Round 1

Reviewer 1 Report

The reviewer agrees with most context of the manuscript. Indeed, a review of CT-CCM is in requirement and helpful for surgeon, cardiologist, or nursing staff. However, the review ignored pediatric population who needs the care of CT-CCM. First, with the advancement of prenatal diagnostic techniques and pediatric cardiac surgical techniques, the number of children born with congenital heart disease is gradually decreasing but the number of such children growing into adult is increasing. Second, How to take care such patients? Whether the inherent or postoperative hemodynamic abnormalities of children with congenital heart disease, such as pressure overload or volume overload, affect the maturation of their hearts, and ultimately their life quality?

The reviewer hope that the authors will added pediatric CT-CCM to make the review more complete. 

Author Response

We thank the Reviewer for their interest in our manuscript and appreciate their specific revisions outlined below

• The reviewer agrees with most context of the manuscript. Indeed, a review of CT-CCM is in requirement and helpful for surgeon, cardiologist, or nursing staff. However, the review ignored pediatric population who needs the care of CT-CCM. First, with the advancement of prenatal diagnostic techniques and pediatric cardiac surgical techniques, the number of children born with congenital heart disease is gradually decreasing but the number of such children growing into adult is increasing. Second, How to take care such patients? Whether the inherent or postoperative hemodynamic abnormalities of children with congenital heart disease, such as pressure overload or volume overload, affect the maturation of their hearts, and ultimately their life quality?
• The reviewer hope that the authors will added pediatric CT-CCM to make the review more complete. 

• We thank the reviewer for their insightful comments. As the primary focus of the special issue, as well as the CT-CCM review focuses on the adult population and the unique challenges and requirements necessary to manage that population; pediatrics was not addressed.  Pediatrics poses an array of alternative considerations as well as treatment modalities which remain outside of the scope of this review and our expertise, as we are adult intensivists.

• We added word “adult” in line 54 to ensure readers are not confused.

Reviewer 2 Report

This is a review paper regarding the current state and future goals of cardiothoracic surgical intensive care medicine. The review addresses knowledge gaps and directions to future scientific endeavors.

Comments

1. General Comment: Tables and Figures are necessarily needed. E.g., a table with all published guidelines regarding cardiothoracic surgical intensive care medicine or a table with the most important clinical trials. Or a figure with an algorithm or diagram of main knowledge gaps or a network of who should work in the cardiothoracic surgical intensive care unit. The presence of such illustrations (not only one… consider adding 2-3 tables/figures) is imperative.

2. You could also add a third part with some direct 2–3-line opinions/perceptions/interviews of medical personnel working in CT-ICUs

3. Since interventional cardiology emerged, a lot of medical conditions were treated with interventional and non-surgical procedures. How did this trend affect the work of cardiothoracic surgical intensive care units? Eg less CABGs? Or change in age distributions? Since when?

4. Page 98 abbreviation CT-CCM?

5. Line 191-192: “Acute kidney injury is the most common major complication occurring after cardiac surgery with incidence reaching 40%” – shouldn’t this be the first condition to be reported (before delirium) since it is the most common?

6. Line 304-310: What is finally the strategy recommended regarding the hemoglobin threshold for transfusion?

7. Line 347 “Paralysis After Aortic Aneurysm Surgery” – what is the role of physiotherapy?

8. What was the impact of COVID-19 on CT-ICUs?

9. Line 674 “patients or their families have the right to refuse therapies at any point” – that’s the ethical part that we should respect our patients’ wishes. What about the legal part? Do patients sign a form if they do not wish any further procedures or medical handling? What if the patient cannot sign etc?

Author Response

Reviewer 1: We thank the Reviewer for their interest in our manuscript and appreciate their specific revisions outlined below. We have corrected the formatting of our references to meet the journal’s guidelines.

• Since interventional cardiology emerged, a lot of medical conditions were treated with interventional and non-surgical procedures. How did this trend affect the work of cardiothoracic surgical intensive care units? Eg less CABGs? Or change in age distributions? Since when?

