PONE-D-22-14900

Course of recovery of respiratory muscle strength and its associations with exercise capacity and handgrip strength: a prospective cohort study among survivors of critical illness

PLOS ONE

Dear Dr. Major,

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Please revise the text following reviewer's comments

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PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript entitled "Course of recovery of respiratory muscle strength and its associations with exercise capacity and handgrip strength: a prospective cohort study among survivors of critical illness" is very well written and it is well balanced between the different sections; It is a valuable contribution and its topic is of interest to PLOS ONE.

The only weakness of the paper is that the authors have not considered the singular importance of the sex variable in the prediction of muscle strength. The important characteristics demarcated by literature are the muscle strength differences between male and female, involves biological and cultural issues that determine different levels of muscle strength, which can have repercussions on their recovery after a critical illness. It seems evident from the analyzes presented in table 4, that there is an important modification of the effect in the associations when adjusted for the sex variable, which leads us to identify a possible interaction factor between sex and the outcomes. Therefore, we recommend considering stratification by sex or evaluating the existence of interaction factor and assuming it in the analyses.

We also recommend standardizing the presentation of confidence intervals (CI). The use of the expression "to" to separate the values ​​of the intervals, since there are negative values ​​that can be confused with the "-" sign used in the separation of lower and upper limits.

Reviewer #2: Good morning, first of all I wanted to congratulate you on your scientific paper; I found it very interesting as it deals with aspects of a very important topic on which unfortunately too little is still known (the course of recovery of respiratory muscle strength in patients undergoing mechanical ventilation).

I think your paper can make an interesting contribution to the contemporary scientific literature and poses insights for further study.

In light of this, the changes I would recommend are:

1) As you have already exhaustively described in the paper, the study has some limitations among which the main ones are: the relatively small sample size, the lack of important information on patients' characteristics such as the presence of comorbidities, the presence of diseases and conditions already known prior to ICU admission or developed during ICU stay that may themselves result in reduced MIP, MEP, FEC and HGS, the absence of scores indicating the severity of the main disease for whose patient is admitted to ICU, etc...

Among these limitations, it would be good to add that no difference is made between the type of mechanical ventilation performed on patients in the ICU, particularly whether non-invasive ventilation (NIV) or invasive ventilation (IV) was performed.

There is a huge difference between NIV and IV (which involves oro-tracheal intubation or less frequently naso-tracheal intubation or tracheostomy) in terms of the contribution made by the ventilator to the respiratory muscles during the respiratory cycle and consequently also on the extent of respiratory muscle damage related to mechanical ventilation: during NIV the respiratory muscle work is only partially performed by the ventilator (assisted or supported ventilation), whereas during IV the respiratory muscle work can be either totally (controlled ventilation) or partially performed by the ventilator; moreover, as is logical, during IV the patient is generally more sedated than in NIV, in which more cooperation from the patient is required.

2) Better describe the two minute step test (TMST) in the paragraph "measurements" on page 5. In particular, to be more precise and complete, describe how to obtain for each patient "the set criterion height" (height reached by the right knee of the patient so that the step is considered valid) and what are the contraindications to the test, which in some cases did not allow to perform the test.

3) On page 11, line 261, replace "PImax = observed maximum expiratory mouth pressure" with "PEmax = observed maximum expiratory mouth pressure"

4) On page 12, line 281, add "S3 Fig" to "Supporting information: S1-S3 Table, S1 Fig, S2 Fig."

5) Check and resolve the inconsistency between the MIP at T0 in the abstract "68.1" and in Table 2, page 9 "68.4"

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Reviewer #1: No

Reviewer #2: No

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Course of recovery of respiratory muscle strength and its associations with exercise capacity and handgrip strength: a prospective cohort study among survivors of critical illness

PONE-D-22-14900R1

Dear Dr. Major,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Marjan Mansourian

Academic Editor

PLOS ONE

Reviewers' comments:

 In line 274, Table 4, "PImax" has not been replaced with "PEmax".

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Partly

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: I Don't Know

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: Good evening, I think that the corrections and changes you have made to the text have improved its quality. I just wanted to point out that in line 274, Table 4, "PImax" has not been replaced with "PEmax". I again offer my congratulations for your paper.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

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