Hipotermia no intencionada y su repercusión en la morbilidad posoperatoria / Inadvertent hypothermia and its repercussion on postoperative morbidity

Introducción: la anestesia disminuye los mecanismos conductuales y fisiológicos de la termorregulación, lo que unido a la pérdida de calor en el acto quirúrgico, logra un impacto significativo en la aparición de hipotermia, Objetivo: describir la repercusión posoperatoria de la hipotermia no intencionada en pacientes que recibieron anestesia general para cirugía abdominal mayor, Métodos: se realizó estudio descriptivo, prospectivo y longitudinal en pacientes que requirieron anestesia general para procederes quirúrgicos abdominales electivos, en el Hospital Clínico Quirúrgico Hermanos Ameijeiras, en el período comprendido entre enero de 2012 y enero de 2015, Resultados: de los 114 pacientes, 80,7 % tenían entre 40 y 59 años, El sexo masculino, los pacientes normopeso, la clasificación ASA II y la laparotomía exploradora presentaron mayor frecuencia, La temperatura basal media fue de 36,45ºC, Una hora después disminuyó a 35,73 ºC, a las dos horas 35,18 ºC, a las tres horas 34,67ºC y al finalizar 34,30 ºC. Del total, presentaron hipotermia intraoperatoria no intencionada 69,3 %, En ninguno se constató hipotermia severa, El tiempo quirúrgico promedio fue de 4,18 horas en pacientes con hipotermia, El 72,2 % de los transfundidos presentaron hipotermia, Se verificaron 113 complicaciones, asociadas a hipotermia, Conclusiones: la frecuencia de hipotermia fue 2,25 veces más frecuente, Las transfusiones, el no uso de medidas preventivas de hipotermia, así como el tiempo quirúrgico influyeron significativamente en la presencia de hipotermia, Las complicaciones posoperatorias atribuibles a la presencia de hipotermia intraoperatoria se asociaron en 99,1 % de complicaciones,.

Lack of integrative control of body temperature after capsaicin administration

BACKGROUND: Body temperature is usually regulated by opposing controls of heat production and heat loss. However, systemic administration of capsaicin, the pungent ingredient of hot peppers, facilitated heat production and heat loss simultaneously in rats. We recently found that the capsaicin-induced heat loss and heat production occur simultaneously and that the biphasic change in body temperature is a sum of transient heat loss and long-lasting heat production. Moreover, suppression of the heat loss response did not affect capsaicin-induced heat production and suppression of heat production did not affect capsaicin-induced heat loss. These observations suggest the independent peripheral mechanisms of capsaicin-induced thermal responses. Thus, the capsaicin-induced thermal responses apparently lack an integrated control. METHODS: Male Wistar rats were maintained at an ambient temperature of 24 1 degrees C on a 12 h on-off lighting schedule at least for two weeks before the experiments. They were anesthetized with urethane (1.5 g/kg, i.p.) and placed on a heating pad, which was kept between 29 and 30 degrees C. Skin temperature(Ts) was measured with a small thermistor, which was taped to the dorsal surface of the rat's tail, to assess vasoactive changes indirectly. Colonic temperature(Tc) was measured with another thermistor inserted about 60 mm into the anus. O2 consumption was measured by the open-circuit method, and values were corrected for metabolic body size (kg0.75). Capsaicin (Sigma) was dissolved in a solution comprising 80+ACU- saline, 10+ACU- Tween 80, and 10+ACU- ethanol, and injected subcutaneously at a dose of 5 mg/kg. Each rat received a single injection of capsaicin because repeated administration of capsaicin renders an animal insensitive to the subsequent administration of capsaicin. Laminectomy was performed at the level of the first and second cervical vertebrae to expose the cervical spinal cord for sectioning. The brain was transected at 4-mm rostral from the interaural line with an L-shaped knife. RESULTS: After administration of capsaicin, O2 consumption increased from 13.5 0.4 mL/min/kg0.75 at 0 min to a peak of 15.9 0.4 mL/min/kg0.75 at 71 min and gradually declined but remained higher than the basal value until the end of the 4-h observation period. Ts also immediately increased from 27.7 0.2 degrees C to 31.9 0.3 degrees C at 39 min, and it returned to the baseline level within 90 min after the capsaicin administration. Tc initially decreased from 37.1 0.1 degrees C to 36.8 0.2 degrees C at 43 min and then gradually increased over the baseline level and remained at 37.6 0.2 degrees C until the end of the experiment. In spinalized rats, the capsaicin-induced increases in O2 consumption was largely attenuated, while the basal O2 consumption was similar to that of control rats. The basal Ts of spinalized rats was 32.4 0.3 degrees C, which was higher than that of control rats. Capsaicin increased Ts by less than 1 degree C, and Tc did not change after the capsaicin administration. O2 consumption of decerebrated rats was statistically higher than that of control rats after the injection of capsaicin. However, capsaicin did not increase Ts, showing a lack of a vasodilatory response. Decerebration between the hypothalamus and midbrain prevented the capsaicin-induced heat loss but not the heat production response. CONCLUSION: These results show that the capsaicin-induced heat production and heat loss are controlled separately by the brainstem and by the forebrain, respectively, and suggest that the body temperature regulation is performed without an integrative center.

