2.5% is dissolved in plasma. Oxygen is combined with hemoglobin in the bloodstream, with each gram of hemoglobin combined with 1.34 cm3 of oxygen. This represents a physiologic maximum. Under normal conditions at sea level, the arterial hemoglobin saturation is 97%, and the venous hemoglobin saturation is 70%. The oxygen content can be calculated with the following equation:
• oxygen content = 1.34 mL of O₂/g of Hb X g of Hb/100 cm³ X %saturation
Above 200 mL of mercury of pressure, the oxygen dissolved in plasma significantly increases. This is calculated with the Henry law:
• dissolved oxygen (vol %) = 0.0031 (mL O₂/100 cm³/mm Hg) X PaO₂
The total oxygen content of blood under hyperbaric conditions is equal to the oxygen content calculation plus the dissolved oxygen content. The average metabolic consumption of oxygen by the human body at sea level is 6.6 cm3/100 cm3 of blood. Under hyperbaric conditions of 3 atm while breathing 100% oxygen, the total dissolved oxygen content delivered is in excess of this metabolic requirement, meaning that oxygen can be supplied under these conditions even in the absence of hemoglobin. Carbon dioxide, the byproduct of cellular respiration, is carried in the blood as bicarbonate (75%), as carboxy hemoglobin (20%), and dissolved in plasma (5%). Through the Haldane effect, the saturation of hemoglobin with carbon dioxide depends on deoxygenation. As oxygen is released from hemoglobin, carbon dioxide may combine. Under conditions in which the hemoglobin remains saturated, such as in hyperbaric medicine, the PaCO2 therefore may rise. Unless the normal respiratory compensatory conditions are present to exhale the extra carbon dioxide, the patient may develop significant carbon dioxide retention, as may be observed with chronic obstructive pulmonary disease. This can be exacerbated by an increase in the work of breathing fostered by hyperbaric treatments. The work of breathing is dependent on pressure and volume, and it becomes greater as hyperbaric pressure increases. Patients who already are compromised with increased airway pressures may be subject to respiratory failure. Cardiovascular effects of hyperbaric treatment are listed in Table 2. Decreased cardiac output is a direct result of decreased heart rate (cardiac output = stroke volume X heart rate). Cardiac output may be compromised further in patients with congestive heart failure in whom the preload is high. An increase in the systemic vascular resistance increases the after load, which can worsen congestive heart failure. The mechanism of action of hyperbaric treatments is attributed to the immediate direct physical affects of oxygen and other gases under pressure and to the delayed secondary physiologic and biochemical effects that are set into motion with each hyperbaric treatment. These primary and secondary effects of hyperbaric treatment are listed in Table 3 and Table 4. Benefits of hyperbaric treatment often use both the primary and secondary mechanisms to promote the desired effect. Charles law states that if a volume of gas is kept constant, the temperature varies with the pressure. Together, Charles and Boyle laws are known as the general gas law, expressed as D1V1/T1 = P2V2//T2. Henry law states that "at a constant temperature, the amount of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas." Each of the physical laws directly governs the principles of hyperbaric medicine through hyperoxygenation bubble size change and the myriad secondary effects noted above. These principles account for the clinical application in the adjunctive therapies below. Elemental oxygen is required to maintain cellular respiration and to allow for normal cellular protein production. Hyperbaric medicine is considered extremely safe under appropriate supervision and utility. Toxic effects of oxygen are observed at extremely high doses over prolonged periods. HBO treatment increases the relative dose of oxygen; thus susceptible patients need to be recognized and modifications made to prevent the manifestations of oxygen toxicity. Damaging or toxic effects of oxygen therapy likely are related to the unbridled formation and release of reactive oxygen species, such as superoxide, hydroxyl radical, and hydrogen peroxide. Superoxide dismutase, catalase, glutathione, and glutathione reductase keep the formation of these radicals in check until the oxygen load overwhelms the enzymes, leading to the detrimental affects on cell membranes, proteins, and enzymes. Other antioxidants used by the body include vitamins C and E, selenium, and glutathione. Lavoisier first observed the detrimental effects of hyperoxygenation in 1789. In 1878, Paul Bert demonstrated that HBO induced seizures. This became known as the "Paul Bert effect" or oxygen-induced seizures. This neurologic effect may be related to the free radical–induced peroxidation of neurons and glial cells upon interaction with iron. Alternatively, a decrease in the GABA levels induced by hyperbaric pressures and increased oxygen may be important in seizure induction. In 1899, Lorraine Smith reported the pathologic effects of increased oxygen tension on the respiratory system. The