J OralMaxillofac Surg 50:1081-1086,199Z

Hyperbaric Oxygen Therapy: Contraindications and Complications LT COL JAMES

H. FOSTER,

DDS*

The literature is replete with references regarding the use of hyperbaric oxygen (HBO) therapy to treat various human maladies. However, the oral and maxillofacial surgery literature is lacking in information regarding patient selection criteria and possible contraindications to HBO therapy, as well as possible risks and/or complications of such therapy. This article details patient selection criteria, discusses relative and absolute contraindications to HBO therapy, and describes the potential risks and complications of this therapy. Over the past 300 years, health care practitioners have used hyperbaric oxygen (HBO) as a treatment for a multitude of human diseases, ranging from syphilis to multiple sclerosis, senility to myocardial infarction, and gangrene to decompression sickness.’ Since the 1960s however, clinicians have more critically evaluated their treatment successes and failures, as well as the uses of HBO as an adjunctive treatment. and therefore its uses have become more focused on specific disease entities. The use of HBO involves the intermittent, systemic administration of 100% oxygen under pressure greater than one atmosphere. Topical application, such as to an extremity, does not meet the description of HBO as outlined by the Hyperbaric Oxygen Committee of the Undersea Medical Society.* Both therapeutic and detrimental effects can result from two features of this treatment: the mechanical effects of the increased pressure and the physiological effects of hyperoxia.3 HBO therapy produces improved tissue oxygenation due to increased arterial oxygen tension and increased dissolved plasma oxygen content. HBO therapy also produces a vasoconstrictive response of arteries that is related to the degree of hyperbaric pressure.4

As with any medication, the use of oxygen as a therapeutic drug is not without complications or risks. Some complications result from mechanical problems. The first reported fatal accident involving a hyperbaric chamber occurred in 1976.” In the Federal Republic of Germany, 5 of 20 patients died from complications of decompression sickness after an uncontrolled decompression resulting from the chamber door being blown off the hinges. Although these fatalities did not result from therapeutic complications, they do illustrate a potential for complications related to the technology required to deliver hyperbaric oxygen. HBO therapy has specific applications in oral and maxillofacial surgery (OMFS). The literature contains numerous references regarding its use for the prevention6 and adjunctive treatment of osteoradionecrosis ( 0RN).7.8 It is also accepted that the immune system. wound healing, and vascular tone are affected by an improved oxygen s~pply.~ Researchers have demonstrated that once hemoglobin is saturated with oxygen, additional oxygen can be carried by the serum in physical solution by increasing the relative oxygen concentration with increased pressure.4.9 The literature also provides guidance in the use of HBO, protocols for HBO application. and a recommended treatment regimen for ORN prophylaxis, but it is essentially devoid of information regarding patient selection and evaluation, contraindications to HBO treatment, known risks of HBO treatment, or fundamentals of the HBO technology. One article listed the major difficulties with HBO treatment only as time and expense. ” The purpose of this article is to provide some insight into this application of oxygen as a medication, to explain some of the risks and complications associated with HBO, to discuss some of the physical or medical contraindications to HBO treatment, and to detail some criteria for patient selection.

* Chairman, Department of Oral and Maxillofacial Surgery, 3rd Medical Center, Elmendorf Air Force Base. AK. Opinions expressed therein, unless otherwise specifically indicated, are those of the author. They do not purport to express views of the government. Address correspondence and reprint requests to Lt Co1 Foster: Department of Oral and Maxillofacial Surgery, 3rd Medical Center, Elmendorf AFB. AK 99506-5300. This is a US government use. 0278-2391/92/501

