Different Pulmonary Retentions In Holmium Laser Lithotripsy Surgery Under General Anesthesia Using Laryngeal Mask Airway

Objective:To observe whether the lung protective ventilation strategies(LPVS)of laryngeal mask combined with low positive end-expiratory pressure(PEEP),small tidal volume,and different lung recruitment methods(RMs)can reduce Postoperative pulmonary complications(PPCs)in patients with holmium laser lithotripsy surgery under laryngeal mask general anesthesia compared with that of patients without recruitment.And compare the effects of intermittent and continuous recruitment on the circulation of patients and the impact of perioperative pulmonary complications.Methods:252 patients(aged 18 to 65 years,no gender limitation,ASAⅠ～Ⅲ,BMI18～30 kg/m2,undergoing elective holmium laser lithotripsy surgery under general anesthesia)were randomly divided into 3 group:Group A,RMs for 30 seconds at a time and one time in total;Group B,RMs for 10 seconds at a time and three times in total and interval 10s;Group C,control group,no RMs.After routine induction,the three groups patients were placed appropriate laryngeal mask,inhale 50%oxygen 2 L/min,tidal volume 6ml/kg,PEEP 5 cmH2O,inhalation-expiration ratio 1:2,ventilation frequency 12-18 times/min,All the three groups maintained the End-expiratory carbon dioxide concentration:35-50 mmHg.During the operation,group A and Group B underwent RMs every 30 minutes,and after RMs was completed,converted to mechanical controlled respiration.Group C did not undergo RMs.The operation of RMs is as follows:adjust the pressure valve to 20 cmH2O,and adjust to the manually controlled breathing valve,then to squeeze the air bag to maintain the airway pressure at 20 cmH2O.Group A continued 30 s at a time and one time in total.Group B continued 10s and interval 10s,3 times in total.All patients received the same anesthesia.Vital signs,airway peak pressure(Ppeak),plateau pressure(Pplat),positive end-expiratory pressure(PEEP),oxygenation index(Pa02/FiO2)were record.Arterial blood gas analysis,heart rate and mean arterial pressure was tested before operation(T1),controlled ventilation for one hour(T2),and the end of the operation(T3).Main indicators observed:intraoperative circulation and pulmonary function(heart rate,mean arterial pressure,oxygenation index,airway peak pressure,arterial blood gas analysis value)and Pulmonary complications(common complications such as atelectasis,hypoxemia,pneumothorax,pneumonia and pleural effusion,as well as bronchospasm,type Ⅰ and type Ⅱ respiratory failure).Secondary observation indicators:general conditions of patients,operation time,postoperative nausea and vomiting,body temperature,hospitalization days,ICU occupancy rate,mortality rate,etc.Results:69 patients were excluded due to the following reasons:intraoperative laryngeal mask airway(LMA)placement failure or poor alignment,operation time less than 1 hour,sepsis due to urethral bacteria entering the blood during or after surgery,urethrotomy instead due to failure of lithotripsy,and excessive circulatory fluctuation during RMs.Finally,183 participants were included in the statistical analysis,including 56 patients in group A,60 patients in group B and 67 patients in group C.There were no statistically significant differences in ventilator parameters,laryngeal mask airway related complications,postoperative cough and sputum,fever,postoperative hospital stay,patient satisfaction in the three groups except during RMs.There were 13 cases of PPCs,with the total incidence of 7.%.4 cases in group A,the incidence rate was 7.%;3 cases in group B,the incidence rate was 5.0%;6 cases in group C,the incidence rate was 8.9%;and the incidence of PPCs in group C was higher than that in group A and B,but the difference was not statistically significant(P>0.05).The mean arterial pressure in group A decreased by 6.12±4.06mmHg,in group B decreased by 4.35±3.35mmHg;the heart rate in group A decreased by 3.25±2.13,in group B decreased by 3.00±1.82 during RMs.Because RMs was not performed in group C,the fluctuation of heart rate and blood pressure was not obvious.The decrease rate of heart rate and mean arterial pressure during RMs in group A and group B was significantly higher than that in group C,and the difference was statistically significant(P<0.01).The decrease rate of blood pressure in group A was significantly higher than that in group B,and the difference was statistically significant(P<0.01).There were no deaths during hospitalization.Conclusion:Intermittent and fractional recruitment maneuvers can redue circulation fluctuationin of patients undergoing holmium laser lithotripsy surgery with laryngeal mask general anesthesia.Low tide volume ventilation and low PEEP combined with RMs can not significantly reduce the incidence of PPCs in healthy lung patients,but had a tendency to reduce lung injury.