Diaphragm thickening fraction as a predictor of successful weaning from mechanical ventilation in patients with chronic obstructive pulmonary disease

Abstract

Objective To evaluate the predictive performance of diaphragm thickening fraction (DTF) assessed by ultrasound in the feasibility of weaning from mechanical ventilation in patients with chronic obstructive pulmonary disease (COPD). Methods Forty-three patients with COPD were enrolled for prospective study.All patients were ventilated mechanically for more than 48 hours and were expected to be weaned when they met clinical criteria in the intensive care unit from February 2015 to August 2015.Patients received a spontaneous breathing trial under pressure support for 1 h. At the end of spontaneous breathing trial, the right hemi-diaphragm was visualized in the zone of apposition using a 6-13 MHz linear ultrasound probe. Diaphragm thickness was recorded at end-inspiration(DTei) and end-expiration(DTee), and the DTF was calculated as percentage from the following formula: (DTei - DTee) / DTee. Also the rapid shallow breathing index (RSBI) was calculated. Patients meeting weaning criteria were extubated. Weaning successfully was defined as spontaneous breathing for >48 h without any form of ventilation support. Results Twenty-five patients were weaned successfully and failure of weaning was found in 18 patients. A significant differences in DTF(39.66±13.22)%vs.(23.84±8.85)%, P<0.05 and RSBI(62.74±26.05)vs.(98.89±35.44), P<0.05 were observed between patients with successful weaning and patients with failure. The sensitivity and specificity of DTF≥30 % for successful weaning were 84% and 83.88 %, respectively. The area under the receiver operating characteristic curve was 0.872(95 % CI: 0.759-0.985)for DTF. By comparison, when RSBI was ≤105, there was a sensitivity of 92 %, and a specificity of 38.89 % for determining successful weaning. The area under the receiver operating characteristic curve was 0.804(95 % CI: 0.669-0.940)for RSBI. Conclusions This study shows that in a cohort of COPD patients, the assessment of DTF using diaphragm ultrasound may be useful to predict success weaning or failure during spontaneous breathing trial. Key words: Ultrasound; Diaphragm; Chronic obstructive pulmonary disease; Mechanical ventilation; Weaning; Bedside; Critical ill; Predictive value