Thermosensitivity is reduced during fever induced by Staphylococcus aureus cells walls in rabbits

Thermosensitivity (TS) and threshold core temperature for metabolic cold defence were determined in six conscious rabbits before, and at seven different times after i.v. injection of killed Staphylococcus aureus (8⋅10⁷ or 2⋅10⁷ cell walls⋅kg⁻¹) by exposure to short periods (5–10 min) of body cooling. Heat was extracted with a chronically implanted intravascular heat exchanger. TS was calculated by regression of metabolic heat production (M) and core temperature, as indicated by hypothalamic temperature. Threshold for cold defence (shivering threshold) was calculated as the core temperature at which the thermosensitivity line crossed preinjection resting M. The shivering thresholds followed the shape of the fever response. TS was significantly reduced (up to 49%) during the time course of fever induced by the highest dose of pyrogen only. At both high and low doses of pyrogen TS correlated negatively with shivering threshold (r = 0.66 and 0.79 respectively) with similar slopes. The reduction in TS during fever was thus associated with the increase in shivering threshold resulting from the pyrogen injection and not by the dose of pyrogen. Model considerations indicate, however, that changes in sensitivity of the thermosensory input to the hypothalamic controller may affect threshold changes but cause negligible TS changes. It is more likely that the reduction in TS is effected in the specific hypothalamic effector pathways. Received: 25 August 1995/Received after revision: 27 November 1995/Accepted: 30 November 1995     

Fetal sheep temperatures in utero during cooling and application of triiodothyronine,norepinephrine, propranolol and suxamethonium

Fetal sheep (n=13) were chronically instrumented to measure temperatures in the maternal femoral artery (MAT), the amniotic fluid (AFT), the fetal brown adipose tissue (BFT) and the fetal arterial blood (DAT). Cooling loops were inserted into the amniotic cavity. In 4 fetuses osmotic minipumps delivering triiodothyronine (T3) were implanted subcutaneously. One to seven days after surgery the following results were obtained: 1) During control DAT was 0.59±0.2°C (SD), BFT 0.60±0.24°C and AFT 0.38±0.31°C higher than MAT. T3 levels in treated fetuses were 3.4±1.5 g/l. 2) Infusion of norepinephrine (NE) (5.2±0.9 g/min per kg fetal body weight) with phentolamine tolamine (26.1±4.3 g/min per kg) into a fetal vein did not change temperatures. 3) During cooling (–53±15 W) MAT decreased 0.45±0.3°C, DAT 1.9±0.39°C, BFT 1.61±0.52°C and AFT 4.2±1.8°C. 4) The amniotic fluid was cooled until steady state temperatures were achieved. Then propranolol (26.1±4.3 g/min per kg) or suxamethonium (3±1 mg/kg) were introduced into the fetal vein. No consistent and significant changes of temperatures could be detected. It is concluded that 1) lowering the fetal core temperature by 1.6–1.9°C and its ambient temperature (AFT) by 4.2°C does not induce shivering or non-shivering thermogenesis suppressible by pharmacologic agents, 2) thermogenesis in fetal brown adipose tissue cannot be induced by NE (with or without supplemention of T3). In utero the fetal sheep does not respond to cold stress with an increase of heat production.Supported by Deutsche Forschungsgemeinschaft Schr 165/8-1     

蛛网膜下腔注射芬太尼对剖宫产产妇寒战的影响

目的研究蛛网膜下腔注射芬太尼对剖宫产产妇寒战的影响。方法剖宫产产妇100例,随机等分为Ⅰ组(实验组)和Ⅱ组(对照组)。选用蛛网膜下腔阻滞麻醉-硬膜外联合麻醉,于L2～3椎间隙蛛网膜下腔注入蛛网膜下腔阻滞麻醉液2·4ml,Ⅰ组蛛网膜下腔阻滞麻醉液含芬太尼20μg。记录阻滞平面、血压(Bp)、心率(HR),观察患者寒战发生情况。结果寒战发生例数Ⅰ组12例,明显低于Ⅱ组30例(P<0·01);轻度寒战Ⅰ组8例,Ⅱ组19例;重度寒战Ⅰ组4例,Ⅱ组11例。Ⅰ组明显低于Ⅱ组(P<0·01);胎儿娩出前出现寒战者Ⅰ组4例,明显少于Ⅱ组13例(P<0·01)。结论蛛网膜下腔注射芬太尼可降低剖宫产产妇胎儿娩出前寒战发生率及总发生率。     

