Accessory and Expiratory Muscles Activation During Spontaneous Breathing Trial: A Physiological Study by Surface Electromyography

Matteo Pozzi; Emanuele Rezoagli; Alfio Bronco; Francesca Rabboni; Giacomo Grasselli; Giuseppe Foti; Giacomo Bellani

doi:10.3389/fmed.2022.814219

Accessory and Expiratory Muscles Activation During Spontaneous Breathing Trial: A Physiological Study by Surface Electromyography

Front Med (Lausanne). 2022 Mar 10:9:814219. doi: 10.3389/fmed.2022.814219. eCollection 2022.

Authors

Matteo Pozzi^{1

2}, Emanuele Rezoagli¹, Alfio Bronco^{1

2}, Francesca Rabboni¹, Giacomo Grasselli^{3

4}, Giuseppe Foti^{1

2}, Giacomo Bellani^{1

2}

Affiliations

¹ Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
² Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy.
³ Department of Anesthesia, Intensive Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
⁴ Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy.

Abstract

Background: The physiological and prognostical significance of accessory and expiratory muscles activation is unknown during a spontaneous breathing trial (SBT). We hypothesized that, in patients experiencing weaning failure, accessory and expiratory muscles are activated to cope with an increased respiratory workload.

Purpose: To describe accessory and expiratory muscle activation non-invasively by surface electromyography (sEMG) during an SBT and to assess differences in electrical activity (EA) of the inspiratory and expiratory muscles in successful vs. failing weaning patients.

Methods: Intubated patients on mechanical ventilation for more than 48 h undergoing an SBT were enrolled in a medical and surgical third-level ICU of the University Teaching Hospital. Baseline characteristics and physiological variables were recorded in a crossover physiologic prospective clinical study.

Results: Of 37 critically ill mechanically ventilated patients, 29 (78%) patients successfully passed the SBT. Rapid shallow breathing index (RSBI) was higher in patients who failed SBT compared with the successfully weaned patients at baseline and over time (group-by-time interaction p < 0.001). EA of both the diaphragm (EAdi_surf) and of accessory muscles (ACC_surf) was higher in failure patients compared with success (group-by-time interaction p = 0.0174 and p < 0.001, respectively). EA of expiratory muscles (ESP_surf) during SBT increased more in failure than in weaned patients (group-by-time interaction p < 0.0001).

Conclusion: Non-invasive respiratory muscle monitoring by sEMG was feasible during SBT. Respiratory muscles EA increased during SBT, regardless of SBT outcome, and patients who failed the SBT had a higher increase of all the inspiratory muscles EA compared with the patients who passed the SBT. Recruitment of expiratory muscles-as quantified by sEMG-is associated with SBT failure.

Keywords: electrical activity; expiratory muscles; inspiratory muscles; non-invasive surface electromyography; spontaneous breathing trial (SBT); weaning.