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. 2023 Apr 6;11(1):14.
doi: 10.1186/s40560-023-00662-7.

Mechanical power and 30-day mortality in mechanically ventilated, critically ill patients with and without Coronavirus Disease-2019: a hospital registry study

Basit A Azizi  1   2 , Ricardo Munoz-Acuna  1   2 , Aiman Suleiman  1   2 , Elena Ahrens  1   2 , Simone Redaelli  1   2 , Tim M Tartler  1   2 , Guanqing Chen  2 , Boris Jung  1   2 , Daniel Talmor  1 , Elias N Baedorf-Kassis #  3 , Maximilian S Schaefer #  4   5   6
Affiliations

Mechanical power and 30-day mortality in mechanically ventilated, critically ill patients with and without Coronavirus Disease-2019: a hospital registry study

Basit A Azizi et al. J Intensive Care. .

Abstract

Background: Previous studies linked a high intensity of ventilation, measured as mechanical power, to mortality in patients suffering from "classic" ARDS. By contrast, mechanically ventilated patients with a diagnosis of COVID-19 may present with intact pulmonary mechanics while undergoing mechanical ventilation for longer periods of time. We investigated whether an association between higher mechanical power and mortality is modified by a diagnosis of COVID-19.

Methods: This retrospective study included critically ill, adult patients who were mechanically ventilated for at least 24 h between March 2020 and December 2021 at a tertiary healthcare facility in Boston, Massachusetts. The primary exposure was median mechanical power during the first 24 h of mechanical ventilation, calculated using a previously validated formula. The primary outcome was 30-day mortality. As co-primary analysis, we investigated whether a diagnosis of COVID-19 modified the primary association. We further investigated the association between mechanical power and days being alive and ventilator free and effect modification of this by a diagnosis of COVID-19. Multivariable logistic regression, effect modification and negative binomial regression analyses adjusted for baseline patient characteristics, severity of disease and in-hospital factors, were applied.

Results: 1,737 mechanically ventilated patients were included, 411 (23.7%) suffered from COVID-19. 509 (29.3%) died within 30 days. The median mechanical power during the first 24 h of ventilation was 19.3 [14.6-24.0] J/min in patients with and 13.2 [10.2-18.0] J/min in patients without COVID-19. A higher mechanical power was associated with 30-day mortality (ORadj 1.26 per 1-SD, 7.1J/min increase; 95% CI 1.09-1.46; p = 0.002). Effect modification and interaction analysis did not support that this association was modified by a diagnosis of COVID-19 (95% CI, 0.81-1.38; p-for-interaction = 0.68). A higher mechanical power was associated with a lower number of days alive and ventilator free until day 28 (IRRadj 0.83 per 7.1 J/min increase; 95% CI 0.75-0.91; p < 0.001, adjusted risk difference - 2.7 days per 7.1J/min increase; 95% CI - 4.1 to - 1.3).

Conclusion: A higher mechanical power is associated with elevated 30-day mortality. While patients with COVID-19 received mechanical ventilation with higher mechanical power, this association was independent of a concomitant diagnosis of COVID-19.

Keywords: COVID-19; Intensive care unit; New England; Respiratory distress syndrome; Respiratory insufficiency; Ventilator-induced lung injury.

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Conflict of interest statement

DT received speaking fees and grant funds from Hamilton Medical, Inc. and Mindray Medical, outside the submitted work. EBK has received lecturing fees from Hamilton Medical, Inc., outside the submitted work and has received a KL2 award from Harvard Catalyst | The Harvard Clinical and Translational Science Center (National Center for Advancing Translational Sciences, National Institutes of Health award No. KL2 TR002542). MSS has received a grant for investigator-initiated trials not related to this article from Merck & Co and received speaking fees from Mindray Medical, Inc. MSS also received a philanthropic donation from Jeff and Judy Buzen. The other authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Study flow diagram. BMI body mass index. *385 patients with missing APACHE-II scores were imputed
Fig. 2
Fig. 2
Distribution of mechanical power. Histograms depicting mechanical power distribution between a patients with and without 30-day mortality (median [interquartile range] mechanical power in patients who died within 30 days after start of invasive ventilation was 16.8 [12.0–22.3] J/min and in patients who survived 13.7 [10.2–18.6] J/min); and b patients with and without Coronavirus Disease 2019 (19.3 [14.6–24.0] J/min in patients with and 13.2 [10.2–18.0] J/min in patients without the disease)
Fig. 3
Fig. 3
Dominance analyses. Relative dominance of a individual parameters of mechanical power and b different components of mechanical power with regard to prediction of 30-day mortality. Higher R-squared values depict a higher dominance in predicting 30-day mortality
Fig. 4
Fig. 4
Respiratory system compliance before a and after b matching. Distribution of standardized respiratory system compliance, defined as the initial respiratory system compliance normalized to ideal body weight, for patients whose lungs were ventilated with low (light grey) versus high (red) median mechanical power before a and after b matching for respiratory system compliance. Low versus high mechanical power was defined based on the cohort median of 14.5 J/min
See this image and copyright information in PMC

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