Faculty Bibliography

OBJECTIVE:The Pediatric Acute Lung Injury Consensus Conference has developed a pediatric-specific definition of acute respiratory distress syndrome, which is a significant departure from both the Berlin and American European Consensus Conference definitions. We sought to test the external validity and potential impact of the Pediatric Acute Lung Injury Consensus Conference definition by comparing the number of cases of acute respiratory distress syndrome and mortality rates among children admitted to a multidisciplinary PICU when classified by Pediatric Acute Lung Injury Consensus Conference, Berlin, and American European Consensus Conference criteria. DESIGN:Retrospective cohort study. SETTING:Tertiary care, university-affiliated PICU. PATIENTS:All patients admitted between March 2009 and April 2013 who met inclusion criteria for acute respiratory distress syndrome. INTERVENTIONS:None. MEASUREMENTS AND MAIN RESULTS:Of 4,764 patients admitted to the ICU, 278 (5.8%) met Pediatric Acute Lung Injury Consensus Conference pediatric acute respiratory distress syndrome criteria with a mortality rate of 22.7%. One hundred forty-three (32.2% mortality) met Berlin criteria, and 134 (30.6% mortality) met American European Consensus Conference criteria. All patients who met American European Consensus Conference criteria and 141 (98.6%) patients who met Berlin criteria also met Pediatric Acute Lung Injury Consensus Conference criteria. The 137 patients who met Pediatric Acute Lung Injury Consensus Conference but not Berlin criteria had an overall mortality rate of 13.1%, but 29 had severe acute respiratory distress syndrome with 31.0% mortality. At acute respiratory distress syndrome onset, there was minimal difference in mortality between mild or moderate acute respiratory distress syndrome by both Berlin (32.4% vs 25.0%, respectively) and Pediatric Acute Lung Injury Consensus Conference (16.7% vs 18.6%, respectively) criteria, but higher mortality for severe acute respiratory distress syndrome (Berlin, 43.6%; Pediatric Acute Lung Injury Consensus Conference, 37.0%). Twenty-four hours after acute respiratory distress syndrome onset, the presence of severe acute respiratory distress syndrome (using either Berlin or Pediatric Acute Lung Injury Consensus Conference) was associated with nearly 50% mortality. CONCLUSIONS:Applying the Pediatric Acute Lung Injury Consensus Conference definition of acute respiratory distress syndrome has the potential to significantly increase the number of acute respiratory distress syndrome patients identified, with a lower overall mortality rate. However, severe acute respiratory distress syndrome is associated with extremely high mortality, particularly if present at 24 hours after initial diagnosis.

OBJECTIVE:Elevated dead space has been consistently associated with increased mortality in adults with respiratory failure. In children, the evidence for this association is more limited. We sought to investigate the association between dead space and mortality in mechanically ventilated children. DESIGN/METHODS:Single-center retrospective review. SETTING/METHODS:Tertiary care pediatric critical care unit. PATIENTS/METHODS:Seven hundred twelve mechanically ventilated children with an arterial catheter. INTERVENTIONS/METHODS:None. MEASUREMENTS AND MAIN RESULTS/RESULTS:The end-tidal alveolar dead space fraction ((PaCO2-PETCO2)/PaCO2), a dead space marker, was calculated with each arterial blood gas. The initial end-tidal alveolar dead space fraction (first arterial blood gas after intubation) (per 0.1 unit increase: odds ratio, 1.59; 95% CI, 1.40-1.81) and day 1 mean end-tidal alveolar dead space fraction (odds ratio, 1.95; 95% CI, 1.66-2.30) were associated with mortality. The relationship between both initial and day 1 mean end-tidal alveolar dead space fraction and mortality held in multivariate modeling after controlling for any of the following individually: PaO2/FIO2, oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III (all p<0.01), although end-tidal alveolar dead space fraction was no longer significant after controlling for the combination of oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III. In 217 children with acute hypoxemic respiratory failure, initial end-tidal alveolar dead space fraction (per 0.1 unit increase odds ratio, 1.38; 95% CI, 1.14-1.67) and day 1 mean end-tidal alveolar dead space fraction (per 0.1 unit increase odds ratio, 1.60; 95% CI, 1.27-2.0) were associated with mortality. Day 1 mean end-tidal alveolar dead space fraction remained associated with mortality after controlling individually for any of the following in multivariate models: PaO2/FIO2, oxygenation index, and 24-hour maximal inotrope score (p≤0.02), although end-tidal alveolar dead space fraction was no longer significant after controlling for the combination of oxygenation index, 24-hour maximal inotrope score, and Pediatric Risk of Mortality III. CONCLUSIONS:Increased dead space is associated with higher mortality in critically ill children, although it is no longer independently associated with mortality after controlling for severity of oxygenation defect, inotrope use, and severity of illness. However, because end-tidal alveolar dead space fraction is easy to calculate at the bedside, it may be useful for risk stratification and severity-of-illness scores.

PURPOSE/OBJECTIVE:Requiring PaO2/FiO2 ratio (PF) to define ARDS may bias towards children with cardiovascular dysfunction and hypoxemia. We sought to evaluate (1) the Berlin definition of ARDS in children using PF; (2) the effect of substituting SpO2/FiO2(SF) ratio; (3) differences between patients with and without arterial blood gases; and (4) the ability of SpO2 and PaO2 indices to discriminate ICU mortality. METHODS:Single center retrospective review (3/2009-4/2013) of mechanically ventilated (MV) children. Initial values for PF, SF, oxygenation index (OI), and oxygen saturation index (OSI) after intubation and average values on day 1 of MV were analyzed against ICU mortality, subgrouped by Berlin severity categories. RESULTS:Of the 1,833 children included, 129 met Berlin PF ARDS criteria (33 % mortality); 312 met Berlin SF ARDS criteria (22 % mortality). Children with a PaO2 on day 1 of MV had higher mortality and severity of illness, were older, and had more vasoactive-inotropic infusions (p < 0.001). SF could be calculated for 1,201 children (AUC for ICU mortality 0.821), OSI for 1,034 (0.793), PF for 695 (0.706), and OI for 673 (0.739). Average SF on day 1 discriminated mortality better than PF (p = 0.003). CONCLUSIONS:Berlin PF criteria for ARDS identified less than half of the children with ARDS, favoring those with cardiovascular dysfunction. SF or OSI discriminate ICU mortality as well as PF and OI, double the number of children available for risk stratification, and should be considered for severity of illness scores and included in a pediatric-specific definition of ARDS. Multicenter validation is required.