Hyperbaric oxygen therapy in the treatment of post cardiac surgical strokes--a case series and review of the literature.

Strokes remain an uncommon but significant complication of cardiac surgery. Cerebral air embolism is the likely aetiology in the majority of cases. Hyperbaric oxygen therapy is the recognised treatment for cerebral air embolism associated with compressed air (SCUBA) diving accidents and is therefore also the standard of care for iatrogenic causes of air embolism. It follows that there is a logic in treating post-cardiac surgical stroke patients with hyperbaric oxygen. The aim of this retrospective review was to examine the outcomes of 12 such patients treated in the Christchurch Hospital hyperbaric unit and to appraise the evidence base for the use of hyperbaric oxygen therapy in this setting. Despite delays of up to 48 hours following surgery before the institution of hyperbaric oxygen therapy, 10 of the 12 patients made a full neurological recovery or were left with mild residual symptoms, with nine returning to their previous level of care. One patient remained hemiplegic and there was one early neurological death. There is a paucity of prospective data in this area, but based on sound pathophysiological principles and clinical experience, we believe that patients suffering a stroke following open cardiac surgery should be considered for hyperbaric oxygen therapy.

Delayed hyperbaric oxygen therapy for carbon monoxide intoxication--two case reports.

The severity of signs and symptoms following carbon monoxide intoxication often does not relate to admission carboxyhaemoglobin levels. Two cases are presented with severe neurological impairment despite carboxyhaemoglobin levels of 2% and 1.7% on admission to hospital, who responded well to hyperbaric oxygen therapy. In one case, symptoms recurred several days later, but responded to further hyperbaric oxygen therapy. The role of and possible mechanism of action of late hyperbaric oxygen treatment in carbon monoxide intoxication are discussed.

Hyperbaric oxygen therapy in the management of Clostridium perfringens infections.

Patients with Clostridium perfringens infections treated in Christchurch over a 14 year period to 1984 were reviewed retrospectively. Of the 46 documented cases, 21 died. Twenty-nine patients were treated with hyperbaric oxygen (HBO) therapy. Of these, nine died, whilst 12 of 17 other patients who did not receive HBO died, including five in whom the diagnosis was only made at postmortem. The clinical features and predisposing factors for clostridial infections are discussed. The importance of early vigorous treatment with a combination of surgical debridement, antibiotics and HBO to reduce the morbidity and mortality of this lethal infection is emphasised.

Effect of sterol replacement in vivo on the fatty acid composition of Tetrahymena.

The addition of ergosterol to cultures of Tetrahymena pyriformis results in (a) the accumulation of the sterol by the cells; (b) the inhibition of the synthesis of the pentacyclic triterpenoid alcohol, tetrahymanol; (c) the replacement of tetrahymanol by ergosterol in the ciliate membranes. The dry weight and lipid content of sterol-supplemented ciliates did not differ from the controls. Examination of the lipid classes revealed no change in composition except for a higher content of ergosterol in supplemented cells than tetrahymanol in control cultures. The relative proportions of triglycerides, the major classes of polar lipids, 1-alkyl phospholipids and phosphonolipids, appeared unaltered. A complex array of fatty acids is found in this ciliate. Several acids not reported previously in this organism were isolated and identified, and the novel fatty acid 18:2 delta 6, 11, was found in substantial amounts. Ergosterol supplementation altered the proportions of the fatty acids, although not all lipid classes were affected to the same extent. The changes noted were of three general types: (a) a shortening of the fatty acyl chain length in the acids of the normal series; (b) a lowering in the degree of unsaturation; (c) a discrimination between two isomers of lionoleate, 18:2 delta 6, 11 and 18:2 delta 9, 12. The former is elevated in the presence of ergosterol while the latter is depressed. Each class of polar lipids has a distinctive fatty acid composition. Among the glycerophospholipids, cardiolipin and phosphatidylcholine were least affected, while the mixture of 1-alkyl-2-acyl-sn-glycero-3-(2-aminoethyl)-phosphonate and 1,2-diacyl-sn-glycero-3-(2-aminoethyl)-phosphonate was most markedly altered. Sphingolipid fatty acid composition was influenced by ergosterol supplementation. Two changes were noted: (a) a reduction in the length of the hydrocarbon chain; (b) an increase in the proportion of alpha-hydroxy acids. The impact of ergosterol on the fatty acid composition of the polar lipids may be on fatty acid biosynthesis, on incorporation of fatty acids, or on the turnover rates of the fatty acyl groups. Ergosterol is concentrated in the ciliary (limiting) membrane, as are the polar lipids most affected. This localization allows the speculation that the change in fatty acid composition may be related to the maintenance of optimal membrane properties upon the introduction of the sterol.