Virtual PICU Systems Research Articles

969: FACTORS AFFECTING DISCHARGE TIMING AFTER INITIAL TRACHEOSTOMY PLACEMENT IN CHILDREN

Introduction: Variability in timing of initial tracheostomy has been described in pediatric patients. However, variability in timing from tracheostomy to PICU discharge has not been described, nor have factors that affect discharge timing have been identified. There are factors beyond the degree of critical illness which affect discharge from PICU, such as rehabilitation facilities, availability of a technology dependent unit within the hospital, and social resources to care for complex technology dependent patients. Methods: The Virtual PICU Systems database was used to analyze a multicenter sample of 2365 patients who received an initial tracheostomy during the PICU stay. Quantile regression was used to identify factors related to timing of discharge following the tracheostomy. Results: The median PICU length of stay (PLOS) after tracheostomy was 10.8d (7.0 – 21.1), which was longer than that predicted by the PRISM3 score (6 days, p< 0.001). Patients admitted with higher PIM2 and PRISM3 s had longer PLOS (p< 0.001 and 0.021). Compared to neonates, children < 2yrs had a significant shorter LOS (-6.8d, p=0.043) and all age groups >2yrs had a significantly shorter LOS (-10d, all p< 0.008). There were no differences in LOS by race or sex. A healthier baseline Pediatric Overall Performance Category (POPC) and a larger POPC change at baseline to discharge were inversely associated with PLOS (p=0.015 and 0.017, respectively). Patients hospitalized for cardiac indications had longer LOS, while those with primary immune or heme/onc diagnoses had shorter PLOS (all p< 0.01). Having a foreign payer was associated with a shorter PLOS (-4d, p=0.001). Conclusions: In patients who received initial tracheostomy, there was variability in the timing from tracheostomy to PICU discharge. These patients had a longer PLOS than predicted by their degree of critical illness. This presents a potential for more efficient, cost-effective care for patients who are medically appropriate for PICU discharge but require complex care coordination. At a conservative estimate of $2500 difference from PICU to a step-down charge per day, would represent nearly a $25 million in potential cost savings in this patient group if actual LOS was the same as PRISM3 predicted LOS.

Variation in Arterial and Central Venous Catheter Use in Pediatric Intensive Care Units

Describe patient and hospital characteristics associated with Arterial Catheter (AC) or Central Venous Catheter (CVC) use among pediatric intensive care units (ICUs). Hierarchical mixed effects analyses were used to identify patient and hospital characteristics associated with AC or CVC placement. The ICU adjusted median odds ratios (ICU-AMOR) for the admission ICU, marginal R2, and conditional intraclass correlation coefficient were reported. 166 PICUs in the Virtual PICU Systems (VPS, LLC) Database. 682,791 patients with unscheduled admissions to the PICU. None. ACs were placed in (median, [interquartile range]) 8.2% [4.9%-11.3%] of admissions, and CVCs were placed in 14.9% [10.4%-19.3%] of admissions across cohort ICUs. Measured patient characteristics explained about 25% of the variability in AC and CVC placement. Higher Pediatric Index of Mortality 2 (PIM2) illness severity scores were associated with increased odds of placement (Odds Ratio (95th% Confidence Interval)) AC: 1.88 (1.87-1.89) and CVC: 1.82 (1.81-1.83) per 1 unit increase in PIM2 score. Primary diagnoses of cardiovascular, gastrointestinal, hematology/oncology, infectious, renal/genitourinary, rheumatology, and transplant were associated with increased odds of AC or CVC placement compared to a primary respiratory diagnosis. Presence of in-house attendings 24/7 was associated with increased odds of AC placement 1.32 (1.11-1.57). Admission ICU explained 4.9% and 3.5% of the variability in AC or CVC placement, respectively. The ICU-AMOR showed a patient would have a median increase in odds of 55% and 43% for AC or CVC placement, respectively, if the same patient moved from an ICU with lower odds of placement to an ICU with higher odds of placement. Variation in AC or CVC use exists among PICUs. The admission ICU was more strongly associated with AC than with CVC placement. Further study is needed to understand unexplained variation in AC and CVC use.

Rates of Venous Thromboembolism and Central Line-Associated Bloodstream Infections Among Types of Central Venous Access Devices in Critically Ill Children.

