Mechanical Power Is Associated With Mortality in Pressure-Controlled Ventilated Patients: A Dutch, Single-Center Cohort Study

Abstract

Importance: Mechanical power (MP) could serve as a valuable parameter in clinical practice to estimate the likelihood of adverse outcomes. However, the safety thresholds for MP in mechanical ventilation remain underexplored and contentious.

Objectives: This study aims to investigate the association between MP and hospital mortality across varying degrees of lung disease severity, classified by Pao2/Fio2 ratios.

Design, setting, and participants: This is a retrospective cohort study using automatically extracted data. Patients admitted to the ICU of a tertiary referral hospital in The Netherlands between 2018 and 2024 and ventilated in pressure-controlled mode were included.

Main outcomes and measures: Logistic regression, adjusted for age, sex, Acute Physiology and Chronic Health Evaluation-IV score, and Pao2/Fio2 ratio, was used to calculate the odds ratio (OR) for all-cause in-hospital mortality.

Results: A total of 2184 patients were analyzed, with a mean age of 62.5 ± 13.8 years, of whom 1508 (70.2%) were male. The mean MP was highest in patients with the lowest Pao2/Fio2 ratios (21.5 ± 6.5 J/min) compared with those with the highest ratios (12.0 ± 3.8 J/min; p < 0.001). Adjusted analyses revealed that increased MP was associated with higher mortality (OR, 1.06; 95% CI, 1.03-1.09 per J/min increase). Similarly, MP normalized for body weight showed a stronger association with mortality (OR, 1.004; 95% CI, 1.002-1.006 per J/min/kg increase). An increase in mortality was seen when MP exceeded 16-18 J/min.

Conclusions and relevance: Our findings demonstrate a significant association between MP and hospital mortality, even after adjusting for key confounders. Mortality increases notably when MP exceeds 16-18 J/min. Normalized MP presents an even stronger association with mortality. These results underscore the need for further research into ventilation strategies that consider MP adjustments.

Figure 1.

Flowchart of data inclusion. A first layer of filters was applied necessary to calculate the mechanical power in pressure-controlled mode. A second layer included filters to reduce errors and erratic numbers. ^aPatients were excluded with filters in this order (blood gas, pressure-controlled mode, breathing spontaneously). **Data were filtered with the following parameters: (tidal volume > 100 mL, inspiratory pressure < 50 cm H₂O, peak pressure > 9 cm H₂O, compliance < 150 mL/cm H₂O, resistance < 25 cm H₂O/L/s, inspiratory time > 0.3 s, inspiratory time constant between 0.1 and 2.5 s, Pao₂/Fio₂ ratio < 100 kPa or 400 mm Hg).

Figure 2.

The relation between mechanical power (MP) and Pao₂/Fio₂ (P/F) ratio. 13.3 kilopascal (kPa) = 100 mm Hg, 26.7 kPa = 200 mm Hg, 40 kPa = 300 mm Hg, 60 kPa = 450 mm Hg, 80 kPa = 600 mm Hg, 1000 kPa = 750 mm Hg. A generalized additive model with integrated smoothness estimation was used. The blue line depicts the smooth regression line with the light blue area being the 95% CI thereof.

Figure 3.

Odds ratios for hospital mortality per mechanical power group, adjusted for age, sex, APACHE-IV score, and Pao₂/Fio₂ ratio. A, Odds ratio (OR) for hospital mortality per mechanical power (MP) group calculated in the entire cohort. Horizontal black line depicts an OR of 1. B, OR for hospital mortality per MP group calculated for all patients who were mechanically ventilated for at least 24 hr. Horizontal black line depicts an OR of 1. J = joules.