Evaluation of the Modified Pulmonary Index Score to Evaluate Pediatric Asthma Severity in the Pediatric Intensive Care Unit

Abstract

Background: Scoring systems are frequently used to assess the severity of pediatric asthma exacerbations. The modified pulmonary index score (MPIS) is used in our institution as part of our pediatric asthma pathway. Total MPIS has been found to be highly correlated with pediatric intensive care unit (PICU) length of stay (LOS); however, this was a single center study with a relatively small sample size. We sought to evaluate the use of the MPIS to predict hospital LOS for patients admitted to our PICU. Methods: Following IRB approval, the medical records of all pediatric asthma subjects aged 2 to 17 years of age admitted to our PICU between June 2014 and November 2017 were retrospectively reviewed. Subjects were identified via ICD9 and ICD10 codes. We a priori divided subjects into three groups based upon each subject’s first MPIS documented in PICU, low (MPIS 0-5) medium (MPIS 6-9) and high (MPIS ≥10). Hospital LOS, PICU LOS, time on continuous albuterol, and need for increased respiratory support were compared between groups. Data were analyzed with SPSS v24 with nonparametric, chi-squared, and one-way ANOVA performed. Poisson regression analysis was performed to identify PICU admission factors associated with hospital length of stay. Results: A total of 143 subjects were included. There were no differences for age, gender, weight, home medications, medical history, cause of exacerbations, noninvasive ventilation use, or need for intubation between groups. There were significant differences between groups for mean heart rate (P < .001), respiratory rate (P < .001), SpO₂ (P = .01) and FIO₂ (P < .004). There were significant differences between groups for median hospital length of stay (1.2 vs. 2.3 vs. 3.4 days, P < .001), PICU length of stay (0.39 vs. 1.3 vs. 2 days, P < .001), and time on continuous albuterol (7.4 vs. 20.6 vs. 34.7 h, P < .001). There were significant differences between groups for route of admission (P = .03), high-flow nasal cannula use (P < .001), and heliox use (P < .001). After adjusting for demographics and medical history, the incidence risk ratio for hospital LOS was 2.47 for PICU admission MPIS of 7-10 and 3.25 for an MPIS >10 when compared to an MPIS ≤6. Conclusions: The MPIS thresholds used in our pathway appear to differentiate exacerbation severity. A higher MPIS is associated with increased hospital LOS, PICU LOS, time on continuous albuterol, need for high-flow nasal cannula and need for heliox.