Lorraine Smith effect became known as a clinical syndrome of decreased vital capacity, sternal chest pain, and patchy atelectasis. Table 5 lists the wide variety of manifestations of oxygen toxicity. These effects may occur at any point in the treatment regimen. A distinct correlation between the number of treatments and oxygen toxicity is not apparent, but rather the duration of the treatments (ie, >2 h) and the patient's susceptibility appear to be related to toxicity. The patient's susceptibility is an ill-defined variable, but a number of conditions may make certain individuals poor candidates for hyperbaric therapy (see Table 6). The most important factor that may decrease the potential predisposition to oxygen toxicity is intermittent exposure to room air. Give susceptible patients "air breaks" at some point during the treatment. During this time, the patient is breathing room air that is piped into the chamber. A 10-minute air break may be all that is required to prevent the symptoms of oxygen toxicity. Other potential counteractive measures to decrease oxygen toxicity include inducing hypothermia or administering vitamin E, disulfiram, glutathione, phenobarbital, diazepam, or adrenergic blockers. Decompress patients who develop oxygen toxicity. During a seizure, initiate decompression following the tonic phase of the seizure, as the patient is holding his or her breath. During the chronic phase, the patient is breathing. While in the chamber, the patient can be cooled and allowed to breathe room air. Correct any metabolic conditions (eg, acidosis). The administration of diazepam or phenobarbital may be required if the seizure persists. Oxygen toxicity seizures usually last only 1-2 minutes. Closely observe the patient for the next 4-6 hours. Such oxygen-induced seizures do not require a neurologic assessment unless other confounding medical conditions have indicated a thorough workup. Oxygen toxicity seizures occur in approximately 1 in 10,000 exposures. If intravenous (IV) access is available in either a monoplace or multiplace chamber, diazepam or phenobarbital can be administered via this route. Slowly decompress patients in monoplace chambers without IV access. The hyperbaric attendant must be observant that the patient is not air trapping to avoid pulmonary barotrauma. Other potential complications of hyperbaric treatments relate to direct barotrauma. Because of the properties of gases, any gas-containing organ or cavity within the body may be subject to barotrauma. This represents injury related to gas expansion in closed spaces. Table 7 lists organs that may be subject to barotrauma. The most common barotrauma is middle ear injury. The Teed scale denotes a graduated injury of the middle ear tympanic membrane (see Table 8). Grade 0 and 1 require only improved ear pressure equalization maneuvers (eg, Frenzel maneuver, Valsalva maneuver). Perform the Frenzel maneuver by raising the pressure in the oral pharynx, pinching the nostrils, and closing the glottis. This opens the eustachian tubes. The Valsalva maneuver forces respiratory air into the oropharynx while closing the nose and mouth. Grade II Teed scale ear injuries require topical decongestants as well as ear decompression maneuvers, since the patient is symptomatic. Grade III injuries often occur while patients are in the ascending phase of the treatment. A more central decongestant may be required. Teed scale grades IV and V require definitive evaluation by otolaryngology. Myringotomy tubes often are required in patients with significant middle ear symptoms. Occasionally, patients may experience reversible myopia that presumably is related to retrolental oxygen effects. Treat intrachamber emergencies (eg, cardiac respiratory arrest) with immediate decompression and standard resuscitation measures. A pneumothorax obtained during treatment should alert the attendant to assemble a team required for chest tube insertion and possible resuscitation. The patient then may be decompressed rapidly. Fires also may arise in a chamber, since oxygen readily fosters combustion. This is an extremely rare, although disastrous, consequence of something igniting within the chamber. Begin rapid decompression and resuscitation after stopping the oxygen. Patients with diabetes mellitus deserve special mention. Hyperbaric therapies may affect glucose uptake and metabolism. The vasoconstricting effects of hyperbaric therapy also may impair the subcutaneous absorption of insulin, rendering the patient hypoglycemic. Other medications also may have detrimental affects when administered in conjunction with hyperbaric therapy, as may pertinent medical history and conditions specific to individual patients. Perform a full history and physical examination prior to hyperbaric treatments so that the absolute and relative contraindications can be recognized and appropriately handled. Clinical applications of hyperbaric medicine take advantage of the primary and secondary properties of pressurized oxygen therapy. The Undersea and Hyperbaric Medical Society recognized conditions that have definitive and adjunctive benefit from hyperbaric therapy (listed in Table 9).
