Effect Of Continuous Positive Pressure Ventilation Strategy During General Anesthesia Induction Period On Atelectasis After General Anesthesia Induction In Obese Patients

Objective:To evaluate the effect of continuous positive airway pressure ventilation（CPAP）during the induction period of general anesthesia on postinduction atelectasis in obese patients.Methods:A total of 86 patients,aged 30～60 yr,with body mass index 28～35kg/m²,of American Society of Anesthesiologists physical statusⅡorⅢ,scheduled for cerebrovascular intervention under general anesthesia.It was divided into two groups using a random number table methods（n=43）:continuous positive airway pressure in the induction period（Group C）and regular group（Group R）.In Group C,CPAP of 5 cm H₂O was provided to assisted ventilation when preoxygenated during spontaneous respiration,after pressure control ventilation was adopted,and CPAP of 5 cm H₂O was converted to PEEP of the same value.In Group R,adopted the conventional method for spontaneous breathing without positive pressure assisted ventilation,and had no additional positive pressure ventilation parameters when performing pressure-controlled ventilation after spontaneous breathing disappeared.Chest CT tomography and blood gas analysis results were recorded after entering the operating room（T₁）and 5min after endotracheal intubation（T₂）,record the percentage of lung area and Pa O₂;record lung dynamic compliance（Cdyn）and platform pressure（Pplat）at T₂;mean minute ventilation（MV）,mean end-tidal partial carbon pressure(P_ETCO₂)under 3min pressure controlled respiration were recorded and vasoactive drug use during the induction process.Record the occurrence of reflux and aspiration during mask ventilation.The follow-up of pulmonary complications 3d after surgery was recorded.Results:Compared with group R,the percentage of lung area decreased,PaO₂、Cdyn increased and Pplat decreased in group C at T₂（P<0.05）.Compared with T₁,the percentage of lung area increased at T₂in two groups（P<0.05）.MV、P_ETCO₂、vasoactive drugs and 3d postoperative pulmonary complications were no statistically significant difference during two groups（P>0.05）.No adverse events such as reflux or aspiration occurred during mask ventilation in two groups.Conclusions:A CPAP（5cm H₂O）ventilation strategy when used during the induction phase of anesthesia reduces the formation of pulmonary atelectasis and to the improved oxygenation after induction in obese patients.However,there was no obvious effect on the occurrence of postoperative pulmonary complications.