Abstract
Background:
Mechanical power (W) is ventilator energy transferred to the respiratory system (ie, WRS) over time (J/min). WRS > 12 J/min and > 25 J/min are associated with ventilator-induced lung injury (VILI) onset and severe VILI respectively.1 Yet, baseline WRS of ∼ 28 J/min previously was not found to differentiate ARDS survivors from non-survivors.2 This retrospective study examined whether increasing WRS and WL intensity corresponds with increasing mortality as ARDS intensity worsens.
Methods:
948 ARDS subjects were studied who: 1) met the Berlin definition, 2) were managed with ARDSNet protocols initiated ≤ 24 h after ARDS onset, 3) survived ≥ 24 h after protocol initiation. A simplified WRS calculation (0.098 x frequency x VT x [PEEP + PDR]),2 was used wherein WL was estimated using fractional subcomponents respiratory system elastance: EL/ERS (0.72).3 Data were analyzed using the Mann-Whitney test. Alpha was set at 0.05.
Results:
Within ∼36-48 h of ARDS onset, significantly higher WRS and WL were observed in non-survivors with median WRS approximating levels associated with severe VILI (ie, ∼25 J/min). Hospital mortality rates were similar to Berlin Taskforce findings (ie, 27%, 32%, and 45%).4 Lower estimates of WL also reached the threshold wherein some degree of VILI appeared likely.
Conclusions:
Contrary to previous findings,2 WRS ∼25 J/min was associated with increased mortality risk and, by extension, perhaps severe VILI risk.1. Silva PL et al. Anesthesiology 2020;132:949. 2. Wu H-P et al. Diagnostics 2023;13:1226. 3. Kallet RH et al. Respir Care 2007; 52(8):989. 4. Berlin Taskforce. JAMA 2012; 307:2526.
*data presented as median (IQR),† P=0.034, ‡ P<0.001, ‖ P=0.004 View all access options for this article.Table 1
Berlin
Power(W) J/m
Surv
Non-Surv
Mortality
Mild
Wrs
18.5 (14.6-25)*
24.7 (14.1-33.2) †
26%
WL
13.3 (10.5-18)
17.8 (10.1-23.9) †
Moderate
Wrs
21.3 (16.6-27.2)
25.7 (19.7-34.5)‡
32%
WL
15.4 (12-19.6)
18.5 (14.1-24.9) ‡
Severe
Wrs
23.5 (18.1-31.8)
28.7 (15.6-27.9) ‖
42%
WL
16.9 (13-22.9)
20.6 (15.6-27.9) ‖
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