work. There are no restrictions

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HYPERBARIC OXYGEN THERAPY

HBO Environment Patients receiving HBO therapy enter into a specialized and unique environment. Hyperbaric chambers are of two basic types: monoplace and multiplace. Only the patient is inside the monoplace chamber, whereas the patient(s) and technician/provider(s) enter the multiplace chamber. The monoplace chamber resembles an iron lung with clear plastic sides. The multiplace chamber is a reinforced metal structure large enough to accommodate stretchers and chairs. Hyperbaric conditions within the multiplace chamber are achieved by forcing compressed air into the chamber to simulate pressures “at depth.” Hyperbaric conditions in the monoplace chamber result from pure oxygen being forced into the chamber. Patients in the multiplace chamber receive HBO while at depth by breathing pure oxygen via a face mask, a plastic hood over the head and neck, or through an endotracheal tube. Monoplace chamber patients breath the pure oxygen within the chamber and thus do not require a mask or hood. The environment outside and within the chamber is potentially dangerous. The air within the chamber may become explosive due to its being oxygen enriched. Another potential source of explosion is rupture of the chamber, as related previously. Such a sudden loss of pressure in the chamber can result in decompression sickness. People within the multiplace chamber are not readily accessible and require decompression stops to exit from the chamber without danger of the bends. Because the multiplace chamber is metallic, defibrillation of a patient within the chamber is potentially dangerous because of the risk of sparks as well as the possibility of electrocution of the provider performing the defibrillation.

Contraindications

to HBO

Oxygen administered therapeutically under pressure is generally very safe with the currently recommended protocols and doses, but it is not totally innocuous. There are certain contraindications to HBO treatment, which range from medical problems to physical abnormalities. The contraindications may only be relative, but patients should be evaluated and treated with these contraindications in mind. Patients for whom HBO is considered to be contraindicated by the Hyperbaric Oxygen Committee of the Undersea Medical Society are listed in Table 1.5,7 PNEUMOTHORAX

The only absolute contraindication is an untreated pneumothorax.

to HBO therapy

Patients with a history of severe asthma, emphysema, or any of the other chronic obstructive pulmonary diseases (COPD) are at risk for formation of a tension pneumothorax. A radiograph of the chest should be obtained on any patient with a history of chest compressions, intubation, or central venous line placement (or attempted placement) to rule out an existing pneumothorax before HBO therapy.” An existing pneumothorax must be treated with placement of a chest tube with a one-way Heimlich valve prior to allowing the patient to participate in the HBO treatment. OPTIC NEURITIS

Optic neuritis is an accepted contraindication to HBO therapy. However, this contraindication may only be relative because there is a 25% incidence of optic neuritis in multiple sclerosis patients’ and HBO is used as a treatment for this disease in some centers. There have been no reports of blindness from optic neuritis exacerbated by HBO therapy. It should be noted, however, that multiple sclerosis is not an indication for HBO approved by the Hyperbaric Oxygen Committee of the Undersea Medical Society. ACUTE VIRAL INFECTION

HBO has been shown to have an antimicrobial effect.12 Oxygen inhibits aerobic as well as anaerobic organisms, and can be considered a broad-spectrum antibi0tic.j However, oxygen has not been shown to have antiviral activity. In fact, experiments have demonstrated that hyperbaric oxygen tends to potentiate viral infections. This adverse effect is believed to be secondary to interference with the release of interferon by sullhydryl groups. There are no studies to show whether patients with viral infections who require HBO for other indications can have the HBO treatment safely after receiving an interferon-stimulating agent.5 There is evidence, however, that a viral infection will become

Table 1. Contraindications to HBO Therapy Pneumothorax Severe chronic obstructive pulmonary disease with carbon dioxide retention, pulmonary blebs, and/or dyspnea with slight exertion Optic neuritis Acute viral infection Congenital spherocytosis Uncontrolled, acute seizures disorders Upper respiratory tract infection Uncontrolled high fever Pregnancy (questionable) Psychiatric problems History of prior thoracic or ear surgery, which would make it impossible to equalize middle ear pressure or pulmonary

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JAMES H. FOSTER

fulminant and possibly even lethal with HBO treatment. I3 UPPER RESPIRATORYINFECTION Patients with a history of upper respiratory infection should delay hyperbaric oxygen treatment until the acute symptoms of congestion and rhinitis subside. The congestion may make pressure equalization in the sinuses and middle ear difficult, if not impossible. Such patients are also at potential risk of viral infection. In addition, patients with high fever have a relative contraindication to HBO hyperbaric treatment because such fever seems to lower the threshold to oxygen toxicity seizures. I4 CONGENITAL

SPHEROCYTOSIS

HBO treatment is contraindicated in patients with congenital spherocytosis. In this condition there are abnormal structural proteins that cause the loss of the red blood cell membrane following glucose deprivation. This results in hemolysis of the cell.” HBO has been reported to cause increased hemolysis of the red blood cells in patients with congenital spherocytosis.‘4 PREGNANCY