Central venous access devices, including peripherally inserted central catheters and central venous catheters, are often needed in critically ill patients, but also are associated with complications, including central-line associated bloodstream infections and venous thromboembolism. We compared different central venous access device types and these complications in the PICU. Multicenter, cohort study. One hundred forty-eight participating Virtual PICU Systems, LLC, hospital PICU sites. Pediatric patients with central venous access placed from January 1, 2010, to December 31, 2015. None. Patient and central venous access device variables postulated to be associated with central-line associated bloodstream infection and venous thromboembolism were included. Data were analyzed using Pearson chi-square test or Fisher exact test for categorical variables, Mann-Whitney U test for continuous variables, and logistic regression and classification trees for multivariable analysis that examined significant predictors of venous thromboembolism or central-line associated bloodstream infection. Analysis included 74,196 first lines including 4,493 peripherally inserted central catheters and 66,194 central venous catheters. An increased rate of venous thromboembolism (peripherally inserted central catheter: 0.93%, central venous catheter: 0.52%; p = 0.001) (peripherally inserted central catheter: 8.65/1,000 line days, central venous catheter: 6.29/1,000 line days) and central-line associated bloodstream infection (peripherally inserted central catheter: 0.73%, central venous catheter: 0.24%; p = 0.001) (peripherally inserted central catheter: 10.82/1,000 line days, central venous catheter: 4.97/1,000 line days) occurred in peripherally inserted central catheters. In multivariable analysis, central venous catheters had decreased association with central-line associated bloodstream infection (odds ratio, 0.505; 95% CI, 0.336-0.759; p = 0.001) and venous thromboembolism (odds ratio, 0.569; 95% CI, 0.330-0.982; p = 0.043) compared with peripherally inserted central catheters. Peripherally inserted central catheters are associated with higher rates of central-line associated bloodstream infection and venous thromboembolism than central venous catheters in children admitted to the PICU.

68) Neurologic Morbidity in Previously Healthy PICU Patients with Bronchiolitis

Purpose: Despite its high prevalence, neurologic outcomes of PICU patients with bronchiolitis are poorly described. We aimed to estimate acute and chronic neurological dysfunction in previously healthy critical bronchiolitis patients using two large, multicenter databases. Methods: With IRB approval, we separately interrogated the Virtual PICU Systems (VPS, LLC, Los Angeles CA) and the Pediatric Health Information System (PHIS, Children’s Hospital Association, Lenexa KS) databases for subjects < 2 years old admitted to a participating center (VPS: n=152; PHIS: n=48) between 2009-2015 with a primary diagnosis code of bronchiolitis. Pre-existing …

Association of Freestanding Children's Hospitals With Outcomes in Children With Critical Illness.

Little is known about the relationship between freestanding children's hospitals and outcomes in children with critical illness. The purpose of this study was to evaluate the association of freestanding children's hospitals with outcomes in children with critical illness. Propensity score matching was performed to adjust for potential confounding variables between patients cared for in freestanding or nonfreestanding children's hospitals. We tested the sensitivity of our findings by repeating the primary analyses using inverse probability of treatment weighting method and regression adjustment using the propensity score. Retrospective study from an existing national database, Virtual PICU Systems (LLC) database. Patients less than 18 years old admitted to one of the participating PICUs in the Virtual PICU Systems, LLC database were included (2009-2014). None. A total of 538,967 patients from 140 centers were included. Of these, 323,319 patients were treated in 60 freestanding hospitals. In contrast, 215,648 patients were cared for in 80 nonfreestanding hospitals. By propensity matching, 134,656 patients were matched 1:1 in the two groups (67,328 in each group). Prior to matching, patients in the freestanding hospitals were younger, had greater comorbidities, had higher severity of illness scores, had higher incidence of cardiac arrest, had higher resource utilization, and had higher proportion of patients undergoing complex procedures such as cardiac surgery. Before matching, the outcomes including mortality were worse among the patients cared for in the freestanding hospitals (freestanding vs nonfreestanding, 2.5% vs 2.3%; p < 0.001). After matching, the majority of the study outcomes were better in freestanding hospitals (freestanding vs nonfreestanding, mortality: 2.1% vs 2.8%, p < 0.001; standardized mortality ratio: 0.77 [0.73-0.82] vs 0.99 [0.87-0.96], p < 0.001; reintubation: 3.4% vs 3.8%, p < 0.001; good neurologic outcome: 97.7% vs 97.1%, p = 0.001). In this large observational study, we demonstrated that ICU care provided in freestanding children's hospitals is associated with improved risk-adjusted survival chances compared to nonfreestanding children's hospitals. However, the clinical significance of this change in mortality should be interpreted with caution. It is also possible that the hospital structure may be a surrogate of other factors that may bias the results.

