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.
ABSTRACT
Objective To evaluate the effectiveness of noninvasive positive pressure ventilation(NPPV) as a weaning strategy in patients with acute respiratory failure after failure to wean from invasive positive pressure ventilation(IPPV). Method A prospective randomized and controlled clinical trial of weaning of IPPV was carried out in patients mechanically ventilated in mode of IPPV for more than 48 hours with failure in a spontaneous breathing trial(SBT: PSV 6 cmH_2O). Patients with contraindications to NPPV were excluded. After failure the SBT, patients were randomly divided(random number) in two groups. Patients in NPPV group were extubated after being ventilated with high pressure support for 30 minutes and then placed on NPPV. Patients in IPPV group were weaned following conventional procedure. Arterial blood gases, maximal inspiratory pressure, respiratory rate,tidal volume, rapid shallow breathing index, heart rate, arterial blood pressure, and peripheral oxygen saturation were measured before and after failing the SBT. The rate of complications, including pneumonia and tracheotomy duration mechanical ventilation, days of hospital stay and outcome were observed. Findings of the two groups were vompared using the Student t test and the chi-square test. Results The percentage of complications in the NPPV group was lower(22.9% versus 72.2%, P <0.01) ,with lower incidences of pneumonia(6.1%,36.1%; P <0.01) and tracheotomy. Compared between the two groups, days of ICU stay( 14.16(3.45) d vs. 22.57( 7.71 ) d; P <0.01) and total days of mechanical ventilation(14.88±3.76 days vs. 20.68± 2.79 days, P <0.01) of NPPV group are shorter than IPPV group. Conclusions NPPV is a good alternative to the mechanically venti-lated patients who fail in initial weaning attempts. The key to successful NPPV weaning is the proper selection of weaning candidates and using NPPV as soon as possible after extubation.