氧化亚氮在单肺通气时对肺内氧合和动脉血乳酸水平的影响

目的:探讨应用氧化亚氮持续气道内正压在单肺麻醉时对病人氧合、肺内分流和动脉血乳酸水平的影响。方法:择期行肺癌手术病人22例,美国麻醉医生协会(ASA)Ⅰ-Ⅲ级,随机分为对照组(A组)和N₂O组(B组),每组11例。A组在单肺麻醉期间非通气侧肺的支气管导管直接开口于大气中,B组单肺麻醉期间非通气侧持续给予N₂O(压力2cmH₂O),并在仰卧双肺通气20min,仰卧单肺通气20min,侧卧单肺通气20min、40min和关胸时,分别采取动脉血做血气分析并计算分流率(Qs/Qt),同时监测乳酸含量的变化。结果:在单肺麻醉后20min、40min时,B组氧合明显高于A组(P＜0.01),B组分流率(Qs/Qt)明显低于A组(P＜0.05),单肺麻醉后40min时B组乳酸含量明显低于A组(P＜0.05)。结论:单肺麻醉期间,非通气侧持续给予N₂O(压力2cmH₂O),有助于提高氧合,减少肺内分流,可减少低氧血症的发生率。

Effects of non-ventilated lung with nitrous oxide on intrapulmonary oxygenation and lactic acid level in arterial blood during one lung anesthesia

AIM: To investigate the effects of non-ventilated lung with N₂O on systemic oxygenation and lactic acid level in arterial blood during one lung anesthesia. METHODS: Twenty-two patients, ASA Ⅰ-Ⅲ, scheduled for selective pulmonary surgery, were randomly divided into two groups: control group (group A, n=11) and observation group (group B, n=11). Group A: the non-ventilated lung was kept open to the air; group B: N₂O 2 cmH₂O through CPAP system was insufflated into the non-ventilated lung during one lung ventilation. The anesthesia was induced with intravenous midazolam (0.05 mg·kg^-1), propofol (0.5-1.0 mg·kg^-1), fentanyl (4 μg·kg^-1), and vecuronium (0.1 mg·kg^-1) and was maintained with inhaling isoflurane. Blood gas analysis and lactic acid was recorded 20 min after two-lung ventilation (TLV) in the supine position, 20 min after one-lung ventilation (OLV) in the supine position, 20 min and 40 min after OLV in the lateral position and at the end of operation and the shunt fraction was calculated. RESULTS: PaO₂ in group B was significantly higher than that in group A (P＜0.05). Qs/Qt in group B was significantly lower than that in group A (P＜0.05), and lactic acid level in group B was significantly lower than that in group A during OLV. CONCLUSION: Non-ventilated lung with N₂O (2 cmH₂O) improves systemic oxygenation, reduces intrapulmonary shunt and prevents hypoxemia during OLV.