Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats.

Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing. We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture while at 285 kPa or following immediate recompression to either 285 or 405 kPa, breathing 80:20 and 50:50 heliox mixtures. During the isobaric shifts, some bubbles in adipose tissue grew marginally for 10-30 min, subsequently they shrank and disappeared at a rate similar to or faster than during air breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent shrinkage of all air bubbles, until they disappeared from view. Deep tissue isobaric counterdiffusion may cause some air bubbles to grow transiently in adipose tissue. The effect is marginal and of no clinical consequence. Bubble disappearance rate is faster with heliox breathing mixtures as compared to air. We see no reason for reservations in the use of heliox breathing during treatment of air-diving-induced decompression sickness.

Hyperbaric oxygen therapy as a treatment for stage-I avascular necrosis of the femoral head.

Avascular necrosis (AVN) of the head of the femur is a potentially crippling disease which mainly affects young adults. Although treatment by exposure to hyperbaric oxygen (HBO) is reported as being beneficial, there has been no study of its use in treated compared with untreated patients. We selected 12 patients who suffered from Steinberg stage-I AVN of the head of the femur (four bilateral) whose lesions were 4 mm or more thick and/or 12.5 mm or more long on MRI. Daily HBO therapy was given for 100 days to each patient. All smaller stage-I lesions and more advanced stages of AVN were excluded. These size criteria were chosen in order to compare outcomes with an identical size of lesion in an untreated group described earlier. Overall, 81% of patients who received HBO therapy showed a return to normal on MRI as compared with 17% in the untreated group. We therefore conclude that hyperbaric oxygen is effective in the treatment of stage-I AVN of the head of the femur.

Erotomania following an orchiectomy: a case report.

A case report of young male patient with erotomania following seminoma and orchiectomy is described in this article. The probable dynamics that lead to this delusion are then discussed. This case report demonstrates the cooperation between the oncology ward and the psychiatric liaison service.

Modification of in vivo and in vitro TNF-alpha, IL-1, and IL-6 secretion by circulating monocytes during hyperbaric oxygen treatment in patients with perianal Crohn's disease.

Treatment of perianal inflammatory lesions in Crohn's disease (CD) is unsatisfactory and novel treatment modalities are pursued. We have recently reported a good clinical effect of hyperbaric oxygen (HBO) treatment in perianal CD. In the present study, seven patients with perianal CD were subjected to daily sessions of HBO in a multiplace hyperbaric chamber. Each patient received a total of 20 sessions during a time period of 1 month, and IL-1, IL-6, and TNF-alpha measurements were done several times during the initial sessions and after completing therapy. Pretreatment cytokine levels were elevated in patients compared to age-matched 10 normal controls. During the first 7 days of treatment, IL-1, IL-6, and TNF-alpha levels in supernatants of LPS-stimulated monocytes derived from patients' peripheral blood were decreased compared to pretreatment levels. Parallel measurements of serum IL-1 levels revealed an initial elevation and thereafter decreased levels, which remained low throughout the first week of HBO treatment. After completion of therapy, cytokine levels increased to pretreatment values. We conclude that alterations in secretion of IL-1, IL-6, and TNF-alpha may be related to the good clinical effect of HBO treatment in CD patients with perianal disease.

Gas embolism complicating obstetric or gynecologic procedures. Case reports and review of the literature.

Gas embolism is a rare life-threatening complication of obstetric or gynecologic procedures, arising as a result of gas bubbles being introduced into the circulation via severed blood vessels. Extensive brain damage and acute cardiovascular collapse will lead to a fatal outcome. A favourable outcome depends on early diagnosis and prompt treatment. Hyperbaric oxygenation, which reduces bubble size and increases the supply of oxygen to hypoxic tissues, is the definitive treatment for gas embolism. We report four cases of gas embolism complicating obstetric or gynecologic procedures which were treated at the Israel Naval Medical Institute followed by an updated review of the literature.

Hyperbaric oxygen for perianal Crohn's disease.

Perianal involvement in Crohn's disease is common (< or = 50%), distressing, and frequently refractory to treatment. Clinical features include painful induration and stenosis, discharging fistulas, and fissures. The pathogenesis of these lesions is unclear, but local ischemia and secondary anaerobic infection may play a role. Following three sporadic reports of successful treatment with hyperbaric oxygen (HBO), we undertook a trial of this method in 10 patients with refractory perianal disease. These patients' perianal Crohn's disease had not responded to treatment that included local medications, salicylates, corticosteroids, metronidazole, or 6-mercaptopurine were treated. Treatment was administered in a hyperbaric chamber at a pressure of 2.5 atm absolute. Each session lasted 90 min, and each course consisted of 20 daily sessions. Complete healing occurred in 5 patients after one to two courses. In an additional 2, after three courses, 1 patient improved but did not heal, and 2 did not improve. No adverse effects were noted by any of the 10 patients. Follow-up of 18 months did not reveal any recurrence. These preliminary results confirm that HBO therapy is a safe and efficient therapeutic option for perianal Crohn's disease.

