Effect of hypotensive drugs on perioperative core and peripheral temperatures.

引言：老年人在没有麻醉的情况下体温调节功能受损。此外，血管收缩和寒战阈值在老年人比年轻手术患者减少更多。从这些观察中可以预料到，老年人最容易出现围手术期低体温，也可能更容易出现低体温引起的并发症。我们最近证明了咪达唑仑在用药前会导致体温过低。在老年人中，咪达唑仑的热效应可能被夸大了。因此，我们验证了老年人在咪达唑仑预用药和全身麻醉后体温过低会加重的假设。方法：经IRB批准和知情同意，我们研究了15例年龄在20-50岁和15例年龄在65-80岁的患者。所有患者的ASA身体状态为I-II，计划进行持续3小时以上的腹部开放手术。麻醉前40 min给予咪达唑仑0.05 mg/kg。然后用异丙酚（1.5 mg/kg）和维库溴铵诱导全身麻醉。麻醉以67%的氧化亚氮和1-1.5%的潮末浓度异氟醚维持。结果：年轻患者潮末异氟烷浓度平均为1.3*0.3%，老年患者潮末异氟烷浓度平均为1.2*0.2%。老年患者咪达唑仑预用药后30、40 min的鼓膜温度明显低于年轻患者。随后，老年患者的Ttym明显低于年轻患者。结论：0.05 mg/kg咪达唑仑对年轻患者的低体温作用与我们在志愿者身上的经验一致，志愿者在0.075 mg/kg咪达唑仑后体温才显著下降。然而，值得注意的是，0.05 mg/kg可引起老年人明显的低体温。这表明动能或动力效应增加了老年患者的敏感性。随后，老年患者在手术过程中比年轻患者更容易出现体温过低的情况，这与之前的报道可能一致。我们的数据表明，老年人可能特别受益于温度监测和热管理。少

Introduction : Thermoregulatory control is impaired in the elderly without anesthesia. Furthermore, the vasoconstriction and shivering thresholds are reduced more in elderly than young surgical patients. As might be expected from these observations, the elderly are most susceptible to perioperative hypothermia, and may also be a greater risk of hypothermia-induced complications. We recently demonstrated that midazolam pre-medication causes hypothermia. It is likely that thermal effects of midazolam are exaggerated in the elderly. Accordingly, we tested the hypothesis that hypothermia would be aggravated in the elderly after midazolam premedication and during general anesthesia.Methods : With IRB approval and informed consent, we studied 15 patients aged 20-50 yr and 15 patients aged 65-80 yr. All were ASA physical status I-II and scheduled to undergo open abdominal surgery lasting more than 3 hours. The patients were premedicated with IM midazolam 0.05 mg/kg 40 min before induction of … More anesthesia. General anesthesia was then induced with propofol (1.5 mg/kg) and vecuronium. Anesthesia was maintained with nitrous oxide 67% and isoflurane at an end-tidal concentration of 1-1.5%.Results : End-tidal isoflurane concentrations averaged 1.3*0.3% in the young patients and 1.2*0.2% in the elderly ones. Tympanic membrane temperature (Ttym) 30 and 40 min after midazolam premedication was significantly lower in the elderly than young patients. Subsequently, Ttym decreased significantly more in elderly than in young patients.Conclusions : That midazolam 0.05 mg/kg caused minimal hypothermia in the young patients is consistent with our experience in volunteers in whom temperature decreased significantly only after 0.075 mg/kg. It is notable, however, that 0.05 mg/kg was caused significant hypothermia in the elderly. This indicates that kinetic or dynamic effects increased sensitivity in the older patients. The elderly patients subsequently became more hypothermic during surgery than the younger ones, as might be expected from previous reports. Our data suggest that the elderly may especially benefit from temperature monitoring and thermal management. Less