The Setting Of Individualized Tidal Volume And Its Effect On Lung Function Of Obese Preschoolers

Objective Compared with fixed tidal volume level,the application of individualized tidal volume level based on lung dynamic compliance（Cdyn）and its influence on lung function in obese preschoolers was studied to select appropriate tidal volume parameters for this population.Methods A total of 80 preschoolers who underwent selective tonsillectomy and/or adenoidectomy in our hospital from December 2020 to December 2021 were selected and divided into obese group（group H）and normal weight group（group M）according to Body mass index（BMI）.Each group was divided into H₁,H₂and M₁,M₂groups,in which H₁and M₁groups were given individualized tidal volume ventilation program,while H₂and M₂groups were given conventional tidal volume ventilation program.That is H₁and M₁gradually reduce tidal volume from 10 ml/kg to 6 ml/kg[predicted body weight（PBW）was used for tidal volume calculation],and each tidal volume level（10,9,8,7,6 ml/kg）was maintained for 1 min.The Cdyn of the last respiratory cycle was calculated in every minute,and the tidal volume level which could produce the maximum Cdyn was selected as the optimal tidal volume level to maintain the whole mechanical ventilation process.Conventional tidal volume（8 ml/kg）was used to maintain ventilation in H₂and M₂groups.The heart rate,systolic blood pressure and diastolic blood pressure of each group were recorded at T₁（before anesthesia）,T₂（10minutes after intubation）and T₃（1 hour after surgery）.End-tidal carbon dioxide pressure,platform pressure and peak airway pressure were recorded at T₂,and lung dynamic compliance,driving pressure and mechanical ventilation time were calculated.The number of pulmonary adverse reactions and length of hospital stay in T₄（within 7 days after operation）were recorded.Results（1）The tidal volume corresponding to the maximum Cdyn in obese children and normal weight children was 9 ml/kg and 10 ml/kg,with no statistical significance（P>0.05）.（2）There were no significant differences in end-tidal carbon dioxide pressure and peak airway pressure among all groups（P>0.05）;There were no statistically significant differences in respiratory mechanical indexes between H₁and M₁,H₂and M₂groups（P>0.05）;There were statistically significant differences in platform pressure,driving pressure and lung dynamic compliance between H₁and H₂,M₁and M₂groups（P<0.05）.（3）There was no significant difference in the length of hospital stay among all groups（P>0.05）,the incidence of postoperative adverse reactions in H₁and H₂groups was statistically significant（P<0.05）.Conclusion（1）Individualized ventilation with titrated tidal volume of Cdyn is suitable for obese children in preschoolers and is beneficial to lung protection of obese children.（2）The tidal volume of obese children and normal weight children was set in the range of 8-10 ml/kg（PBW）,and the optimal tidal volume was 9 ml/kg and 10 ml/kg（PBW）,respectively.