Microvascular flow alterations in critically ill COVID-19 patients: A prospective study

Osama Abou-Arab; Christophe Beyls; Abdelilah Khalipha; Mathieu Guilbart; Pierre Huette; Stéphanie Malaquin; Benoit Lecat; Pierre-Yves Macq; Pierre Alexandre Roger; Guillaume Haye; Michaël Bernasinski; Patricia Besserve; Sandrine Soriot-Thomas; Vincent Jounieaux; Hervé Dupont; Yazine Mahjoub

doi:10.1371/journal.pone.0246636

Peer Review History

Original SubmissionOctober 19, 2020
24 Nov 2020 Decision Letter - Yu-Chang Yeh, Editor PONE-D-20-32823 Systemic microcirculatory patterns of critically ill Covid-19 patients: a prospective study PLOS ONE Dear Dr. abou arab, 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 Jan 08 2021 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. 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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 authors showed interesting microcirculatory patterns in COVID-19 patients. I have some comments and questions : 1) The authors mentioned that sublingual microcirculation was assessed within 48 hours after ICU admission. What about the median inclusion time ? Did sublingual microcirculatory assessment was faster in critical group than severe group? (p.7) 2) For data collection for systemic hemodynamic variables, Was cardiac output measured by echocardiography in all patients ? if yes , was echocardiography performed by 1 persons due to operator dependent? For capillary refill time, could you mention how did you performed capillary refill time by eye ball or using chronometer ? 3) For demographic data, were SOFA and SAPS II scores calculated at ICU admission or time of inclusion ? It would be better if you mention severity scores at inclusion time. Was PaO2/FiO2 ratio in severe group different from patients in critical group. The authors mentions number of patients who required vasopressor, in these patients, were they shock ? Could you possibly mention numbers of patients with shock and without shock and did microcirculatory profiles differ between patients with and without shock. 4) Was the microcirculatory profiles related to lung recovery in critical group ? 5) Did microcirculatory alter in patients with COVID19 compare with healthy volunteers? Reviewer #2: I would like to congratulate the authors for their courage and enthusiasm in performing such time consuming and labor intensive study protocol in the ICU. I have just minor concerns: 1. The title could be more focussed beginning by deleting the word "systemic". Please rewrite the title specifically by adding more microcirculatory items like capillary, microvascular flow, alterations etc... 2. Please write COVID-19 with capital letters everywhere. 3. Abstract: Conclusion should be specified by replacing "better microcirculatory pattern" to more focussed description. What is better???? What is still wrong in the microcirculation??? 4. Introduction: "Microcirculation pattern of Covid-19 might differ from other sepsis causes" could implicate that COVID-19 is (pre)sepsis. Please rewrite this sentence that doesn't confuse sepsis with this new disease. 5. Methods: MFI=microvascular flow index 6. Results: Please refer to figure 1 and 2 for the responsible data. 7. Discussion: First sentence is very superficial. Higher microcirculation parameters does mean nothing. Please redifine this e.g. hyperdynamic at least?? High density vasculary flows? high red blood cell velocity? 8. From limitations you could delete the third limitation hence there are thousands of studies which support the idea of sublingual microcirculation as the best paramter for follow-up of the end-organ perfusion ("systemic (micro)circulation"). 9. Finaly add in your discussion the more advanced novel automated microcirculation analysis which could be used for more detailed and accurate microcirculatory analysis published by Hilty et al. Crit Care Med 2020. Novel studies with novel and efficient microcirculation analysis programs could make the clinicians ICU life scientifically comfortable. Tables: Please add more clinical data into the tables - CT lungs for detecting pulmonary embolism; how many performed how many positive in each group? - Day of illness? - Day of intubation? - Day of optiflow during the microcirculation measurement? - What was the anticoagulation strategy? Profylaxes, therapeutic? which agent? UFH? LMWH? What was the follow-up/monitoring strategy for coagulation? ****** 6. 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 #1: No Reviewer #2: 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". 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Revision 1