Carbon monoxide poisoning : smoke inhalation injuries are common in house fires and other fire and/or smoke situations in closed spaces. Carbon monoxide, found in smoke, is the leading cause of poisoning deaths in the US. Carbon monoxide is a colorless, odorless, tasteless, and nonirritating gas that has a 210-fold greater affinity for hemoglobin than oxygen. Carboxyhemoglobin produces a leftward shift of the oxygen dissociation curve, making oxygen less available to the tissues (Haldane effect). The half-life of carboxyhemoglobin at room air, 100% oxygen, and 3 ATA 100% oxygen is 320, 90, and 23 minutes, respectively. This indicates HBO treatment for patients with carbon monoxide poisoning. Clinically, a wide variety of signs and symptoms may be noticed in patients with carbon monoxide poisoning. Cardiac dysrhythmias, visual impairments, memory loss, decreased level of consciousness, motor and sensory loss, cognitive dysfunction, and dysphagia may be identified in carbon monoxide–intoxicated patients. Lab tests drawn at the time of insult can reveal a markedly increased carboxyhemoglobin level and a mild metabolic anion gap acidosis. Late neuropsychiatric symptoms may develop 2-3 weeks after exposure. The duration and severity of these changes vary, but they may last months. Hyperbaric treatment of carbon monoxide poisoning attempts to accelerate the release and subsequent elimination of carbon monoxide from hemoglobin, hyperoxygenate tissues, antagonize brain lipid peroxidation (potential cerebral sequela of carbon monoxide), reactivate cellular enzymes and proteins, and decrease cerebral edema and neuropsychiatric sequelae. Indications for hyperbaric treatment of carbon monoxide poisoning include comatose patients, patients with ischemic changes on ECG, those with abnormal psychological and neurologic tests, those with carboxyhemoglobin levels greater than 40%, symptomatic pregnant patients or those with carboxyhemoglobin level greater than 15%, and patients who are symptomatic after 4 hours of 100% oxygen treatment.
Decompression sickness : naval investigations and experiments have increased understanding and treatment of severe decompression sickness ("bends"). During decompression or resurfacing, gases within the vasculature and other tissues come out of solution and expand to promote a mechanical and proinflammatory reaction. The gas bubbles disrupt vascular endothelium and nerve tissue, cause middle ear and cochlear dysfunction, foster edema via vascular and lymphatic occlusion, and promote ischemia by blocking vessels. Proinflammatory cytokines are released from neutrophils, platelets, and endothelial cells while the complement and coagulation cascade systems are activated. The CNS and other tissues develop microhemorrhages. Patients present clinically with joint and/or muscle pain, pruritus, edema, and mottled skin. More severe and ominous symptoms include upper lumbar cord and CNS dysfunction, cardia dysrhythmias, respiratory embarrassment, and severe abdominal pain. Onset of symptoms usually occurs within the first 30 minutes postdive but can take up to 12 hours. HBO attempts to reduce the bubble size until the inert gas is eliminated while tissues are hyperoxygenated.
Clostridial gas gangrene is a life-threatening and/or limb-threatening infection that mandates emergent surgical intervention. Only use HBO in conjunction with surgery. Hyperbaric medicine works by a number of mechanisms to decrease the production of the alpha toxin released from clostridium, limit bacterial replication, and oxygenate tissues. Perform treatments immediately following surgery and continue them at least twice daily until evidence of the toxin hemolysis subsides.