Pediatric Triage in a Severe Pandemic: Maximizing Survival by Establishing Triage Thresholds.

To develop and validate an algorithm to guide selection of patients for pediatric critical care admission during a severe pandemic when Crisis Standards of Care are implemented. Retrospective observational study using secondary data. Children admitted to VPS-participating PICUs between 2009-2012. A total of 111,174 randomly selected nonelective cases from the Virtual PICU Systems database were used to estimate each patient's probability of death and duration of ventilation employing previously derived predictive equations. Using real and projected statistics for the State of Ohio as an example, triage thresholds were established for casualty volumes ranging from 5,000 to 10,000 for a modeled pandemic with peak duration of 6 weeks and 280 pediatric intensive care beds. The goal was to simultaneously maximize casualty survival and bed occupancy. Discrete Event Simulation was used to determine triage thresholds for probability of death and duration of ventilation as a function of casualty volume and the total number of available beds. Simulation was employed to compare survival between the proposed triage algorithm and a first come first served distribution of scarce resources. Population survival was greater using the triage thresholds compared with a first come first served strategy. In this model, for five, six, seven, eight, and 10 thousand casualties, the triage algorithm increased the number of lives saved by 284, 386, 547, 746, and 1,089, respectively, compared with first come first served (all p < 0.001). Use of triage thresholds based on probability of death and duration of mechanical ventilation determined from actual critically ill children's data demonstrated superior population survival during a simulated overwhelming pandemic.

Unscheduled Pediatric Intensive Care Unit Admissions in Patients With Cardiovascular Disease: Clinical Features and Outcomes.

An unscheduled readmission to the intensive care unit (ICU) is associated with increased morbidity and mortality in children. There is a paucity of data examining the impact of unscheduled admissions on outcomes in children with specific disease processes such as cardiovascular disease. We investigated the impact of scheduled versus unscheduled ICU admission on clinical outcomes and differences in patient characteristics in children with cardiovascular disease. This was a retrospective analysis of contemporaneously collected clinical data using the Virtual PICU Systems database. All consecutive admissions at 102 participating pediatric ICUs in patients with cardiovascular disease were collected from October 2010 to September 2012. There were 48,653 admissions included in the analysis (44% scheduled and 56% unscheduled). The median patient age was 31 months. Unscheduled admissions were associated with longer ICU length of stay and increased mortality (both P < .001). Adjusting for age, weight, and primary ICU admission diagnosis (cardiovascular vs noncardiovascular), patients with unscheduled admissions had an increased odds of mortality (odds ratio = 4.8, P < .001). Unscheduled ICU admissions were associated with worse clinical outcomes including increased mortality. Efforts targeted at reducing unscheduled admissions in at-risk patients are warranted.

Association of 24/7 In-House Intensive Care Unit Attending Physician Coverage With Outcomes in Children Undergoing Heart Operations

Multicenter data regarding the around-the-clock (24/7) presence of an in-house critical care attending physician with outcomes in children undergoing cardiac operations are limited. Patients younger than 18 years of age who underwent operations (with or without cardiopulmonary bypass [CPB]) for congenital heart disease at 1 ofthe participating intensive care units (ICUs) in the Virtual PICU Systems (VPS, LLC) database were included (2009-2014). The study population was divided into 2 groups: the 24/7 group (14,737 patients; 32 hospitals), and the No 24/7 group (10,422 patients; 22 hospitals). Propensity-score matching was performed to match patients 1:1 in the 24/7 group and in the No 24/7 group. Overall, 25,159 patients from 54 hospitals qualified for inclusion. By propensity matching, 9,072 patients (4,536 patient pairs) from 51 hospitals were matched 1:1 in the 2 groups. After matching, mortality at ICU discharge was lower among the patients treated in hospitals with 24/7 coverage (24/7 versus No 24/7, 2.8% versus 4.0%; p= 0.002). The use of extracorporeal membrane oxygenation (ECMO), the incidence of cardiac arrest, extubation within 48 hours after operation, the rate of reintubation, and the duration of arterial line and central venous line use after operation were significantly improved in the 24/7 group. When stratified by surgical complexity, survival benefits of 24/7 coverage persisted among patients undergoing both high-complexity and low-complexity operations. The presence of 24-hour in-ICU attending physician coverage in children undergoing cardiac operations is associated with improved outcomes, including ICU mortality. It is possible that 24-hour in-ICU attending physician coverage may be a surrogate for other factors that may bias the results. Further study is warranted.