21 Dec 2020 Author Response Reviewer #1: The authors showed interesting microcirculatory patterns in COVID-19 patients. I have some comments and questions: 1) The authors mentioned that sublingual microcirculation was assessed within 48 hours after ICU admission. What about the median inclusion time? Answer: We thank the reviewer for his comment. We checked for ICU exact admission time on our electronic health record software and match it with the Cytocam software record for each patient. The median time inclusion was similar between group, around 20 hours. We added it in table 2 as follows: Time from ICU admission to inclusion; hours 20 [5-32] 21 [6-30] 0.682 Comment: Did sublingual microcirculatory assessment was faster in critical group than severe group? (p.7) Answer: Regarding the assessment, we proceeded with the same manner whatever the patient severity. We took the necessary time to record 5 videos of good quality as required by the semi-automatic software analysis. In cases of bad quality of videos, we tried as many attempts as necessary to obtain 5 videos of good quality. We did not specifically record the assessment duration. However, it seems to the operator that the duration of the assessment was faster in sedated patients compared to awake patients. 2) Comment For data collection for systemic hemodynamic variables, Was cardiac output measured by echocardiography in all patients ? if yes , was echocardiography performed by 1 persons due to operator dependent? For capillary refill time, could you mention how did you performed capillary refill time by eye ball or using chronometer ? Answer: We thank the reviewer for his comment. Cardiac output was measured by Doppler echocardiography. All measurements for all patients were performed by the same operator (CB). We added a sentence in the method section: “Cardiac output was measured by Doppler echocardiography by the same operator(CB).” Regarding capillary refill time, measurements were standardized using a chronometer. We added details on the standardization of measurement as follows: “Capillary refill time was performed as follows: a firm pressure was applied to the surface of the index finger distal phalanx. The pressure was increased until the skin became blank and maintained for 10s. The pressure was then released. The time for return to pre-existent skin color was measured using a chronometer [14].” 3) For demographic data, were SOFA and SAPS II scores calculated at ICU admission or time of inclusion ? It would be better if you mention severity scores at inclusion time. Answer: We agree with reviewer. SAPS II and SOFA were calculated at inclusion time (time of microcirculation assessment) as mentioned in data collection section. We added “at inclusion” in the results section and in Table 1. Comment: Was PaO2/FiO2 ratio in severe group different from patients in critical group. Answer: We thank the reviewer for his relevant comment. However, in the severe group patients had a facial mask or a nasal canula which makes the exact estimation of FiO2 difficult. That is why we apologize for not being able to report this value for the severe group. Comment: The authors mentions number of patients who required vasopressor, in these patients, were they shock? Could you possibly mention numbers of patients with shock and without shock and did microcirculatory profiles differ between patients with and without shock. Answer: We thank the reviewer for his relevant comment. No patient had a shock state at inclusion. As reported in table 2, the dose of norepinephrine was quite low (0.02 μg.kg.min-1). Macro hemodynamics parameters were similar regarding cardiac output and heart rate with no septic shock pattern. Vasopressors use was probably related to sedation drugs (propofol) used to ensure mechanical ventilation. 4) Was the microcirculatory profiles related to lung recovery in critical group? Answer: We thank the reviewer for his relevant comment. Unfortunately, only one time point measurement was performed. We agree that several a time point monitoring of microcirculation during the stay would had been very interesting. However, microcirculatory record was performed shortly after initiation of mechanical ventilation( i.e: worsening of lung function). 5) Did microcirculatory alter in patients with COVID19 compare with healthy volunteers? Answer: We thank the reviewer for his relevant comment. The guidelines on sublingual assessment (doi: 10.1007/s00134-018-5070-7) described the convective property according to the red blood cell velocities (explored by the MFI and the PVD), the diffuse capacity (explored by the TVD) and the heterogeneity in perfusion (HI) No reference values were admitted but healthy subjects values are available from previous studies (doi: 10.1097/CCM.0b013e31823dae59). In a healthy subject, a normal MFI is expected to be over 2.6 which was the case for our critical group but not in the severe group. PVD in healthy subject was reported to be about 15 mm/mm2. PVD was less decreased in the severe group. To summarize, the critical group tend to have higher red blood velocities when comparing the severe group (PVD and MFI higher) In a healthy subject, TVD is around 15 mm/mm2 and HI around 0.03. In our population, these parameters were close to healthy subjects’ values. Hence, in our cohort COVID-19 patients did not seem to have convective impairment. Reviewer #2: I would like to congratulate the authors for their courage and enthusiasm in performing such time consuming and labor intensive study protocol in the ICU. Answer: we are very grateful to the reviewer for his consideration and encouragements. I have just minor concerns: 1. The title could be more focussed beginning by deleting the word "systemic". Please rewrite the title specifically by adding more microcirculatory items like capillary, microvascular flow, alterations etc... Answer: We thank the reviewer for his helpful comment. We changed the title as follows: “Microvascular flow alterations in critically ill COVID-19 patients: a prospective study.” 