Correlation Between The Efficacy Of Non-invasive Positive Pressure Ventilation And Body Mass Index In Patients With AECOPD Combined With Type Ⅱ Respiratory Failure

Objective:The morbidity and mortality rate of chronic obstructive pulmonary disease（COPD）are increasing and becoming the fourth leading cause of death in the world,and the acute exacerbation of severe COPD is often accompanied by type Ⅱ respiratory failure.In addition to the conventional treatment of oxygen uptake,anti-infection,preventing asthma,airway diastole,relieve a cough,reduce phlegm,acid-base and electrolyte balance correction and symptomatic treatment,non-invasive respiratory support therapy is becoming an important treatment.In this study,the correlation between body mass index and the effect of non-invasive positive pressure ventilation therapy was studied to clarify the effect of nutritional status on the effect of non-invasive support therapy in patients with AECOPD and type Ⅱ respiratory failure,to clarify the importance of nutritional support therapy for COPD patients and to help clinicians predict the efficacy of non-invasive positive pressure ventilation therapy.Methods:This study retrospectively analyzed a total of 171 patients with complete data on AECOPD combined with type Ⅱ respiratory failure who were hospitalized at the Department of Respiratory and Critical Care Medicine,Department Ⅱ,First Hospital of Jilin University from December 2018 to July 2021 and applied non-invasive assisted ventilation,excluding 8 cases and including 163 cases,including 82 males and 81 females,Among them,19 failed patients（11.7%）were treated（Pa CO₂ difference between admission and discharge≤0 mm Hg）.The Pa CO₂ at admission and non-invasive positive pressure ventilation at 2 hours,24 hours,48 hours,72 hours,92 hours and at discharge were compared respectively.The difference between Pa CO₂ at admission and Pa CO₂ at 2 hours,Pa CO₂ at 24 hours,Pa CO₂ at 48 hours, Pa CO₂ at 72 hours,Pa CO₂ at 96 hours,and Pa CO₂ at discharge was used to evaluate the therapeutic effect of non-invasive mechanical ventilation,respectively.Patients were divided into four groups according to body mass index:low body mass index group（<18.50 kg/m~2）,normal body mass index group（18.50-23.99 kg/m~2）, overweight group（24-27.99 kg/m~2）,and obese group（≥28 kg/m~2）,and the treatment effects of Pa CO₂ at discharge and different time periods of non-invasive positive pressure ventilation were compared among the groups.Regression equations were constructed with age,body mass index and blood phosphorus to study the correlation between body mass index and Pa CO₂ at admission and at discharge,and the relationship between body mass index and the treatment effect of non-invasive mechanical ventilation was evaluated by rank correlation analysis.Results:1、The body mass index of patients with AECOPD and type Ⅱ respiratory failure was distributed at 22.41（20.00,24.34）kg/m~2.2、With the prolongation of the time of applying non-invasive positive pressure ventilation in the patients,the Pa CO₂ of the patients gradually decreased,in which there was a statistically significant difference（P<0.05）between the Pa CO₂ of the patients at admission and non-invasive mechanical ventilation at 48 hours,72 hours,96 hours,and at discharge,and there was no statistically significant difference （P>0.05）between Pa CO₂ at admission and non-invasive assisted ventilation at 2 hours and 24 hours..3、The differences in age of patients in different BMI groups were statistically significant（P<0.05）;the differences in gender,blood calcium,blood phosphorus levels and the prevalence of hypertension,diabetes mellitus and coronary heart disease in different BMI groups were not statistically significant（P>0.05）.4、A negative correlation between age and body mass index was obtained using rank correlation analysis（P<0.05）.5、Using multivariate rank-sum test to compare the effect of non-invasive positive pressure ventilation treatment in each group yielded a statistically significant difference between body mass index and the effect at 48 hours,72 hours,96 hours after non-invasive positive pressure ventilation treatment and discharge（P<0.05）,while there was no statistically significant difference with the effect at 2 hours and 24hours after non-invasive positive pressure ventilation treatment（P>0.05）.6、The effect of patient age and blood phosphorus level on Pa CO₂ at admission and discharge was statistically different using univariate and multifactorial correlation analysis（P<0.05）,while the effect of patient gender,body mass index,prevalence of hypertension,prevalence of diabetes mellitus,prevalence of coronary heart disease,and blood calcium on Pa CO₂ at admission and discharge was not statistically significant（P>0.05）.7、The effect of body mass index on the therapeutic effect of non-invasive mechanical ventilation at 24 hours,48 hours,72 hours,96 hours,and after treatment was statistically different using rank correlation analysis（P<0.05）,and the effect of body mass index on the therapeutic effect of non-invasive mechanical ventilation at 2hours was not statistically different（P>0.05）.Conclusion:1、There was no correlation between body mass index and the degree of respiratory failure in patients with AECOPD and type Ⅱ respiratory failure,but there was a correlation between age and blood phosphorus level on the degree of respiratory failure.2、The higher the body mass index,the better the effect of non-invasive positive pressure ventilation treatment and the faster the recovery rate of patients.