Application Value Of Point-of-care Ultrasound In Diaphragmatic Function Assessment In Chronic Obstructive Pulmonary Disease

Objective To evaluate the diaphragmatic function of patients with chronic obstructive pulmonary disease（COPD）by point-of-care ultrasound,and to explore the relationship between diaphragmatic function parameters and pulmonary function and its value in evaluating the condition.Methods A total of 75 COPD patients admitted to our hospital from July 2021 to December 2022 were included as the case group or COPD group.Thirty healthy volunteers with age and gender matched with the COPD group were recruited as the control group.Diaphragmatic ultrasound and pulmonary function tests were performed.The common diaphragmatic function parameters,including diaphragmatic excursion during calm breathing（DCB）,diaphragmatic excursion during deep inspiration（DDI）,diaphragmatic thickness at the end of calm expiration(TD_CE)and diaphragmatic thickness at the end of deep inspiration(TD_DI),were measured.Tidal volume（VT）,maximum mid-expiratory flow（MMEF）,forced expiratory volume in one second as a percentage of predicted value（FEV1%pred）and forced expiratory volume in one second as a percentage of forced vital capacity（FEV1/FVC）were recorded.According to the results of the pulmonary function test,the case group was further divided into the mild-moderate group（30 cases,FEV1%pred≥50%）and the severe to very severe group（45 cases,FEV1%pred<50%）.The differences of diaphragmatic function parameters between the COPD group and the control group were compared,and the differences of diaphragmatic function parameters among the healthy control group,mild-moderate group and severe-very severe group were compared,and the relationship between diaphragmatic function parameters and lung function in COPD patients and its value in evaluating the condition was explored.Results（1）There was no statistically significant difference in the diaphragmatic excursion（DCB）during calm breathing between the COPD group and control group（P>0.05）,but the diaphragmatic excursion（DDI）during deep inspiration was significantly lower in the COPD group than that in the control group（40.03±7.19mm vs50.20±4.77mm,P<0.05）.There was no significant difference in DCB among the healthy control group,mild-moderate group and severe-extremely severe group（P>0.05）.Compared with the healthy control group,the DDI of the mild-moderate group was decreased（44.8±5.98mm）vs（50.20±4.77mm）,and the difference was statistically significant（P<0.05）.Compared with the mild-moderate group,the DDI of the severe-extremely severe group further decreased（36.85±6.13mm vs 44.8±5.98mm,P<0.05）.（2）Compared with the control group,the diaphragm thickness at the end of calm expiration(TD_CE)was not significantly different（P>0.05）,while the diaphragm thickness at the end of deep inspiration(TD_DI)was significantly decreased in the COPD group（3.88±0.91mm）vs（4.71±0.65mm）,the difference was statistically significant（P<0.05）.There was no significant difference in TD_CEamong the healthy control group,mild-moderate group,and severe-extremely severe group（P>0.05）.Compared with the healthy control group,the TD_DIof the mild-moderate group was decreased（4.25±0.85mm）vs（4.71±0.65mm）,and the difference was statistically significant（P<0.05）.Compared with the mild-moderate group,the TD_DIof the severe-very severe group was further decreased（3.64±0.87mm）vs（4.25±0.85mm）,and the difference was statistically significant（P<0.05）.（3）There was no correlation between DCB and any variables in COPD patients（P>0.05）,while DDI was positively correlated with MMEF（r=0.450）,FEV1%pred（r=0.486）,FEV1/FVC（r=0.383）（P<0.05）,and there was no correlation with other variables（P>0.05）.In COPD patients,TD_CEwas positively correlated with VT（r=0.266,P<0.05）,but there was no correlation with its variables（P>0.05）,while TD_DIwas positively correlated with VT（r=0.342,P<0.05）and FEV1%pred（r=0.312,P<0.05）.There was no correlation with other variables（P>0.05）.（4）The diaphragm function parameters DDI and TD_DIcould be used as indicators to distinguish mild-moderate group and severe-extreme group COPD patients.The area under the ROC curve was 0.818 and 0.695（P<0.05）,and the cut-off values were43.9mm and 3.45mm,respectively.The sensitivity and specificity for diagnosing severe to very severe COPD were 84.4%and 63.3%,51.1%and 80%,respectively.Logistic regression analysis showed that DDI≤43.9mm and TD_DI≤3.45mm were risk factors for COPD exacerbation,with OR values of 8.893 and 3.908,respectively（P<0.05）.Conclusions The diaphragmatic function of COPD patients measured by point-of-care ultrasound is lower than that of healthy people,and the diaphragmatic function of COPD patients with severe disease is worse.Diaphragmatic function parameters in COPD patients are correlated with lung function parameters,and diaphragmatic function parameters can be used as simple surrogate indicators to evaluate the condition of COPD patients.