2. Please write COVID-19 with capital letters everywhere. Answer: We made changes in the manuscript. 3. Abstract: Conclusion should be specified by replacing "better microcirculatory pattern" to more focussed description. What is better???? What is still wrong in the microcirculation??? Answer: We thank the reviewer for his comment and made changes to better describe the profiles. We made changes as follows: Critical COVID-19 patients under mechanical ventilation seem to have higher red blood cell velocity than severe non-ventilated patients. 4. Introduction: "Microcirculation pattern of Covid-19 might differ from other sepsis causes" could implicate that COVID-19 is (pre)sepsis. Please rewrite this sentence that doesn't confuse sepsis with this new disease. “Timing for intubation and invasive ventilation in COVID-19 patients is a subject of debate [6]. In this new disease, microcirculatory impairment might explain disease progression and differences between invasively and non-invasively ventilated patients. [3] 5. Methods: MFI=microvascular flow index Answer: We apologize for this mistake and made changes 6. Results: Please refer to figure 1 and 2 for the responsible data. Answer: We made changes and referred to figure 1 and 2 when required in the result section. 7. Discussion: First sentence is very superficial. Higher microcirculation parameters does mean nothing. Please redifine this e.g. hyperdynamic at least?? High density vasculary flows? high red blood cell velocity? Answer: We thank the reviewer for his relevant comments and hope we better describe the profiles. Here we made the following changes. “Our findings suggest that the critical group had higher red blood cell velocity (higher MFI values) and a better vessel density (higher DBS and PVD). Capillary diffuse properties seem to be preserved given the values of PPV, TVD and HI.” 8. From limitations you could delete the third limitation hence there are thousands of studies which support the idea of sublingual microcirculation as the best paramter for follow-up of the end-organ perfusion ("systemic (micro)circulation"). Answer: We made changes and removed the sentence. 9. Finaly add in your discussion the more advanced novel automated microcirculation analysis which could be used for more detailed and accurate microcirculatory analysis published by Hilty et al. Crit Care Med 2020. Novel studies with novel and efficient microcirculation analysis programs could make the clinicians ICU life scientifically comfortable. Answer: We thank the reviewer for his comment and added a sentence explaining the MicroTools. “A new tool called MicroTools software allowing an automated video analysis have been recently validated in a large international retrospective database [29]. This kind of automated analysis allowing resuscitation therapies targeted on microcirculatory parameters should be applied in further investigations.” Comments Tables: Please add more clinical data into the tables - CT lungs for detecting pulmonary embolism; how many performed how many positive in each group? - Day of illness? - Day of intubation? - Day of optiflow during the microcirculation measurement? Answer: We thank the reviewer for his comment and completed Table 1 and Table 2 as follows. - What was the anticoagulation strategy? Profylaxes, therapeutic? which agent? UFH? LMWH? What was the follow-up/monitoring strategy for coagulation? Answer: during the first wave of COVID-19 pandemic, our local institutional protocol included for all COVID-19 patients admitted to ICU, a therapeutic anticoagulation strategy with unfractioned heparin to achieve anti Xa activity between 0.5 and 0.8 UI/ml. UFH was started at ICU admission. Anti Xa activity was checked daily and 4 hours after each dose change. We added a sentence in the method section “All COVID-19 patients were under unfractionned heparin to achieve anti Xa activity between 0.5 and 0.8 UI/ml” Attachments Attachment Submitted filename: reveiwer answer.docx https://doi.org/10.1371/journal.pone.0246636.r002