• Since the advancement of percutaneous coronary and structural heart interventions there have been variable outcomes.  There remains a certain subset of patients who are either not amenable or have unsuccessful percutaneous therapies. Some of these patients can require overt full mechanical circulatory support [ECLS].  These patients with complex valvular and cardiac disease are best-served in a CT-ICU managed by cardiothoracic intensivists familiar with their physiology.  In addition, as the aging population being treated continues to increase, so too does the severity and chronicity of disease.  Even the treatment of coronary artery disease is still heavily relying on a surgical intervention (CABG), especially in patients with comorbidities such as diabetes, or with complex lesions.¹ This continuing necessity of the cardiothoracic intensivist in managing these complex patients is unlikely to go away any time soon, but in fact, increase over the next decades. This will be driven by:
• Aging baby-boomer population with increased burden of disease
• This will result in higher degree of coronary artery disease and ischemic cardiomyopathy patients requiring care.
• A subset of these patients will require durable mechanical support, such as LVADs, or heart transplants.
• Recent developments in xenotransplantation² gives hope of an increase in organ availability. These patients will require significant CT-ICU care.
• Other will only qualify for destination therapy with LVADs.³
• Increase in lung failure and lung transplantation need
• Increasing number of patients with congenital heart lesions who survived until adulthood, who will require redo surgeries, or heart transplantations
• Unforeseen events like a pandemic
• We have added a section in our introduction addressing these points. Lines 38-42 address this comment and are highlighted in in Tracked Version of the manuscript.

1. Welt FGP. CABG versus PCI - End of the Debate?. N Engl J Med. 2022;386(2):185-187. doi:10.1056/NEJMe2117325
2. Griffith BP, Goerlich CE, Singh AK, et al. Genetically Modified Porcine-to-Human Cardiac Xenotransplantation. N Engl J Med. 2022;387(1):35-44. doi:10.1056/NEJMoa2201422
3. Michaels A, Cowger J. Patient Selection for Destination LVAD Therapy: Predicting Success in the Short and Long Term. Curr Heart Fail Rep. 2019;16(5):140-149. doi:10.1007/s11897-019-00434-1
4. Khakban, A., et al., The projected epidemic of chronic obstructive pulmonary disease hospitalizations over the next 15 years. A population-based perspective. American journal of respiratory and critical care medicine, 2017. 195(3): p. 287-291.
5. Sauleda, J., et al., Idiopathic pulmonary fibrosis: epidemiology, natural history, phenotypes. Medical Sciences, 2018. 6(4): p. 110.
6. Nathan, S.D., The future of lung transplantation. Chest, 2015. 147(2): p. 309-316.
7. Azzi, M., et al., Extracorporeal CO2 removal in acute exacerbation of COPD unresponsive to non-invasive ventilation. BMJ Open Respir Res, 2021. 8(1).

• What was the impact of COVID-19 on CT-ICUs?
• Thank you for this comment. The COVID-19 pandemic placed strains on modern-day critical care medicine unlike any other period in history. The CT-ICU in addition to all the other critical care areas served as epicenters for advanced supportive care.  Many centers which utilized extracorporeal life support in severe cases were staffed solely by cardiothoracic intensivists with little to no other medical provider assistance; requiring their knowledge base and care provided to be at its highest levels.  Additionally, the COVID-19 pandemic forced cardiothoracic intensivists to analyze global data for scarce resource allocation as well as command end-of-life care conferences in the most severe of circumstances; all while dealing with a relatively unknown disease process.

• Page 98 abbreviation CT-CCM?
  • Thank you for this comment. CT-CCM has been defined in the first sentence of the manuscript.

• Line 191-192: “Acute kidney injury is the most common major complication occurring after cardiac surgery with incidence reaching 40%” – shouldn’t this be the first condition to be reported (before delirium) since it is the most common?
• • Thank you for this comment. We changed the sequence per your suggestion. Please see Tracked Version reflecting this change in red.

