Effects Of Continuous Positive Airway Pressure Ventilation During Induction Of Anesthesia On Perioperative Atelectasis And Oxygenation In Elderly Patients

Objective:To evaluate the effect of continuous positive airway pressure ventilation during induction of anesthesia on perioperative atelectasis and oxygenation in elderly patients.Methods:46 elderly patients,aged 65～80 years,BMI 19～28 kg/m²,of American Society of Anesthesiologists physical status Ⅱ or Ⅲ,undergoing elective cerebrovascular intervention surgery under general anesthesia,were divided into 2 groups（n=23 each）according to the random number table method:control group（group C）and CPAP ventilation group（group CPAP）.During the induction period of anesthesia,in group CPAP,CPAP was set to 5 cm H₂O during spontaneous respiration,and PEEP was set to 5cm H₂O when spontaneous breathing disappeared to PCV ventilation;CPAP was not set in Group C,PEEP was set to 0 cm H₂O for PCV ventilation when spontaneous breathing disappeared.During the anesthesia maintenance period,PCV-VG mode was used in both groups,and PEEP was set at 5 cm H₂O.Whole lung CT scanning was performed immediately after radial artery catheterization（T₀）,1 minute after endotracheal intubation（T₂）,and before extubation（T₃）at the end of the operation,to calculate percentage of atelectasis area on the 1 cm level of the right diaphragm;At T₀,T₂,T₃,and 30 min after entering PACU（T₄）,radial artery blood samples were taken to record PaO₂ and Pa CO₂and calculate the oxygenation index（OI）.Results:Compared with group C,the percentage of atelectasis area decreased and PaO₂ and OI increased at T₂and T₃ in group CPAP（P<0.05）.Compared with T₀,the percentage of atelectasis area increased at T₂ and T₃;PaO₂ increased at T₂ and T₃,decreased to T₀ at T₄in two groups（P<0.05）;in group C,OI decreased at T₂ and T₃,increased to T₀ at T₄（P<0.05）;in group CPAP,OI increased at T₂ and T₃,decreased to T₀ at T₄（P<0.05）.There was no significant difference in Pa CO₂ between the two groups at each time point（P<0.05）.Conclusion:Continuous positive airway pressure ventilation during the induction of anesthesia can reduce the formation of atelectasis and improve the oxygenation in elderly patients undergoing elective cerebrovascular intervention surgery.