Lung Ultrasound Score To Investigate Thoracic Surgery During Single Lung Ventilation Comparison Of Best PEEP With Traditional Lung Protection Ventilation

Objective:To explore the use of intraoperative pulmonary ultrasound to set optimal PEEP,to find the relationship between PEEP and height,weight,and BMI,and to use intraoperative pulmonary ultrasound to titrate PEEP.Methods:We recruited 80 patients scheduled for elective lobectomy from August 2017 to February 2018 and randomized the patients to a randomized pulmonary ultrasound（L group）and general lung protective ventilation group（P group）.All patients signed informed consent.Lung ultrasound scores（LUS）were recorded prior to patient anesthesia and recorded as a baseline LUS.Before the induction of general anesthesia,arterial blood samples were collected and blood gas analysis was performed.The PaO₂/FiO₂ values of the patients were recorded and general anesthesia induction was performed.During the single-lung ventilation during operation,patients in group L were given a tidal volume of 4 ml/kg of standard body weight at the time of one-lung ventilation,initially given a PEEP of 5 cmH₂O,and lung ultrasonography at 15 min after one-lung ventilation.If the score was found to be greater than the baseline score,then,2cmH₂O PEEP was up-regulated after ultrasound reexpansion under direct ultrasound（manual revascularization method:the anesthesia pressure limiting valve was adjusted to 30cmH₂O level,and pressure was applied slowly until the lung ultrasound image decreased in this area score,maintaining 10s）.If the LUS does not change from the baseline score,adjust the PEEP with a 1cmH₂O drop in the mechanical ventilation mode,and then repeat the lung ultrasound examination every 20min until you find a minimum PEEP（limited to 3-10cmH₂O）that keeps the lungs inflated.Patients in Group P were initially given a tidal volume of 4 ml/kg of standard body weight after one-lung ventilation,and were given PEEP at a level of 5 cmH₂O.When intraoperative SpO₂ was<90%,anesthesiologists were allowed to maintain blood oxygen using methods such as manual lung recruitment and adjusting mechanical ventilation patterns.When intraoperative hypertension or hypotension occurs,anesthesiologists are allowed to use vasoactive drugs to maintain hemodynamic stability.Record each patient’s age,gender,weight,height,preoperative lung function,comorbidities,preoperative blood gas analysis,BIS values from surgical incision to end of surgery,occurrence of intraoperative hypertension and hypotension,single Lung ventilation time,anesthesia time,operation time.The oxygen saturation of the fingertips at the ultrasound time point of each lung in the L group,the blood gas analysis value before the double lung ventilation,the mean arterial blood pressure change,and the amount of intraoperative liquid influx after the last manual lung recruitment and PEEP adjustment were recorded.The number of intraoperative hypoxic events,the final tidal volume in the two groups of patients,the final PEEP value in the L group,and the blood gas analysis values and LUS after extubation 30 minutes after the two groups of patients were extubated.Three PaO₂/FiO₂ values were calculated based on three blood gas analysis values.Postoperative follow-up assessment of postoperative pulmonary complications,postoperative pain scores,cough,sputum,postoperative hospital stay,postoperative outcomes（discharge,signed leave,and death）.Results:The final 67 patients were included in the study,34 patients were included in the L group and 33 were included in the P group.The final tidal volume during the single-lung ventilation during the operation was greater in the P group than in the L group（5.606±0.609 vs4.147±0.359,P<0.05）,and the intraoperative PaO₂/FiO₂ value in the L group was greater than in the P group（325.382±106.970vs230.512±78.964,P<0.05）.The length of postoperative hospital stay in both groups was less than in group P,with statistical significance（P<0.05）.The final PEEP values in the two groups were statistically significant in the L group and the P group（P<0.05）.The relationship between PEEP and height,weight,and BMI was analyzed using the Pearson correlation coefficient.There was no correlation between PEEP and height.The difference was not statistically significant.There was a moderate positive correlation between PEEP and body weight.The correlation coefficient was r=0.761,P=0.000,and the difference was statistically significant.There was a highly positive correlation between PEEP and BMI,and the correlation coefficient was r=0.914,P=0.000.The difference was statistically significant.When using PEEP as the dependent variable,weight,and BMI as independent variables to create a linear regression equation,there was no statistically significant body weight,and BMI was statistically significant.Using PEEP as the dependent variable and BMI as the independent variable,the linear regression equation was created as follows.PEEP=-2.950+0.444·BMIConclisions:1.It is feasible to use lung ultrasound to guide the setting of mechanical ventilation parameters and lung repopulation during single lung ventilation in thoracic surgery;2.In single-lung ventilation,the use of optimal PEEP for pulmonary titration can reduce tidal volume and plateau pressure during one-lung ventilation and improve oxygenation during one-lung ventilation,compared to conventional lung protective ventilation patterns.3.There is a highly linear correlation between the PEEP setting and BMI in one-lung ventilation.Using PEEP as the dependent variable and BMI as the independent variable to create the linear regression equation are as follows:PEEP=-2.950+0.444·BMI...