Dear Dr. Lee,

1. Abstract: Please provide a structured abstract, with headings such as Background, Methods, Results, and Conclusions, or as otherwise requested by the Journal. It is very difficult to understand the methods and background for this study from the abstract as it mainly focuses on results.2. Introduction: The introduction is far too long (3.5 pages). This should be around 1 page, double spaced, with normal margins. Please make it more concise with a focus on relevant things without getting too detailed (i.e. the history of PICC, etc.). Other aspects can perhaps be placed in the Discussion if the authors feel is necessary. 3. Methods: Please place the Methods section directly after the Introduction and directly before the Results. 4. Methods: Please add the STROBE checklist and mention this in the Methods: https://www.strobe-statement.org/checklists/ 5. Methods: It is unclear why mean and SD were used. I am concerned that the data distribution may be skewed. Please either provide data to suggest otherwise or consider median and IQR, along with non-parametric statistical tests 6. Methods: As outlined in Table 5, please mention the exact regression technique in the methods (i.e. "logistic regression modelling was conducted...") along with these covariates and how they were selected. Importantly, were they checked for colinearity? Please also provide the univariable, unadjusted estimates in a separate column for each variable (i.e. row). 7. Tables: There are far too many tables. Please consider combining or place some in a Supplementary File, alongside the STROBE checklist (as outlined in point 4 above) 8. Figures: Please add risk tables with events/total Ns to Figures 1 and 2. As per STROBE checklist, please also add a patient flow diagram that shows how patients were selected/how many excluded/how many finally included. Figure 3 should also ideally be proportion rather than number, please consider having the y-axis as %. 9. The study would also benefit from a close read and extensive typographical edits. For instance: 1) "A total of 241 patients (n=241)". The (n=241) is unnecessary. 2) Rather than discussing granular age distributions, you can mention the mean or median (SD or IQR). 3) Figures 1 and 2 have no numerical data and so it is not sufficient to just refer to them in the text. Please provide some numbers in the actual results. 4) I am not sure why the results are all of a sudden summarized mid way through the Discussion. Ideally, the first paragraph of Discussion should provide a concise summary, then findings can be contextualized and discussed. 5) Limitations should be in one cohesive paragraph and each point should be expanded upon (i.e. retrospective design, leading to the potential for misclassification and/or residual confounding). There are several other instances, including capitalization/grammatical changes needed. 10. The title is far too long. Consider something like: "Outcomes of a bedside central catheter placement protocol across critically ill older adults: A retrospective study"

Please submit your revised manuscript as soon as possible or by May 12 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

• A rebuttal letter that responds to each point raised by the academic editor. You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Kiyan Heybati

Academic Editor

PLOS ONE

Journal requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Thank you for stating the following financial disclosure:

“This study was supported by a grant from the Jeju National University Hospital Research Fund (Grant No. 2019-35).”

Please state what role the funders took in the study.  If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

If this statement is not correct you must amend it as needed.

Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf.

3. For studies involving third-party data, we encourage authors to share any data specific to their analyses that they can legally distribute. PLOS recognizes, however, that authors may be using third-party data they do not have the rights to share. When third-party data cannot be publicly shared, authors must provide all information necessary for interested researchers to apply to gain access to the data. (https://journals.plos.org/plosone/s/data-availability#loc-acceptable-data-access-restrictions)

For any third-party data that the authors cannot legally distribute, they should include the following information in their Data Availability Statement upon submission:

1) A description of the data set and the third-party source

2) If applicable, verification of permission to use the data set

3) Confirmation of whether the authors received any special privileges in accessing the data that other researchers would not have

4) All necessary contact information others would need to apply to gain access to the data.

4. Please amend either the title on the online submission form (via Edit Submission) or the title in the manuscript so that they are identical.

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

Dear Dr. Lee,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jul 30 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Kiyan Heybati, MD MSc

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

Reviewer #3: All comments have been addressed

Reviewer #4: (No Response)

Reviewer #5: (No Response)

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

Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Partly

Reviewer #4: Yes

Reviewer #5: (No Response)

**********

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

Reviewer #1: Yes

Reviewer #2: I Don't Know

Reviewer #3: Yes

Reviewer #4: Yes

Reviewer #5: (No Response)

**********

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

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

Reviewer #5: (No Response)

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

Reviewer #5: (No Response)

**********

Reviewer #1: 1-We therefore conducted this single-center, retrospective study to describe our protocol in a single small-volume center in an ICU setting in Korea. What do you mean protocol. What is the results of protocol. Protocol or outcome.

2- The patients underwent PICC placement under maximal barrier precautions using 2% chlorhexidine for skin preparation, surgical drapes, a surgical cap, sterile gown and gloves. 2% chlorhexidine alone or in combination with alcohol 70%.

3-In our series, there were a total of five cases (2.1%) of the PICC-related infection. What is the definition of PICC infection in your study.

Reviewer #2: The inclusion and exclusion criteria were not well described. Equally, the study question was not well described.

