Department of Anesthesiology and Pain Medicine, Chonbuk National University Medical School, Jeonju, Korea.
Korean J Anesthesiol. 2012 Mar;62(3):256-9. doi: 10.4097/kjae.2012.62.3.256. Epub 2012 Mar 21.
Although one lung ventilation (OLV) is frequently used for facilitating thoracic surgical procedures, arterial hypoxemia can occur while using one lung anesthesia. Continuous positive airway pressure (CPAP) in 5 or 10 cmH(2)O to the non-ventilating lung is commonly recommended to prevent hypoxemia. We evaluated the effects of incremental CPAP to the non-ventilating lung on arterial oxygenation and pulmonary shunt without obstruction of the surgical field during OLV.
Twenty patients that were scheduled for one lung anesthesia were included in this study. Systemic and pulmonary hemodynamic data and blood gas analysis was recorded every fifteen minutes according to the patient's positions and CPAP levels. CPAP was applied from 0 cmH(2)O by 3 cmH(2)O increments until a surgeon notifies that the surgical field was obstructed by the expanded lung. Following that, pulmonary shunt fraction (Q(S)/Q(T)) was calculated.
There were no significant differences of Q(S)/Q(T) between supine and lateral positions with two lung ventilation (TLV). OLV significantly decreased arterial oxygen partial pressure (PaO(2)) and increased Q(S)/Q(T) compared to TLV. PaO(2) and Q(S)/Q(T) significantly improved at 6 and 9 cmH(2)O of CPAP compared to 0 cmH(2)O. However, there were no significant differences of PaO(2) and Q(S)/Q(T) between 6 and 9 cmH(2)O CPAP. In 18 patients (90%), surgical fields were obstructed at 9 cmH(2)O CPAP.
This study suggests that 6 cmH(2)O CPAP effectively improved arterial oxygenation without interference of the surgical field during OLV when CPAP was applied from 0 cmH(2)O in 3 cmH(2)O increments.
虽然单肺通气（OLV）常用于辅助胸外科手术，但在使用单肺麻醉时可能会发生动脉低氧血症。通常建议向非通气肺施加 5 或 10 cmH2O 的持续气道正压通气（CPAP）以防止低氧血症。我们评估了向非通气肺递增 CPAP对动脉氧合和肺分流的影响，同时不阻塞手术视野。
本研究纳入了 20 名计划接受单肺麻醉的患者。根据患者的体位和 CPAP 水平，每 15 分钟记录一次全身和肺血流动力学数据和血气分析。CPAP 从 0 cmH2O 以 3 cmH2O 的增量施加，直到外科医生通知扩张的肺阻塞了手术视野。之后，计算肺分流量（Q(S)/Q(T)）。
双肺通气（TLV）时，仰卧位和侧卧位之间的 Q(S)/Q(T) 没有显著差异。与 TLV 相比，OLV 显著降低了动脉氧分压（PaO2）并增加了 Q(S)/Q(T)。与 0 cmH2O 相比，CPAP 为 6 和 9 cmH2O 时，PaO2 和 Q(S)/Q(T) 显著改善。然而，CPAP 为 6 和 9 cmH2O 时，PaO2 和 Q(S)/Q(T) 之间没有显著差异。在 18 名患者（90%）中，在 CPAP 为 9 cmH2O 时，手术视野被阻塞。
这项研究表明，当 CPAP 从 0 cmH2O 以 3 cmH2O 的增量施加时，6 cmH2O CPAP 有效地改善了动脉氧合，而不干扰手术视野。
