Abstract
Background:
Previous abstract (Part 4) compared mechanical power transferred to the respiratory system (WRS), in which below/above the 20 J/min threshold revealed a widening mortality departure (ie, 24% vs. 42% respectively). Those whose WRS > 20 J/min accounted for 65% of subjects. Thresholds in plateau pressure (Pplat) > 30 cm H2O and driving pressure (PDR) > 15 cm H2O are also associated with increasing mortality risk in ARDS.1,2 This study examined the relevance of all three thresholds on mortality risk when compared to prominent non-pulmonary factors that drive mortality in ARDS.3
Methods:
948 ARDS subjects previously described (abstracts part 1-4) had threshold values for WRS, Pplat and PDR compared to non-pulmonary factors (ie, age, ARDSNet study comorbidity exclusion criteria,1 and APACHE II scores) both in univariate and multivariate logistic regression modeling. Alpha was set at 0.05.
Results:
In univariate analyses all variables were associated with mortality risk (P < .001). Low collinearity was found between dichotomous expressions of the inter-related variables WRS, Pplat and PDR (R2:0.19, 0.19, 0.23 respectively). Multivariate modelling revealed Pplat and WRS thresholds, but not PDR threshold, remained strongly associated with mortality when controlled for non-pulmonary variables (Table). Area under receiver operative curve of 0.80 (95%CI: 0.77-0.83), P < .001.
Conclusions:
When lung protective ventilation is initiated ≤ 24 h after ARDS onset, exceeding Pplat and WRS thresholds influences mortality rather than PDR threshold > 15 cm H2O.1. ARDS Network. N Engl J Med 2000;342(18):1301. 2. Amato MB et al. N Engl J Med 2015;372(8):747. Kallet RH et al. Respir Care 2019;64(5):493.
*APACHE = acute physiology and chronic health evaluation View all access options for this article.Table 1
Variables
Odds Ratio (95%CI)
P
Age
1.03 (1.02-1.04)
<0.001
ARDSNet Exclusion+
2.52 (1.83-3.47)
<0.001
APACHE II*
1.09 (1.06-1.11)
<0.001
Wrs > 20 J/m
1.76 (1.22-2.56)
0.003
Pplat > 30 cmH2O
3.16 (1.92-5.25)
<0.001
Pdr > 15 cmH2O
1.23 (0.86-1.76)
0.25
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