Department of Anaesthesiology and Critical Care, BP Koirala Institute of Health Sciences, Dharan, Nepal.
Kathmandu Univ Med J (KUMJ). 2020 Apr-Jun;18(70):165-170.
Background Preoxygenation is performed before induction of anaesthesia which increases oxygen reserve and provides delayed onset of hypoxia during period of apnea. Several techniques such as positive airway pressure and head-up tilt during preoxygenation have shown to prolong safe apnea period compared to conventional technique. However, uniform recommendations have not yet been made. Objective To find out the effect of combination of 5 cmH2 O continuous positive airway pressure (CPAP) and 25° head up position during preoxygenation on safe apnea period. Method In this comparative study 60 non-obese adult patients were divided into three equal groups; Group C receiving preoxygenation in conventional technique, Group S receiving preoxygenation with 5 cmH2 O continuous positive airway pressure in supine position and Group H receiving preoxygenation in 25° head-up position with 5 cmH2 O continuous positive airway pressure. After 3 min of preoxygenation, intubation was performed after induction of anaesthesia with propofol, fentanyl and succinylcholine. After confirming the tracheal intubation by direct visualization, all patients were administered vecuronium to maintain neuromuscular blockade. Postintubation, patients in all groups were left in same position with the tracheal tube exposed to atmosphere and without being ventilated till the SpO2 dropped to 92%. The primary outcome compared between the groups was the safe apnea period (time from loss of consciousness to fall of SpO2 to 92%). Result The duration of safe apnea period was longer (p < 0.05) in Group H patients (405.9 ± 106.69 s) as compared to the Group C (296.9 ± 99.01s) and Group S (319.65 ± 71.54s). Although the duration of safe apnea period was longer in the Group S as compared to Group C the difference was not statistically significant. Conclusion Preoxygenation in 25° head-up position with 5 cm H2O continuous positive airway pressure significantly prolongs safe apnea period in non-obese adults compared to supine position, with or without 5 cmH2O continuous positive airway pressure.
麻醉诱导前进行预充氧可增加氧储备，并在呼吸暂停期间延迟缺氧的发生。与传统技术相比，几种技术，如预充氧期间的正压通气和头高位倾斜，已显示可延长安全的呼吸暂停期。然而，尚未提出统一的建议。目的：找出在预充氧期间使用 5cmH2O 持续气道正压通气（CPAP）和 25°头高位组合对安全呼吸暂停期的影响。方法：在这项比较研究中，将 60 名非肥胖成年患者分为三组；组 C 接受常规技术的预充氧，组 S 接受仰卧位 5cmH2O 持续气道正压通气的预充氧，组 H 接受 25°头高位 5cmH2O 持续气道正压通气的预充氧。预充氧 3 分钟后，在异丙酚、芬太尼和琥珀胆碱诱导麻醉后进行插管。在直接可视化确认气管插管后，所有患者均给予维库溴铵以维持神经肌肉阻滞。插管后，所有组的患者均处于相同位置，气管导管暴露在空气中，在 SpO2 降至 92%之前不进行通气。组间比较的主要结果是安全呼吸暂停期（从意识丧失到 SpO2 降至 92%的时间）。结果：组 H 患者（405.9 ± 106.69s）的安全呼吸暂停期（p<0.05）长于组 C（296.9 ± 99.01s）和组 S（319.65 ± 71.54s）。尽管与组 C 相比，组 S 的安全呼吸暂停期更长，但差异无统计学意义。结论：与仰卧位相比，在非肥胖成年人中，在 25°头高位使用 5cmH2O 持续气道正压通气进行预充氧可显著延长安全呼吸暂停期，无论是否使用 5cmH2O 持续气道正压通气。