Conservative multidisciplinary treatment approach in an unusual odontodysplasia.

An unusual case of odontodysplasia is presented, involving both primary and permanent dentition, with oligodontia of permanent teeth and hypoplasia, taurodontism and incomplete eruption of a first permanent molar. In order to improve the patient's appearance, occlusion and function, his intra- and inter-arch relationships were altered. To accomplish this, a multidisciplinary treatment approach was adopted, involving restorative and prosthetic treatments by a pediatric dentist, accompanied by periodontal surgery, endodontics and orthodontics.

Hyperbaric oxygenation for arterial air embolism during cardiopulmonary bypass.

The incidence of systemic air embolism during cardiopulmonary bypass is estimated to be 0.1%. However, the vast majority of instances are unreported and quietly ignored. The result may be disability or death. The control of air embolism obviously lies in prevention. The definite and specific treatment of this complication is hyperbaric oxygen. We report 6 patients referred to our institute because of air embolism during cardiopulmonary bypass. Of the 4 patients in whom hyperbaric oxygen therapy was delayed for 17 to 20 hours, 2 showed partial neurological improvement, as opposed to the success of hyperbaric oxygen therapy in the 2 patients in whom the delay was minimal. We conclude that as soon as the proposed open heart operation has been completed and there is an indication that air embolism has occurred, the patient should be treated with hyperbaric oxygen as quickly as possible, even before neurologic manifestations of cerebral ischemia appear.

Delayed hyperbaric treatment of cerebral air embolism.

Urgent exposure to hyperbaric oxygen (HBO) is currently accepted as an effective therapy for cerebral air embolism. The diagnosis of air embolism in the critically ill post-surgical patient is frequently difficult and therefore the initiation of specific therapy is often delayed. Only limited information is currently available on the effects of delayed HBO treatment in these patients. We recently used HBO to treat five patients with cerebral air embolism resulting from invasive medical procedures; hyperbaric treatment was begun 15-60 h after the embolic event. The causes of air embolism were: cardiopulmonary bypass accidents, pulmonary barotrauma induced by mechanical ventilation, and central vein catheterization. All patients received initial treatment according to U.S. Navy Compression Table 6A in a multiplace chamber, followed by subsequent treatments with 100% O2 at 2.5 to 2.8 ATA for 90 min as indicated. Significant, partial or complete recovery was observed in three patients, one patient did not respond, and one died. The salutary effects of HBO in our subgroup of patients suggest that this treatment should be used in cerebral air embolism even when referral to a hyperbaric facility is delayed.

Massive air embolism--a possible cause of death after operative hysteroscopy using a 32% dextran-70 pump.

Although considered a safe procedure, operative hysteroscopy has been reported to result in serious and even fatal complications. A fatal outcome is described after operative hysteroscopy. The attending team made a diagnosis of massive air embolism. However, HBO therapy, which is the specific treatment for air embolism, yielded only transient improvement. The pathologist's diagnosis on autopsy was anaphylaxis. These two complications must be borne in mind during the procedure, and a contingency plan developed for dealing with them should they arise.

Sialolithiasis. A survey on 245 patients and a review of the literature.

245 patients with sialolithiasis, treated during a period of 20 years, were evaluated and the literature has been reviewed. The submandibular gland was involved in 231 patients, the parotid gland in 11 patients, and the sublingual gland only in 1 patient. There is some indication that patients with sialolithiasis are more prone to develop nephrolithiasis. A relationship with other systemic disorders could not be detected. Laser treatment seems to be a promising treatment modality for stone removal, even in acute phases.

Hyperbaric oxygenation for necrotizing (malignant) otitis externa.

Two patients with extensive necrotizing otitis externa have been treated by hyperbaric oxygenation. One patient had facial nerve palsy and the other suffered from skull base involvement. Due to severe side effects, the preferred combined intravenous antibiotic therapy was changed to monotherapy in one case and completely withdrawn in the second. This was done before the commencement of hyperbaric oxygenation, while the necrotizing infection was still active. Hyperbaric oxygenation therapy was followed by complete resolution of the necrotizing otitis externa, which did not recur. The pathogenesis of the disease and mechanisms by which hyperbaric oxygenation might be of benefit are described. We conclude that hyperbaric oxygenation should be considered as adjuvant therapy for necrotizing otitis externa whenever a therapeutic pressure chamber is available.

