The transiency of oropharyngeal colonization with gram-negative bacilli in residents of a skilled nursing facility.

To determine the duration and persistence of gram-negative bacillary (GNB) oropharyngeal colonization over a specified period and the risk of subsequent GNB pneumonia developing in nursing home patients, we prospectively cultured for 31 weeks the oropharynges of patients in a skilled nursing facility. Over a 31-week period, an average of 13.8 percent of the patients showed colonization (weekly prevalence rates ranged from 0 to 29 percent). No patient had pneumonia during the study period. We concluded that the presence of GNB in the oropharynx of our patients is transient, continually changing over an extended period, and that GNB colonization as a transient occurrence is not directly associated with an increased risk of GNB pneumonia. Our data also emphasize the limitations of previously described single-culture survey studies in predicting the importance of GNB oropharyngeal colonization.

Ethical and legal aspects of liver transplantation.

Catholic teaching on transplants derives from the principle of fraternal love, which would allow transplantation, provided no harm to the donor would result. It is based on the concept of functional integrity to guarantee that the body's systematic integrity is not destroyed. Since donating an organ is not an obligation but a choice, obtaining the donor's free, informed consent is essential. The competent donor should receive complete information concerning the transplant procedure, the prognosis, the material risks, and any alternative procedures. In the case of incompetent donors, consent of the parent or guardian usually is necessary. Some states, however, have laws that allow treatment despite parental objection. For example, the court may substitute its judgment for the incompetent patient's or may appoint a guardian. With the signing of the National Organ Transplantation Act in October 1984, the law now provides for a computer registry to speed the matching of donors and recipients. As transplant technology continues to advance and use of the organ procurement system increases, Catholic health care professionals must ensure that Christian concepts guide the resolution of transplantation's bioethical issues.

Effects of fluctuating skin temperature on thermoregulatory responses in man.

Fluctuations in the skin temperature of volunteers in water, of up to +/- 1.5 degrees C, were induced by circulating water through a tube suit at a fluctuating temperature for 80 min. Fluctuations with a cycle length of 2.5, 5.0 or 10.0 min all slowed the fall in core temperature that otherwise occurred in water at 29 degrees C, and reduced thermal comfort. Metabolic rate increased. Symmetrical fluctuations, or ramp fluctuations with either slow cooling and rapid warming phases or slow warming and rapid cooling phases, were all effective. Similar but less clear effects on core temperature were usually produced by fluctuating skin temperature in water at 25 and 33 degrees C; metabolic rate tended to increase during fluctuation in the 25 degrees C experiments, but not in the 33 degrees C experiments. Stability of the temperature of cutaneous receptors appears to be factor in insidious hypothermia produced by immersion in mildly cool water.

The influence of cold stress and a 36- h fast on the physiological responses to prolonged intermittent walking in man.

In a previous study, rectal temperature (Tre) was found to be lower, and oxygen consumption (VO2) and the respiratory exchange ratio (R) were higher in a cold (+5 degrees C), wet and windy environment (COLD), compared with a thermoneutral environment during intermittent walking at approximately 30% of peak VO2 (Weller AS, Millard CE, Stroud MA et al. Am J Physiol 272:R226-R233, 1997). The aim of the present study was to establish whether these cold-induced responses are influenced by prior fasting, as impaired thermoregulation has been demonstrated in cold-exposed, resting men following a 48-h fast. To address this question, eight men attempted a 360-min intermittent (15 min rest, 45 min exercise) walking protocol under COLD conditions on two occasions. In one condition, the subjects started the exercise protocol approximately 120 min after a standard meal (FED/ COLD), whereas in the other the subjects had fasted for 36 h (FASTED/COLD). The first two exercise periods were conducted at a higher intensity (HIGHER, 6 km x h[-1] and 10% incline), than the four subsequent exercise periods (LOW, 5 km x h[-1] and 0% incline). There was no difference in the time endured in FED/ COLD and FASTED/COLD. In FASTED/COLD compared with FED/COLD, R was lower during HIGHER and LOW, and Tre was lower during LOW, whereas there was no difference in VO2, mean skin temperature and heart rate. Therefore, although the 36-h fast impaired temperature regulation during intermittent low-intensity exercise in the cold, wet and windy environment, it was unlikely to have been the principal factor limiting exercise performance under these experimental conditions.

