More severe PARDS tied to longer time to resolution of oxygenation defects

In patients with paediatric acute respiratory distress syndrome (PARDS), the time to disease resolution is longer in those with more severe disease, according to a Singapore study.

Of the 121 children enrolled in this prospective observational study, 27.3 percent (n=33) and 36.4 percent (n=44) had mild and moderate PARDS, respectively, while 36.4 percent (n=44) had severe disease. Oxygenation index (OI) and oxygen saturation index (OSI) were measured in each group daily over 28 days. [Front Pediatr 2022;doi:10.3389/fped.2022.993175]

During the first week, OI and OSI could clearly distinguish the three severity groups from each other, with patients suffering from more severe PARDS showing higher values than those with milder disease. After 7 days, however, OI and OSI values became comparable across the three severity groups.

Resolution of PARDS, the study’s primary endpoint and defined as OI <4 or OSI <5.3 for two consecutive days, showed a stepwise increase according to disease severity. For instance, mild patients took a median of four days to resolution, while those with moderate and severe disease needed five and 7.5 days, respectively (p<0.0001).

Conversely, Cox regression analysis revealed that patients with moderate (hazard ratio [HR], 0.35, 95 percent confidence interval [CI], 0.16–0.76; p=0.008) and severe (HR, 0.17, 95 percent CI, 0.08–0.39; p<0.001) PARDS had a significantly lower likelihood of resolution than those with mild disease.

“There is currently no physiologic marker that indicates recovery from lung injury. Here, the oxygenation defect that characterizes PARDS, which was demonstrated to improve with time, could be used as a respiratory-specific outcome corresponding to the physiologic recovery of lung injury,” the researchers said.

Despite being significantly correlated with the severity of PARDS specifically, time to resolution showed no important links to overall illness severity as determined by the Pediatric Index of Mortality (HR, 1.01, 95 percent CI, 0.99–1.02; p=0.253) and the Pediatric Logistic Organ Dysfunction (HR, 1.02, 95 percent CI, 0.99–1.05; p=0.326) scores.

Time to resolution indicative of other outcomes

Aside from disease severity, a longer time to PARDS resolution was also linked to a significantly longer duration of mechanical ventilation (incidence rate ratio [IRR], 1.10, 95 percent CI, 1.05–1.15; p<0.001) and a longer stay in the paediatric intensive care unit (IRR, 1.11, 95 percent CI, 1.06–1.16; p<0.001).

Moreover, overall hospital stay was longer in those who needed more time to resolve PARDS (IRR, 1.06, 95 percent CI, 1.01–1.11; p=0.018). Time to resolution was also inversely associated with lower ventilator-free (IRR, 0.93, 95 percent CI, 0.87–1.00; p=0.046) and intensive care unit-free (IRR, 0.84, 95 percent CI, 0.76–0.92; p<0.001) days.

“We propose time to resolution as a surrogate outcome measure for PARDS, in addition to conventional outcomes like mortality and duration of mechanical ventilation which are less specific for PARDS,” the researchers said. “External validation of these findings in a larger and independent cohort is necessary to evaluate time to resolution as a relevant clinical outcome measure.”