Obesity and Mortality Risk in Critically Ill Children.

Childhood obesity is epidemic and may be associated with PICU mortality. Using a large multicenter PICU database, we investigated the association between obesity and PICU mortality, adjusting for initial severity of illness. We further investigated whether height- and weight-based classifications of obesity compared with a weight-based classification alone alter the mortality distribution. This retrospective analysis used prospectively collected data from the Virtual PICU Systems database. Height, weight, age, and gender were used to calculate z score groups based on Centers for Disease Control and Prevention and World Health Organization growth curves. A random effects mixed logistic regression model was used to evaluate the association between obesity and PICU mortality, controlling for hospital, initial severity of illness, and comorbidities. A total of 127,607 patients were included; the mortality rate was 2.48%. Being overweight was independently associated with increased PICU mortality after controlling for severity of illness with the Pediatric Index of Mortality 2 score and preexisting comorbidities. Mortality had a U-shaped distribution when classified according to weight-for-age or weight-for-height/BMI. When classifying patients using weight-for-age without respect to height, the nadir of the mortality curve was shifted, potentially falsely implying a benefit to mild obesity. Risk-adjusted PICU mortality significantly increases as weight-for-height/BMI increases into the overweight and obese ranges. We believe that height data are necessary to correctly classify body habitus; without such information, a protective benefit from mild obesity may be incorrectly concluded.

ICU-Acquired Weakness Is Associated With Differences in Clinical Outcomes in Critically Ill Children.

ICU-acquired weakness, comprised critical illness myopathy and critical illness neuropathy, occurs in a significant proportion of critically ill adults and is associated with high morbidity and mortality. Little is known about ICU-acquired weakness among critically ill children. We investigated the incidence of ICU-acquired weakness among PICUs participating in the Virtual PICU Systems database. We also sought to identify associated risk factors for ICU-acquired weakness and evaluate the hypothesis that ICU-acquired weakness is associated with poor clinical outcomes. Retrospective cohort study. PICU. Virtual PICU System was queried for critical illness myopathy and critical illness neuropathy between January 2009 and November 2013. Demographic, admission, and clinical outcome variables including mechanical ventilation days, PICU length of stay, and discharge disposition were analyzed. The Pediatric Index of Mortality-2 was used to evaluate and control for illness severity and risk of mortality. Among 203,875 admissions, there were 55 cases of critical illness myopathy reported and no cases of critical illness neuropathy, resulting in an incidence of 0.02%. Mechanical ventilation days were higher among patients with ICU-acquired weakness versus those who did not develop ICU-acquired weakness (31.6 ± 28.9 vs 9.3 ± 20.6; p < 0.001). In our multivariable analysis, when controlling for Pediatric Index of Mortality-2, ICU-acquired weakness was more frequently reported in those with admission diagnoses of respiratory illness and infection and the need for mechanical ventilation, renal replacement therapy, extracorporeal life support, and tracheostomy. ICU-acquired weakness was associated with a longer PICU length of stay, episodes requiring mechanical ventilation, and discharge to an intermediate, chronic care, and rehabilitation care unit. ICU-acquired weakness was not independently associated with mortality. ICU-acquired weakness is uncommonly diagnosed among PICU patients reported in Virtual PICU System. ICU-acquired weakness is associated with critical care therapies, invasive procedures, and resource utilization. Limitations of our retrospective study include underrecognition of ICU-acquired weakness and lack of standardized diagnostic criteria within Virtual PICU System. Prospective studies are needed to better understand the true incidence, risk factors, and clinical course for patients who develop ICU-acquired weakness.

