The calculation of mechanical power is not suitable for intra-patient monitoring under pressure-controlled ventilation
Original correspondence from Dr. Zhao et al.
Dear Editor,
We read with interest the paper by Serpa Neto et al. showing that mechanical power (MP) of ventilation is independently associated with in-hospital mortality and other outcomes in critically ill invasively ventilated patients [1]. Although MP might become a practical clinical outcome predictor, we would like to point out that MP calculation may not be suitable for intra-individual monitoring of ventilator-related causes of lung injury under pressure-controlled ventilation.
Serpa Neto et al. used a simplified equation for MP calculation [
2], which is suitable in patients under volume-controlled ventilation. In pressure-controlled mode,
R
aw cannot be substituted by (
P
peak –
P
plat
)/Flow and Flow by
V
T/
T
insp. Further, an increase in
V
T is always negatively weighted in both original and simplified calculations, while the effect of recruitment is neglected. Considering the original calculation in [
2]:
$$ {\text{MP}} = 0.098 \times...
Notes
Compliance with ethical standards
Conflicts of interest
The authors declared that they have no conflict of interest.
References
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