多沙普仑 曲马多 氟芬合剂预防全身麻醉术后寒战的观察

目的探讨多沙普仑、曲马多和小剂量氟芬合剂预防全身麻醉术后寒战的效能及对呼吸循环功能的影响。方法选择ASAⅠ~Ⅱ级择期手术患者80例,随机分为4组:0.9%生理盐水组(N组)、多沙普仑组(D组)、曲马多组(T组)、氟芬合剂组(F组)。麻醉诱导:昂丹司琼0.1 mg/kg、咪唑安定0.1 mg/kg、芬太尼1~2μg/kg、维库溴铵0.1 mg/kg、依托咪酯0.2 mg/kg。麻醉维持:丙泊酚4~10 mg.kg-1.h-1持续泵入,间断追加芬太尼、维库溴铵。手术结束前10 min停药,术毕,N组注入生理盐水5 mL,D组注入多沙普仑1 mg/kg,T组注入曲马多1 mg/kg,F组注入氟芬合剂0.5μg/kg。记录注药后5、10、30 min寒战发生例数和平均动脉压(MAP)、心率(HR)、血氧饱和度(SpO2)变化值,同时记录各组的苏醒时间。结果与对照组比较,注药后103、0 min,多沙普仑组、曲马多组、氟芬合剂组寒战发生率显著下降(P<0.01),后3组相比差异无统计学意义(P>0.05);注药前后,多沙普仑组、曲马多组MAP、HR无显著变化(P>0.05),氟芬合剂组MAP、HR有下降趋势,但差异无统计学意义(P>0.05)。注药后多沙普仑组、曲马多组、氟芬合剂组SpO2较注药前差异无统计学意义(P>0.05)。多沙普仑组与对照组、曲马多组及氟芬合剂组相比,苏醒时间明显缩短,差异有统计学意义,氟芬合剂组与对照组、曲马多组相比,苏醒时间差异无统计学意义(P>0.05)。结论多沙普仑、曲马多以及小剂量氟芬合剂可有效预防全麻术后寒战发生,且对呼吸循环功能无明显影响,小剂量氟芬合剂的应用无苏醒延迟发生。     

右美托咪定鼻内滴注对妇科腹腔镜全麻患者拔管反应和术后寒战的影响

目的探讨鼻内滴注右美托咪定对妇科腹腔镜全麻患者拔管反应和术后寒战的影响。方法选择2017年6月至2018年6月在我院妇科行全身麻醉下腹腔镜全子宫切除术的患者160例,年龄40~65岁,BMI 18~25 kg/m^2,ASAⅠ或Ⅱ级。按随机数字表法分为四组,右美托咪定0.5μg/kg组(D1组)、右美托咪定1.0μg/kg组(D2组)、右美托咪定1.5μg/kg组(D3组)和曲马多组(T组),每组40例。手术结束30 min前D1组、D2组和D3组分别经鼻滴注右美托咪定0.5、1.0和1.5μg/kg;T组经鼻滴入曲马多1 mg/kg。记录患者给药前(T0)、给药后10 min(T1)、拔管即刻(T2)、拔管后3 min(T3)的HR、BP。记录拔管时患者呛咳和躁动的发生情况。记录患者在PACU期间寒战发生情况,并对镇静情况进行评分,记录患者镇静满意度。同时记录患者在PACU期间心动过缓、恶心呕吐和皮肤瘙痒等不良反应的发生情况。结果 T1-T3时D2组和D3组HR明显慢于T组(P<0.05),T2-T3时D2组和D3组SBP和DBP明显低于T组(P<0.05)。D2组和D3组拔管时呛咳和躁动发生率明显低于D1组和T组(P<0.05)。D1组寒战发生率明显高于T组(P<0.05);D2组、D3组寒战发生率明显低于D1组(P<0.05)。D1组、D2组和D3组镇静满意率明显高于T组(P<0.05)。T组头晕、恶心呕吐和术后躁动发生率明显高于D1组、D2组和D3组(P<0.05);D3组心动过缓发生率明显高于D1组、D2组和T组。结论鼻内滴注右美托咪定可抑制妇科腹腔镜全麻患者的拔管反应,降低术后寒战的发生率,是一种值得推广的全身麻醉辅助用药方法。     