Risk factors for mechanical ventilation and reintubation after pediatric heart surgery

ObjectiveTo determine the prevalence of and risk factors associated with the need for mechanical ventilation in children following cardiac surgery and the need for subsequent reintubation after the initial extubation attempt. MethodsPatients younger than 18 years who underwent cardiac operations for congenital heart disease at one of the participating pediatric intensive care units (ICUs) in the Virtual PICU Systems (VPS), LLC, database were included (2009-2014). Multivariable logistic regression models were fitted to identify factors likely associated with mechanical ventilation and reintubation. ResultsA total of 27,398 patients from 62 centers were included. Of these, 6810 patients (25%) were extubated in the operating room (OR), whereas 20,588 patients (75%) arrived intubated in the ICU. Of the patients who were extubated in the OR, 395 patients (6%) required reintubation. In contrast, 2054 patients (10%) required reintubation among the patients arriving intubated postoperatively in the ICU. In adjusted models, patient characteristics, patients undergoing high-complexity operations, and patients undergoing operations in lower-volume centers were associated with higher likelihood for the need for postoperative mechanical ventilation and need for reintubation. Furthermore, the prevalence of mechanical ventilation and reintubation was lower among the centers with a dedicated cardiac ICU in propensity-matched analysis among centers with and without a dedicated cardiac ICU. ConclusionsThis multicenter study suggests that proportion of patients extubated in the OR after heart operation is low. These data further suggest that extubation in the OR can be done successfully with a low complication rate.

New Insights Into Multicenter PICU Mortality Among Pediatric Hematopoietic Stem Cell Transplant Patients.

Over 2,500 children undergo hematopoietic stem cell transplantation in the United States each year, and up to 35% require PICU support for life-threatening complications. PICU mortality has dropped from 85% to 44%, but interpretation is confounded by significant cohort heterogeneity. Reports conflict regarding outcomes for patients with different underlying hematopoietic stem cell transplantation indications, and the burden of infectious complications for these patients has not been evaluated. We aim to describe infections, critical care interventions, and mortality for pediatric hematopoietic stem cell transplantation patients requiring PICU admission. A retrospective multicenter cohort analysis. One hundred twelve centers in the Virtual PICU Systems database, January 1, 2009, to June 30, 2012. A total of 1,782 admissions for patients who are 21 years old or younger with prior hematopoietic stem cell transplantation. None. Pediatric Index of Mortality-2, Pediatric Risk of Mortality-3, transplant indication, infections, interventions, and mortality were recorded from admission through PICU death or discharge. Pediatric hematopoietic stem cell transplantation patients comprised 0.7% of all PICU admissions (1,782/246,346), which resulted in 16.2% mortality compared with 2.4% mortality for non-hematopoietic stem cell transplantation admissions (odds ratio, 7.8; 95% CI, 6.8-8.8; p < 0.001). Mortality for admissions with underlying hematologic malignancy (22.7%) was similar to that of admissions with primary immunodeficiency (19.4%; p = 0.41) but significantly greater than admissions with underlying nonmalignant non-primary immunodeficiency hematologic disease (15.4%; p = 0.020), metabolic disorder (8.1%; p < 0.001), or solid malignancy (5.7%; p < 0.001). Infection was documented in 45.7% of admissions with 22.2% mortality; viral and fungal mortality were 28.5% and 33.7%, respectively. Invasive positive pressure ventilation and renal replacement therapy were used in only 34.6% and 11.9% of admissions, with mortality of 42.5% and 51.9%, respectively. PICU mortality for pediatric hematopoietic stem cell transplantation patients may be as low as 16.2% but higher for those receiving intubation (42.5%) or replacement therapy (51.9%). Hematologic malignancy and primary immunodeficiency had greater risk for mortality than other transplant indications. Greater understanding of other risk factors affecting mortality and the need for critical care support is needed.

Off-hours admission to pediatric intensive care and mortality.

