Elsevier

Journal of Critical Care

Volume 51, June 2019, Pages 133-138
Journal of Critical Care

The evolution of diaphragm activity and function determined by ultrasound during spontaneous breathing trials

https://doi.org/10.1016/j.jcrc.2019.02.016Get rights and content

Highlights

  • Patient inspiratory effort significantly increases during spontaneous breathing trial (SBT)

  • Rapid shallow breathing index is still the most reliable index for monitoring during SBT and predicting the weaning outcome.

  • No difference in TFditidal between patients with SBT success and failure except at the beginning of the trial.

  • Diaphragm dysfunction may occur in patients with longer duration of mechanical ventilation.

Abstract

Purpose

Rapid shallow breathing index (RSBI) is a commonly used index for predicting the outcome of spontaneous breathing trial (SBT). Ultrasound is a non-invasive technique for assessing diaphragm activity and function. This study aimed to investigate changes in diaphragm activity during SBT, and to compare diaphragm function between patients with and without SBT success.

Materials and methods

Forty-five patients undergoing SBT were enrolled. Thickening fraction of the diaphragm was assessed during tidal breathing (TFditidal), and RSBI was measured during 30 min of SBT. Diaphragm function measured by maximum TFdi (TFdimax) and diaphragmatic excursion (DEmax) was also evaluated.

Results

TFditidal and RSBI significantly increased during SBT (TFditidal0 vs. TFditidal30 = 29.8 ± 13.8 vs. 37.4 ± 13.0%; p < .001, and RSBI0 vs. RSBI30 = 64.8 ± 25.9 vs.70.8 ± 29.1 breaths/min/L; p = .034). In SBT failure (n = 13), there was no significant difference in TFditidal compared to SBT success, except at the beginning of the trial (p = .043); however, RSBI significantly increased throughout SBT. No differences in TFdimax or DEmax were observed between groups.

Conclusions

Patient inspiratory efforts significantly increased during SBT. TFditidal measured by diaphragm ultrasound could not distinguish between patients with SBT success and failure. RSBI was significantly higher during SBT in patients with SBT failure.

Introduction

Weaning from mechanical ventilation is an important process after patient recovery from acute respiratory failure, and it is a process that may account for approximately 40% of the total duration of mechanical ventilation. Weaning can be divided into two parts, including 1) assessment of readiness to wean, and 2) spontaneous breathing trial (SBT) [1]. Several parameters have been used to assess pulmonary function and to predict weaning success, including respiratory rate, minute ventilation, vital capacity, and rapid shallow breathing index (RSBI) [2]. RSBI, which is the ratio of respiratory frequency divided by average tidal volume in one minute, is the most accurate and commonly used parameter in routine clinical practice [3]. The cut-off point below 105 breath/min/L can predict the likelihood of successful weaning from mechanical ventilation [4]. Once the patient is ready to wean, SBT should be performed as a diagnostic test to determine the likelihood of successful weaning [5]. Several SBT techniques can be used, including T-tube, flow-by technique, or low-level pressure support for 30–120 min. Each of these 3 techniques may have different impact on inspiratory effort and clinical outcome [[6], [7], [8]].

In mechanically ventilated patients, the diaphragm can develop atrophy and weakness leading to prolonged duration of mechanical ventilation. Many studies reported a high prevalence of diaphragm dysfunction during weaning, and it was found to be associated with poorer clinical outcomes [[9], [10], [11]]. Several factors are associated with the development of diaphragm dysfunction, including inappropriate pressure support setting, days of mechanical ventilation, and use of sedative drugs and neuromuscular blocking agents [12,13]. Fluoroscopy, measurement of transdiaphragmatic pressure, and electrical activity of the diaphragm are all techniques that can be used to evaluate the diaphragm; however, these techniques are not easy to perform at bedside. In contrast, diaphragm ultrasound is a non-invasive, real-time, and widely available technique for assessing the activity and function of the diaphragm, and it is being used with increasing frequency in mechanically ventilated patients. Assessment of diaphragm activity by measuring the thickening fraction of the diaphragm during tidal breathing (TFditidal) was shown to be well correlated with the effort exerted by the diaphragm during breathing as measured by diaphragmatic pressure-time product (PTPdi) [14]. Measurement of maximum TFdi (TFdimax) and diaphragmatic excursion (DEmax) has also been used to evaluate diaphragm function. However, few studies have evaluated diaphragm activity using diaphragm ultrasound during the course of SBT. The objectives of this study were to evaluate changes in diaphragm activity by serial measurement of TFditidal and RSBI during the course of SBT, to compare changes in TFditidal between patients with SBT success and SBT failure in comparison to RSBI, to evaluate diaphragm function between patients with SBT success and patients with SBT failure, and to assess the effect of duration of mechanical ventilation on diaphragm function.

