Kim Min-Soo, Kim Na Young, Lee Ki-Young, Choi Young Deuk, Hong Jung Hwa, Bai Sun-Joon
Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Korea.
Can J Anaesth. 2015 Sep;62(9):979-87. doi: 10.1007/s12630-015-0383-2. Epub 2015 Apr 14.
Volume-controlled ventilation with a prolonged inspiratory to expiratory ratio (I:E ratio) has been used to optimize gas exchange and respiratory mechanics in various surgical settings. We hypothesized that, when compared with an I:E ratio of 1:2, a prolonged I:E ratio of 1:1 would improve respiratory mechanics without reducing cardiac output (CO) during pneumoperitoneum and steep Trendelenburg positioning, both of which can impair respiratory function in robot-assisted laparoscopic radical prostatectomy. Furthermore, we evaluated its effect on oxygenation during robot-assisted laparoscopic radical prostatectomy.
Eighty patients undergoing robot-assisted laparoscopic radical prostatectomy were randomly allocated to receive an I:E ratio of either 1:1 (group 1:1) or 1:2 (group 1:2). The primary endpoint, peak airway pressure (Ppeak), as well as hemodynamic data, including cardiac output (CO) and arterial oxygen tension (PaO2), were compared between groups at four time points: ten minutes after anesthesia induction (T1), 30 and 60 min after pneumoperitoneum with steep Trendelenburg positioning (T2 and T3), and ten minutes after supine positioning (T4). Overall comparisons were made between groups using linear mixed model analysis with post hoc testing of individual time points adjusted using a Bonferroni correction.
Linear mixed model analysis showed a significant overall difference in Ppeak between the two groups (P < 0.001). Post hoc analysis showed a significantly lower mean (SD) Ppeak in group 1:1 than in group 1:2 at T2 [28.4 (4.0) cm H2O vs 32.8 (5.2) cm H2O, respectively; mean difference, 4.3 cm H2O; 95% confidence interval (CI), 2.3 to 6.4; P < 0.001] and T3 [27.8 (3.9) cm H2O vs 32.6 (5.0) cm H2O, respectively; mean difference, 4.7 cm H2O; 95% CI, 2.7 to 6.7; P < 0.001]. The CO assessed over these time points was comparable in both groups (P = 0.784). In addition, there were no significant differences in PaO2 between the two groups (P = 0.521).
Compared with an I:E ratio of 1:2, a ratio of 1:1 lowered Ppeak without reducing CO during pneumoperitoneum and steep Trendelenburg positioning. Nevertheless, our results did not support its use solely for improving oxygenation. This trial was registered at http://clinicaltrials.gov/ (NCT01892449).
在各种手术场景中，采用延长吸气与呼气比（I:E比）的容量控制通气已被用于优化气体交换和呼吸力学。我们推测，在气腹和陡峭的头低脚高位（这两种情况在机器人辅助腹腔镜根治性前列腺切除术中均会损害呼吸功能）期间，与1:2的I:E比相比，延长至1:1的I:E比可改善呼吸力学且不降低心输出量（CO）。此外，我们评估了其在机器人辅助腹腔镜根治性前列腺切除术中对氧合的影响。
80例行机器人辅助腹腔镜根治性前列腺切除术的患者被随机分配接受1:1（1:1组）或1:2（1:2组）的I:E比。在四个时间点比较两组的主要终点指标气道峰压（Ppeak）以及包括心输出量（CO）和动脉血氧分压（PaO2）在内的血流动力学数据：麻醉诱导后10分钟（T1）、气腹并采用陡峭头低脚高位后30分钟和60分钟（T2和T3）、仰卧位后10分钟（T4）。使用线性混合模型分析进行组间总体比较，并对各个时间点进行事后检验，采用Bonferroni校正进行调整。
线性混合模型分析显示两组间Ppeak存在显著总体差异（P < 0.001）。事后分析显示，在T2时，1:1组的平均（标准差）Ppeak显著低于1:2组[分别为28.4（4.0）cmH₂O和32.8（5.2）cmH₂O；平均差值为4.3cmH₂O；95%置信区间（CI）为2.3至6.4；P < 0.001]，在T3时也是如此[分别为27.8（3.9）cmH₂O和32.6（5.0）cmH₂O；平均差值为4.7cmH₂O；95%CI为2.7至6.7；P < 0.001]。在这些时间点评估的两组CO相当（P = 0.784）。此外，两组间PaO2无显著差异（P = 0.521）。
与1:2的I:E比相比，1:1的I:E比在气腹和陡峭头低脚高位期间降低了Ppeak且未降低CO。然而，我们的结果不支持仅将其用于改善氧合。本试验已在http://clinicaltrials.gov/注册（NCT01892449）。