Critically ill patients are admitted to the pediatric ICU at all times, while staffing and other factors may vary by day of the week or time of day. The purpose of this study was to evaluate whether admission during off-hours is independently associated with mortality in PICUs. A retrospective cohort study of admissions of patients <18 years of age to PICUs was performed using the Virtual PICU Systems (VPS, LLC) database. "Off-hours" was defined as nighttime (7:00 pm to 6:59 am) or weekend (Saturday or Sunday any time). Mixed-effects multivariable regression was performed by using Pediatric Index of Mortality 2 (PIM2) to adjust for severity of illness. Primary outcome was death in the pediatric ICU. Data from 234,192 admissions to 99 PICUs from January 2009 to September 2012 were included. When compared with regular weekday admissions, off-hours admissions were less likely to be elective, had a higher risk for mortality by PIM2, and had a higher observed ICU mortality (off-hours 2.7% vs weekdays 2.2%; P < .001). Multivariable regression revealed that, after adjustment for other significant factors, off-hours admission was associated with lower odds of mortality (odds ratio, 0.91; 95% confidence interval, 0.85-0.97; P = .004). Post hoc multivariable analysis revealed that admission during the morning period 6:00 am to 10:59 am was independently associated with death (odds ratio, 1.27; 95% confidence interval, 1.16-1.39; P < .0001). Off-hours admission does not independently increase odds of death in the PICU. Admission from 6:00 am to 10:59 am is associated with increased risk for death and warrants further investigation in the PICU population.

Epidemiology and outcomes of in-hospital cardiac arrest in critically ill children across hospitals of varied center volume: A multi-center analysis

ObjectiveTo describe epidemiology and outcomes associated with cardiac arrest among critically ill children across hospitals of varying center volumes. MethodsPatients <18 years of age in the Virtual PICU Systems (VPS, LLC) Database (2009–2013) were included. Patients with both cardiac and non-cardiac diagnoses were included. Data on demographics, patient diagnosis, cardiac arrest, severity of illness and outcomes were collected. Hierarchical cluster analysis was performed to categorize all the participating centers into low, low-medium, high-medium, and high volume groups using the center volume characteristics (annual hospital discharges per center, annual extracorporeal membrane oxygenation per center, and annual mechanical ventilators per center). Multivariable models were used to evaluate association of center volume with incidence of cardiac arrest, and mortality after cardiac arrest, adjusting for patient and center characteristics. ResultsOf 329,982 patients (108 centers), 2.2% (n=7390) patients had cardiac arrest with an associated mortality of 35% (n=2586). In multivariable models controlling for patient and center characteristics, center volume was not associated with either the incidence of cardiac arrest (OR: 1.00; 95% CI: 0.95–1.06; p=0.98), or mortality in those with cardiac arrest (OR: 0.93; 95% CI: 0.82–1.06; p=0.27). These associations were similar across cardiac and non-cardiac disease categories. Furthermore, we demonstrated that there was no correlation between incidence of cardiac arrest and mortality in those with cardiac arrest across different study hospitals in adjusted models. ConclusionsBoth incidence of cardiac arrest, and mortality in those with cardiac arrest vary substantially across hospitals. However, center volume is not associated with either of these outcomes, after adjusting for patient and center characteristics.

Relationship Between Risk-Adjustment Tools and the Pediatric Logistic Organ Dysfunction Score

The Risk-Adjusted Classification for Congenital Heart Surgery (RACHS-1) method and Aristotle Basic Complexity (ABC) scores correlate with mortality. However, low mortality rates in congenital heart disease (CHD) make use of mortality as the primary outcome measure insufficient. Demonstrating correlation between risk-adjustment tools and the Pediatric Logistic Organ Dysfunction (PELOD) score might allow for risk-adjusted comparison of an outcome measure other than mortality. Data were obtained from the Virtual PICU Systems database. Patients with postoperative CHD between 2009 and 2010 were included. Correlation between RACHS-1 category and PELOD score and between ABC level and PELOD score was examined using Spearman rank correlation. Consistency of PELOD scores across institutions for given levels of case complexity was examined using Kruskal-Wallis nonparametric analysis of variance. A total of 1,981 patient visits among 12 institutions met inclusion criteria. Positive correlations between PELOD score and RACHS-1 category (r s = .353, P < .0001) as well as between PELOD score and ABC level (r s = .328, P < .0001) were demonstrated. Variability in PELOD scores across individual centers for given levels of case complexity was observed (P < .04). Risk-Adjusted Classification for Congenital Heart Surgery categories and ABC levels correlate with postoperative organ dysfunction as measured by PELOD. However, the correlation was weak, potentially due to limitations of the PELOD score itself. Identification of a more accurate metric of morbidity for the congenital heart disease population is needed.