Radiation injury alters the normal tissue physiology and anatomy. Marx observed the triad of hypocellularity, hypovascularity, and hypoxia in tissues subjected to radiotherapy. A progressive tissue fibrosis and capillary loss are associated with the endarteritis obliterans related to the sensitivity of cell lines (eg, endothelial cells, fibroblasts, muscle, nerve cells). The resulting tissue insult may manifest as nonhealing ulcers, pigmentary skin changes, tissue induration, loss of elasticity, and local erythema and tenderness. Bone may progress to an avascular necrosis. The central avascular region of ulcers and osteoradionecrosis is rendered hypoxic, and the surrounding tissues have greater oxygen content. Hyperbaric treatment promotes angiogenesis and hyperoxygenation to the radiated affected tissues. Increasing the oxygen content to the surrounding tissues markedly increases the overall oxygen gradient between these tissues and the central hypoxic area. The increased oxygen gradient is the essential catalytic factor for angiogenesis. Multiple hyperbaric treatments are required to significantly increase the capillary density in the affected tissues. Prophylactic hyperbaric medicine is recommended by the National Cancer Institute for procedures (eg, tooth extraction) that are performed on irradiated mandibles.
Chronic nonhealing wounds : the rationale for treatment of chronic nonhealing wounds with hyperbaric therapy uses the known secondary mechanism of action. Oxygen is required for angiogenesis (which is fostered by the increased oxygen gradient), collagen deposition, re-epithelialization, cellular respiration, and oxidative killing of bacteria. Decreased edema noted following hyperbaric treatment allows better diffusion of oxygen and nutrients through tissues while also relieving pressure on surrounding vessels and structures. In this light, HBO has been used for treating foot ulcers in patients with diabetes, venous and arterial insufficiencies, burn wounds, crush injuries, marginal flaps, and skin grafts. Before initiating hyperbaric treatment, optimize the patient's overall medical status, facilitate nursing care of the patient, and address local wound care and dressing. The patient's nutritional status is extremely important for wound healing. Proteins, cofactors, essential fatty acids, and proper calorie intake must be optimized for the collagen deposition, angiogenesis, epithelization, and ground substance to facilitate wound healing. The cardiopulmonary and endocrine systems should be primed to allow adequate perfusion. Hyperbaric treatment is not a substitute for appropriate limb revascularization. For adjunctive therapeutic value of HBO to have effect, correct peripheral vascular disease as much as possible via the vascular surgery service. Similarly, local wound management with appropriate debridement, irrigation, infection control, and daily dressing changes is required to aid in healing. Patient positioning and pressure relief with special beds, orthosis, or splints may be necessary to optimize the local wound milieu. Advise patients to stop smoking, since nicotine adversely affects the wound's vascularity and increases potential complications of hyperbaric treatments. The general approach to these problem wounds is therefore multidisciplinary.
Foot wounds of patients with diabetes : foot wounds of patients with diabetes offer a particularly difficult problem. These patients often have an impaired immune system, predisposing them to infections. Blood supply to the wounds is hindered by large and small disease. The red blood cells are sticky and nonpliable, which leads to capillary occlusion and distal ischemia. Neuropathies render the foot insensate and impair motor function. This impaired motor function flattens the foot so that the metatarsal heads become prominent and promote further susceptibility to ulceration via pressure. Use of hyperbaric therapy in foot wounds of patients with diabetes engenders much controversy. Many early reports were anecdotal and fraught with confounding information that did not support or justify hyperbaric treatment. Recently, a number of randomized prospective studies demonstrated the benefit of hyperbaric therapy in healing foot wounds of patients with diabetes. Other retrospective studies demonstrated similar results. Problem wounds are just that, difficult problems that have not responded to other treatment modalities. HBO may offer added fuel to the overall armamentarium in the treatment of chronic wounds.
Reperfusion injuries : the benefits of hyperbaric treatment on ischemic insults, ischemia reperfusion injuries, and crush injuries also have been subject to controversy. These injuries result from the reperfusion that follows an extended period of ischemia. Oxygen free radicals rise, thromboxane A2 and adhesion molecules are activated, platelet aggregation occurs, and vascular vasoconstriction activity is increased. The endothelium is damaged, which promotes vascular leakage, edema, and thrombosis. Tissue necrosis ensues, and the activation of white blood cells is pivotal to the reperfusion injury. Using hyperbaric treatment that may increase oxygen free radicals to benefit the reperfusion injury seems paradoxical. Zamboni et al demonstrated that HBO promotes hyperoxygenation and vasoconstriction to decrease edema and neurovascularization and inhibits neutrophil activation, preventing margination, rolling, and accumulation of white cells. Neutrophils therefore are not permitted to produce detrimental oxygen free radicals. As further work in hyperbaric physiology progresses, further well-organized prospective randomized studies should help identify the appropriate therapeutic benefits of HBO.
