Observation Of The Effects Of Positive End Expiratory Pressure And Lung Recruitment On The Oxygenation And Lung Compliance In Tatients With Trendelenburg Position Laparoscopic Surgery

Objective:Observe the end-expiratory positive pressure ventilation and lung recruitment techniques applied to mechanical ventilation during Trendelenburg position laparoscopic surgery,and the difference in the effect on oxygenation function and lung compliance of patients.Methods:Choose 60 patients between March 2019 and December 2019,electively undergoing laparoscopy rectal and sigmoid colon surgery at the head of the Affiliated Tumor Hospital of Guangxi Medical University,between 40 and75 years old,regardless of gender,United States The Society of Anesthesiologists（ASA）grade I to II,body mass index is less than 30kg/m²,lung function and lung imaging examination did not incorporate other abnormalities.The patients were randomly divided among three groups with random number table method,20 cases in each group.Patients in each group were treated with rapid vein induction and full-screen vein maintenance.Inhaled anesthetics were not used during the operation.After induction of intubation,the ventilation parameters were:volume control mode,inhaled oxygen concentration 100%,oxygen flow rate 2L/min,inhalation ratio It is 1/2,the tidal volume（VT）is set to8ml/kg,and the respiratory rate is set to 12 times/min.After the head and feet are fixed high and the pneumoperitoneum starts,group N continues to ventilate according to the original protocol.Group P is adjusted to 7ml/kg,plus end-expiratory pressure（PEEP）7cm H₂O,and group R is adjusted to 7ml/kg,and lung recruitment maneuver every 30min after adjusting the parameters,the specific method is:every 30min,the ventilator is adjusted to the machine control mode,the APL valve is adjusted to 30cm H₂O,the balloon is squeezed,the lung recruitment maneuver is performed once,Recruitment lasted for 30 seconds,and then resumed ventilation mode before recuperation.The three groups dynamically adjusted the respiratory rate during operation to maintain the end-expiratory carbon dioxide partial pressure（PETCO₂）at 35⁴5mm H₂O after the pneumoperitoneum and resumed supine,and resumed the ventilation program at the completion of induction,all at the beginning of mechanical ventilation 10min（T0）,posture At the end of the adjustment,the pneumoperitoneum starts 10min（T1）,40min（T2）,70min（T3）,and the end of pneumoperitoneum returns to lying position for 10min（T4）,and the patient’s vital signs are recorded,including invasive arterial blood pressure（IBP）,heart rate（HR）,Pulse oxygen saturation（Sp O₂）,mean arterial pressure（MAP）,and ventilator parameters tidal volume（VT）,respiratory rate（RR）,peak airway pressure（Ppeak）,end-expiratory carbon dioxide concentration（PETCO₂）calculation dynamics Pulmonary dynamiccompliance（Cdyn）.At 10 minutes after the start of ventilation（T0）,at the end of posture adjustment,at the beginning of pneumoperitoneum,at 40 minutes（T2）,70 minutes（T3）,at the end of pneumoperitoneum,return to supine position for 10 minutes（T4）.Arterial blood carbon dioxide partial pressure（Pa CO₂）,alveolar arterial oxygen partial pressure difference（P（A-a）O₂）,oxygenation index（OI）.Results:1.Ppeak,Cdyn,Pa O₂,Pa CO₂,P（A-a）O₂,Qs/Qt of the three groups of patients all changed significantly with the operation（P<0.05）.2.At T0^T1,Cdyn decreased and Ppeak increased;at T1^T3,Cdyn decreased slowly and Ppeak increased slowly;at T3^T4,Cdyn increased and Ppeak decreased,and T0^T2 each time point,There was no significant difference in Cdyn among the three groups（P>0.05）.At each time point from T3 to T4,Cdyn in group P was significantly greater than that in groups R and N.At time T1,Ppeak in group P was higher than that in group R,and at T3,Ppeak in group P was lower than that in groups N and R,which was statistically significant（P<0.05）.Throughout the analysis,the average values ??of Cdyn and Ppeak among the three groups were not statistically different（P>0.05）.3.From time T0 to T2,Pa O₂and Pa CO₂rise faster,from time T2 to T4,Pa O₂slows down and Pa CO₂is more stable;at time T0^T4,P（A-a）O₂and Qs/Qt continue during the operation reduce.At each time point,the difference between the groups was not statistically significant（P>0.05）.Conclusions:1.During anaesthesia mechanical ventilation during laparoscopy surgery,the pneumoperitoneum and the high position of the head and feet can adversely affect the patient’s lung dynamic compliance,oxygenation function and other indicators.2.Three ventilation modes can make the patient’s interpretative respiratory mechanics index produce different trends within the tolerable range;but it does not affect the trend of the oxygenation index.3.Compared with the other two modes of ventilation,small tidal volume combined with positive end-expiratory pressure ventilation can start from the pneumoperitoneum at 70 minutes,which show the improvement of the patient’s lung dynamic compliance,but this improvement has limited clinical significance.