椎管内给药预防剖宫产术中寒战的Meta分析

目的 评价椎管内给药预防剖宫产术中寒战的有效性与安全性.方法 检索Cochrane图书馆、PubMed、Embase,检索时间从建库至2015年8月.收集椎管内给药预防剖宫产术中寒战的临床随机对照试验(RCTs).采用Cochrane协作网系统评价法评价纳入文献的质量,采用RevMan 5.3软件对收集的资料进行Meta分析.结果 纳入10项研究,共677例,其中试验组390例,对照组287例.与对照组比较,分别体现在芬太尼、哌替啶可减少术中寒战的发生,合并效应的比值比(odda radio,OR和95％可信区间(95％confidence interval,95％CI)为(OR =0.29,95％CI 0.14～0.59)、(OR =0.09,95％CI 0.04～0.18)、舒芬太尼椎管内给药与对照组比较,并不能减少术中寒战的发生(OR=1.74,95％CI 0.33～9.02).结论 芬太尼、哌替啶椎管内给药可有效且安全预防剖宫产术中寒战的发生,而舒芬太尼椎管内给药可能并不能减少术中寒战的发生;在椎管内给予上述药物时应注意药物相关并发症.     

术中应用积极保温措施防止剖宫产产妇低体温寒颤

目的探讨术中应用积极的保温措施对防止剖宫产产妇低体温寒颤的影响。方法选取拟行剖宫产产妇100例,随机分为保温组和对照组,每组50例。对照组术中按传统护理常规进行护理,保温组采用多种积极的综合保温措施。结果低体温寒颤发生率对照组为60%,保温组16%,两组比较差异有显著性（P〈0.05）。结论术中采取积极有效的保温措施有助于预防剖宫产产妇低体温寒颤的发生。     

Effect of low dose phenylephrine infusion on shivering and hypothermia in patients undergoing cesarean section under spinal anesthesia: a randomized clinical trial

BackgroundShivering is a common complication of spinal anesthesia. Phenylephrine, due to its peripheral vasoconstrictive effect, may limit the core to periphery redistribution of body temperature following spinal anesthesia, and reduce hypothermia and shivering. We hypothesized that prophylactic phenylephrine infusion would reduce shivering and hypothermia in women undergoing cesarean section under spinal anesthesia.MethodsA two-arm randomized, double-blind, placebo-controlled trial in term pregnant patients undergoing cesarean section. In the phenylephrine group (n=75) prophylactic phenylephrine infusion was administered at 25 µg/min immediately after initiation of spinal anesthesia and continued until the end of the operative period. In the placebo group (n=75) a normal saline infusion was administered during the same period. The primary outcome was the incidence of shivering; secondary outcomes were severity of shivering, changes in nasopharyngeal (core) temperature, and incidence of hypotension and bradycardia.ResultsThe incidence of shivering in the phenylephrine and control groups was 24.0% (95% CI 14.3% to 33.7%) and 53.3% (95% CI 42.0% to 64.6%), respectively. The severity of shivering was greater in the control group (P=0.002) and the mean (±SD) end of surgery core temperature was significantly higher in the phenylephrine group (35.84°C ± 0.60) compared with controls (35.61°C ± 0.48) (P=0.009). The incidence of hypotension was higher in controls (53.4% vs. 2.7%; P <0.001) but bradycardia more frequent in group P (P=0.023).ConclusionThe incidence of shivering and degree of hypothermia were significantly reduced by a prophylactic phenylephrine infusion during cesarean section under spinal anesthesia.     

Os efeitos do aquecimento de cristaloides sobre a temperatura corporal materna e nas condições fetais: ensaio clínico randômico

Background and objectives

Hypothermia occurs in about 60% of patients under anesthesia and is generally not managed properly during short lasting surgical procedures. Hypothermia is associated with adverse clinical outcomes. The current study is designed to assess the effects of crystalloid warming on maternal and fetal outcomes in patients undergoing elective cesarean section with spinal anesthesia.