• Line 304-310: What is finally the strategy recommended regarding the hemoglobin threshold for transfusion?
  • Thank you for this comment. The best studies we have state that threshold <7.5 is safe, with threshold of 7.0 not explicitly studies. We have reflected this in Tracked Version, with new comments added in red.
  • 437-447: For the general cardiac surgical population, a threshold of <7.5 g/dL is safe: a 5,243-participant study of a <7.5 g/dL versus a <9.5 g/dL trigger for transfusion during and after moderate-to-high-risk cardiothoracic surgery found reduced transfusions and no evidence of harm in the restrictive group, with consistent outcomes at six monthsIt is quite likely that a threshold of 7.0 is comparable to 7.5, but that has not been explicitly studied in large cardiac surgery trials. For non-surgical patients with active ischemia, a threshold between 7-8 g/dL is likely safe, but not firmly established: a trial of 668 patients with anemia and myocardial infarction found that a transfusion trigger of <7 g/dL was noninferior to a trigger of 10 g/dL for major adverse cardiac events at 30 days – although the confidence interval for this result may include clinically significant harm The results of the 3,500-patient Myocardial Ischemia and Transfusion (MINT) trial, expected to

• “patients or their families have the right to refuse therapies at any point” – that’s the ethical part that we should respect our patients’ wishes. What about the legal part? Do patients sign a form if they do not wish any further procedures or medical handling? What if the patient cannot sign etc?
  • Thank you for your comment. The legality of the situation is the same as the ethical suggestions. For example, formal change in code status does not require a signature rather just a conversation with the care team. Patient and their surrogate decision makers have the right to refuse any treatment at any time, even if it is recommended by the medical team. In fact, without signed consent the patient would not undergo any treatment, particularly invasive procedures.

• Line 347 “Paralysis After Aortic Aneurysm Surgery” – what is the role of physiotherapy?
  • Thank you for this comment. Physical therapists play an integral role in the recovery of our patients with spinal cord ischemia after aortic surgery. The interventions utilized by these physical therapists are aimed at guiding locomotion utilizing exercise therapy and other similar measures. There is a lack of randomized controlled trials, however, describing the efficacy of any single physical therapy intervention. This is yet another gap in the knowledge of treating patients with this condition. Future studies are required which investigate different types of physical therapy interventions at improving the recovery after aortic surgery, and if there is a role of physical therapy in reversing the pathophysiology and return of functional status in these patients.
  •  
• You could also add a third part with some direct 2–3-line opinions/perceptions/interviews of medical personnel working in CT-ICUs
  • Thank you for this comment. Given the broad topic of scientific knowledge gaps and future of CT-CCM as its own science, we find that adding Part 3 with opinions/perceptions/interviews inappropriate for the topic. Please see our other manuscript included in this special issue of Medicina titled “Developing of Cardiothoracic Surgical Critical Care Intensivists: A Case for Distinct Training” addressing this topic.

• General Comment: Tables and Figures are necessarily needed. E.g., a table with all published guidelines regarding cardiothoracic surgical intensive care medicine or a table with the most important clinical trials. Or a figure with an algorithm or diagram of main knowledge gaps or a network of who should work in the cardiothoracic surgical intensive care unit. The presence of such illustrations (not only one… consider adding 2-3 tables/figures) is imperative.
  • Thank for your insightful comments. Please see new tables and figures included in the manuscript. Copies are provided below.

Table 1. Barriers to Knowledge Expansion in Cardiothoracic Surgical Critical Care Medicine 

Legend. CT-CCM, Cardiothoracic Surgical Critical Care Medicine

Figure 1: Representation of the most common network of team members required to be involved in patient care and multidisciplinary rounds in the CTICU due to the complex nature of critical illness.

Figure 2. Framework of major tenants and actionable items of CT-CCM

Figure 3. General Categories of Research Gaps in the Field of CT-CCM

Table 3. Summary of Specific Knowledge Gaps and Research Goals in CT-CCM

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Please review the whole manuscript meticulously and perform necessary corrections - e.g., in Table 3 different font types/sizes are used, in some places CTCCM is used, in other places CT-CCM. This is very unpleasant for the reader and may convey an impression of unprofessionalism.

Author Response

We want to thank reviewer # 2 for their insightful comments. The fonts have been corrected and shortcuts have been made consistent throughout the manuscript. Please see the tracked changes in the re-submitted version of the manuscript.