患者低流量吸入地氟醚或异氟醚的药代动力学

Pharmacokinetics of desflurane and isoflurane administered with low-flow in patients

目的比较腹部手术患者低流量吸入地氟醚或异氟醚的药代动力学。方法腹部手术患者40例,ASAⅠ级或Ⅱ级,年龄18～64岁,BMI＜35kg/m^2。随机分为2组（n=20）：地氟醚组（D组）和异氟醚组（Ⅰ组）。麻醉诱导后调节纯氧流量3L/min,术中调整挥发罐刻度,维持肺泡浓度（FA）0．8 MAC,稳定5min后纯氧流量改为1L/min。调节瑞芬太尼静脉输注速率,维持HR和BP波动幅度不超过基础值20%。手术结束时,停止吸入地氟醚或异氟醚,同时吸入纯氧3L/min。记录设定的吸入麻醉药浓度（FD）、吸入麻醉药浓度（FI）、FA/FI=1/2时间、FA/FAO=1/2时间（FAO为关闭挥发罐即时的肺泡浓度）,并计算各时点FA/FI、FA/FD。结果D组FA/FI=1/2时间及FA/FAO=1/2时间均较Ⅰ组缩短（P＜0．05）。低流量麻醉下,D组FD稳定,Ⅰ组FD波动较大。D组FA/FI、FA/FD上升速率较Ⅰ组快,且同一时点各比值D组均高于Ⅰ组。结论与异氟醚比较,腹部手术患者低流量吸入地氟醚时达到预定的肺泡浓度更迅速,可控性好,停止吸入时排泄较快。

Objective To compare the pharmacokinetics of desflurane and isoflurane administered to maintain anesthesia for elective abdominal surgery and to determine if desflurane is more suitable for low-flow anesthesia than isoflurane. Methods Forty ASA Ⅰ or Ⅱ patients aged 18-64 yr undergoing elective abdominal surgery were randomly divided into 2 groups （ n = 20 each） ： desflurane group （D） and isoflurane group （I）. Anesthesia was induced with midazolam 0.02 mg/kg, fentanyl 1 μg/kg, propofol 1.5 mg/kg and rocuronium 0.6 mg/kg. The patients were intubated and mechanically ventilated. Anesthesia was maintained with desflurane or isoflurane. The concentration of desflurane delivered by vaporizer （ FD ） was initially set at 6 % and isoflurane at 2% and fresh gas flow （FGF, 100% O2 ） was set at 3 L/min until FA （end-tidal or alveolar concentration） attained 0.8 MAC. After 5 min of stabilization FGF was reduced to 1 L/min and 0.8 MAC was maintained throughout the operation by adjusting FD. Remifentanil was infused during operation to make anesthesia stable. The changes in BP and HR were maintained within 20 percent of the baseline. At the end of operation, inhalation anesthetics were discontinued and FGF was increased to 3 L/min again. The anesthetic gas was detected by infra-red absorption technique. FD, FI （inspired concentration of the inhalational anesthetic） and FA were continuously monitored. The durations of FA/FI = 1/2 and FA/FAO = 1/2 were recorded（FAO, alveolar concentration at turning-off of vaporizer）. Results The two groups were comparable with respect to age, weight and duration of anesthesia. There was no significant difference in BP and HR throughout the anesthesia and in PACU between the 2 groups. The durations of FA/FI = 1/2 and FA/FAO = 1/2 were significantly shorter in group D than in group Ⅰ （ P 〈 0.05）. The FD curve was stabler in group D than in group Ⅰ. With the same FGF rate, FA/FI and FA/FD of desflurane rose significantly faster than those of isoflurane and were higher at every time point. Conclusion Desflurane has significant advantage for low-flow anesthesia over isoflurane more controllable, more rapid recovery and less waste.