RESULTS
During the study timeframe, 115 patients had a clinically performed echocardiogram completed within 24 hours of PARDS onset with 76 patients meeting full inclusion criteria (Figure 1). Median age was 6.2 years (IQR 1.9-9.8), 50% were male, and 22 patients (32%) were immunocompromised (Table 1). The most common diagnoses were infectious pneumonia (43%) and sepsis (29%) and the distribution of PARDS severity was: 34% mild, 34% moderate, and 32% severe (Table 1). Median time between PaCO2 and EtCO2values was 15 min and median time from ARDS diagnosis to echocardiogram was 1.2 hours (IQR -4.6 to 4.4). Mortality was 34%.
Median RV GLS value for the cohort was –21.0% (IQR –24.3 to -16.8) with 24 patients (32%) having abnormal RV GLS (> -18%). 17 patients (24%) were found to have PH. The median values (IQRs) for other echocardiographic measures of RV systolic function are displayed in Supplemental Table 1. There were no differences in the distribution of AVDSf between those with and without abnormal RV GLS or those without or without echocardiographic evidence of PH (Figure 2).
Unadjusted logistic regression showed no association of AVDSf at onset with the primary outcome of echocardiographic evidence of RV systolic dysfunction defined as RV GLS > -18% nor with the secondary outcome of echocardiographic evidence of PH within 24 hours of PARDS diagnosis (Table 2). This remained true when adjusting individually for other clinically important covariates including immunocompromised status, PRISM III score, OI, iNO use, and age (Table 2). Similar analyses showed no association of AVDSf at onset with other secondary outcomes of echocardiographic measures of RV systolic function (Supplemental Table 2). Sensitivity analyses were performed including the use of AVDSf as a binary variable based on various cutoffs (0.15, 0.25, and 0.35) and the use of RV dysfunction measures as continuous variables with the regression models showing no association between AVDSf at onset with measures of RV systolic dysfunction or PH (data not shown).
AVDSf at onset did not discriminate RV systolic dysfunction with AUROC 0.51 (95% CI 0.36-0.66) for abnormal RV GLS and AUROC 0.56 (95% CI 0.44-0.73) for PH. Similarly, AVDSf at onset did not discriminate PH or RV systolic dysfunction as measured by other echocardiographic parameters (Supplemental Figure 1).
AVDSf at onset was associated with secondary outcome measures of oxygenation (OI and P/F ratio) in both unadjusted and adjusted linear regression models (Table 3). There was no difference in AVDSf at onset between different ARDS severities (Kruskal-Wallis p=0.3678, Cuzick non-parametric test of trend p=0.214, Supplemental Figure 2).