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Chest

Volume 152, Issue 6, December 2017, Pages 1140-1150
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Original Research: Critical Care
Diaphragm and Lung Ultrasound to Predict Weaning Outcome: Systematic Review and Meta-Analysis

https://doi.org/10.1016/j.chest.2017.08.028Get rights and content

Background

Deciding the optimal timing for extubation in patients who are mechanically ventilated can be challenging, and traditional weaning predictor tools are not very accurate. The aim of this systematic review and meta-analysis was to assess the accuracy of lung and diaphragm ultrasound for predicting weaning outcomes in critically ill adults.

Methods

MEDLINE, the Cochrane Library, Web of Science, Scopus, LILACS, Teseo, Tesis Doctorales en Red, and OpenGrey were searched, and the bibliographies of relevant studies were reviewed. Two researchers independently selected studies that met the inclusion criteria and assessed study quality in accordance with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The summary receiver-operating characteristic curve and pooled diagnostic OR (DOR) were estimated by using a bivariate random effects analysis. Sources of heterogeneity were explored by using predefined subgroup analyses and bivariate meta-regression.

Results

Nineteen studies involving 1,071 people were included in the study. For diaphragm thickening fraction, the area under the summary receiver-operating characteristic curve was 0.87, and DOR was 21 (95% CI, 11-40). Regarding diaphragmatic excursion, pooled sensitivity was 75% (95% CI, 65-85); pooled specificity, 75% (95% CI, 60-85); and DOR, 10 (95% CI, 4-24). For lung ultrasound, the area under the summary receiver-operating characteristic curve was 0.77, and DOR was 38 (95% CI, 7-198). Based on bivariate meta-regression analysis, a significantly higher specificity for diaphragm thickening fraction and higher sensitivity for diaphragmatic excursion was detected in studies with applicability concerns.

Conclusions

Lung and diaphragm ultrasound can help predict weaning outcome, but its accuracy may vary depending on the patient subpopulation.

Section snippets

Search Strategy and Selection Criteria

In this systematic review and meta-analysis, we included any studies in participants aged ≥ 18 years, admitted to an ICU, and subjected to invasive MV for at least 24 h; patients underwent lung and/or diaphragmatic ultrasound and had data available on weaning outcome. Weaning failure was defined broadly as the need for reintubation with reconnection to invasive MV, unscheduled postextubation noninvasive MV, tracheostomy, death within the first 72 h, or SBT failure. Because weaning success and

Results

The initial database search yielded a total of 3,819 references, and four additional records were identified from other sources. Fourteen subsequent references were also obtained from Google Scholar Alerts. A total of 3,837 records were thus obtained. After removing duplicates and screening titles and abstracts, we considered the full text of 55 studies, of which 36 were excluded (reasons detailed in Fig 1). Therefore, 19 references met the inclusion criteria and were included in the

Discussion

DTF is considered a good indicator of the diaphragmatic inhalation effort,49 and low values are associated with an increase in the duration of MV, ICU stay, and mortality.50 Our data suggest that DTF is also a good predictor of weaning outcome, with overall consistency across studies, except for one outlier reporting lower specificity (Tenza-Lozano, unpublished data, 2017). This discordant result may be because investigators performed the ultrasound before the SBT, during a brief MV

Conclusions

Our data suggest that DTF is by itself a modest predictor of weaning outcome in the general population of critically ill patients. We do not support the use of DE because its accuracy is lower, and its measurement and interpretation entail several pitfalls. The LUS score seems to be an accurate predictor, but more studies are needed to reduce uncertainty.

Acknowledgments

Author contributions: A. M. L.-A. had full access to all of the data in the study; takes responsibility for the integrity of the data and the accuracy of the data analysis; is guarantor for the entire manuscript; and contributed to the study concept and design, the literature search, data collection and analysis, methodologic quality assessment, figures, translation and drafting of the manuscript. E. M. T.-L. contributed to the literature search, data collection, and methodologic quality

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    FUNDING/SUPPORT: This study was supported by the Department of Clinical Medicine, Miguel Hernández University. The Department of Clinical Medicine of Miguel Hernández University provided nonfinancial support supplying translation assistance.

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