Effects Of Prolonged Inspiratory Time On Respiratory Function During General Anesthesia In Patients Undergoing Gynecological Laparoscopic Surgery

ObjectiveThis study observes the influence of prolonged inspiratory time properly on respiratory function and hemodynamics during general anesthesia in patients undergoing gynecological laparoscopic surgery and explores the appropriate respiratory parameters in laparoscopic surgery.MethodsForty patients aged between 30 and 60 years old,weighing 45-70kg and American Society of Anesthesiologists physical status classification of ? or ?,who scheduled for gynecological laparoscopic surgery in our hospital from August 2018 to January 2019 were enrolled in the trial.These patients were randomly divided into the inverse ratio ventilation group?group A,I:E=1:1?and the conventional ventilation group?group B,I:E=1:2?with 20 patients in each group using the random number table method.Endotracheal intubation was performed after induction using the same anesthesia method in the two groups of patients.End-expiratory partial pressure of carbon dioxide(P_ETCO₂)is monitored during surgery.The ventilation mode was volume control mode,with tidal volume?VT?of 6-8 ml/kg,respiratory rate?RR?of12-14 beats/min.The inspiration and expiration ratio?I:E=1:1?was set in group A and?I:E=1:2?in group B,other parameters and anesthesia methods were the same.Airway pressure?Ppeak,Pmean,Cdyn?and hemodynamic variables were assessed and recorded at four time points?T1:10 min after induction of general anesthesia,T2:30 min after the initiationofpneumoperitoneum,T3:60minafter pneumoperitoneum,T4:10 min after pneumoperitoneum remove restore supine?.Meanwhile,patients'dorsal foot artery blood was extracted at time T2 and T3 for blood gas analysis to measure oxygenation function[arterial partial oxygen pressure?PaO₂?and arterial partial carbon dioxide pressure?PaCO₂?].ResultsThere were no statistically significant differences in general clinical data between the two groups,such as age,body mass,ASA composition,total volume of infusion,duration of pneumoperitoneum and operative time.Under the premise of maintaining the same anesthesia depth,there were no statistically significant differences in HR and MAP between the two groups at each time point?P>0.05?.The MAP at T2 and T3 of the two groups increased in different degrees compared with T1,and the difference was statistically significant?P<0.05?.There was a significant increase in HR at T2-T4 compared to baseline value of T1 for both groups?P<0.05?.Compared with group B,Ppeak in group A decreased while Pmean and Cdyn increased at T2-T4,and the difference was statistically significant?P<0.05?.There was no significant difference in P_ETCO₂between the two groups?P>0.05?.There was a significant increase in Ppeak,Pmean,P_ETCO₂ at T2-T4 compared to baseline value of T1 for both groups,while Cdyn decrease?P<0.05?.PaO₂ in group A was higher than that in group B at T2 and T3,and the difference was statistically significant?P<0.05?.Meanwhile,PaCO₂increased at T3 without any inter-group difference.With the increase of pneumoperitoneum time,PaCO₂ increased gradually,and the difference was statistically significant?P<0.05?.ConclusionIn gynecological laparoscopic surgery,prolonged inspiratory time properly can improve the respiratory function during general anesthesia without increasing CO₂ accumulation,promote gas exchange,decrease airway resistance,and improve oxygenation.