The Threshold for Thermoregulatory Vasoconstriction During Nitrous Oxide/Sevoflurane Anesthesia Is Reduced in the Elderly

Abstract

Elderly patients become more hypothermic during surgery, shiver less postoperatively, and take longer to rewarm than younger patients. Similarly, the vasoconstriction threshold (triggering core temperature) is reduced approximately 1 degree C in elderly patients during nitrous oxide/isoflurane anesthesia. Accordingly, we tested the hypothesis that the vasoconstriction threshold in the elderly is also reduced approximately 1 degree C during nitrous oxide and sevoflurane anesthesia. Eleven young patients aged 30-50 yr and 14 elderly patients aged 60-80 yr were anesthetized with nitrous oxide (50%) and sevoflurane (1%). Mean skin temperature was calculated from four sites. Fingertip blood flow was estimated using forearm minus fingertip skin-temperature gradients, with a gradient of 0 degree C identifying onset of vasoconstriction. The distal esophageal temperature triggering onset of vasoconstriction identified the threshold for this thermoregulatory defense. The data from five patients who did not vasoconstrict at minimum core temperatures of 33-34 degrees C were eliminated, leaving 10 patients in each group. The vasoconstriction threshold was significantly less in the elderly (35.0 +/- 0.8 degrees C) than in younger patients (35.8 +/- 0.3 degrees C), despite similar mean skin temperatures (mean +/- SD, P < 0.01, Student's t-test). Age dependence of thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is similar to that previously observed during nitrous oxide/isoflurane anesthesia.

Risk factors for hypothermia in patients under general anesthesia: Is there a drawback of laminar airflow operating rooms? A prospective cohort study

“…Because older patients have less subcutaneous fat, lower resting muscle tone, a larger body surface area to body weight ratio, and a lower metabolic rate, their ability to effectively regulate and maintain a normal body temperature is weak, even in a non-anesthetized state. When the ambient temperature changes, thermoregulation actions (such as vasoconstriction and shivering) of the elderly are significantly weaker than those of the young [25]. Furthermore, the effect of general anesthesia weakens the thermoregulatory abilities of the body, and hypothermia is thus more likely to occur.…”

A comparison of the Effects of Intravenous Fluid Warming and Skin Surface Warming on Peri-operative Body Temperature and Acid Base Balance of Elderly Patients with Abdominal Surgery

“…역치가 성인보다 낮기 때문에 저체온이 발생할 가능성이 높 다 (Ozaki, Sessler, & Matsukawa, 1997). 수술 중 저체온은 순 환 혈중 catecholamine을 증가시켜 빈맥, 고혈압, 말초혈관 수 축, 그리고 심근의 산소 요구량 및 공급량 간에 불균형을 초 래한다 (Frank et al, 1997;Kasai et al, 2003;Lenhardt et al, 1997).…”

Factors Influencing Intra-Operative Body Temperature in Laparoscopic Colectomy Surgery under General Anesthesia: An Observational Cohort

“…It has been reported that age, pre-operative SBP, www.bionursingjournal.or.kr and heart rate influence intraoperative hypothermia in laparotomic surgery [3,4]. Advancing age decreases the responsiveness of the sympathetic nerves to hypothermia [28] and leads to incomplete thermoregulatory vasoconstriction and decreased metabolic heat production [29]. However, presently age did not influence intra-operative hypothermia during the 2 hours after pneumoperitoneum.…”