Hyperoxaemia and hypoxaemia are associated with harm in patients with ARDS

BMC Pulmonary Medicine

Table 3 Univariable and multivariable analysis for ICU mortality

Predictor	Univariable analysis		Multivariable analysis
Predictor	Odds ratio [95% CI]	p-value	Odds ratio [95% CI]	p-value
Age (years)	1.05 [1.03, 1.07]	< 0.001	1.04 [1.02, 1.07]	< 0.001
Male	0.85 [0.46,1.58]	0.61
APACHE II	1.03 [0.98, 1.09]	0.21
Non-respiratory SOFA score	1.12 [1.03, 1.22]	0.01	1.09 [0.98, 1.22]	0.10
Admission source
Emergency	1.09 [0.57, 2.17]	0.79
Elective	0.82 [0.17, 2.94]	0.77
Medical	0.93 [0.51, 1.7]	0.82
Surgical	1.47 [0.79, 2.71]	0.22
ARDS severity^a
Moderate	1.01 [0.53,1.94]	0.98
Severe	0.76 [0.30,1.83]	0.56
ARDS risk factor
Trauma	0.58 [0.23, 1.3]	0.20
Pneumonia	1.04 [0.55, 2.01]	0.91
Non-pulmonary sepsis	1.52 [0.71, 3.19]	0.27
Baseline ventilation parameters
Tidal volume (ml/kg PBW)	1.08 [0.92, 1.26]	0.33
PEEP (cmH₂O)	0.88 [0.78, 0.99]	0.04	0.87 [0.76, 0.99]	0.05
Mean airway pressure (cmH₂O)	0.99 [0.93, 1.02]	0.58
Lactate (mmol/L)	1.18 [1.01, 1.39]	0.04	1.17 [0.96, 1.43]	0.12
Vasopressor use	1.68 [0.92, 3.15]	0.10
Adjunctive therapies
Neuromuscular blockade	0.54 [0.27, 1.06]	0.08
Nitric oxide	1.28 [0.51, 3.03]	0.58
Prone positioning	1.25 [0.37, 3.77]	0.70
Highest PaO₂ (kPa/mmHg)
Quadratic term	1.00 [1.00, 1.01]	0.04
Linear term	0.85 [0.73, 0.99]	0.04
Highest FiO₂	1.01 [0.93, 1.1]	0.72
Highest P/F ratio	0.97 [0.95, 0.99]	0.02
Average time-weighted PaO₂ (kPa/mmHg)
Quadratic term	1.07 [1.01, 1.14]	0.02	1.08 [1.01, 1.16]	0.03
Linear term	0.16 [0.03, 0.67]	0.01	0.12 [0.02, 0.66]	0.02

Average time-weighted PaO₂ was obtained by calculating the value between consecutive time points prior to multiplying this value by the period of time between these points. The sum of these time-weighted values was then divided by the total time of mechanical ventilation (up to 7 days from onset of ARDS) within the timepoints of interest
APACHE II, Acute physiology and chronic health evaluation II; SOFA, Sequential organ failure assessment score; PaO₂, partial pressure of arterial oxygen; FiO₂, Fraction of inspired oxygen; P/F ratio, partial pressure of arterial oxygen to fraction of inspired oxygen ratio; PBW, predicted body weight; PEEP, Positive end-expiratory pressure
^aThe reference category for the comparison was Mild

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