Effects Of Lung Protective Ventilation Strategy In Different Ventilation Modes On Respiratory Mechanics And Postoperative Pulmonary Complications In Elderly Patients Undergoing Laparoscopic Radical Gastrectomy

Objective:The purpose of this study was to investigate the effects of different ventilation modes combined with lung protective ventilation strategy（LPVS）on respiratory mechanics and postoperative pulmonary complications（PPCs）during laparoscopy-assisted radical gastrectomy surgery in elderly patients.Methods:The study included 100 elderly patients aged 60 to 80 years old,of both sexes,ASA class I to III,who were undergoing selective laparoscopy-assisted radical gastrectomy.Using the random number method divided the patients into two groups with 50 patients each:group A（pressure regulated volume control mode,PRVC）,group B（volume control ventilation mode,VCV）.The same LPVS were used in the two groups:tidal volume（TV）of 8 ml/kg（PBW）with post end-exoiratory pressure（PEEP）of 5 cm H₂O,recruitment maneuver（RM）was performed every 30 minutes during pneumoperitoneum.At the end of pneumoperitoneum and the end of operation,the RM was performed once respectively.The ratio of inspiratory to expiratory（I:E）was 1:2.The respiratory frequency was adjusted to keep the end-expiratory carbon dioxide partial pressure(P_ETCO₂)at 35-45 mm Hg.Heart rate（HR）,mean arterial pressure（MAP）,peak airway pressure（Ppeak）,mean airway pressure（Pmean）and pulmonary compliance（Cdyn）were recorded at 10 minutes after intubation（T₀）,immediately after pneumoperitoneum（T₁）,30 minutes after pneumoperitoneum（T₂）,60 minutes after pneumoperitoneum（T₃）,120 minutes after pneumoperitoneum（T₄）,and the end of operation（T₅）.The cardiac output indexes such as CO,CI,SV,SVI,SVV were monitored by Flo Trac/Vigileo system.Arterial blood gas analysis was tested at T₀,T₃-T₅ respectively.p H,Pa O₂ and Pa CO₂ were recorded and oxygenation index（OI）was calculated.The postoperative hospitalization time,clinical pulmonary injection score（CPIS）at 24 hours and PPCs at 72 hours were observed and recorded.Results:1. There were no significant difference in general characteristics between the two groups（P>0.05）.2. Respiratory mechanics indexes（1）Ppeak:Compared with T₀,Ppeak in the two groups increased significantly lower than that in group B（P?0.05）;（2）Pmean:Compared with T₀,Pmean in the two groups increased at T₁to T₄（P<0.05）;Compared with group B,group A increased at T₂ to T₄（P<0.05）;（3）Cdyn:Compared with T₀,Cdyn in the two groups decreased at T₁ to T₄（P<0.05）;Compared with group B,it was significantly higher in group A at T₁ to T₅（P<0.05）;At T₅,the Cdyn of group A recovered to T₀ level,while group B did not（P<0.05）.3. Blood gas index（1）p H:Group B was lower than group A at T₃ to T₄（P?0.05）;（2）Pa O₂ and OI:They were significantly higher in group A than in group B at T₃ to T₅（P<0.05）;（3）Pa CO₂:Pa CO₂ increased gradually with the prolongation of operation time in the two groups;At T₃ to T₄,Pa CO₂ in group B was higher than that in group A,the difference was statistically significant（P?0.05）;4. Hemodynamic indexesThere were no significant differences in HR,MAP and cardiac output indexes between the two groups（P>0.05）;5. The postoperative hospitalization time in group A was 1.9 days lower than that in group B;Compared with group B,the postoperative CPIS and PPCs were decreased in group A（P<0.05）.Conclusions:For the elderly patients undergoing laparoscopic radical gastrectomy,PRVC combined with LPVS can produce lower peak airway pressure,better intraoperative oxygenation,reduce the incidence of PPCs,shorten the length of hospital stay,and it is beneficial to the rapid recovery of patients.