Correlation Between Peripheral Blood Eosinophils Count And Type Ⅱ Respiratory Failure In Patients With Acute Exacerbation Of COPD

BACKGROUNDChronic obstructive pulmonary disease（COPD）is a common respiratory disease worldwide,with high morbidity and mortality.The airway inflammation of COPD is mainly neutrophilic inflammation followed by eosinophilic inflammation.Current studies have found that peripheral blood eosinophils levels are correlated with respiratory failure in patients with acute exacerbation of COPD（AECOPD）,but no further study have clarified whether there is a curve relationship between them.OBJECTIVEThe purpose of this study was to clarify the relationship between peripheral blood eosinophils count and clinical features in patients with AECOPD,and to estimate the possible curve relationship between peripheral blood eosinophils count and type II respiratory failure,so as to provide some references for clinicians to make effective treatment decisions.METHODSThis single-center,cross-sectional study was conducted in Shenzhen Second People’s Hospital in China.Patients who were hospitalized in Department of Respiratory and Critical Care Medicine for AECOPD between January 2017 to June 2020 were enrolled.The electronic medical record system was used to collect relevant medical records of patients,including general information,laboratory indicators and clinical treatment indicators.The study population was divided into low-level group(peripheral blood eosinophils count less than 100 eosinophils·μL^-1)and medium-level group(peripheral blood eosinophils count are not less than 100 eosinophils·μL^-1,but less than 300eosinophils·μL^-1)and high-level group(peripheral blood eosinophils count not less than 300 eosinophils·μL^-1).RESULTSA total of 330 COPD patients who experienced acute exacerbation were analyzed,and they were divided into low-level group（n=146）,medium-level group（n=147）,and high-level group（n=37）.Compared with the other two groups,the probability of type II respiratory failure,high-sensitivity C-reactive protein,procalcitonin,white blood cell counts,neutrophil counts,fibrinogen,NT-Pro BNP and the percentage of patients received non-invasive mechanical ventilation were higher in the low-level group,while the lymphocyte count,platelet count,serum albumin and serum uric acid were lower in the low-level group.The results of univariate analysis indicated that male sex,low body mass index,without coronary heart disease,low lymphocyte counts,low eosinophils count,low serum albumin and with cor pulmonary were risk factors for type II respiratory failure.After adjusting for clinical confounding variables,non-linearity relationship was found between peripheral blood eosinophils count and type II respiratory failure in patients with AECOPD.There was a threshold effect between peripheral blood eosinophils count and type II respiratory failure in patients with AECOPD,and the cut-off value of peripheral blood eosinophils count was 0.2*10⁹eosinophils/L(200 eosinophils·μL^-1).When the peripheral blood eosinophil count is less than 200 eosinophils·μL^-1,the probability of type II respiratory failure decreases as the peripheral blood eosinophil count increases.In the subgroup analysis,the hazard ratio for type II respiratory failure remained consistent across subgroups in patients with AECOPD.CONCLUSIONSIn conclusion,the peripheral blood eosinophils count in the patients with AECOPD was statistically significantly associated with incident type II respiratory failure.There was a threshold effect in AECOPD patients between peripheral blood eosinophils count and type II respiratory failure,and the cut-off value of peripheral blood eosinophils count was 0.2*10⁹eosinophils/L(200 eosinophils·μL^-1).When the peripheral blood eosinophil count is less than 200 eosinophils·μL^-1,the probability of type II respiratory failure decreases as the peripheral blood eosinophil count increases.peripheral blood eosinophils count was strong negatively with incident type II respiratory failure.Peripheral blood eosinophils count in patients with acute exacerbation of COPD can be used as an independent biomarker for predicting type II respiratory failure events.