Physiological responses to cold stress during prolonged intermittent low- and high-intensity walking.

In a previous study [Am. J. Physiol. 272 (Regulatory Integrative Comp. Physiol. 41): R226-R233, 1997], the physiological responses to 240 min of intermittent low-intensity walking exercise in a cold (+5 degrees C), wet, and windy environment (Cold) may have been influenced by a 120-min preceding phase of intermittent higher-intensity exercise. Furthermore, the physiological responses observed during this latter phase may have been different if it had been more prolonged. To address these questions, active men attempted a 360-min intermittent (15 min of rest, 45 min of exercise) exercise protocol in Cold and a thermoneutral environment (+15 degrees C, Neutral) at a low (0% grade, 5 km/h; Low; n = 14) and a higher (10% grade, 6 km/h; High; n = 10) intensity. During Low, rectal temperature was lower in Cold than in Neutral, whereas O2 consumption, carbohydrate oxidation, plasma norepinephrine and epinephrine, and blood lactate were higher. During High, Cold had a similar but less marked influence on the thermoregulatory responses to exercise than during Low. In conclusion, the physiological responses to Low are similarly influenced by Cold whether or not they are preceded by High. Furthermore, during intermittent exercise up to an intensity of approximately 60% of peak O2 consumption, a cold, wet, and windy environment will influence the physiological responses to exercise and potentially impair performance.

Physiological responses to a cold, wet, and windy environment during prolonged intermittent walking.

The potentially deleterious influence of body cooling on the thermoregulatory and metabolic responses to prolonged walking exercise has not been established. To address this problem, 10 men completed a 6-h intermittent (15 min rest, 45 min exercise) walking protocol in a thermoneutral (+15 degrees C) condition (Neutral) and a cold (+5 degrees C), wet, and windy condition (Cold). The first two exercise periods were conducted at a higher intensity (Higher, 6 km/h and 10% incline) than the subsequent four exercise periods (Lower, 5 km/h and 0% incline). Rectal temperature was lower and heart rate no different in Cold compared with Neutral, whereas the following were higher: oxygen consumption, respiratory exchange ratio, plasma norepinephrine and epinephrine, and blood lactate and glucose. There was no environmental influence on these variables during Higher. In conclusion, heat production during Lower was not sufficient to offset heat loss to the cold environment, and the resulting reduction in rectal temperature and metabolic perturbations may be detrimental if exercise is prolonged.

Effects of dehydration, hypohydration, and hyperhydration on tolerance during uncompensable heat stress.

The present study examined the effects of dehydration from prior exercise on subsequent exercise tolerance time (TT) that involved wearing nuclear, biological, and chemical (NBC) protective clothing. It was hypothesised that TT would be reduced in the dehydrated state. Ten men undertook continuous treadmill walking at 4.8 km.h-1 at 35 degrees C and 50% relative humidity, wearing NBC clothing while euhydrated (EU) or dehydrated (D) by 2.3% of body weight. Hydration status had no impact on thermoregulatory or cardiovascular responses during exercise. Also rectal temperature at exhaustion did not differ between EU (38.52 +/- 0.39 degrees C) and D (38.43 +/- 0.45 degrees C). Exercise TT during this uncompensable heat stress was reduced significantly for D (47.7 +/- 15.3 min) compared with EU (59.0 +/- 13.6 min). It was concluded that prior exercise leading to levels of dehydration to 2.3% of body weight, together with subsequent fluid restriction during exposure to uncompensable heat stress, impaired TT while wearing the NBC protective clothing. The integration of these findings together with other comparable studies that have examined the influence of hypo- and hyperhydration on TT while wearing NBC protective clothing revealed that hydration status has less effect on TT as the severity of uncompensable heat stress increases.