Spontaneous breathing trial (SBT) in ASV mode

Article

Auteur: Jean-Michel Arnal, Simon Franz

Date: 16.02.2018

How can I perform a spontaneous breathing trial when my patient is being ventilated with ASV^®?

Spontaneous breathing trial (SBT) in ASV mode

SBT with pressure augmentation more successful

Spontaneous breathing trials (SBTs) are among the most commonly used techniques to facilitate weaning from mechanical ventilation. Conducting the initial SBT with pressure augmentation was more likely to be successful, produced a higher rate of extubation success and was associated with a trend towards lower ICU mortality when compared with the T-piece SBT (Schmidt GA, Girard TD, Kress JP, et al. Official Executive Summary of an American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults. Am J Respir Crit Care Med. 2017;195(1):115-119. doi:10.1164/rccm.201610-2076ST1).

Performing an SBT in ASV

If your patient is on ASV, you can perform a pressure-support SBT as follows. Firstly, decrease PEEP to 5 cmH2O and lower the target minute volume (%MinVol) setting to reduce the pressure support as needed. If the pressure support on the current %MinVol setting is higher than 15 cmH2O, the %MinVol setting can be lowered first to 70%, and then to 25% to gradually reduce the level of pressure support down to 5-8 cmH2O for the SBT.

Screenshot showing settings, ASV graph and target

Monitoring during the SBT

The patient should be monitored both clinically and using the Vent Status panel. Clinical monitoring includes neurological status, effort to breathe, heart rate, and blood pressure.

Respiratory monitoring includes SpO2, PetCO2, respiratory rate, and tidal volume. Patient exhaustion may lead to an increase in the respiratory rate with a small tidal volume, and cause an increase in pressure support according to the ASV algorithm.

If the patient remains stable for 30 minutes, you can consider extubation (Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Eur Respir J. 2007;29(5):1033-1056. doi:10.1183/09031936.000102062).

Relevant devices: all

Notes en bas de page

Références

1. Schmidt GA, Girard TD, Kress JP, et al. Official Executive Summary of an American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults. Am J Respir Crit Care Med. 2017;195(1):115-119. doi:10.1164/rccm.201610-2076ST
2. Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Eur Respir J. 2007;29(5):1033-1056. doi:10.1183/09031936.00010206

Official Executive Summary of an American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults.

Schmidt GA, Girard TD, Kress JP, et al. Official Executive Summary of an American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults. Am J Respir Crit Care Med. 2017;195(1):115-119. doi:10.1164/rccm.201610-2076ST

Link to article

BACKGROUND

This clinical practice guideline addresses six questions related to liberation from mechanical ventilation in critically ill adults. It is the result of a collaborative effort between the American Thoracic Society and the American College of Chest Physicians.

METHODS

A multidisciplinary panel posed six clinical questions in a Population, Intervention, Comparator, and Outcomes format. A comprehensive literature search and evidence synthesis was performed for each question, which included appraising the certainty in the evidence (i.e., the quality of evidence) using the Grading of Recommendations, Assessment, Development, and Evaluation approach. The Evidence-to-Decision framework was applied to each question, requiring the panel to evaluate and weigh the importance of the problem, the confidence in the evidence, the certainty about how much the public values the main outcomes, the magnitude and balance of desirable and undesirable outcomes, the resources and costs associated with the intervention, the impact on health disparities, and the acceptability and feasibility of the intervention.

RESULTS

Evidence-based recommendations were formulated and graded initially by subcommittees and then modified after full-panel discussions. The recommendations were confirmed by confidential electronic voting; approval required that at least 80% of the panel members agree with the recommendation.

CONCLUSIONS

The panel provides recommendations regarding liberation from mechanical ventilation. The details regarding the evidence and rationale for each recommendation are presented in the American Journal of Respiratory and Critical Care Medicine and Chest.

Weaning from mechanical ventilation.

Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Eur Respir J. 2007;29(5):1033-1056. doi:10.1183/09031936.00010206

Link to article

Weaning covers the entire process of liberating the patient from mechanical support and from the endotracheal tube. Many controversial questions remain concerning the best methods for conducting this process. An International Consensus Conference was held in April 2005 to provide recommendations regarding the management of this process. An 11-member international jury answered five pre-defined questions. 1) What is known about the epidemiology of weaning problems? 2) What is the pathophysiology of weaning failure? 3) What is the usual process of initial weaning from the ventilator? 4) Is there a role for different ventilator modes in more difficult weaning? 5) How should patients with prolonged weaning failure be managed? The main recommendations were as follows. 1) Patients should be categorised into three groups based on the difficulty and duration of the weaning process. 2) Weaning should be considered as early as possible. 3) A spontaneous breathing trial is the major diagnostic test to determine whether patients can be successfully extubated. 4) The initial trial should last 30 min and consist of either T-tube breathing or low levels of pressure support. 5) Pressure support or assist-control ventilation modes should be favoured in patients failing an initial trial/trials. 6) Noninvasive ventilation techniques should be considered in selected patients to shorten the duration of intubation but should not be routinely used as a tool for extubation failure.