Pulmonary Protection Of One-lung Ventilation Preconditioning In Patients Of Left-sided Radical Surgery For Esophageal Carcinoma

One lung ventilation(OLV) is inevitably associated with gross changes in respiratory physiology. Unilateral ventilation creates an obligatory right-to-left transpulmonary shunt due to continuing blood flow through the collapsed, non-ventilated lung, and results in mixed venous blood. The mechanism of acute lung injury induced by one lung ventilation is more complex, is not yet entirely clear. For single lung ventilation induced lung injury mechanism, there are two main reasons: hypoxic lung injury, including hypoxia and oxidative stress reaction; mechanical stretch lung injury.Most patients with poor lung function can’t tolerate one lung ventilation through double-lumen endobronchial tube (DLT) because of hypoxia even though applying conventional protective ventilation strategies such as increasing fraction of inspired oxygen (FiO2) to 1, continuous positive airway pressure ventilation or insufflation of oxygen to the non-ventilated lung, and pressure control ventilation or positive end-expiratory pressure ventilation to the dependent lung. However the surgeries can only be carried out under two-lung ventilation using lower tidal volumes (VT), which may cover the exposure of the surgical filed and hinder the surgical procedure. It is worthwhile to note that during video-assisted thoracic surgery (VATS) it is easier to stab the lung parenchyma resulting in persistent postoperative leak. Patients with normal lung function need OLV for lung and other thoracic surgery are more prone to hypoxemia comparing to patients under pulmonary lobectomy.It has been reported that when treated with mechanical traction, epithelial cells and endothelial cells will increase the transcriptional of inflammatory factors including TNF-α, IL-6 and IL-8, which may attribute to the acute lung injure.Lung ischemia-reperfusion injury (I/R) often occurs in cardiopulmonary bypass, pulmonary embolism, pulmonary resection, low lung transplantation, and other thoracic surgery. Recent years a number of studies showed that ischemic preconditioning (IPC) has a significant protective effect on lung I/R, improves lung oxygenation and reduces the release of inflammatory substances. However, no research studies the organic protection on OLV preconditioning. The present study is to explore whether OLV preconditioning is a simple method, which can reduce the hypoxic lung injury, decrease inflammatory factors such as IL-6, IL-8, improves oxygenation and reduces perioperative complications.ObjectiveTo observe the perioperative pulmonary protection of one-lung ventilation preconditioning in patients of left-sided radical surgery for esophageal carcinoma.Materials and methods1.1 Patients and randomizationThis study was approved by the ethics committee of Nanfang Hospital, Southern Medical University. All patients provided written informed consent themselves prior to treatment. A total of 198 patients (age range,32-64 year; ASA physical status Ⅰ or Ⅱ; body mass index range,18-25 kg/m2) undergoing elective lower esophageal surgery via a left thoracotomy incision were included. All the patients in the study have the normal lung function. Patients with asthma, active upper respiratory tract infection, known or suspected difficult airway, pulmonary infection; atelectasis, pulmonary function tests revealed a forced expiratory volume at one second< 90% of predicted or forced vital capacity <90% of predicted; cardiac insufficiency, hypertension, hepatic inadequacy, nephrosis, anemia, or for any contraindication to the anaesthetic drugs described below were excluded from the study.All the patients were randomly divided into 6 groups:Group Ⅰ (OLV preconditioning with FiO2 60%);Group Ⅱ (OLV preconditioning with FiO2 60%);Group III (OLV preconditioning with FiO260%);Group IV (OLV preconditioning with FiO260% and then FiO2 100% during OLV);Group V (FiO260% throughout the operation without preconditioning);Group VI (FiO2100% during OLV without preconditioning).Every group has 33 patients estimated by statistics according to the incidence of hypoxemia in OLV.1.2 Anesthetic and Surgical ManagementA radial artery cannula was inserted for measuring the arterial pressure and sampling the arterial blood gas. After intravenous infusion of dexmedetomidine in 0.6 ug/kg in 15 min, anesthesia was induced and maintained by propofol target controlled infusion. At the same time intravenous sufentanil 0.3μg/kg and Cisatracuriμm 0.2mg/kg, calculating the depth of insertion of right DLT, and fiberoptic bronchoscopy (FOB) adjustment tube end position, the inflated bronchial sleeve capsule proximal just above the carina. Nasopharyngeal temperature was examined after the completion of the intubation. A catheter was placed in the internal jugular vein for monitoring the central