Critical Analysis of Hemodynamic Risk Assessment

I read the paper "Hemodynamic risk assessment by thermodilution and direct Fick measurement of cardiac output in pulmonary hypertension" by Brownstein et al,1Brownstein A.J. Cooper C.B. Jasuja S. Sherman A.E. Saggar R. Channick R. Hemodynamic risk assessment by thermodilution and direct Fick measurement of cardiac output in pulmonary hypertension.CHEST Pulm. 2024; 100059Google Scholar published in CHEST Pulmonary (2024). The study provides valuable insights into the risk assessment methods for pulmonary hypertension, particularly comparing thermodilution (TD) and direct Fick (DF) for cardiac output (CO) measurements. I would like to raise a few questions and comments for the authors that I think could further enrich the discussion and add clarity to the findings. The authors found that TD tended to underestimate CO compared with DF, leading to different hemodynamic risk assessments in nearly 20% of cases. Could this underestimation affect clinical decision-making, particularly in terms of therapeutic escalation or de-escalation in patients with pulmonary hypertension? Further elaboration on the clinical implications of this discrepancy would be valuable.2Volodarsky I. Kerzhner K. Haberman D. et al.Comparison between cardiac output and pulmonary vascular pressure measured by indirect Fick and thermodilution methods.J Pers Med. 2023; 13: 559Crossref Scopus (1) Google Scholar Given the significant association between higher resting Vo2 and greater negative bias in TD, what specific technical factors might contribute to this observation? Additionally, could patient characteristics (eg, BMI, other comorbidities) influence the accuracy of TD CO measurements? Understanding these variables could help practitioners better interpret TD results. The study reported 78% concordance between DF and TD for hemodynamic risk stratification. Could the authors elaborate on the clinical significance of this concordance level? Is there a threshold at which the discrepancy between DF and TD might warrant additional investigation or caution in risk stratification?3Genecand L. Adler D. Beghetti M. Lador F. Cardiac output determination in precapillary pulmonary hypertension: a systematic review.Respiration. 2021; 100: 1243-1250Crossref Scopus (4) Google Scholar The authors suggest using Vo2 measurement with assurance of steady-state resting conditions to improve DF CO accuracy. Are there any recommendations for clinicians who rely primarily on TD, especially in centers where DF might not be readily available? Practical advice on managing these limitations would be helpful for broader clinical application. I appreciate the authors' thorough examination of this important topic and look forward to their responses to these questions. I think that addressing these points would further contribute to the growing body of knowledge surrounding pulmonary hypertension and its associated risk assessments. Thank you for your time and consideration. None declared. Author contributions: A. A. contributed to conceptualization, project administration, and writing - original draft. R. A. B. contributed to data curation and writing - review & editing. ResponseCHEST PulmonaryPreviewWe appreciate the comments regarding our research published in CHEST Pulmonary.1 The author raises important questions that we subsequently address.