Acetazolamide (A) is a potent inhibitor of carbonic anhydrase. It has been shown to be efficacious in preventing acute mountain sickness as well as decreasing the O2 desaturation that occurs during sleep in individuals with chronic mountain sickness who live at altitude. Very little data, however, are available about its effect on exercise. We studied six healthy males in a double-blind cross-over design using acetazolamide and placebo (P) during normoxic and hypoxic (fractional inspired O2 = 0.118) progressive work exercise to exhaustion on a bicycle ergometer. A metabolic acidosis was documented in all subjects on A (P less than 0.045). Before exercise, subjects on A had 2.0 and 3.5 l/min increase in minute ventilation (VE) during normoxia (P = not significant) and hypoxia (P less than 0.005), respectively, and a 2.2% increase in arterialized O2 hemoglobin saturation (SaO2) during hypoxia. During normoxic and hypoxic exercise, VE/kpm and SaO2/kpm were significantly higher while the respiratory exchange ratio (R) was significantly lower on A. These effects were greater on hypoxia. During normoxia, maximal O2 consumption (1/min) was lower on A [3.1 +/- 0.4 (A) vs. 3.8 +/- 0.2 (P), P less than 0.025] and higher during hypoxia on A[2.6 +/- 0.7 (A) vs. 2.4 +/- 0.1 (P), P less than 0.05]. The increase in exercise VE on A may result in an increased alveolar and subsequent arterial O2 tension which may be important for exercise at altitude. Carbonic anhydrase inhibition may also affect CO2 transport in the lung, which may explain the lower R.

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Acalculous cholecystitis is difficult to diagnose by clinical means or contrast radiography. Because sonography and cholescintigraphy have both been shown to do well in the diagnosis of calculous cholecystitis, the sensitivity of these newer imaging methods was assessed retrospectively in 33 proven cases of acalculous cholecystitis. The sensitivities to acalculous cholecystitis for sonography (67%) and for cholescintigraphy (68%) were not as high as has been reported for these tests in calculous cholecystitis. Reasons for the lower sensitivfty with each test and the pathogenesis of acalculous cholecystitis are discussed. Acalculous cholecystitis is chronic or acute gallbladder wall inflammation in the absence of biliary stones. This disease makes up 5%-i 5% of all cholecystitis [i,

A new method of measuring cerebral atrophy using a ratio of brain parenchyma to ventricular and subarachnoid space is described. It uses digitized brain CT. This ratio was measured prospectively on 117 consecutive elderly patients referred for evaluation of cognitive dysfunction. Diagnosis was determined by preestablished criteria and confirmed by follow-up. Despite the improved accuracy and reproducibility of this method, its ability to differentiate persons with senile dementia of the Alzheimer's type (SDAT) from those suffering from pseudodementia was confounded by age, and was hence of limited utility. We conclude that even with sophisticated measures of cerebral atrophy, CT is unable to discriminate among common causes of cognitive dysfunction in the elderly.

In a multicenter, randomized clinical trial, we assessed the early neurologic development of 93 children born prematurely whose heart rates were monitored electronically during delivery and compared it with that of 96 children born prematurely whose heart rates were periodically monitored by auscultation. All the children were singletons with cephalic presentation, and all weighed less than or equal to 1750 g at birth. The mental and psychomotor indexes of the Bayley Scales of Infant Development (standardized mean score +/- SD, 100 +/- 16) and a formal neurologic examination were administered at three follow-up visits (at 4, 8, and 18 months of age, corrected for gestational age). At 18 months, the mean mental-development scores in the groups receiving electronic fetal monitoring and periodic auscultation were 100.5 +/- 2.4 and 104.9 +/- 1.8, respectively (P greater than 0.1). The mean psychomotor-development scores in the two groups at 18 months were 94.0 +/- 2.4 and 98.3 +/- 1.8, respectively (P greater than 0.1). The incidence of cerebral palsy was higher in the electronically monitored group--20 percent as compared with 8 percent in the group that was monitored by auscultation (P less than 0.03). In the electronic-fetal-monitoring group (but not in the periodic-auscultation group), the risk of cerebral palsy increased with the duration of abnormal fetal-heart-rate patterns, as assessed by retrospective review (chi 2 trend = 12.71, P less than 0.001). The median time to delivery after the diagnosis of abnormal fetal-heart-rate patterns was 104 minutes with electronic fetal monitoring, as compared with 60 minutes with periodic auscultation. We conclude that as compared with a structured program of periodic auscultation, electronic fetal monitoring does not result in improved neurologic development in children born prematurely.