Nonocclusive intestinal ischemia: improved outcome with early diagnosis and therapy.

Nonocclusive intestinal infarction (NOII) is described as bowel necrosis at celiotomy or autopsy without evidence of thromboembolism, vasculitis, or mechanical obstruction. The mortality for this entity is as high as 90 per cent in some series. From January 1990 to January 1995, we identified 15 patients who met the criteria for NOII identified at celiotomy or autopsy. We collected data on demographics, comorbidities, presenting signs and symptoms, laboratory workup, time to definitive therapy, and outcome. Our goal was to improve our ability to identify and treat this devastating surgical problem. There was a 4.5:1 female to male ratio, and patients had an average age of 73 +/- 10 years. Significant comorbidities included coronary artery disease (87%) and atrial fibrillation (73%). Eleven patients were diagnosed at celiotomy and four at autopsy. Overall mortality was 67 per cent. The most common presenting symptoms were abdominal pain (93%) and distention (80%) and mental status changes (60%). Peritonitis was less common, present in only 40 per cent of the patients. Leukocytosis, bandemia, increased creatinine, metabolic acidosis, and hypoxemia were common among all patients. There was a significant difference in time to definitive therapy in survivors versus nonsurvivors (1.2 +/- 0.89 vs 4.8 +/- 2.0 days; P < 0.02, t test). These data suggest that NOII is a lethal surgical problem. A history of coronary artery disease and atrial fibrillation was common among all patients. Various nonspecific presenting signs, symptoms, and laboratory values are suggestive of this diagnosis. A high index of suspicion in select patients and early intervention may lead to improved outcome.

Monitoring of comprehension: the role of text difficulty in metamemory for narrative and expository text.

The effect of text difficulty on metamemory for narrative and expository text was investigated. In Experiment 1, we found an interaction between type of text and type of question (thematic or detailed). For readers of narrative texts, correlations between predicted and actual performance were highest for detailed questions, but this pattern was reversed for readers of expository texts. Next, text difficulty was explored as a possible factor affecting metamemory accuracy. In Experiments 2 and 3, metamemory accuracy was a nonmonotonic function of text difficulty. Subjects made remarkably accurate predictions of future performance (mean G > .6) for both narrative and expository texts that were of intermediate difficulty (approximately a 12th-grade reading level). We propose an optimum effort hypothesis, predicting greatest metamemory accuracy when the texts are of intermediate difficulty.

Physiological responses to maximal treadmill and handweighted exercise.

The purpose of this investigation was to compare the peak physiological responses among four protocols that employed different amounts of handweighted exercise in 16 males (aged 26.3 +/- 4.1 years). The four protocols were (a) uphill treadmill running (UR; 3.36 m.s-1, 2.5% grade increase-3 min-1); (b) uphill treadmill walking while pumping 1.36-kg handweights (HW) (UWHW; 1.79 m.s-1, 5.0% grade increase x 3 min-1; (c) treadmill walking while pumping .91-kg HW (WHW; 1.79 m.s-1, 0% grade, .91-kg HW increase x 3 min-1); and (d) standing in place and pumping HW (SHW; arm work as described in WHW). It was hypothesized that the peak responses would be inversely proportional to the estimated muscle mass activated (i.e., UR = UWHW > WHW > SHW). Dependent variables included peak oxygen uptake (VO2 peak), peak heart rate (HRpeak), peak ventilation (Ve peak), and peak respiratory exchange ratio (RERpeak). No differences were noted between UR and UWHW with respect to any of the dependent variables. All variables (except RERpeak) were greater (p < .01) in UR and UWHW than either WHW or SHW. RERpeak was greater (p < .01) in UR and UWHW than in WHW. VO2 peak and HRpeak were greater (p < .01) in WHW when compared to SHW. Mean VO2 peak was 97.5, 69.7, and 60% of UR for UWHW, WHW, and SHW, respectively. Therefore, walking and pumping handweights provides a maximal stimulus to the oxygen transport system.

Peripheral thermal responsivity to facial cooling during sleep.

A recently developed technique for examining thermal sensitivity during sleep was used to assess whether skin and core temperature responses to thermal stimulation were altered by sleep state. The technique was designed to probe thermal responsivity without altering core body temperature or inducing awakening. Twenty-seven young men and women were studied during a sleep deprivation night and a sleep night three nights later. Cold water stimulation of the face alternated with an equal period of rewarming across a 40-min cycle throughout the night. Skin temperature from the finger and rectal temperature were continuously assessed. Sleep continuity and architecture were largely uninfluenced by the thermal stimulation. Finger skin temperature decreased during cold facial stimulation in both sleep and waking states. Skin temperature changes during sleep were approximately one-fifth the magnitude of those during waking. Core temperature was minimally influenced. REM sleep was associated with a greater amplitude decrease in finger temperature than was non-REM (NREM) sleep. The results support the utility of the technique as a probe of thermal responsivity during sleep and suggest a reduction of thermal responsivity during sleep and, more tentatively, an altered responsivity during REM versus NREM sleep.