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. 2016 Sep 28;20(1):305.
doi: 10.1186/s13054-016-1479-y.

Can diaphragmatic ultrasonography performed during the T-tube trial predict weaning failure? The role of diaphragmatic rapid shallow breathing index

Savino Spadaro  1 , Salvatore Grasso  2 , Tommaso Mauri  3 , Francesca Dalla Corte  4 , Valentina Alvisi  4 , Riccardo Ragazzi  4 , Valentina Cricca  4 , Giulia Biondi  4 , Rossella Di Mussi  2 , Elisabetta Marangoni  4 , Carlo Alberto Volta  4
Affiliations

Can diaphragmatic ultrasonography performed during the T-tube trial predict weaning failure? The role of diaphragmatic rapid shallow breathing index

Savino Spadaro et al. Crit Care. .

Abstract

Background: The rapid shallow breathing index (RSBI), which is the ratio between respiratory rate (RR) and tidal volume (VT), is one of the most widely used indices to predict weaning outcome. Whereas the diaphragm plays a fundamental role in generating VT, in the case of diaphragmatic dysfunction the inspiratory accessory muscles may contribute. If this occurs during a weaning trial, delayed weaning failure is likely since the accessory muscles are more fatigable than the diaphragm. Hence, we hypothesised that the traditional RSBI could be implemented by substituting VT with the ultrasonographic evaluation of diaphragmatic displacement (DD). We named the new index the diaphragmatic-RSBI (D-RSBI). The aim of this study was to compare the ability of the traditional RSBI and D-RSBI to predict weaning failure in ready-to-wean patients.

Methods: We performed a prospective observational study. During a T-tube spontaneous breathing trial (SBT) we simultaneously evaluated right hemidiaphragm displacement (i.e., DD) by using M-mode ultrasonography as well as the RSBI. Outcome of the weaning attempt, length of mechanical ventilation, length of intensive care unit and hospital stay, and hospital mortality were recorded. Receiver operator characteristic (ROC) curves were used to evaluate the diagnostic accuracy of D-RSBI and RSBI.

Results: We enrolled 51 patients requiring mechanical ventilation for more than 48 h who were ready to perform a SBT. Most of the patients, 34 (66 %), were successfully weaned from mechanical ventilation. When considering the 17 patients that failed the weaning attempt, 11 (64 %) had to be reconnected to the ventilator during the SBT, three (18 %) had to be re-intubated within 48 h of extubation, and three (18 %) required non-invasive ventilation support within 48 h of extubation. The areas under the ROC curves for D-RSBI and RSBI were 0.89 and 0.72, respectively (P = 0.006).

Conclusions: D-RSBI (RR/DD) was more accurate than traditional RSBI (RR/VT) in predicting the weaning outcome.

Trial registration: Our clinical trial was retrospectively registered with ClinicalTrials.gov (identifier: NCT02696018 ). ClinicalTrials.gov processed our record on 25 February 2016.

Keywords: Diaphragmatic displacement; Rapid shallow breathing; Spontaneous breathing trial; Ultrasonography; Weaning.

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Figures

Fig. 1
Fig. 1
Time-line of the study protocol. Patients requiring mechanical ventilation for at least 48 h (H) were consecutively included. After 30 min of a T-tube spontaneous breathing trial (SBT), patients breathing patterns were examined. We used a multimodal evaluation combining ultrasound evaluation of diaphragmatic displacement and spirometry. At the end of a 2-h SBT, the treating physician decided to extubate or to reinstitute mechanical ventilation without being aware of the results of the ultrasound exploration of the diaphragm. Weaning success was monitored for a 48-h follow-up period; the reinstitution of mechanical ventilation during or at the end of the SBT, reintubation within 48 h, or the use of non-invasive ventilation (NIV) within 48 h from extubation were registered as a failed weaning attempt
Fig. 2
Fig. 2
M-mode sonography of the diaphragm of a a representative patient with an impaired right diaphragmatic displacement (DD = 6 mm) and b a representative patient with a conserved right hemidiaphragm function (DD = 14.8 mm). DD was measured on the vertical axis of a frozen image from the baseline, at the end of expiration, to the point of maximum height of inspiration
Fig. 3
Fig. 3
Flow chart of the study. MV mechanical ventilation, NIV non-invasive ventilation, SBT spontaneous breathing trial
Fig. 4
Fig. 4
Correlation between diaphragmatic rapid shallow breathing index (D-RSBI) and traditional rapid shallow breathing index (RSBI)
Fig. 5
Fig. 5
Receiver operating characteristic (ROC) curve for diaphragmatic rapid shallow breathing index (D-RSBI) and traditional rapid shallow breathing index (RSBI). The D-RSBI curve is shown in black and the RSBI curve is presented by a grey dashed line
See this image and copyright information in PMC

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