We appreciate the insightful comments from He [1] regarding our recent study on acute respiratory distress syndrome (ARDS) classification and mechanical power ratio (MPR) calculations [2]. We welcome the opportunity to address the methodological concerns raised, which allow us to clarify key aspects of our approach.
First, regarding the assumption of airway resistance (Raw), we wish to emphasise that the numerator of our equation does not assume a standardised Raw value of 10 cmH2O/L/s. Instead, Raw in our calculations is based on individual patient data, incorporating the specific measurements obtained during mechanical ventilation. This ensures that the variability in airway resistance, influenced by the heterogeneity of ARDS pathophysiology, is accounted for.
Similarly, the inspiratory-to-expiratory time (I:E) ratio used in the MPR calculation is not a fixed value of 1:2, as suggested. The ratio in the numerator of our equation is explicitly incorporated as measured for each patient, reflecting the real-time ventilatory settings and conditions. Using these patient-specific parameters, our method aims to capture the complexity of ARDS mechanics rather than relying on standardised values.
We would also like to clarify that the denominator of the mechanical power ratio (MPR) reflects normal lungs under normal conditions of quiet breathing. This denominator is not intended to represent the pathophysiological conditions of patients with ARDS but serves as a reference point for comparison analogously to the ventilatory ratio for dead-space ventilation [3]. We believe that this provides a consistent method for evaluating mechanical power in relation to baseline physiological conditions.
We acknowledge the importance of addressing the dynamic and heterogeneous nature of ARDS and appreciate the opportunity to reiterate that our approach was designed to reflect these complexities accurately.
Funding
Open Access funding enabled and organized by Projekt DEAL.
Declarations
Conflicts of interest
None.
Footnotes
This comment refers to the article available online at 10.1007/s00134-024-07771-3.
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References
- 1.He Z, Wang C, Tian H (2025) Dynamic nature of airway resistance in ARDS: methodological concerns in MPR calculations. Intensive Care Med. 10.1007/s00134-024-07771-3 [DOI] [PubMed]
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