Prone Positioning Is a Feasible Approach in the Diagnostic Work-Up of Posterior Pulmonary Nodules and a Means to Limit CT-to-Body Divergence: A Retrospective Cohort Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review this manuscript on robotic-assisted navigational bronchoscopy in the prone position. While this is an interesting and clinically relevant technique, I would like to raise several concerns for your consideration.

 

1. I believe it is difficult to perform a meaningful comparison between two groups based on only nine cases in the prone cohort. Instead, I would recommend identifying the characteristics of cases in which a diagnosis could not be achieved in the supine position, and then describing the safety and feasibility of the nine prone cases in that context. A reconsideration of the overall structure of the manuscript is warranted. Furthermore, the safety of performing procedures in the prone position requires more thorough discussion, including which types of patients may be appropriate candidates for this approach.

 

2. Only nine cases were performed in the prone position over a six-month period. Based on the inclusion criteria, a larger number of cases might have been expected. Were there relatively few cases of posterior pulmonary nodules, or was the consent rate for prone positioning low? Clarification on this point would be helpful.

 

3. It would improve clarity if the Introduction included a discussion of the potential challenges associated with performing procedures in the prone position compared to the supine position, including issues related to patient repositioning and procedural complexity. In addition, prone positioning may carry significant risks, such as difficulty in managing complications should they arise, and this should be explicitly addressed.

 

4. The description in lines 225–226 appears to refer to Table 3 rather than Table 2.

 

5. Including a figure demonstrating bronchoscopy performed in the prone position may help readers better understand the procedure.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Overall, this is an interesting and clinically relevant study addressing the potential utility of prone positioning during robotic navigational bronchoscopy for posterior pulmonary nodules. The concept is practical and important, particularly in relation to anesthesia-induced atelectasis and CT-to-body divergence. However, several points require further clarification and discussion to allow readers to better interpret the findings.

1. The authors describe the diagnostic yield in the prone cohort as comparable to that in the supine cohort. However, the diagnostic yield was 93.3% in the supine cohort and 77.8% in the prone cohort. Although this difference may not reach statistical significance because of the very small prone cohort, describing these results as “comparable” seems somewhat overstated. Please consider revising this wording and provide a more detailed discussion of why the diagnostic yield was numerically lower in the prone cohort. In particular, it would be helpful to discuss possible procedural or technical factors observed during the actual cases, such as lesion size, bronchus sign, catheter stability, access difficulty, sampling limitations, CT-to-body divergence despite prone positioning, or challenges specific to prone positioning.
2. Conversely, no complications were observed in the prone cohort, whereas pneumothorax, bronchopulmonary hemorrhage, and respiratory failure occurred in the supine cohort. Although the small sample size of the prone cohort precludes firm conclusions, this difference is clinically interesting. Please discuss possible reasons for the absence of complications in the prone cohort based on the authors’ procedural experience. For example, this may relate to differences in lesion characteristics, biopsy technique, number of sampling attempts, catheter stability, reduced atelectasis, ventilation strategy, or patient selection.
3. Airway collapse and airway pressure are likely to be closely related during robotic bronchoscopy, especially when attempting to maintain airway patency and reduce atelectasis. The manuscript describes a detailed anesthesia protocol, including PEEP, tidal volume, recruitment maneuvers, and breath-hold imaging. If available, please provide data on the actual airway pressures recorded during the procedures, such as peak airway pressure, plateau pressure, PEEP, and pressures used during recruitment maneuvers. These data would be particularly useful if summarized in a table comparing the supine and prone cohorts.
4. The rationale that prone positioning may improve visualization of posterior nodules by reducing dependent atelectasis is understandable. However, to make this point more convincing for readers, representative imaging would be very helpful. Ideally, if there were any cases in which the same patient or lesion was assessed in both the supine and prone positions, please provide paired images demonstrating improved visualization after prone positioning. If such cases are not available, please consider presenting representative examples comparing pre-procedural planning CT images with intra-procedural 3D fluoroscopic or cone-beam CT images in the supine and prone cohorts, highlighting differences in atelectasis, lesion visibility, and catheter-to-lesion relationship.

These additions would strengthen the manuscript by providing a more balanced interpretation of the diagnostic yield, a clearer explanation of the observed safety findings, and more direct evidence supporting the proposed mechanism by which prone positioning may reduce CT-to-body divergence.

Author Response

Please see the attachment. 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Most of the concerns raised in my previous review have been adequately addressed, and the revised manuscript is now much easier to follow and understand. Please see the minor comment below.

Minor comment

Although it is stated that no specific inclusion criteria were established for patients undergoing prone positioning, it appears that contraindicated patients described in the Discussion section were likely excluded when introducing this novel technique. It may therefore be appropriate to explicitly state these conditions in the exclusion criteria. Since ensuring patient safety is particularly important when implementing a new procedural approach, clearly describing the conditions that led to patient exclusion would improve the credibility of the safety assessment.

Author Response

Comments 1: Although it is stated that no specific inclusion criteria were established for patients undergoing prone positioning, it appears that contraindicated patients described in the Discussion section were likely excluded when introducing this novel technique. It may therefore be appropriate to explicitly state these conditions in the exclusion criteria. Since ensuring patient safety is particularly important when implementing a new procedural approach, clearly describing the conditions that led to patient exclusion would improve the credibility of the safety assessment.

 

Response 1: We thank the reviewer for this thoughtful suggestion. We agree that explicit description of exclusion criteria is important, particularly in the context of a novel procedural approach in which patient safety is paramount. Accordingly, we revised the Methods section to clarify the exclusion criteria, which includes the absolute and relative contraindications to prone positioning. These additions improve the transparency regarding patient selection and safety considerations during implementation of this technique.

Reviewer 2 Report

Comments and Suggestions for Authors

The revisions have adequately addressed my concerns, and the additional discussion has strengthened the manuscript. I have no further comments.

Author Response

Please see the attachment. 

Author Response File: Author Response.docx