555

Introduction: While critically ill patients may be admitted to the pediatric intensive care unit (ICU) at any time, staffing and other factors may vary by day of the week or time of day. The purpose of this study was to evaluate whether off-hours admissions (nights and weekends) were independently associated with increased mortality in a large database sample of pediatric ICUs. Methods: A retrospective cohort study of admissions of children <18 years of age to pediatric ICUs was performed using the Virtual PICU Systems (VPS,LLC) database. Off-hours was defined as nighttime (7:00pm-06:59am) and weekend (Saturday or Sunday any time). Regression analysis was performed using a mixed-effects multivariate model with clustering at the hospital level, using Pediatric Index of Mortality 2 to adjust for severity of illness. The primary outcome was death in the pediatric ICU. Results: Data from 246,184 admissions to 100 pediatric ICUs from January 1st, 2009 to September 29th, 2012 were included in the analysis. Patients admitted during off-hours were more likely to be unscheduled admissions, had a higher predicted risk of mortality, and had a higher unadjusted ICU mortality (off-hours 2.8% mortality vs. weekdays 2.2%, p<0.001). Multivariate regression revealed that, after adjusting for severity of illness and other significant factors, off-hours admission was associated with reduced odds of mortality (OR 0.91, 95%CI 0.85-0.97, p=0.004), as was nighttime admission (OR 0.87, 95%CI 0.82-0.93, p<0.0001), while weekend admission had no association with mortality (OR 1.0, 95%CI 0.93-1.07, p=0.9). Peak mortality was observed during the morning hours from 06:00-10:59am, and post-hoc multivariate analysis revealed that admission during this period was independently associated with death (OR 1.22, 95%CI 1.10-1.33, p<0.0001). Conclusions: Off-hours admission does not independently increase odds of death in a large sample of pediatric ICUs. Admission during the morning period from 06:00-10:59am, which often includes morning rounds, is associated with increased risk of death in our cohort and may warrant further investigation in the pediatric ICU population.

602

Introduction: ICU resources may be overwhelmed by a mass casualty (MC) event. MC triage schemes to allocate scarce resources have been proposed for adults, diverting ICU care from patients with high predicted mortality. Similar schemes have not been developed for children. Methods: 150,000 patients from the Virtual PICU Systems LLC database were used. 100,000 randomly selected children admitted 2009-12 were utilized to train prediction models for mortality, duration of mechanical ventilation (DMV), and PICU length of stay (LOS). The models included only variables available on PICU admission for the prediction equations (PEs). Variables that demonstrated univariate association with the outcomes of interest were added stepwise to generate multivariate regressions. The PEs were validated and calibrated on the 50,000 additional patients via receiver operating characteristic (ROC) and Hosmer-Lemeshow (H-L) tests for dichotomous outcomes, and by determining adjusted R2 for continuous outcomes. Results: Because PICU mortality during non-MC periods < 5%, a triage scheme based only on risk of mortality would minimally impact resources. Therefore, PICU exclusion was based on either Low Risk (LR, defined as mortality < .05% + PICU LOS < 3 days + no intubation) and therefore no need for ICU; or because of High Risk (HR, unlikely to benefit from, or disproportionate use of, ICU care), defined as high mortality, or prolonged DMV or LOS. The remainder comprised the Optimal Treatment (OT) group who would receive critical care. The equation predicting LR had area under the ROC (AROC) .70; H-L < .01. The equations predicting HR possessed the following characteristics: mortality: AROC > .85, H-L > .05; DMV: R2 > .10, LOS: R2 > .11 The scheme was designed so that the thresholds for assigning children to the LR, HR, and OT groups could be adjusted to change the size of the OT group and hence match evolving resource availability. For example, if probability of belonging to the LR group was adjusted to > .60, and HR was defined by predicted mortality > .70 and DMV/LOS > 90th percentile, the proportion assigned to OT and thus admitted to PICU = 30%. If probability of belonging to LR was > .50; and HR was defined by predicted mortality > .50 and DMV/LOS > 80th percentile, the proportion assigned to OT and admitted to PICU = 23%. Conclusions: We have demonstrated a pediatric triage model based on multistep triage decisions that is adaptable over a wide spectrum of MC scenarios.