Transcutaneous oxygen : assessment of the perfusion and oxygenation in and around a particular wound is another important aspect of general wound care that needs to be addressed. Transcutaneous oxygen has emerged as an easy yet reliable noninvasive means of measuring local oxygenation relative to a standard area on the body. Transcutaneous oxygen measurements attempt to measure the local ramifications of macrovascular and microvascular disruption. Transcutaneous oxygen is affected by local factors such as improper electrode placements, cellulitis, edema, and increased skin thickness. Systematically, ventilation and cardiac output, limb macroperfusion, and the patient's hemoglobin may influence the results of transcutaneous oxygen measurements. The vasoconstrictive effects of smoking also may interfere with transcutaneous oxygen levels. The normal lower extremity transcutaneous oxygen measurement should be approximately 50 mm Hg. Minor physiologic variations may occur in the same individual. A standard control on the trunk of the patient (usually the second intercostal space) is used in conjunction with the local wound and surrounding tissue transcutaneous oxygen mapping. Obtain at least 4 sites at equal distances around the ulcer. A hyperoxic challenge (100% oxygen for 20 min) normally increases the transcutaneous oxygen reading to greater than 300 mm Hg. Generally, responses less than 50 mm Hg require a vascular workup, and HBO likely is of little benefit. Patients with intermediate responses may benefit from hyperbaric treatments. An appropriate candidate for hyperbaric treatment is a patient who has local ischemia but responds to the oxygen challenge. Confirm a response to the hyperbaric treatment by further transcutaneous oxygen testing after 14-20 hyperbaric treatments. Hyperbaric medicine has a definite role in treating certain conditions. Its use in the future depends on continued enthusiasm, research, and practice based on sound principles. The future of HBO therapy depends on continued sound, scientific, and clinical studies. Wound healing centers may harbor most hyperbaric chambers. Reimbursement issues for physicians and hospitals also may alter practices traumatically; for the physician and hospital to be paid, present guidelines urge for physicians to be present throughout the hyperbaric treatment. In 2000, more than 300 hyperbaric chambers were operating in the US. For an objective assessment of wound perfusion and oxygenation, transcutaneous oximetry provides a simple, reliable, noninvasive, diagnostic technique. It can be used for assessment of tissue perfusion in the vicinity of the problem wound. Transcutaneous oximetry may be used in the assessment of wound healing potential, selection of amputation level, and patient selection for HBOT. In diabetic patients with chronic foot ulcers peri-wound transcutaneous oxygen tensions (TcP(O₂)) over 400 mmHg in 2.5 ATA hyperbaric oxygen > 50 mmHg in normobaric pure oxygen predict healing success with adjuncted HBOT with high accuracy^ref.
• the FluidFocus lens presented at the 2004 CeBIT technology trade fair in Hanover, Germany, is made up of a water-based solution and an oil. The two are contained in a cylinder 3 mm across and 2.2 mm high. A water-repellent chemical coats the tube's walls and one of its caps. This pushes the watery droplet away from the cylinder's sides and forces it into a hemisphere. As the 2 liquids have different optical properties, the curved boundary between them bends light like a lens. The focal distance of the lens can be changed simply by applying an electric field. This makes the tube's coating less hydrophobic, relaxing the water droplet's tendency to shy away from the walls and allowing it to sag and spread. As the liquid curve bends towards the bottom of the tube, it focuses light closer to the device. At its most convex, the FluidFocus lens can focus on an object 5 centimetres away. As the electric field drops, the lens flips from close-up to distant focusing in just 10 milliseconds. The lenses in our eyes also change shape to focus on different distances, but our eyes use muscles attached to the lens to do this, rather than an electric field. Philips Research has already built an electronic display using technology similar to that in the FluidFocus lens^ref. The pixels of the display use two liquids of different colours; the overall colour of each pixel changes as the liquids shift shape. Joosse thinks the lens is suitable for mass production, and could soon show up in miniature cameras, hand-held computers and telephone cameras. Such tiny lenses might also be useful in medical tools such as endoscopes

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