A Study in the Comparison of Body Temperature Change between General Anesthesia and Epidural Anesthesia / 대한마취과학회지

BACKGROUND: Core hypothermia after induction of anesthesia results from an core-to-peripheral redistribution of body heat and a loss of body heat to environment. The purpose of this study is finding body temperatures during operation by either general of epidural anesthesia and evaluates content of total body heat. METHODS: We measured tympanic membrane temperature, 4 point skin temperature (mid calf, mid thigh, upper extremity, nipple). And we calculate mean skin temperature, mean body temperature, total body heat content changes based on tympanic membrane temperature and 4 point skin temperature. RESULTS: Tympanic membrane temperature of the first group decreased significantly after 10 minutes of induction (p<0.005), the second group decreased after 45 minutes of induction. Although upper extremity temperature has continuously increased as time passed, there was no significant difference in both group. Lower extremity temperature has significantly increased after 30 minutes of induction in the first group, and the second group has significantly increased after 10 minutes of induction (p<0.05). Mean skin temperature hasdecreasd temperaturily in both group after 10 minutes of induction and increased as time passed. Mean body temperature of the first group has significantly decreased after 10 minutes of induction (p<0.05) and second group has no significant changes. Total body heat content has continuously decreased after induction with no significance. CONCLUSIONS: General anesthesia reveals more significant decrease than epidural anesthesia. Both groups show significant decrease of body temperature after induction. We think that we need to close attention to temperature changes after induction for preventing possible side effects due to core hypothermia.

The effect of measures minimizing body heat loss on the prevention of neonatal hypothermia in the delivery room.

The prospective study was undertaken to observe the pattern of fall in the rectal temperature that occurred in neonates after birth and to determine the birth rectal temperature, the relationship of birth temperature between mothers and babies and the effect of measures minimizing body heat loss on the prevention of neonatal hypothermis in the delivery room. The measure given were placing a radiant warmer close to the mother’s lower extremities to provide a higher thermal environment for the neonate before the anticipated time of delivery, drying the neonate immediately after birth with a prewarmed dry towel, placing it under a preheated overhead rediant warmer from the time it was moved to the bathing area to the time being transferred to the nursery. Rectal temperatures were taken immediately after birth, immediately transferred to the bathing area, after cleaned and on admission to the nursery. Three groups, each of 37 infants, of term infants with normal deliveries and with Apgar scores of > 8 were studied. Infants in group 1 receiving routine care provided in the delivery room were observed for the fall in the rectal temperature. Those in group 2 and 3 were studied to evaluate the effect of measures minimizing body heat loss on the prevention of hypothermia: group 2 received only routine care; group 3 received both routine care and the measures minimizing heat loss. The mean birth rectal temperature was 37.6+0.5 oC (range 36.7 – 39.1). The correlation coefficient of the relationship between the birth and temperatures of mothers and babies was 0.61 (p = 0.01). Under routin care newborns lost heat rapidly at birth and during the period they were in the delivery room. Washing soon 5 – 20 minutes after birth caused a rapid fall in body temperature. By 18.7 mins after birth the mean rectal temperature was 36.4 oC and at a mean age of 68.5 mins 95% of the neonates had hypothermia. Swaddling neonates with towel could not prevent body heat loss. The fall in body temperature that occurred in group 3 was significantly less when compared to group 2 and non in group 3 suffered from hypothermia. This study demonstrates that efforts to limit heat loss should be concentrated immediately after birth and on the practice of cleaning neonates in the delivery room. Measures minimizing heat loss can effectively prevent hypothermia in the dilvery room.

The effect of environment temperature on thermal regulation during prolonged exercise. From the standpoint of individual variation / 体力科学

The purpose of this study was to investigate the possible individual difference in temperature regulating ability during identical relative exercise load under various temperature environments.<BR>Seven healthy males, aged 21 to 26 years, performed bicycle ergometer exercise of 60% VO<SUB>2</SUB>max for 60 minutes. All exercises were carried out in a climatic chamber under the conditions of 15°C (RH=70%), 25°C (RH=55%) or 35°C (RH=45%) . Herat rate, O<SUB>2</SUB> consumption, pulmonary ventilation, rectal temperature, mean skin temperature, local sweat rate at the lower part of scapula and total sweat rate were determined intermittently through the experiments. Moreover, heat loss by evaporation, radiation, convection and effective sweat rate was calculated using the heat valance equations.<BR>The results obtained are as follows :<BR>1. The increase in rectal temperature at the end of exercise was almost identical in 15°C and 25°C but significantly higher in 35°C.<BR>2. A significant positive correlation was observed between mean skin temperature (ΔTsk) at the end of exercise and effective sweat rate (r=0.468, p<0.05) during exercise.<BR>3. Inspite of the equality of relative exercise intensity (60%VO<SUB>2</SUB>max), marked individual variations were observed in rectal temperature during exercise.<BR>4. The subjects who showed marked increase in rectal temperature during exercise showed less marked increase in mean skin temperature in 15°C and 25°C and less marked increase in local sweat rate in 35°C than other subjects.<BR>It would be concluded that the main cause of individual variation in rectal temperature during exercise depends on difference in evaporative heat loss in hot environment and difference in skin temperature in mild or cold environment.