15 Jan 2021 Decision Letter - Yu-Chang Yeh, Editor PONE-D-20-32823R1 Microvascular flow alterations in critically ill COVID-19 patients: a prospective study PLOS ONE Dear Dr. abou arab, Thank you for submitting your manuscript to PLOS ONE. 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 Mar 01 2021 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. Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). 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For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols We look forward to receiving your revised manuscript. Kind regards, Yu-Chang Yeh, M.D., Ph.D. Academic Editor PLOS ONE Additional Editor Comments: Thank you for carefully revising your manuscript. We have received the reply from all reviewers. Please revise the sentence mentioned by the reviewer. Please consider drawing a dot-boxplot to refine Figure 1. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions 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 #1: All comments have been addressed Reviewer #2: All comments have been addressed ******** 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 #1: Yes Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 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 #1: Yes Reviewer #2: Yes ****** 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 #1: Yes Reviewer #2: Yes ****** 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 #1: All comments are well addressed and it is much better than the previous one. However, I have few comments. 1 In discussion part "Finally, we did not record SvO2 which would have been valuable to compare oxygen consumption between groups". I think that this sentence should be change because we did not insert pulmonary arterial (PA) catheter in all patients and we will insert this PA catheter in case of pulmonary hypertension or in case that we would like to evaluate shunt effect in ARDS patients, May be you can write " we did not evaluate central venous oxygen saturation which was valuable to compare balance between oxygen consumption and oxygen delivery or you can say that we did not record central venous oxygen derived variables to compare oxygen consumption. 2 Please note Data was expressed in .... in Tables Reviewer #2: Nice revision. Good luck! By adding the newest methods for analysing the microcirculation you make the follow-up for your study (and your patients ICU care) easier. "“A new tool called MicroTools software allowing an automated video analysis have been recently validated in a large international retrospective database [29]. This kind of automated analysis allowing resuscitation therapies targeted on microcirculatory parameters should be applied in further investigations.” Great sentence. ****** 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 #1: No Reviewer #2: 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. https://doi.org/10.1371/journal.pone.0246636.r003
Revision 2
19 Jan 2021 Author Response Response to reviewer 1 Reviewer #1: All comments are well addressed and it is much better than the previous one. Response: Thank you However, I have few comments. 1 In discussion part "Finally, we did not record SvO2 which would have been valuable to compare oxygen consumption between groups". I think that this sentence should be change because we did not insert pulmonary arterial (PA) catheter in all patients and we will insert this PA catheter in case of pulmonary hypertension or in case that we would like to evaluate shunt effect in ARDS patients, May be you can write " we did not evaluate central venous oxygen saturation which was valuable to compare balance between oxygen consumption and oxygen delivery or you can say that we did not record central venous oxygen derived variables to compare oxygen consumption. Response: Thank you. We changed the sentence in the manuscript. 2 Please note Data was expressed in .... in Tables Response: Thank you. We made changes in both Tables as follows: “Data were expressed as median [interquartile range] or as number (percentage)” Response to reviewer 2 Reviewer #2: Nice revision. Good luck! By adding the newest methods for analysing the microcirculation you make the follow-up for your study (and your patients ICU care) easier. "“A new tool called MicroTools software allowing an automated video analysis have been recently validated in a large international retrospective database [29]. This kind of automated analysis allowing resuscitation therapies targeted on microcirculatory parameters should be applied in further investigations.” Great sentence. Response: thank you. https://doi.org/10.1371/journal.pone.0246636.r004
25 Jan 2021 Decision Letter - Yu-Chang Yeh, Editor Microvascular flow alterations in critically ill COVID-19 patients: a prospective study PONE-D-20-32823R2 Dear Dr. abou arab, 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. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. 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, Yu-Chang Yeh, M.D., Ph.D. Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0246636.r005
Formally Accepted
27 Jan 2021 Acceptance Letter - Yu-Chang Yeh, Editor PONE-D-20-32823R2 Microvascular flow alterations in critically ill COVID-19 patients: a prospective study Dear Dr. Abou-Arab: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. 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. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Yu-Chang Yeh Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0246636.r006

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