Parab Swapnil Yeshwant, Chatterjee Aparna, Saxena Rishi S
Department of Anaesthesiology, Critical Care and Pain, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, Maharashtra, India.
Department of Critical Care Medicine, Ramakrishna Care Hospital Raipur, Chhattisgarh, India.
Indian J Anaesth. 2021 Oct;65(10):744-749. doi: 10.4103/ija.ija_591_21. Epub 2021 Oct 29.
Baseline difference in the perfusion of two lungs is the cause of intra-operative shunt during one-lung ventilation (OLV). This study aimed to test the hypothesis that the gradient of end-tidal carbon dioxide (EtCO) between two lungs in lateral position (D-EtCO) would predict the quantity of shunt and hence the drop in the oxygenation during OLV.
An observational study was conducted to include consecutive 70 patients undergoing thoracic surgery using a double-lumen tube in a lateral position. D-EtCO was calculated by subtracting EtCO from the non-dependent lung from that of the dependent lung when ventilation parameters are the same for each lung. Oxygenation was assessed by measuring PaO/FiO ratios (P/F ratio) at 10, 20 and 40 min after OLV. Correlations between D-EtCO and P/F ratios were calculated. Receiver operating curves were analysed to test the ability of D-EtCO to identify patients with a P/F ratio of <100 during OLV.
A moderate correlation was found between D-EtCO and P/F ratios at 10 and 20 min of OLV. Among lung resection cases (n = 61), correlation was moderate at 10 (r = 0.64), and 20 min (r = 0.65) ( < 0.001) and became weak at 40 min (r = 0.489, < 0.001). Areas under curve for D-EtCO to predict the drop in P/F ratio <100 at 10, 20 and 40 min after OLV were 0.90 (cut-off: 2.5), 0.78 (cut-off: 3.5) and 0.78 (cut-off: 4.5), respectively.
D-EtCO could predict the drop in oxygenation in the early part of OLV in lung resection surgeries.
两肺灌注的基线差异是单肺通气（OLV）期间术中分流的原因。本研究旨在验证以下假设：侧卧位时两肺之间的呼气末二氧化碳（EtCO）梯度（D-EtCO）可预测分流的量，进而预测OLV期间氧合的下降。
进行一项观察性研究，纳入70例连续接受胸外科手术且采用双腔管行侧卧位通气的患者。当两肺通气参数相同时，用依赖肺的EtCO减去非依赖肺的EtCO来计算D-EtCO。通过测量OLV后10、20和40分钟时的动脉血氧分压/吸入氧分数值（P/F比值）来评估氧合情况。计算D-EtCO与P/F比值之间的相关性。分析受试者工作曲线以检验D-EtCO识别OLV期间P/F比值<100的患者的能力。
在OLV 10分钟和20分钟时，发现D-EtCO与P/F比值之间存在中度相关性。在肺切除病例（n = 61）中，10分钟时相关性为中度（r = 0.64），20分钟时为中度（r = 0.65）（P<0.001），40分钟时变弱（r = 0.489，P<0.001）。OLV后10、20和40分钟时，D-EtCO预测P/F比值下降<100的曲线下面积分别为0.90（临界值：2.5）、0.78（临界值：3.5）和0.78（临界值：4.5）。
D-EtCO可预测肺切除手术中OLV早期氧合的下降。
