Abnormal Vital Signs Predict Critical Deterioration in Hospitalized Pediatric Hematology-Oncology and Post-hematopoietic Cell Transplant Patients

Abstract

Introduction: Hospitalized pediatric hematology-oncology and post-hematopoietic cell transplant (HCT) patients have frequent deterioration requiring Pediatric Intensive Care Unit (PICU) care. Critical deterioration (CD), defined as unplanned PICU transfer requiring life-sustaining interventions within 12 h, is a pragmatic metric to evaluate emergency response systems (ERS) in pediatrics, however, it has not been investigated in these patients. The goal of this study was to evaluate if CD is an appropriate metric to assess effectiveness of ERS in pediatric hematology-oncology and post-HCT patients and if it is preceded by an actionable period of vital sign changes. Methods: A retrospective review of all unplanned PICU transfers and floor cardiopulmonary arrests in a dedicated pediatric hematology-oncology hospital between August 2014 and July 2016. Vital signs and physical exam findings 48 h prior to events were converted to Pediatric Early Warning System-Like Scores (PEWS-LS) using cardiovascular, respiratory, and neurologic criteria. Results: There were 220 deterioration events, with 107 (48.6%) meeting criteria for CD, representing a rate of 2.98 per 1,000-inpatient-days. Using the first event per hospitalization (n = 184), patients with CD had higher mortality (17.4 vs. 7.6%, p = 0.045), fewer median ICU-free-days (21 vs. 24, p = 0.011), ventilator-free-days (25 vs. 28, p < 0.001), and vasoactive-free-days (27 vs. 28, p < 0.001). Using vital sign data 48 h prior to deterioration events, those with CD had higher PEWS-LS on PICU admission (p < 0.001), spent more time with elevated PEWS-LS prior to PICU transfer (p = 0.008 to 0.023) and had a longer time from first abnormal PEWS-LS (p = 0.007 to 0.043). Significant difference between the two groups was observed as early as 4 h prior to the event (p = 0.047). Conclusion: Hospitalized pediatric hematology-oncology and post-HCT patients have frequent deterioration resulting in a high mortality. In these patients, CD is over 13 times more common than floor cardiopulmonary arrests and associated with higher mortality and fewer event-free days, making it a useful metric in these patients. CD is preceded by a long duration of abnormal vital signs, making it potentially preventable through earlier recognition.

Keywords: Pediatric Early Warning System (PEWS); cardiopulmonary arrest; critical deterioration; emergency response systems; pediatric intensive care; pediatric oncology.

Figure 1

PEWS-Like-Score (PEWS-LS) in the 48 h prior to deterioration events with and without critical deterioration. PEWS-like-scores (PEWS-LS) were calculated using documented vital signs data in the 48-h prior to PICU admission or floor intervention using the PEWS tool and vital sign limits derived from those previously published (13, 15, 16). The PEWS-LS was constructed by summing cardiovascular (CV), Neurologic, and Respiratory scores in 15-min intervals. The CV score combined capillary refill and heart rate parameters. The neurological score was based on level of consciousness. The respiratory score was based on oxygen use, use, type, and flow of ventilation, oxygen saturation, and respiratory rate. Neurologic, CV, and Respiratory sub-scores each had a possible range of 0–3, with 3 representing the most abnormal score. The PEWS-like score was a sum of these 3 sub-scores and had a theoretical range of 0–9. Documented values were carried forward until a change was noted in the medical record or patient was admitted to the PICU. For patients with <48 h between hospital admission and PICU transfer, only the available period of vital signs was used for analysis.

Figure 2

The predicted PEWS-Like-Score (PEWS-LS) over time prior to deterioration event in hospitalized pediatric hematology-oncology patients. Trends in PEWS-LS prior to PICU admission were analyzed using a generalized estimating equation (GEE) Poisson model implemented in the GLIMMIX procedure of SAS (empirical option) with time as a restricted cubic spline with 4 knots (−11.5, −7.75, −4.25, and −0.5 h), CD as binary variables, and the two-way interaction of time and CD as predictors. Both time (p < 0.001) and CD (p < 0.001) were significant predictors of PEWS-LS, but the two-way interaction was not significant (p = 0.26). At time of PICU transfer or intervention, the predicted mean PEWS-LS was 2.95 (95% CI 2.63, 3.31) for events without CD, and 3.81 (3.53, 4.11) for events with CD. Thus, the predicted PEWS-LS was 0.86 points higher in events with CD at the start of the event, p = 0.0003.