Another of the relative contraindications to HBO treatment is pregnancy. The use of HBO is controversial because to the possible adverse affects that oxygen at high partial pressures may have on the fetus.5 Critics cite possible teratogenicity, retinopathy of prematurity, cardiovascular effects primarily due to alterations of placental blood flow, premature closure of the ductus arteriosus, spina bifida, limb defects, increased incidence of cleft lip, retinal detachment, and retrolental fibroplasia as reasons for not using hyperbaric oxygen for pregnant patients, I4 Nevertheless, HBO has been used in the Soviet Union in more than 700 pregnant patients in all stages of gestation for hypoxemia of various causes. The Soviet literature reports an improvement in the condition of all the mothers and fetuses and none of the above speculated complications.” Practitioners in Great Britain also use hyperbaric oxygen for pregnant patients and report no complications. Clinical and experimental evidence does not substantiate the claim that HBO therapy is harmful to the fetus, but it is necessary to weigh the risk versus benefit of hyperbarics before initiating such treatment. PSYCHIATRIC

PATIENTS

Patients with psychiatric problems may pose logistical problems when hyperbaric oxygen treatment is indicated, The claustrophobic patient may develop

symptoms just from visiting and viewing the chamber area. The psychiatric patient may require extensive counselling, and may even require the medical provider’s presence inside or sitting beside the chamber during the treatment.16 The psychiatric patient may also require premeditation with tricyclic antidepressants or benzodiazepines, and deep-muscle relaxation techniques before treatment. Even if the provider is successful in getting the patient into the chamber, it must be remembered that quick exit from depth is fraught with difficulties. The safe decompression time in the multiplace chamber from depth to sea level is 15 to 20 minutes, depending on the “total bottom time.” However, observer nursing personnel and physicians on duty within a multiplace chamber are prepared to manage any emergency. The safe decompression time in a monoplace chamber is less than 1 minute. PATIENTS WITH PRIOR THORACIC OR MIDDLE EAR SURGERY

A patient with a history of prior thoracic or middle ear surgery may also have a relative contraindication to HBO treatment. l4 Prior thoracic surgery may predispose the patient to pneumothorax and to possible arterial gas emboli. Prior ear surgery may lead to difficulties in pressure equalization of the middle ear. Potential Complications From HBO Therapy

Most of the complications associated with HBO delivery result from barometric pressure changes or oxygen toxicity. The former generally involve cavity (ear, maxillary sinus, or pleural) trauma due to the unequal changes in pressure within the cavity and the tissues as a whole.3 Some of the complications associated with HBO delivery are listed in Table 2.1.“.‘7

Table 2. Possible Complications Associated With HBO Therapy Eustachian tube dysfunction Tympanic membrane rupture Oxygen toxicity Ear. sinus, or tooth pain Decompression sickness Pneumothorax Arterial gas embolism Nitrogen emboli to the central nervous system. lung. or joints Middle ear hemorrhage Deafness Changes in vision Certain types of hemolytic anemia Fire hazard Nausea, fatigue, claustrophobia Equipment malfunction

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HYPERBARICOXYGENTHERAPY MIDDLE EAR DYSFUNCTION

Eustachian tube dysfunction, tympanic membrane rupture, and middle ear hemorrhage are potential complications if the patient is unable to equalize middle ear pressure with the outside pressure. An infrequent middle ear complication is serous otitis media.2 This complication is caused by oxygen displacement of nitrogen within the middle ear. The oxygen is absorbed and results in lower middle ear pressure, which may then cause a transduction of fluid into the middle ear space. When the HBO treatment is begun in a multiplace chamber, compressed air is forced into the chamber, resulting in increased pressure within the chamber as well as on the patient. As the pressure inside the chamber increases, the patient must perform certain maneuvers to equalize the middle ear and chamber pressures. Patients may chew gum, swallow, perform a Valsalva maneuver, or move the mandible back and forth to help equalize the pressures. Should patients have a physical obstruction of the eustachian tube, they may not be able to equalize the pressure. Patients with an upper respiratory tract infection (URI), swollen membranes in the eustachian tube(s), or congenital deformity or blockage of the eustachian tube (as in the cleft palate patient) experience difficulty in equilibrating and will have severe pain if allowed to continue the session. On subsequent sessions, if the patient continues to have equilibration difficulties, the patient myringotomy and/or insertion of pressure equalizing tympanotomy tubes may be required. Often equilibration problems may be ameliorated by the use of decongestants or by providing better instructions and coaching the patient in the physical maneuvers that will help to equalize pressures. OXYGEN TOXICITY Oxygen toxicity is another of the potential complications of HBO treatment. Seizures occur in about 0.03% of the patients treated,12 or 1.3 seizures per 10,000 HBO treatments.3 The seizures, if promptly treated, have no permanent sequelae. Oxygen toxicity seizures usually are not experienced until patients are taken to simulated depths greater than 60 ft sea water (FSW), which is greater than the usual depth for most indications. Oxygen toxicity affects the pulmonary and central nervous systems. Oxygen toxicity involving the central nervous system is termed the Paul Best effect and results in seizures.18 Oxygen toxicity affecting the pulmonary system is termed the Lorrain-Smith effect, and it causes edema in the lungs and subsequent alveolar collapse.‘4 Patients receiving 100% oxygen before their HBO therapy may be at a higher risk for oxygen toxicity. Patients

