双水平气道正压无创通气全身麻醉期间患者胃内压及咽后部pH值的变化

Monitoring of intra-gastric pressure and pH values of pharyngeal secretion during bi-level positive airway pressure mask ventilation under general anesthesia

目的通过对双水平正压无创通气全身麻醉患者行连续胃内压监测，探讨该通气模式引起胃内容物反流的可能机制。方法选择行腹腔镜胆囊切除手术的成年患者60例随机分为2组：双水平气道正压（BiPAP）面罩通气组（Ⅰ组）和气管内插管气道正压通气（IPPV）组（Ⅱ组），每组30例。麻醉前将测压管送达胃内，观察麻醉前、麻醉后30min、气腹后30min、拔管或撤离通气后30min的循环、血气指标、胃内压及咽部pH值。结果麻醉通气期间2组MAP、HR尚平稳，拔管后30minⅡ组PaO2低于麻醉前水平[（78±14．1）mmHg比（85±10．4）mmHg，P〈0．05，1mmHg=0．133kPa]，而Ⅰ组前后差异无统计学意义（P〉0．05）。Ⅰ组麻醉后30min胃内压比麻醉前明显下降[（7．2±2．6）cmH2O比（8．0±3．2）CmH2O，P〈0．05，1cmH2O=0．098kPa]，而Ⅱ组升高[（9．6±2_3）cmH2O比（7．8±4．5）cmH2O，P〈0．05]。气腹后30min2组胃内压骤升，Ⅱ组比Ⅰ组更高[（23±5．3）cmH2O比（20±4．1）cmH2O，P〈0．05），Ⅱ组拔管后30min仍较麻醉前高[（11．8±4．6）CmH2O比（7．8±4．5）cmH2O，P〈0．05]，且比Ⅰ组术后胃内压[（8.3±4．1）cmH2O]明显增高（P〈0．05）。麻醉前和拔管后，2组咽部pH值差异无统计学意义（P〉0．05）。结论双水平气道正压面罩通气能安全有效地维持全身麻醉时进行的机械通气，对围麻醉期的生理干扰较少。在腹腔镜胆囊切除术时胃内压变化剧烈，双水平气道正压面罩通气的胃内压升高幅度较小，导致胃食管反流的风险较低。

Objective To investigate the possible mechanism by which bi-level positive airway pressure （BiPAP） mask ventilation induces gastro esophageal reflux through monitoring the intra-gastric pressures （IGP） under general anesthesia. Methods Sixty adult patients undergone elective laparoscopic eholecystectomy were randomly divided into groups [ （BiPAP, n=30） and Ⅱ intermittent positive pressure ventilation （IPPV, n=30）. An IGP probe was inserted through nostril before anesthesia. Data of cardiovascular dynamics, blood gas, IGP and pharyngeal pH value were measured before anesthesia, 30 min after anesthesia, 30 rain after artificial pneumoperitonium, 30 rain after extubation or weaning of ventilation. Results In both groups, the effects of BiPAP mask ventilation were similar to IPPV. The cardiovascular system function was stable during anesthesia. At 30 min after extubation, patients in group I experienced no change in PaO2 but there was a significant reduction in patients of group Ⅱ [ （78± 14.1 ） mm Hg w （85± 10.4） mm Hg, P〈0.05, 1 mm Hg=0.133 kPa] , as compared with before anesthesia. At 30 min after anesthesia, IGP was lowered in group I and increased in group Ⅱ , as compared with before anesthesia [ （7.2±2.6） cm H2O vs （8.0±3.2） cm H2O, and （9.6±2.3） cm H2O vs （7.8±4.5） cm H2O, P〈0.05, respectively 1 ern H2O= 0.098 kPa]. Thirty minutes after pneumoperitonium, both groups were found with elevated IGP and the group Ⅱ had a higher IGP than group Ⅰ [ （23±5.3） cm H2O vs （20±4.1） cm H2O, P〈0.05] , which persisted higher than before anesthesia even at 30 rain after extubation [ （11.8±4.6） em H2O vs （7.8±4.5） cm H2O, P〈 0.05] and eompared with group Ⅰ [ （8.3±4.1） cm H2O, P〈0.05]. There was no signifieant difference of pH values of pharyngeal secretions in group Ⅱ preanesthesia and in consciousness recovery （P〉0.05）. Conclusion BiPAP mask ventilation is a safe ventilation teehnique under general anesthesia and may be associated with less interferenee to peri-anesthetic physiology. Drastic change in IGP during laparoseopie eholeeysteetomy ean be ameliorated with BiPAP mask ventilation and hence decreases the risk for gastroesophageal reflux.