Unscheduled Readmissions to the PICU

To determine the rate of, and potential risk factors for, unscheduled PICU readmission and assess for variability among PICUs within the United States. This retrospective cohort study used 2005-2008 data from 73 PICUs in the Virtual PICU Systems database. Early (within 48 hr of PICU discharge) and late (later than 48 hr) unscheduled readmission rates were calculated. Hierarchical logistic regression, with a random intercept for site, was used to identify factors independently associated with early readmission. Significant random effects identified sites with an outlying risk of readmission, adjusting for patient and admission characteristics. For 117,923 children meeting inclusion criteria, the unscheduled readmission rate was 3.7% with 38% (1.4%) occurring early. Half of early readmissions had the same primary diagnosis as the first admission. Patients with late readmissions had a higher mortality (6.6% vs 3.3%, p < 0.001) and longer median total PICU length of stay (11 d vs 6 d, p < 0.0001) than those with early readmission. Patient characteristics strongly associated with increased risk of early readmission included the following: age < 6 months, acute respiratory and renal disease, and several underlying chronic conditions such as liver disease, bone marrow transplant, airway stenosis, and abnormal antidiuretic hormone balances. An initial PICU admission that was unscheduled, originated from the general floor, or with a discharge time between 4 PM and 8 AM was associated with higher risk of readmission. A quarter of sites were identified as potential high (16%) or low (8%) outliers. The rate of unscheduled PICU readmission was low but associated with worse outcomes. Patient and admission/discharge characteristics associated with increased risk of readmissions could be used to target high-risk populations or modifiable factors to improve outcome. Variation of risk among centers suggests room for improvement.

Impact of Gender on Sepsis Mortality and Severity of Illness for Prepubertal and Postpubertal Children

To investigate differences in sepsis mortality between prepubertal and postpubertal males and females. This was a retrospective review of the Virtual PICU Systems (VPS) database (including 74 pediatric intensive care units [PICUs]) for 2006-2008. We included prepubertal (aged 2-7 years) and postpubertal (aged 16-21 years) children with a primary diagnosis of sepsis admitted to a participating PICU. Prepubertal females (n = 272; 9.9% mortality) and prepubertal males (n = 303; 10.9% mortality) had similar mortality and severity of illness (Pediatric Index of Mortality 2 risk of mortality [PIM 2 ROM]). Postpubertal females (n = 233; mortality, 5.6%) had lower mortality than postpubertal males (n = 212; mortality, 11.8%; P = .03). PIM 2 ROM was higher for postpubertal males than postpubertal females (P = .02). After controlling for hospital specific effects with multivariate modeling, in postpubertal children, female gender was independently associated with a lower initial severity of illness (PIM 2 ROM: OR, 0.77; 95% CI, 0.62-0.96; P = .02). Sepsis mortality is similar in prepubertal males and females. However, postpubertal males have a higher sepsis mortality than postpubertal females, likely related to their greater severity of illness on PICU admission. These outcome differences in postpubertal children may reflect a hormonal influence on the response to infection or differences in underlying comorbidities, source of infection, or behavior.

Respiratory Failure in Children with Status Asthmaticus: A Review of the VPS Database

Status asthmaticus is a frequent cause of admission to a pediatric intensive care unit (ICU). Children requiring intubation and mechanical ventilation for respiratory failure during these exacerbations comprise the most severely ill population of this cohort. The purpose of this study was to use a large multicenter database to determine the incidence of respiratory failure in children with acute asthma and to characterize clinical predictors associated with its occurrence. We conducted a retrospective data analysis of pediatric asthmatic patients included in the Virtual PICU Systems (VPS) database between January 2007 and December 2008. Patients requiring mechanical ventilation with cuffed or uncuffed nasotracheal or orotracheal tubes were characterized as having respiratory failure. Three thousand three hundred eighteen children were admitted with status asthmaticus during this study period, of which 201 (6.1%) had respiratory failure. There were no differences in age, male gender, or BMI between those w...