Undersea Hyperbar M
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Undersea Hyperbar M · Jan 1999
Electroencephalography and magnetic resonance imaging after diving and decompression incidents: a controlled study.
Electroencephalography and magnetic resonance imaging after diving and decompression incidents: a controlled study. Undersea Hyper Med 1999.; 26(2):61-65.--Diving incidents with symptoms of decompression sickness (DCS) and/or arterial gas emboli (AGE) might increase the degree of pathologic change in the electroencephalogram (EEG) or magnetic resonance imaging (MRI) of the supraspinal central nervous system (CNS). Diving itself, even without known symptoms of DCS and/or AGE, has been proposed to increase the number of CNS lesions using either EEG or MRI. ⋯ The results of MRI do not verify evidence of increased numbers of CNS lesions in normal divers as compared to non-diving, healthy control subjects, whereas some of the divers treated for DCS in a pressure chamber had hyperintense lesions in brain white matter. None of them had any abnormalities in EEG, neurologic performance, or psychologic behavior. Both EEG and MRI are sensitive and non-specific methods for judging suspected evidence of brain lesions from diving or diving accidents.
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Undersea Hyperbar M · Sep 1997
Clinical Trial Controlled Clinical TrialAlterations in pharmacokinetics of carboxyhemoglobin produced by oxygen under pressure.
The pharmacokinetic effect of elevated oxygen partial pressures in the elimination of carboxyhemoglobin (COHb) by O2 administration was studied in an inflatable hyperbaric chamber. A double crossover prospective analysis between the modified Gamow bag and non-rebreather (NRB) mask O2 was conducted among 12 healthy, adult volunteers who smoked five cigarettes sequentially within a 60-min period. COHb levels were measured using co-oximetry before and after smoking. ⋯ Both zero and first order elimination kinetics were tested and the model of best fit determined using the Akaike Information Criterion for each subject. A significant shift in COHb elimination from a zero to first order mechanism with elevation in O2 partial pressure was observed (P = 0.002; McNemar's test). HBO2 provides a pharmacokinetic advantage over NRB mask O2 in eliminating mild carboxyhemoglobinemia.
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Undersea Hyperbar M · Jan 1997
Pharmacologic modulation of pulmonary vascular permeability during air embolism.
Pulmonary air embolism induces the generation of vasoactive and cytotoxic substances leading to lung injury. In the present study we investigated, in isolated and perfused rat lungs, the involvement of arachidonic acid metabolites in the alterations of vascular pressure, lung water content, and the filtration coefficient (Kf). We also tested the effects of a beta-agonist, a calcium channel blocker, and a cyclo-oxygenase inhibitor on the hemodynamic and the permeability changes following pulmonary air embolism. ⋯ These interventions did not alter the hemodynamic responses, except for the isoproterenol infusion, which shortened the half-time (T1/2) for pressure recovery after ending air infusion compared to the group with air embolism alone. Our results showed that indomethacin prevented vascular permeability increase and reduced pulmonary edema, suggesting that the cyclo-oxygenase products partially mediate the lung injury following air embolism. Furthermore, isoproterenol and nifedipine prevented or reduced the permeability increase, suggesting that alterations of the intracellular cAMP and cytosolic Ca2+ level play an important role in the pathophysiology of pulmonary air embolism.
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Undersea Hyperbar M · Mar 1996
Reduction of decompression illness risk in pigs by use of non-linear ascent profiles.
An established swine model of neurologic decompression illness (DCI) was adapted to investigate the influence of no-stop ascent profile shape on DCI risk after deep air and heliox dives. Pigs underwent a simulated air dive in a dry chamber to 200 fsw (613 kPa) for 24 min bottom time. They were then decompressed at either a linear rate of 20 fsw/min (61 kPa/min) or on a non-linear, fast-deep/slow-shallow profile. ⋯ Moderate or severe skin DCI affected 16/20 of the linear group compared to 3/20 of the fast/slow group (P = 0.0002). The study findings suggest that substantial reductions in DCI risk may be obtainable by manipulating the ascent profile after deep no-stop diving. This finding has potential application in both military and civil diving operations.