Short oxygen prebreathe periods reduce or prevent severe decompression sickness in a 70-kg swine saturation model.

Disabled submarine (DISSUB) survivors are expected to achieve saturation with inert gas. However, rescue procedures may not accommodate staged decompression, raising the potential for severe decompression sickness (DCS). Alternatives to standard recompression therapy are needed. It has been demonstrated in humans that isobaric oxygen "prebreathing" (OPB) can accelerate decompression in a DISSUB scenario. In-70 kg swine saturated at 2.82 atm absolute (ATA), 1 h of OPB eliminated death and reduced severe DCS. We hypothesized that even shorter periods (<1 h) of OPB before no-stop decompression from saturation at 2.82 ATA could reduce the incidence of DCS in a large animal model. Catheterized Yorkshire swine (68.8 +/- 1.7 kg) in individual Plexiglas boxes within a large animal hyperbaric chamber were compressed to 2.82 ATA for 22 h. Following saturation and while still at depth, breathing gas was switched to >95% O(2) for 45 min (OPB(45)), 15 min (OPB(15)), or 5 min (OPB(05)) of OPB, or no OPB (control). The chamber was then decompressed without stops (0.91 ATA/min). Observers then entered the chamber and recorded signs of DCS for 2 h. All OPB periods significantly reduced the risk of developing type II DCS. OPB(45) eliminated severe DCS. Controls had a 2.5 times greater risk of developing type II DCS than OPB(05) (P = 0.016). OPB(45) and OPB(15) significantly reduced type I DCS compared with controls. These results support the potential of OPB as an alternative to staged decompression and that OPB could be expected to improve outcome in a DISSUB rescue scenario.

The effects of Donepezil on traumatic brain injury acute rehabilitation outcomes.

PRIMARY OBJECTIVE: To evaluate the effects of administering Donepezil during inpatient rehabilitation for individuals with TBI. RESEARCH DESIGN: Retrospective, age and injury severity matched, mixed between-within subjects analysis. METHODS AND PROCEDURES: Thirty-six patients with moderate-to-severe TBI admitted to acute rehabilitation within 90 days of injury. Main outcome measures included FIM cognitive total scores and rehabilitation lengths of stay. INTERVENTION: Initiation of Donepezil administration beginning at 5 mg daily. Dose titration and continuation based on perceived clinical response. MAIN OUTCOMES AND RESULTS: No differences in cognitive improvement were observed between the Donepezil treatment group and the matched control group. Sub-set analyses suggested that administration of Donepezil early in the rehabilitation stay was significantly related to higher rates of cognitive improvement. CONCLUSIONS: Preliminary evidence suggests that Donepezil administration early in the rehabilitation stay may have advantageous treatment effects. A prospective, randomized, placebo-controlled clinical trial with standard timing, dosage and treatment duration is recommended to further evaluate treatment efficacy.

Effects of lovastatin and pravastatin on cognitive function in military aircrew.

BACKGROUND: As evidence has accumulated for the role of HMG-CoA reductase inhibitors in the primary prevention of coronary artery disease, younger individuals with no other co-morbid conditions will be increasingly exposed to these agents. Some HMG-CoA reductase inhibitors have been reported to cause impairment of daytime cognitive processes that have the potential to directly impact the ability of pilots and other aircrew to perform. These studies suggested that there might be cognitive effects of these medications that would argue against their routine use in populations whose activities required high, sustained levels of cognitive performance. The objective of this study is to establish the effects of pravastatin and lovastatin on aircrew daytime cognitive function using tests that are correlated with actual cockpit tasks and inflight performance. METHODS: Military aircrew with hypercholesterolemia were enrolled in the study and assigned to lovastatin, pravastatin or placebo groups. Baseline cognitive and vigilance testing was performed with computerized test instruments. Following a 4-wk treatment period, subjects were retested on both cognitive and vigilance tasks. RESULTS: Laboratory studies confirmed that both medications were effective in lowering cholesterol. No major treatment-related side effects were encountered. Cognitive performance was not affected by either active treatment, and was not different from that of the placebo group. CONCLUSIONS: The tested medications did not have significant effects on performance as measured by two computerized performance tests. The data suggest that neither medication has significant effects on flight-related performance.