The objetives of the study should be defined so it can guide the statistical analysis and the data comparision with the literature.

Guided by this information, researchers can better choose comparisons with the literature. In the manner of a more robust study.

Reviewer #3: 1. Why sample stop at 2021? Is there any influence in determining the PICC procedure by ultrasound in the era of the Covid pandemic?

2. Is there any data above 2022 that can be added for data updates?

3. Eldery criteria has not been listed

4. In discussion please elaborate more about infection related to PICC

5. What's the novelty about USG guided PICC

6. The results section does not yet discuss risk factors of PICC related infection

Reviewer #4: This manuscript presents a study of 161 patients undergoing ultrasound-guided PICC placement, with findings suggesting that accurate tip positioning is critical for reducing PICC-related infections. After revision, the manuscript shows notable improvements in grammar and background framing, which enhance both the readability and the credibility of the conclusions.

However, several minor but important issues still require attention. Addressing these points would further improve the rigor and overall quality of the manuscript.

1. Issue in the Abstract – Background Section

The background section of the abstract is currently inadequate. Instead of providing scientific context, it merely describes the study itself. A well-constructed background should briefly introduce the clinical significance of the topic and highlight the specific scientific problem the study aims to address. In this case, the authors should synthesize key points from the Introduction: namely, that PICC is a commonly used alternative to central venous catheterization, but its application carries risks—particularly catheter-related bloodstream infections—which warrant further investigation. This study seeks to explore how tip location, side of insertion, and catheter length may influence such complications. The abstract should be revised to reflect this rationale clearly and concisely.

2. Right-Side PICC Placement for Patients Without Prior PICC – Methodological Clarification

In the Methods section, the authors mention a preference for right-sided PICC placement in patients without prior PICC history. While this is a retrospective study and procedures have already been performed, it is important to clarify whether this decision was evidence-based. For example, literature supporting right-sided preference in internal jugular central venous catheterization—due to anatomical landmarks, vessel course, or operator handedness—may be relevant. If such methodological justification exists, it should be cited explicitly.

Furthermore, a potential bias may be introduced by choosing right-sided placement only for patients without prior PICC insertion, who may have had better baseline health conditions compared to those who required previous catheterization. The authors should discuss how such selection bias was addressed or mitigated in their analysis.

In conclusion, addressing these concerns would enhance the scientific integrity of the study and provide more robust evidence for optimizing ultrasound-guided PICC placement strategies to reduce complication rates related to suboptimal catheter positioning.

Reviewer #5: Thank you for the opportunity to review this manuscript. Unfortunately, I believe that the quality of this manuscript does not meet the standards of PLOS One, but this should not discourage the authors from continuing their valuable clinical research and thoroughly reviewing their manuscript before attempting submission elsewhere. Special attention should be given to better organisation of the structured abstract, and also to defining the research goals and hypothesis. It is unclear, but it looks like at least at one point the focus of this manuscript was infection control, in which case the developed protocol for infection control regarding placement, evaluation and maintenance of PICC should be discussed. Including an English language expert to proof-read the manuscript is advised.

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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 #1: No

Reviewer #2: Yes: Felipe Martins Liporaci

Reviewer #3: No

Reviewer #4: No

Reviewer #5: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

Dear Dr. Lee,

In addition to the reviewer comments below, please edit the Methods section of the Abstract to include more methodological items such as study dates, design, inclusion criteria, brief statistical analysis plans, etc. and the current information in the Methods of the Abstract can be condensed and perhaps moved to Results of the Abstract. As a minor point, please change "elderly" to "older adults."

Please submit your revised manuscript by Dec 04 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Kiyan Heybati

Academic Editor

PLOS ONE

Journal Requirements:

If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise.

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

Reviewer #6: All comments have been addressed

**********

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

Reviewer #2: Yes

Reviewer #6: Partly

**********

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

Reviewer #2: I Don't Know

Reviewer #6: Yes

**********

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

The PLOS Data policy

Reviewer #2: Yes

Reviewer #6: Yes

**********

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

Reviewer #2: Yes

Reviewer #6: No

**********

Reviewer #2: An important topic that demands attention from everyone who performs invasive procedures. The authors reviewed and responded to all suggestions from the review team. Based on this, the work ready for publication.

Reviewer #6: Ultrasound is almost standard of care based on CDC and all other guidelines and should be used whenever available. The tip confirmation was still with CXR. So this is very standard operation.

https://www.cdc.gov/infection-control/hcp/intravascular-catheter-related-infections/summary-recommendations.html

Use ultrasound guidance to place central venous catheters (if this technology is available) to reduce the number of cannulation attempts and mechanical complications. Ultrasound guidance should only be used by those fully trained in its technique. IB

**********

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: Yes: Felipe Martins Liporaci

Reviewer #6: Yes: Siddharth Dugar

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org

Outcomes of a Bedside Ultrasound-guided Peripherally-inserted Central Catheter Placement across Critically-ill Older Patients

PONE-D-25-11583R3

Dear Dr. Lee,

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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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Kiyan Heybati

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: