Ultrasound assessment of diaphragmatic dysfunction as a predictor of weaning outcome from mechanical ventilation: a systematic review and meta-analysis

Abstract

ObjectiveThe aim of this systematic review was to assess the diaphragmatic dysfunction (DD) as a predictor of weaning outcome.BackgroundSuccessful weaning depends on several factors: muscle strength, cardiac, respiratory and metabolic. Acquired weakness in mechanical ventilation is a growing important cause of weaning failure. With the development of ultrasonography, DD can be evaluated with ultrasound in weakness patients to predict weaning outcomes.MethodsThe Cochrane Library, PubMed, Embase, Ovid Medline, WanFang Data and CNKI were systematically searched from the inception to September 2017. Ultrasound assessment of DD in adult mechanical ventilation patients was included. Two independent investigators assessed study quality in accordance with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The primary outcome was diaphragmatic thickness and excursion in the weaning success and failure group. The secondary outcome was the influence of DD on weaning outcome.ResultsEleven studies involving a total of 436 patients were included. There were eight studies comparing diaphragmatic excursion (DE), five comparing the diaphragmatic thickening fraction (DTF) and two comparing DD between groups with and without successful weaning. Overall, the DE or DTF had a pooled sensitivity of 0.85 (95% CI 0.77 to 0.91) and a pooled specificity of 0.74 (95% CI 0.66 to 0.80) for predicting weaning success. There was high heterogeneity among the included studies (I2=80%; p=0.0006). The rate of weaning failure was significantly increased in patients with DD (OR 8.82; 95% CI 3.51 to 22.13; p<0.00001).ConclusionsBoth DE and DTF showed good diagnostic performance to predict weaning outcomes in spite of limitations included high heterogeneity among the studies. DD was found to be a predictor of weaning failure in critically ill patients.

ICU-acquired weakness

“…Volitional testing of global respiratory muscle strength via maximal inspiratory and expiratory pressure or of diaphragm strength via transdiaphragmatic pressure is again limited by the requirement of an awake and cooperative patient [24,[37][38][39][40]. Measurement of transdiaphragmatic or endotracheal tube pressure in response to phrenic nerve stimulation can circumvent this problem, but it is invasive, requires magnetic stimulation and is technically difficult [4,[37][38][39][40]. Also imaging techniques are being used.…”

“…Also imaging techniques are being used. However, chest X-rays have low sensitivity and specificity and ultrasonography has limited value during assisted breathing [4,[38][39][40].…”

“…The survival curves visually display the model predicted survival time for the "average" patient according to the Medical Research Council (MRC) sum score at final examination in the ICU as described in [70]. The middle panel compares patients who recovered from weakness (MRC ≥ 48 at last evaluation) with all patients who did not (MRC < 48 at last evaluation), whereas the right panel further distinguishes persistently weak patients into patients who remained moderately weak (MRC [36][37][38][39][40][41][42][43][44][45][46][47] or severely weak (MRC < 36). One-year survival was lower for weak patients as compared with not-weak patients.…”

Current and future applications of ultrasound imaging in peripheral nerve disorders

“…The use of NMUS to determine the optimal site for nerve and muscle biopsy and lumbar puncture is currently gaining further traction. In addition NMUS has more recently been used in the intensive care setting to identify post-operative diaphragmatic palsies, and hence is a useful tool to predict and prevent respiratory decline after extubation[ 257 , 258 ].…”

Utility and validity of dynamic chest radiography in cystic fibrosis (dynamic CF): an observational, non-controlled, non-randomised, single-centre, prospective study

“…Diaphragmatic motion can be directly assessed by ultrasound, traditional fluoroscopy and MRI fluoroscopy. While ultrasound shows promise in areas such as weaning from mechanical ventilation 21 and predicting recovery from non-invasive ventilation in COPD, 22 or assessing the presence of diaphragm dysfunction during exacerbations of COPD, 23 it requires skilled technicians and is not in widespread clinical use for assessing non-ventilated individuals. MRI fluoroscopy has shown correlation between diaphragmatic movement with FEV 1 in people with COPD, 24 but it is both time-consuming and resourceconsuming to perform.…”