with a history of acidosis also have a greater than normal propensity for oxygen toxicity seizures.14 This acidosis should be corrected before instituting HBO therapy. Patients with a high fever also show a higher propensity for oxygen toxicity seizures. l4

SEIZURES Patients with a history of seizures have a relative contraindication to HBO treatment. The patient’s seizures should be well controlled before participation in the hyperbaric therapy to preclude emergent procedures to treat the seizure episode while at depth. HIGH-PRESSURENERVOUSSYNDROME Complications resulting from HBO therapy include a condition known as high-pressure nervous syndrome. This syndrome is a complex of neurological and neuropsychological signs resulting from increased barometric pressures and subsequent decompression.” This syndrome only develops with pressures far greater than those used in clinical HBO treatment. Persons who have long sessions may develop persistent symptoms, with morphologic changes in the brain cortical areas. Researchers have also demonstrated a 7 to 9 beat per minute reduction of the sinus node discharge frequency in “normal” patients while at depth.lg This decreased beat frequency reverts to preexperiment session rates on return to sea level pressures. DECOMPRESSION SICKNESS Caisson disease, also known as decompression sickness (DCS) or the bends, is the condition for which the pressure chamber was first developed, and is a prime emergency indication for HBO treatment. Decompression sickness is also a rare but possible complication following HBO treatment, which can manifest itself in two forms. Type I involves bubble formation outside the cardiovascular system and causes skin manifestations (“skin bends”) or joint pain (“classical bends”). Type II forms intravascular bubbles and causes neurological and pulmonary findings (“the chokes”). Type II DCS is potentially lethal. PNEUMOTHORAX The development of pneumothorax is a rare complication of HBO therapy. A pneumothorax can develop from rupture of air spaces within the lungs or from expansion of free air within the pleural cavity. The best treatment of pneumothorax is prevention by recognition of preexisting lung pathology, such as blebs

JAMES H. FOSTER

i

or bullae, that may predispose the patient to this condition. ARTERIAL GAS EMBOLISM Arterial gas embolism complication

(AGE)

is another potential

of

HBO treatment. It is a sudden and potentially lethal phenomenon involving air or other gas passing directly into the bloodstream. Barotraumatic cerebral air embolism was described in 1930 by Polak and Tibbols. *’ An AGE may result from the rupture of overexpanded lungs (as in ascent from depth without exhaling), from vessel perforation from a pneumothorax, or from mediastinal emphysema. The depth of the dive resulting in AGE may seem trivial, because the lungs will rupture at an overpressure of only 80 mm Hg, which corresponds to just 3.47 feet of seawater. Patients who display new signs of cortical deficit after HBO treatment should be suspected of having AGE.” AGE is a true medical emergency and must be recognized and treated promptly for complete patient recovery. The death from AGE associated with HBO treatment of a 69-year-old diabetic woman with a history of asthma and emphysema has been reported.22 The patient was being treated for a nonhealing foot ulcer. She developed confusion and a left-sided hemiplegia on decompression and died 17 hours later. TOOTH AND SINUS PAIN

