The Application Of Pressure-controlled Ventilation Volume-guaranteed In One-lung Ventilation In Elderly Patients Undergoing Thoracoscopic Surgery

objective:In this paper,pressure-controlled ventilation volume-guaranteed（PCV-VG）was compared with the volume-controlled ventilation（VCV）,so as to explore the impact of different mechanical ventilation modes on the lung physiology in one-lung ventilation in elderly patients undergoing unilateral lobotomy under thoracoscopic surgery,and whether there are differences in the incidence of postoperative lung complications in patients with these two ventilation modes.To observe whether PCV-VG can optimize the effect of mechanical ventilation and improve early postoperative lung ventilation function.Methods:Fifty elderly patients（age>65 years old）who underwent elective thoracoscopic unilateral lobectomy from June 2021 to october 2022 were randomly divided into two groups with 25 cases in each group by double-blind method.observation group P（PCV-VG group）received PCV-VG ventilation during the operation（after anesthesia induction,double-lumen bronchotrachea intubation was performed,tidal volume was 6-8ml/kg,pressure rise time was 0.5s,inspiratory/expiratory ratio was 1:2,respiratory rate was 12-14 times/min）.Control group V（VCV group）received VCV ventilation（double-lumen bronchial intubation after anesthesia induction,tidal volume of 6-8ml/kg,inspiratory pause time of 0s,inspiratory/expiratory ratio of 1:2,respiratory rate of 12-14 times/min）.The following indexes were recorded in the two groups at various time points after entry（T₀）,supine double-lung ventilation for 5 minutes（T₁）,20-minute one-lung ventilation（T₂）,40-minute one-lung ventilation（T₃）,and 30 minutes after extubating（T₄）:（1）Vital signs（HR,MAP of mean arterial pressure,Sp O₂ of blood oxygen saturation）（2）respiratory dynamics parameters（Ppeak airway pressure,Pmean airway pressure,Cdyn of dynamic lung compliance）at T₁、T₂、T₃（3）Arterial blood gas analysis was performed at each time point.Blood gas analysis results（PH value,arterial oxygen partial pressure PaO₂,arterial carbon dioxide partial pressure PaCO₂,lactate concentration Lac）were recorded in the two groups at each time point.（4）Bedside chest X-ray examination was performed daily within three days after surgery.Pulmonary complications（including pleural effusion,atractasis,respiratory tract infection,aspiration pneumonia,respiratory failure,bronchospasm,pneumothorax,etc.）were recorded in the two groups within three days after surgery.Relevant data were analyzed using IBM SPSS Statistics 26.0 statistical software.Results:A total of 50 cases were initially included in this study,including 1 case of thoracotomy and 1 case of intraoperative hypoxemia.A total of 48 cases were eventually included in this study,with 24 cases in each group.There was no significant difference in gender,age,BMI and ASA grading ratio between group P and group V,and no significant difference in operation time and one-lung ventilation time between the two groups.Compared with T₁,Ppeak and Pmean at T₂ and T₃ were significantly increased in group V,while Cdyn was significantly decreased（<0.05）.Ppeak and Pmean of group P were significantly lower than those of group V at T₁-T₃（<0.05）,but Cdyn was significantly higher than that of group V（<0.05）.There was no significant difference in PaO₂ and PaCO₂ between the two groups at T₀;PaO₂ in group P at T₁-T₄ was significantly higher than that in group V,with statistical significance（<0.05）;PaCO₂ in group P at T₂-T₄was significantly lower than that in group V,with statistical significance（<0.05）.There was no significant difference in the incidence of postoperative pulmonary complications between the two groups.There was no significant difference in vital signs between the two groups at any time.Conclusion:Compared with VCV,PCV-VG can reduce intraoperative peak airway pressure and mean airway pressure in elderly patients undergoing thoracoscopic unilateral lobectomy,improve lung dynamic compliance,improve lung ventilation function,increase oxygenation,and reduce arterial carbon dioxide partial pressure,which is more consistent with the lung physiology of elderly patients and suitable for mechanical ventilation mode of one-lung ventilation in elderly patients.