Mechanical power during extracorporeal membrane oxygenation and hospital mortality in patients with acute respiratory distress syndrome

Table 4 Cox proportional hazard regression analysis of factors associated with 90-day hospital mortality

Variables	Univariate analysis		Multivariate analysis model 1		Multivariate analysis model 2		Multivariate analysis model 3
Variables	HR (95% CI)	p	HR (95% CI)	p	HR (95% CI)	p	HR (95% CI)	p
Age (with each year increase)	1.018 (1.004–1.033)	0.012
Pulmonary cause	1.989 (1.211–3.216)	0.007
Extrapulmonary cause	0.785 (0.475–1.296)	0.344
Diabetes mellitus	0.622 (0.358–1.079)	0.091
Chronic liver disease	2.085 (1.184–3.670)	0.011
Immunocompromised status	2.242 (1.411–3.563)	0.001	2.564 (1.488–4.419)	0.001	2.674 (1.556–4.596)	< 0.001	2.554 (1.471–4.433)	0.001
ARDS duration before ECMO (with each hour increase)	1.002 (1.001–1.004)	< 0.001	1.002 (1.001–1.004)	0.003	1.002 (1.001–1.004)	0.003	1.001 (1.000–1.003)	0.074
SOFA score from day 1 to 3 on ECMO (with each point increase)	1.318 (1.178–1.476)	< 0.001	1.202 (1.067–1.355)	0.003	1.207 (1.074–1.356)	0.002	1.222 (1.084–1.377)	0.001
Tidal volume/PBW from day 1 to 3 on ECMO	1.001 (0.896–1.118)	0.992
PEEP from day 1 to 3 on ECMO	0.945 (0.880–1.015)	0.120
Peak inspiratory pressure from day 1 to 3 on ECMO	1.058 (1.019–1.100)	0.004
Dynamic compliance from day 1 to 3 on ECMO	0.953 (0.924–0.984)	0.003
Total respiratory rate from day 1 to 3 on ECMO	1.055 (1.003–1.109)	0.039
MP from day 1 to 3 on ECMO	1.054 (1.017–1.093)	0.004	1.060 (1.018–1.104)	0.005
MP/PBW from day 1 to 3 on ECMO (× 10⁻³ J/min/kg)	1.003 (1.001–1.005)	0.002			1.004 (1.002–1.007)	< 0.001
MP/Compliance from day 1 to 3 on ECMO (J/min/ml/cm H₂O)	3.142 (1.966–5.020)	< 0.001					2.289 (1.214–4.314)	0.010

ARDS acute respiratory distress syndrome, CI confidence interval, ECMO extracorporeal membrane oxygenation, HR hazard ratio, MP mechanical power, PBW predicted body weight, PEEP positive end-expiratory pressure, SOFA Sequential Organ Failure Assessment
Multivariate analysis models included age, pulmonary or extrapulmonary cause of ARDS, diabetes mellitus, chronic liver disease, immunocompromised status, ARDS duration before ECMO, mean SOFA score from day 1 to 3 on ECMO, and mean values of ventilatory parameters from day 1 to 3 on ECMO (tidal volume/PBW, PEEP, peak inspiratory pressure, dynamic compliance, total respiratory rate, MP, MP/PBW, and MP/Compliance)
Model 1: add mean MP from day 1 to 3 on ECMO
Model 2: add mean MP/PBW from day 1 to 3 on ECMO (× 10⁻³ J/min/kg)
Model 3: add mean MP/Compliance from day 1 to 3 on ECMO (J/min/ml/cm H₂O)

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