venous pressure.Patients in all groups were treated with intermittent mechanical positive pressure ventilation as follows:connecting Datex-Ohmeda anesthesia machine intermittent positive pressure ventilation, FiO260%, the tidal volume (VT) 8 ml/kg, respiratory frequency 12bpm. The end tidal carbon dioxide partial pressure (PetCO2) was kept at 35 to 40 mmHg according to the continuous monitoring result of peak inspiratory pressure (Ppeak), VT and end expired carbon dioxide partial pressure (PetCO2).The BIS was maintained at 40-60 by regulating propofol plasma concentration. Maintained the body temperature between 35.5℃ and 37.0℃.Patients were placed in lateral position, the intervention protocol of each group was shown as follow:Group I:After laying the towel, the left side of Y joints of DLT were clamped three times and then switched to two lung ventilation for 1min until 3 minutes before skin incision. The duration of two lung ventilation was kept at 3-5 minutes from the end of preconditioning to the beginning of OLV. During OLV, kept FiO2 60%.Group II:After laying the towel, the left side of Y joints of DLT were clamped five times and then switched to two lung ventilation for 1min until 3 minutes before skin incision. The duration of two lung ventilation was kept at 3-5 minutes from the end of preconditioning to the beginning of OLV. During OLV, kept FiO260%.Group III:After laying the towel, the left side of Y joints of DLT were clamped three times and then switched to two lung ventilation for 2min until 3 minutes before skin incision. The duration of two lung ventilation was kept at 3-5 minutes from the end of preconditioning to the beginning of OLV. During OLV. kept FiO260%.Group IV:After laying the towel, the left side of Y joints of DLT were clamped three times and then switched to two lung ventilation for 1 min until 3 minutes before skin incision. The duration of two lung ventilation was kept at 3-5 minutes from the end of preconditioning to the beginning of OLV. During OLV, FiO2100%. After OLV, FiO2 60%.Group V:FiO260%throughout the operation without preconditioning.Group VI:FiO2100%during OLV without preconditioning. After OLV, FiO2 60%.1.3 The time point of sample collection and observationTO:Before induction of anesthesiaT1:At the end of one lung ventilation preconditioningT2:After 15 minutes of total lung collapsed during OLV;T3:30min after extubation;T4:The first postoperative day;T5:The third postoperative day after breathing exercise.1.4 Blood sample processing and parametersArterial blood was conducted at T0-T5 and then calculated oxygenation index. The respiratory parameters were recorded including MAP, HR, CVP, SpO2, Ppeak, MV, VT, PETCO2 and BIS. Pro-BNP was detected at TO and T4. TNF-α and IL-6 were examined at T1,T2 and T4. X-ray chest film was performed at T5.Other parameters:The duration of operation, OLV and anesthesia; the volume of colloid, urinary, blood loss; the dose of dexmedetomidine, propofol, sufentanil and atracurium; the numbers of patients with SpO2<90%, pneumonia, atelectasis and the patients need to stop surgery for lung ventilation, length of postoperative stay.1.5 Statistical AnalysisStatistical analysis was done using the Statistical Package of Social Sciences version 13.0 for Windows. One-Way ANOVA was used to analyze circulatory related parameters. Paired-sample T test was used to analyze arterial blood gas analysis. Independent-sample T test was applied to compare different groups. P<0.05 was considered to indicate statistical significance.ResultThere was no significant difference in age, weight, height, operation time, and anesthesia time and blood loss between groups. (P>0.05).During OLV, there were 21 patients suffering from hypoxemia, which need 100% FiO2 in group V, however there was only one patient in group Ⅰ, group Ⅱ and group III respectively.2 patients in group V,1 patient in group I and 2 patients in group VI were insufflated oxygen 2L/min to non-ventilation lung. One patient needed to resume two lung ventilation intermittently in group V.PaO2/FiO2 was higher in each preconditioning groups than that in other two groups at T2-T5; Pro-BNP was lower in each preconditioning groups than that in other two groups at T4. TNF-α and IL-6 were lower in one lung ventilation preconditioning group Ⅰ, Ⅱ, Ⅲ than that in other three groups at T4. MAP and Ppeak showed no differences among different groups.There were 5 patients in group V,6 patients in group VI suffering from postoperative atelectasis. However there is only 1 patient suffering from postoperative atelectasis in group Ⅰ, group Ⅱ and group Ⅲ, respectively. Persistent postoperative air leak occurred in 1 patient in group V.ConclusionsOne lung ventilation preconditioning can protect lung well by improving oxygenation function in intra-and postoperative, reducing the release of inflammatory factor and postoperative atelectasis.