Tooth and sinus pain are often mentioned as complications of pressure change. Tooth pain related to HBO treatment is rare. However, pain of sinus origin, confused as tooth pain, may occur. Such pain should not preclude the patient’s receiving HBO therapy. Should the patient develop tooth pain with the pressure changes, evaluation and treatment by a dentist can usually rectify the problem and allow for the resumption of therapy. Sinus pain is the more common problem associated with HBO treatment. Any sinus area of the head can be involved, but the frontal sinus is involved most often.5 Sinus pain is the result of swollen membranes impeding drainage and causing pain from inability to equalize pressures. Sinus pain is usually amenable to treatment with antihistamines or some other form of decongestant. Acute sinus infections should be treated aggressively to allow for early resumption of the HBO therapy. VISUAL CHANGES

Another possible complication of HBO therapy is deterioration of vision. Myopia is the most frequently reported visual side effect of HBO. It generally reverses within several months after cessation of the HBO ther-

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apy.’ The exact cause of the myopia is unknown, but it is thought to be a result of lens changes. Research has shown that HBO treatment produces a vasoconstrictive as well as an increase in tissue oxygenation. There is controversy as to whether any adverse sequelae to the eye occur from the vasoconstrictive effects of the HBO treatment. Ocular changes have been shown to occur during the first 5 minutes of exposure, but these were reversed by 1 minute of air breathing.5 Concern has also been raised as to the potential of HBO to cause retrolental fibroplasia. Studies in the 1950s showed that use of 100% oxygen at normal pressures on premature infants resulted in retrolental fibroplasia and subsequent blindness. Retinal changes secondary to enzyme inactivation by oxygen toxicity has been demonstrated only in experimental animals and not in humans5 Retrolental fibroplasia has not been reported as a complication in adults.3~5~15 More research is required before any definitive statement can be made as to the long-term effects of HBO treatment on vision. GASTRIC DISTRESS

Some patients will have nausea and vomiting during the compression phase of HBO treatment. A IO-year study reported a 6% incidence of emesis in patients receiving HBO treatment for carbon monoxide poisoning. *3 However, awake and alert patients experience few, if any, problems with nausea or vomiting and can maintain their own airway. Providers and inside observers should be aware of the possible compromise of the airway by vomitus in the unconscious patient and should consider protection of the airway by intubation before initiation of the HBO treatment. EQUIPMENT MALFUNCTION

RESULTING

IN PATIENT INJURY

Patients who are intubated present a special set of problems and risks. If the balloon cuff of the endotracheal tube is inflated with air prior to compression during the HBO treatment, the increased pressure inside the chamber will result in decreased size of the balloon. As the size of the balloon becomes smaller, the seal of the trachea is compromised and fluid can enter the trachea and lungs. At depth, the inside observer will be required to increase the amount of air in the balloon cuff. On decompression, if the inside observer does not remove some of the air from the balloon, the balloon will expand and can cause an injury to the trachea or damage the vocal cords. Problems involved with the inflation of the balloon cuff can be remedied by inflating the balloon with normal saline instead of air. The normal saline will not constrict or expand with

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HYPERBARIC OXYGEN THERAPY

the changes in chamber pressure and the balloon size will not fluctuate.22 Equipment subjected to the hyperbaric conditions can pose problems at depth. Unvented glass bottles of intravenous (IV) solutions and glass syringes should not be used as the glass may break from the pressure changes accompanying the changes in air bubble size. The IV bag should be plastic, because it will contract and expand with the air bubble changes. The inside observer should ensure that at least 100 mL of solution are in the IV bag before ascent. On descent, fluids will be forced into the bag; on ascent fluids will be forced from the bag and, when all the fluid is expelled, any air left in the bag will be injected into the circulation resulting in a venous air embolism and perhaps even an arterial gas embolism. Other potential equipment problems involve the use of the mechanical ventilator. The inspiratory and expiratory volumes from the ventilator should be monitored and equilibrated using a respirometer, because the delivered volumes will vary with the hyperbaric conditions. The respirometer should also be calibrated for the hyperbaric conditions. At 6 ATM, gas density is six times greater than at sea leve123;and the pressure required to overcome this resistance puts an added load on the ventilator. Since diabetic patients comprise a large number of the HBO treatment population, blood glucose monitoring is frequently used. Experience has shown that during HBO treatment, patients will have a decreased supplemental, exogenous insulin requirement. If this decreased requirement is not recognized, the patient may become hypoglycemic with the pre-HBO treatment insulin dosing.