Section snippets

Subjects and study design

A prospective cohort study (Thai Clinical Trial Registry #TCTR20160808001) was conducted at the Respiratory Intensive Care Unit, Division of Respiratory Disease and Tuberculosis, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand during the August 2016 to February 2017 study period. The protocol for this study was approved by the Siriraj Institutional Review Board (COA no. 358/2559[EC3]). Written informed consent to participate was obtained from

Results

Forty-five patients were enrolled in this study. Mean age was 70 ± 13 years, and 66.7% of patients were men. Nearly half of enrolled subjects had underlying pulmonary disease. The average ± standard deviation duration of mechanical ventilation before enrollment was 7 ± 4 days. Other baseline characteristics are presented in Table 1. Thirty-two patients (71.2%) successfully passed SBT, and all of them were extubated. The rate of reintubation within 48 h was 15.6% (5/32 patients). Overall 28-day

Discussions

In our study, diaphragm ultrasound was used to evaluate diaphragm activity by serial measurement of TFditidal during the course of SBT, and to evaluate diaphragm function in mechanically ventilated subjects. We found TFditidal and RSBI to be significantly increased during the 30 min of SBT. However, no difference in TFditidal was observed between patients with SBT success and patients with SBT failure, except for time point 0 at the beginning of the trial. In contrast, RSBI was significantly

Conclusions

Patient inspiratory efforts determined by TFditidal significantly increase during SBT. TFditidal did not significantly differ throughout the trial between the success and the failure group except at the beginning of the trial with a higher TFditidal in the failure group. In contrast, RSBI was significantly greater throughout SBT in patients with failed weaning when compared to those who wean successfully. Diaphragm ultrasound might be inferior to RSBI for distinguishing patients with SBT

Declarations of interests

None.

Funding statement

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Authors' contributions

NR, SH, and NC conceived and designed the study. NR and SH collected the data. NR, SH, and NC analyzed and interpreted the data. NR and SH prepared the first draft of the manuscript. All authors contributed to the critical revision and final approval of the manuscript.

Acknowledgements

The authors gratefully acknowledge the patients and/or family members of patients that generously agreed to participate in this study. The authors would also like to thank Mr. Suthipol Udompanthurak (Clinical Epidemiology Unit, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University) and Miss Khemajira Karaketklang (Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University) for their assistance with statistical analysis.

References (34)

  • K.E.A. Burns et al.

    Trials directly comparing alternative spontaneous breathing trial techniques: a systematic review and meta-analysis

    Crit Care

    (2017)
  • A. Demoule et al.

    Diaphragm dysfunction on admission to the intensive care unit. Prevalence, risk factors, and prognostic impact-a prospective study

    Am J Respir Crit Care Med

    (2013)
  • B. Jung et al.

    Diaphragmatic dysfunction in patients with ICU-acquired weakness and its impact on extubation failure

    Intensive Care Med

    (2016)
  • M. Dres et al.

    Diaphragm dysfunction during weaning from mechanical ventilation: an underestimated phenomenon with clinical implications

    Crit Care

    (2018)
  • E.C. Goligher et al.

    Evolution of diaphragm thickness during mechanical ventilation. Impact of inspiratory effort

    Am J Respir Crit Care Med

    (2015)
  • E.C. Goligher et al.

    Mechanical ventilation-induced diaphragm atrophy strongly impacts clinical outcomes

    Am J Respir Crit Care Med

    (2018)
  • E. Vivier et al.

    Diaphragm ultrasonography to estimate the work of breathing during non-invasive ventilation

    Intensive Care Med

    (2012)
  • Cited by (0)

    View full text