Study On The Effect Of PCV And VCV On Pulmonary Function Of Patients With Artificial Pneumothorax Esophagectomy

Background and ObjectiveEsophageal cancer is one of the malignant tumors with a high morbidity in China,and the incidence has increased by years.Esophagectomy is an essential treatment to the esophageal cancer.In recent years,Endoscopic esophageal cancer radical resection of artificial pneumothorax has been rapidly developed.Compared with the traditional radical esophagectomy,it has the advantages of less trauma and mild postoperative pain.However,no matter which kind of the surgical methods used,the incidence of postoperative pulmonary complications in esophageal cancer patients undergoing radical resection remains high,which significantly increases the patient’s intensive care time and length of hospitalization,and is the main factor affecting the postoperative survival and quality of life.Mechanical ventilation is used for critically ill patients and patients with general anesthesia to maintain gas exchange and assure the oxygenation,but inappropriate mechanical ventilation can make a change of the structure and function of lung tissue,and lead to ventilation-induced lung injury（VILI）.Currently,volume controlled ventilation（VCV）mode is often used in clinical practice.However,It has been found that pressure controlled ventilation（PCV）can improve oxygenation and reduce the postoperative pulmonary complications compared with VCV during one-lung ventilation（OLV）in thoracic surgery.However,PCV has been rarely applicated in endoscopic esophagectomy through artificial CO₂ pneumothorax and the comparative study has not been reported between PCV and VCV.This study mainly investigated the effect of different ventilation modes（VCV or PCV）on the pulmonary ventilation and exchange function and postoperative pulmonary complications during endoscopic esophagectomy through artificial CO₂pneumothorax,in order to improve the prognosis and postoperative quality of patients’life.Method84 cases of patients with ASAⅠ^Ⅰwho were scheduled for artificial pneumothorax esophagectomy were enrolled in this study.The patients aged between40-65 years were divided into two groups by random number table method:pressure controlled ventilation group（group P）and volume controlled ventilation（group V）,42 cases in each group.Before the onset of artificial pneumothorax,both groups were given VCV,oxygen flow rate 2.0 L/min,inhalation ratio 1:2,tidal volume 6-8 mL/kg,respiratory rate 12 times/min,FiO₂ 70%.After the artificial CO₂ pneumothorax（CO₂pressure=8 mmHg,1 mmHg=0.133 kPa）was established,the group V set the tidal volume 5mL/kg and pressure limit<30 cmH₂O,the group P was set to the same driving pressure as the 5 mL/kg tidal volume reached the peak inspiratory pressure.Both groups were set to PEEP=5 cmH2O（1cmH2O=0.098 kPa）,respiratory rate 16-20times/min,FiO₂70%.Lung recruitment was routinely implemented.At the end of the artificial pneumothorax,VCV was performed in both groups,and the ventilation parameters were set as the same with beginning of the artificial pneumothorax established.After VCV was performed 5 minutes,the P group was directly converted to the pressure control mode.The arterial blood was respectively collected and arterial blood gas was detected from patients after intubation（T₀）,start of artificial pneumothorax（T1）,1h after artificial pneumothorax（T2）,end of artificial pneumothorax（T₃）and end of surgery（T₄）.Simultaneous recording of pH value,PaO2,PaCO2,Pplat,PETCO2 and calculate patient’s intrapulmonary shunt rate（Qs/Qt）and respiratory index（RI）,Record the time of extubation after surgery.The arterial blood samples were collected at 6 h,12 h,and 24 h for blood gas analysis after operation and the oxygenation index（PaO2/FiO2）was calculated at each time point.Record patient’s pulmonary complications 7 days after surgery,postoperative ICU incidence,the length of hospitalization and mortality were recorded.Result1.There was no significant difference in the general conditions of the two groups,such as gender,age,body mass index（BMI）,and preoperative lung function（P>0.05）.2.Compared with T₀,Pplat increased significantly at T₁ and T₂（P<0.05）.T₃ and T₄ did not increase significantly（P>0.05）.Compared with group P,Pplat increased at T₁-T₄ in V group,the difference was statistically significant（P<0.05）.3.Compared with T₀,Qs/Qt significantly increased（P<0.05）at T₁-T₄ in both groups,RI increased significantly at T2 and T3 in group P（P<0.05）,and RI was increased at T2-T4 in group V.（P<0.05）;Compared with group P,Qs/Qt increased in group V at T₁ and T₂ and RI increased at T₂-T₄,the difference was statistically significant（P<0.05）.4.Compared with T₀,PaO₂ and pH values of both groups decreased at T₂ and T₃（P<0.05）,PaCO₂ at T₂-T₄ increased significantly（P<0.05）.Compared with group P,the PaO₂ and pH values of group V decreased at T₂ and T₃（P<0.05）.There was no significant difference in PaCO₂ between the two groups at each time point（P>0.05）.5.There was no significant difference in operation time during thoracoscopic and total operation time between the two groups（P>0.05）.In group P,the PaO₂/Fi O₂ was higher than group V at 6h,12h and 24h postoperatively（P<0.05）;the time of postoperative extubation,incidence of pulmonary complications at postoperative 7days,and duration of hospitalization were lower in group P than in group V,and the difference was statistically significant.（P<0.05）.One patient in group P was admitted to ICU,and four patients in group V were admitted to ICU.There were no deaths in both groups.ConclusionPressure-controlled ventilation during artificial pneumothorax esophagectomy can decrease plateau airway pressure,improve tissue oxygenation,reduce the incidence of postoperative pulmonary complications and accelerate the recovery of patients.