全身麻醉患者喉罩通气下平卧位和截石位的呼吸动力学比较

Comparison of respiratory dynamics between lithotomy position and supine position in patients undergoing general anesthesia with laryngeal mask airway

目的比较喉罩通气下平卧位与截石位手术患者的呼吸动力学监测指标，验证不同手术体位对喉罩通气效果的影响。方法选择全身麻醉下行择期手术的患者60例，年龄20～65岁，美国麻醉医师学会（ASA）分级Ⅰ或Ⅱ级。根据手术体位分为平卧位组和截石位组，每组30例。分别于麻醉绣导前（T0）和喉罩置入1min（T1）、5min（T2）、10min（T3）、15min（T4）、30min（T5）、60min（T6）各时间点，记录患者的吸气平台压、吸气峰压（PIP）、平均气道压、吸气峰流速、呼气峰流速和呼气末二氧化碳分压（PetCO2）。麻醉诱导后15min监测动脉血气，记录术中血流动力学指标变化。观察术中、术后喉罩不良反应发生情况。结果两组患者的PIP、吸气平台压、吸气阻力（Ri）、呼吸做功（WOB）、呼气阻力（Re）均随手术时间延长而逐渐升高，而动态顺应性（Cdyn）、静态顺应性（Cst）逐渐降低（P值均〈0．05）。截石位组T2至T6时间点的PIP、吸气平台压均显著高于平卧位组同时间点（P值均〈0．05），T1至T6时间点的吸气峰流速、呼气峰流速、Cdyn、Cst均显著低于平卧位组同时间点（P值均〈0．05），T2至T5时间点的WOB、Ri、Re均显著高于平卧位组同时间点（P值均〈0．05）。两组均无明显的不良反应发生。结论在全身麻醉普通型喉罩通气下，气道压力（吸气平台压、PIP）和气道阻力（Ri、Re）均随手术时间的延长而升高，其中截石位时气道压力和气道阻力显著高于平卧位，且伴有胸-肺顺应性降低，这些呼吸动力学指标的变化正常体重患者1h以内手术中不会导致明显的不良事件发生。

Objective To investigate the differences of respiratory dynamics between supine position and lithotomy position in patients undergoing general anesthesia with laryngeal mask airway （LMA）, and to determine the effectiveness of ventilation through LMA under the two operation positions. Methods Sixty patients undergoing selective operation under general anesthesia （American Society of Anesthesiologists physical status Ⅰ or Ⅱ , aged 20-65 years） were divided into two groups according to the operation position： supine position group （n = 30） and lithotomy position group （n = 30）. Respiratory dynamic parameters such as inspiratory plateau pressure （Pplateau）, peak inspiratory pressure （PIP）, mean airway pressure （Pmean）, maximum forced inspiration （Flmax）, maximum forced expiration （FEmax）, and partial pressure of carbon dioxide in end-expiratory gas （Pet CO2 ） were recorded before and after induction of anesthesia, during the scheduled time points in operation, and after removal of the LMA. Arterial blood gas was monitored 15 minutes after induction. Hemodynamic changes and perioperative complications were recorded. Results With the operation time going, the PIP, Pplateau, inspiratory resistance （Ri）, expiratory resistance （Re） and work of breathing （WOB） were significantly elevated, while the dynamic compliance （Cdyn） and static compliance （Cst） were significantly decreased （all P〈0. 05） in all patients. PIP from T2 to T6 and Pplateau in lithotomy position group were significantly higher than those in supine position group （all P〈0.05）. Flmax, FEmax, Cdyn and Cst from T2 to T6 in lithotomy position group were significantly lower than those in supine position group （all P〈0.05）. Ri, Re and WOB in lithotomy position group were significantly higher than those in supine position group from T2 to T5 （all P〈 0.05）. No obvious complications were founded in both groups. Conclusion During the general anesthesia with controlled ventilation by typical LMA, both the airway pressure （Pplateau and PIP） and airway resistance （Ri and Re） increase with the surgical time going, accompanied by the reduction of pulmonary compliance, which is more obvious in lithotomy position than in supine position. However, these respiratory dynamic changes result in no adverse events in patients with normal body mass index undergoing surgeries within one hour.