Skip to main content

Inspiratory and peripheral muscle strength as predictors for extubation failure in COVID-19 patients

Dear editor,

With great interest, I read the article by Fleuren et al. on determining the predictors for extubation failure in COVID-19 patients [1]. The authors have methodically utilised the machine learning models to identify the potential parameters that would predict the extubation failure in critically ill COVID-19 patients. They discuss the potential predictors selected by a team of intensivists for modeling from the Dutch Data Warehouse (DDW). With this study, they concluded that the individual ventilatory characteristics, inflammatory markers, neurological status and body mass index (BMI) were the most important parameters to predict extubation failure in COVID-19 patients.

However, as the article discusses the indicators for predicting extubation failure, it becomes essential to consider the inspiratory muscle strength and gross peripheral muscle strength as independent indicators for predicting extubation. Extubation is a complicated process and requires a balance between global respiratory load and ability to overcome this load for separation from invasive mechanical ventilation (IMV). Evidence from the meta-analysis carried out shows that non-COVID-19 patients receiving IMV in ICU have a high risk of developing respiratory and limb muscle weakness [2]. Similarly, considering the novelty of the disease, there is sufficient literature available stating that patients with severe COVID-19 requiring prolonged ICU stay and IMV have been diagnosed with ICU-acquired weakness (ICUAW) [3]. Further, from the growing evidence, it has been observed that poor peripheral muscle strength, particularly quadriceps muscle, is effective indicator (p = 0.02) in predicting extubation failure in critically ill patients [4]. We have also observed that in non-COVID-19 patients, inspiratory muscle training (IMT) achieved either by threshold pressure training or adjusting ventilator sensitivity, did not directly predict extubation outcome; however, it concluded that IMT significantly improved maximal inspiratory pressure (MIP) (MD 7 cmH2O, 95% CI 5–9), rapid shallow breathing index (RSBI) (MD 15 breaths/minute/l, 95% CI 8–23) and weaning success (RR 1.34, 95% CI 1.02–1.76) [5].

In closing, I believe that inspiratory and peripheral muscle testing can be added to the variables listed by Fleuren et al. to predict extubation failure and avoid the serious sequelae caused by re-intubation in COVID-19 patients. Once again, I commend the authors for their excellent work in this area, which remains to be the need of the hour.

Availability of data and materials

Not applicable.


  1. Fleuren LM, Dam TA, Tonutti M, et al. Predictors for extubation failure in COVID-19 patients using a machine learning approach. Crit Care. 2021;25:448.

    Article  Google Scholar 

  2. Medrinal C, Combret Y, Hilfiker R, Prieur G, Aroichane N, Gravier F-E, et al. ICU outcomes can be predicted by non invasive muscle evaluation: a meta-analysis. Eur Respir J. 2020;56:1902482.

    Article  Google Scholar 

  3. Van Aerde N, Van den Berghe G, Wilmer A, Gosselink R, Hermans G, Meersseman P, Gunst J, Aerts V, Balthazar T, Barbé A, et al. Intensive care unit acquired muscle weakness in COVID-19 patients. Intensive Care Med. 2020;26:2083–5.

    Article  Google Scholar 

  4. Wang TH, Wu CP, Wang LY. Impact of peripheral muscle strength on prognosis after extubation and functional outcomes in critically ill patients: a feasibility study. Sci Rep. 2021;11(1):1.

    Article  Google Scholar 

  5. Elkins M, Dentice R. Inspiratory muscle training facilitates weaning from mechanical ventilation among patients in the intensive care unit: a systematic review. J Physiother. 2015;61(3):125–34.

    Article  Google Scholar 

Download references


Not applicable.



Author information

Authors and Affiliations



SS contributed in writing the complete manuscript. The author read and approved the final manuscript.

Corresponding author

Correspondence to Shraddha Shah.

Ethics declarations

Ethical approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Shah, S. Inspiratory and peripheral muscle strength as predictors for extubation failure in COVID-19 patients. Crit Care 26, 45 (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: