Cognitive performance over 7 days in a distressed submarine.

BACKGROUND: This article contains the results from a psychological assessment of submariners undergoing a survival trial simulating conditions in a disabled submarine. The aim was to determine whether the environmental conditions and rations in a submarine escape compartment had any detrimental effects on cognitive performance. METHODS: The study was conducted in an environmental chamber in which the temperature fell from 22 degrees C to 4.4 degrees C over 2 d and then remained at 4.4 C for 5 d. Of the 11 subjects who were given daily rations of 100 g of barley sugar and 568 ml of water (none on day 1), only 4 remained for the full trial duration. Subjects were administered 2 psychometric tests (choice reaction time and short term memory) on hand held computers. RESULTS: Results showed that subjects did not exhibit any significant performance decrements during the experimental phase of the trial. However anecdotal evidence from observations and subjects' self reports suggest that sustained performance was impaired.

Tenoxicam does not alter renal function during anaesthesia in normal individuals.

BACKGROUND: Anaesthesia and surgery alter renal function. Inhibition of prostaglandin synthesis by non-steroidal anti-inflammatory drugs (NSAIDs) administered with anaesthesia may further compromise renal function. AIM: To study the effects of tenoxicam (NSAID) administered immediately prior to anaesthesia on renal function in normal individuals undergoing routine surgery. METHODS: A randomised single blind placebo controlled study comparing tenoxicam (40 mg intravenously) with placebo was carried out in 20 healthy (ASA I) patients undergoing lower spinal surgery. Glomerular filtration rate (GFR) was determined by creatinine clearance and renal tubular function measured as osmolar and free water clearance. RESULTS: GFR fell by 60% at the end of surgery but returned to pre-operative values by six hours post-operatively. There was no difference between placebo or tenoxicam with regard to changes in GFR. Tubular function was not altered by tenoxicam. CONCLUSIONS: Current clinical practice of using NSAIDs for post-operative analgesia in low risk individuals appears to have no adverse effects on renal function.

Cerebral perfusion and psychometric testing after exposure to high altitude in the mountains.

Exposure to hypobaric hypoxia is known to cause reductions in mental performance and decision-making and it has been reported that these effects are not fully reversed following descent from altitude. Eight climbers had cerebral perfusion scans performed and undertook a battery of psychometric tests prior to, and upon return from, an expedition to climb the eleventh highest mountain in the world, Gasherbrum 1. No decrements were found in either their performance on the psychometric tests nor to their cerebral perfusion following the expedition. Two subjects had significant cerebral perfusion abnormalities prior to the expedition, which had improved immediately following their return from the expedition. Repeat scans four months later showed the lesion of one of the subjects had returned and there were indications that the lesion in the other subject was beginning to return. These findings are in contrast to previous studies which have suggested that altitude exposure leads to permanent reductions in brain function, this could be because in those studies factors other than hypobaric hypoxia per se lead to the reductions in brain function.