CNS oxygen toxicity in oxygen-inert gas mixtures.

Central nervous system oxygen toxicity in hyperbaric oxygen-inert gas mixtures was studied by exposing male rats to various gas mixtures having the same oxygen partial pressure and varying pressures of inert gases. The duration of the latent period until the appearance of electrical discharges in the electroencephalogram was used as the criterion for the sensitivity to CNS oxygen toxicity. Two hundred and twenty rats with chronically implanted cortical electrodes were subjected to a single exposure to 1 of 11 different gas mixtures at ambient pressures ranging from 5 to 10 ATA. All gas mixtures had a constant oxygen partial pressure of 5 ATA and varying pressures of inert gas (helium or nitrogen). The duration of the latent period was found to be significantly different in the 11 experimental groups (P less than 0.001). While increasing the inert gas pressure, the latency gradually shortened, reaching the lowest values in mixtures of 5 ATA oxygen and 3 ATA of either inert gas. On further increase in the inert gas pressure up to a total ambient pressure of 10 ATA, the latency returned to control (pure 5 ATA oxygen) values. No difference was found between nitrogen and helium of equal partial pressures. These findings suggest that the risk of CNS oxygen toxicity in gas mixtures is not determined solely by the PO2, and even a relatively low pressure of inert gas can contribute to the imminence of hyperbaric-oxygen-induced seizures.

CNS oxygen toxicity in the rat: role of ambient illumination.

The effect of ambient illumination on sensitivity to CNS oxygen toxicity was studied in awake male rats. Continuous recording of the EEG was obtained with chronically implanted cortical electrodes. The appearance of the electrical discharges in the EEG was used as an end point for CNS oxygen toxicity. It was found that sensitivity to CNS oxygen toxicity was inversely related to the level of ambient light illumination. The latent period for appearance of the electrical discharges was significantly shorter in darkness than in light over most of the oxygen pressures. Rats with severely depressed retinal function were as sensitive to oxygen at high pressure as normal rats in darkness, demonstrating the importance of visual input in the modulation of sensitivity to CNS oxygen toxicity.

Necrotizing fasciitis.

Necrotizing fasciitis was diagnosed in 16 patients during the years 1980 to 1984. All patients were managed by a uniform protocol consisting of radical excisional surgery, intravenous antibiotics, and hyperbaric oxygen therapy. An overall mortality rate of 12.5% was achieved. In view of the encouraging results, this therapeutic regimen is highly recommended.

Hyperbaric oxygen therapy for gas gangrene casualties in the Lebanon War, 1982.

Four gas gangrene casualties from the Lebanon War, 1982, were treated with hyperbaric oxygen (HBO). Myonecrosis was diagnosed in three and intraabdominal spread of clostridial infection in one. In all four cases, HBO treatment, in combination with meticulous but conservative surgical debridements and proper antibiotic coverage, was begun within 24 h of diagnosis. HBO therapy was terminated when bacteriostasis was attained, as evidenced by no further spread of myonecrosis and the alleviation of systemic toxic symptoms. All four patients recovered from the clostridial infection, but one died later from other causes. HBO therapy enhances the survival rate of patients with gas gangrene, lowers the anesthetic risk, allows for maximal tissue preservation and helps avoid radical mutilating surgery.

Saturation recompression therapy in a diving accident.

We report a case of cerebral air embolism caused by pulmonary barotrauma in a diver. Severe neurological symptoms, deterioration during decompression, and a prolonged, complicated, initial pressure profile indicated the need for saturation therapy. Few clinical cases treated by saturation recompression therapy (SRT) have been reported since its introduction in 1978 (1,5). SRT is an effective alternative for the management of complicated and persistent accidents involving intravascular bubbles.

Factors affecting ventilatory lung function in young Navy selectees.

Ventilatory lung function was studied in 528 Navy selectees 16 to 23 yr of age. Analysis of the pulmonary function data indicated that height and chest circumference were the best "predictors" of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). Other factors, such as amount of sports activity, ethnicity, weight, or Quetelet index, were of minimal predictive value. Linear prediction formulas of ventilatory lung function for young male adults of this age range were derived. Analysis of variance showed that the apparently greater FVC found in smokers than that found in nonsmokers was related to the smokers being older and consequently taller than the nonsmokers. After adjusting for age (even in this narrow age range) and height, no difference in pulmonary function between the 2 groups could be demonstrated.

Arterial air embolism after penetrating lung injury.

We present a case of cerebral air embolism after a gunshot wound to the lung, combined with mechanical ventilation. Hyperbaric and pharmacologic therapy resulted in complete recovery. The discussion focuses on hyperbaric therapy as the mainstay of treatment, the importance of prophylactic measures, and prompt diagnosis.