Effect of Prewarming during Induction of Anesthesia on Microvascular Reactivity in Patients Undergoing Off-Pump Coronary Artery Bypass Surgery: A Randomized Clinical Trial

BackgroundGeneral anesthesia may induce inadvertent hypothermia and this may be related to perioperative cardiovascular complications. Microvascular reactivity, measured by the recovery slope during a vascular occlusion test, is decreased during surgery and is also related to postoperative clinical outcomes. We hypothesized that microvascular changes during surgery may be related to intraoperative hypothermia. To evaluate this, we conducted a randomized study in patients undergoing off-pump coronary artery bypass surgery, in which the effect of prewarming on microvascular reactivity was evaluated.MethodsPatients scheduled for off-pump coronary artery bypass surgery were screened. Enrolled patients were randomized to the prewarming group to receive forced-air warming during induction of anesthesia or to the control group. Measurement of core and skin temperatures and vascular occlusion test were conducted before anesthesia induction, 1, 2, and 3 h after induction, and at the end of surgery.ResultsIn total, 40 patients were enrolled and finished the study (n = 20 in the prewarming group and n = 20 in the control group). During the first 3 h of anesthesia, core temperature was higher in the prewarming group than the control group (p p = 0.004). However, tissue oxygen saturation and changes in recovery slope following a vascular occlusion test at 3 h after anesthesia induction did not differ between the groups. There was no difference in clinical outcome, including perioperative transfusion, wound infection, or hospital stay, between the groups.ConclusionsPrewarming during induction of anesthesia decreased intraoperative hypothermia, but did not reduce the deterioration in microvascular reactivity in patients undergoing off-pump coronary artery bypass surgery.Trial RegistrationClinicalTrials.gov NCT02186210【背景】全身麻醉可引发意外低体温，该情况或与围手术期心血管并发症相关。通过血管闭塞试验（vascular occlusion test）恢复斜率评估的微血管反应性，在手术过程中会出现降低，且与术后临床转归密切相关。我们提出假说：手术过程中的微血管变化或与术中低体温存在关联。为验证该假说，我们针对接受非体外循环冠状动脉旁路移植术（off-pump coronary artery bypass surgery）的患者开展了一项随机对照研究，旨在评估术前预热（prewarming）对微血管反应性的影响。 【方法】对拟接受非体外循环冠状动脉旁路移植术的患者进行筛查入组。符合条件的患者被随机分为两组：术前预热（prewarming）组与对照组。术前预热组在麻醉诱导期间接受强制空气升温（forced-air warming）干预，对照组则不接受相关升温措施。分别于麻醉诱导前、诱导后1、2、3小时以及手术结束时，测量患者的核心体温与皮肤温度，并实施血管闭塞试验。 【结果】共计40例患者完成本研究（术前预热组与对照组各20例）。麻醉诱导后的前3小时内，术前预热组患者的核心体温显著高于对照组（p=0.004）。然而，麻醉诱导后3小时的组织氧饱和度以及血管闭塞试验后的恢复斜率变化，两组间并未出现显著差异。两组患者的围手术期输血、切口感染、住院时长等临床转归指标均无显著差异。 【结论】麻醉诱导期间实施术前预热可有效减轻非体外循环冠状动脉旁路移植术患者的术中低体温，但未能改善该类患者的微血管反应性恶化情况。 【试验注册】ClinicalTrials.gov NCT02186210