Summary This article discussed many of the preexisting medical and psychological conditions that may preclude or modify a patient’s receiving hyperbaric oxygen treatment. Although the potential for problems and complications exist with such therapy, these complications rarely occur. A complete medical history and physical evaluation of the patient, and an understanding of potential problems, can usually circumvent the occurrence of complications.

References 1. Gabb G, Robin E: Hyperbaric oxygen: A therapy in search of diseases. Chest 92: 1074, 1987 2. UHMS: Hyperbaric Oxygen Therapy, A Committee Report. Bethesda, MD, Undersea and Hyperbaric Medical Society, UHMS Publications No. 30, 1989 3. Grim PS, Gottlieb LJ, Boddie A, et al: Hyperbaric oxygen therapy. JAMA 263:22 16, 1990 4. Ricci B, Calogero G: Oxygen-induced retinopathy in newborn rats: Effects of prolonged normobaric and hyperbaric oxygen supplementation. Pediatrics 82: 193, 1988 5. Fisher B, Jain KK, Braun E, et al: Handbook of Hyperbaric Oxygen Therapy. Berlin, Springer-Verlag, I988 6. Marx RE, Johnson RP, Kline Ww: Prevention of osteoradionecrosis: A randomized prospective clinical trial of hyperbaric oxygen versus penicillin. J Am Dent Assoc 111:49, 1985 7. Complications of hyperbaric oxygenation in the treatment of head and neck disease. Otolaryngol Head Neck Surg 96:2 11, 1987 (letter to the editor) 8. Mansfield MJ, Sonders DW, Heimbach RD, et al: Hyperbaric oxygen as an adjunct on the treatment of osteo-radionecrosis of the mandible. J Oral Surg 39:585, 1981 9. Shannon MD, Hallmon WW, Mills MP, et al: Periodontal wound healing responses to varying oxygen concentrations and atmospheric pressures. J Clin Periodontol 15:222, 1988 10. King GE, Scheetz J, Jacob RF, et al: Electrotherapy and hyperbaric oxygen: Promising treatments for postradiation complications. J Prosthet Dent 62:331, 1989 11. Sloan EP, Murphy DG, Hart R, et al: Complications and protocol considerations in carbon monoxide-poisoned patients who require hyperbaric oxygen therapy: Report from a ten-year experience. Ann Emerg Med 18:629, 1989 12. Holmes C, Garges L: Efforts of hyperbaric oxygen. J Infect Dis 155:1084, 1987 13. The uses of oxygen under pressure. Emerg Med 18:35, 1986 14. Van Hoesen KB, Camporesi EM, Moon RE, et al: Should hyperbaric oxygen be used to treat the pregnant patient for acute carbon monoxide noisonina? JAMA 26 1: 1039. 1989 15. Wirjosemito SA, Touhey JE:Hyperbaric oxygen therapy and hereditary spherocytosis: Report of 2 cases. J Hyperbaric Med 3:45, 1988 16. Hillard JR Severe claustrophobia in a patient requiring hyperbaric oxygen treatment. Psychosomatics 90:107, 1990 17. Giebfried JW, Lawson W, Biller HF: Complications of hyperbaric oxygen in the treatment of head and neck disease. Gtolaryngol Head Neck Surg 94508, 1986 18. Dolmierski KJ, Maslowski J, Matousek M, et al: EEG changes measured by spectrum analysis under hyperbaric conditions. Aviation Space and Environmental Medicine. 6 1:33, 1990 19. Dise CA, Clark JM, Lamberster CT, et al: Hyperbaric hyperoxia reversibly inhibits erythrocyte phospholipid fatty acid turnover. J Appl Physiol62:533, 1987 20. Neuman TS, Hallenbeck JM: Barotraumatic cerebral air embolism and the mental status examination: A report of four cases. Ann Emerg Med 16:220, 1987 2 1. Wolf HK, Folk JC, Goeker NE: Barotrauma and air embolism in hyperbaric oxygen therapy. Am J Forensic Med Pathol 11: 149, 1990 22. Ross MC: Healing under pressure. Am J Nurs 86:1118, 1987 23. Moon RE, Bergquist LV, Conklin B, et al: Monaghan 225 Ventilator use under hyperbaric conditions. Chest 89:846, 1986

Hyperbaric oxygen therapy: contraindications and complications.

The literature is replete with references regarding the use of hyperbaric oxygen (HBO) therapy to treat various human maladies. However, the oral and ...
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