A narrative review of diaphragm ultrasound to predict weaning from mechanical ventilation: where are we and where are we heading?

Abstract

Background The use of ultrasound to visualize the diaphragm is well established. Over the last 15 years, certain indices of diaphragm function, namely diaphragm thickness, thickening fraction and excursion have been established for mechanically ventilated patients to track changes in diaphragm size and function over time, to assess and diagnose diaphragmatic dysfunction, and to evaluate if these indices can predict successful liberation from mechanical ventilation. In the last 2 years, three meta-analyses and a systematic review have assessed the usability of diaphragmatic ultrasound to predict successful weaning. Since then, further data have been published on the topic. Conclusions The aim of this narrative review is to briefly describe the common methods of diaphragmatic function assessment using ultrasound techniques, before summarizing the major points raised by the recent reviews. A narrative summary of the most recent data will be presented, before concluding with a brief discussion of future research directions in this field.

Diaphragm and Lung Ultrasonography During Weaning From Mechanical Ventilation in Critically Ill Patients

“…It is known that DE is positively correlated with inspiratory volumes [ 23 ]. Given the amplitude of diaphragmatic movements, the excursion values of ≤10 mm are associated with diaphragm dysfunction and prolonged MV [ 6 ].…”

Diaphragmatic ultrasound: a review of its methodological aspects and clinical uses

“…That marked heterogeneity among studies makes it difficult to draw general conclusions on the usefulness of diaphragmatic ultrasound in predicting weaning outcomes, which could explain the lack of guidelines. Recent, high-quality studies, including a systematic review, 47 three meta-analyses, 55 - 57 and a narrative review, 58 have synthesized the available knowledge on this subject. Although a complete review of all such studies is beyond the scope of the present report, there is compelling evidence that diaphragmatic ultrasound is a feasible, promising technique for use in critical care, especially in patients with respiratory failure.…”

Diaphragm and Lung Ultrasound Indices in Prediction of Outcome of Weaning from Mechanical Ventilation in Pediatric Intensive Care Unit: Correspondence

“…Integration of DTF of ≥30% combined with lung ultrasound score (LUS) of ≤12 have been reported to predict on successful extubation better compared with DTF alone [4]. Combination of rapid shallow breathing index (RSBI) with right DTF ≥26% can be a more accurate predictor of successful weaning from mechanical ventilation than RSBI alone [5]. The diaphragmatic rapid shallow breathing index (D-RSBI), the ratio between respiratory rate (RR) and DE, is a promising tool which can predict weaning from mechanical ventilation.…”

“…The diaphragmatic rapid shallow breathing index (D-RSBI), the ratio between respiratory rate (RR) and DE, is a promising tool which can predict weaning from mechanical ventilation. D-RSBI (RR/DE) is superior to the traditional RSBI (RR/VT) in predicting weaning outcome especially when monitored at 30 min from the start of spontaneous breathing trial [5]. Given the fact that RSBI can give false positive result in predicting success of extubation and weaning, it is still a valuable clinical tool to predict weaning.…”

“…However, the DE and the speed of diaphragmatic contraction appear to be the best parameter for weaning where ultrasound-based bedside monitoring is feasible. The DE and DTF values also can suffer the intraanalyzer and inter-analyzer reproducibility differences for the measurements [5]. Other important issues in ICU set-up are: diaphragmatic dysfunction may be from pulmonary or neuromuscular disease, impediments to successful visualization, such as the right lung's downward excursion and the miniature window owing to the presence of the spleen, critically-ill patients often cannot properly do breath-holding, and scarcity of skilled personnel for ultrasonography in ICU set-up.…”