ABSTRACT
Introduction: Studies show that pediatric trauma centers produce better outcomes and reduced mortality for injured children. Yet, most children do not have timely access to a pediatric trauma center and require stabilization locally with subsequent transfer. Investigators have demonstrated that pediatric transport teams (PTT) improve outcomes for critically ill children; however, these studies did not differentiate outcomes for injured children. It may be that moderate to severely injured children actually fare worse with PTT due to slower transport times inherent to their remote locations and thus delays in important interventions. Objective: The purpose of this study was to determine if outcomes for injured children are affected by use of PTT for inter-hospital transfer. Methods: We conducted a retrospective chart review of 1,177 children transferred to a pediatric trauma center for injury care between March 1st, 2012 and December 31st, 2013. We compared children who were transported by PTT (ground/air) to those transported by ground advanced life support (ALS) and air critical care (ACC). We described patient characteristics and transport times. For PTT vs. ALS and ACC, we compared hospital length of stay (LOS), transport interventions and adverse events. Results: 1,177 injured children were transferred by the following modes: 68% ALS, 13% ACC, 11% Ground PTT, and 9% Air PTT. Children transported by PTT were younger and had higher ISS and lower GCS scores. PTT had a longer total transport time, departure preparation time, and patient bedside time. After controlling for age, ISS, GCS, transport mode, distance, and time, we found no significant difference in LOS between PTT vs. ALS and ACC. A subgroup analysis of children with higher ISS scores demonstrated a 65% longer LOS for children transported by ACC vs. PTT. There were no differences between transport teams with regard to acidosis, hypocarbia or hypercarbia, or maintenance of tubes and lines. Conclusions: Children transported by PTT were younger and sicker (vs. ACC and ALS). Despite longer transport times, children transported by PTT did not have a longer hospital LOS or adverse events during transport. However, for those children with higher ISS, transport by ACC resulted in longer hospital LOS vs. PTT.
Key words:
Introduction
Traumatic injuries are the leading cause of morbidity and mortality for post-infancy children in the United States.Citation1 Pediatric trauma centers have been shown to produce better outcomes and reduced mortality for injured children.Citation2–4 However, most children do not have timely access to a pediatric trauma center. An estimated 17.4 million children live more than 60 minutes away from the nearest pediatric trauma center, and only 53.1% live within a 50-mile radius.Citation5,6 Often children injured in these outlying communities require stabilization at local hospitals before subsequent transport to pediatric tertiary trauma centers for definitive care.Citation7 Consequently, the “golden hour,” a time period thought to be critical for patient outcome following trauma, may occur outside of the hospital during prehospital care and inter-hospital transport and assessing this time period may help to optimize care for children.Citation8,9
Children are transferred between hospitals by various means. The most common include ground Advanced Life Support (ALS) ambulance, air critical care (ACC), and ground or air pediatric specialized transport team (PTT). Since each of these options offers a specific skill specialization and time en route, it is critical to identify which means of inter-hospital transport provides the best care for injured children. PTT have been identified as being associated with better outcomes for critically ill children. Adverse events such as failed intubation are valid issues, especially in younger and sicker children.Citation10,11 PTT were demonstrated to reduce transport morbidity during high-risk inter-hospital transfers by having fewer adverse clinical events, such as loss of vascular access or misplaced endotracheal tubes.Citation12–17
PTT may be remote to referring hospitals and thus result in a longer period of time before the injured child reaches the pediatric trauma center for definitive care. A direct relationship between EMS scene response time and patient mortality has been demonstrated, however, length of time in inter-hospital transport and resultant patient outcome has not yet been investigated.Citation18 Moderate to severely injured children may have worse outcomes due to increased transport time required to dispatch a remotely located PTT. This would delay important interventions at the pediatric trauma center. It could also be that there are no significant differences in patient outcomes between pediatric versus general transport teams, suggesting that there is no clear benefit to using one over the other.Citation19
In this study we compared patient outcomes between injured children transported by general transport teams (ALS, ACC) and those transported by pediatric transport teams (ground or air PTT). We evaluated hospital length of stay (LOS) and various secondary outcomes, consisting of adverse clinical events and medical interventions, among different transport teams and transportation modes. We also analyzed demographics, injury severity, and transportation times to determine whether differences existed among pediatric specialized and adult generalized transport teams. Our null hypothesis was that there would be no differences in outcomes for injured children undergoing inter-hospital transfer relative to team type after controlling for important covariates.
Methods
Study Design
We conducted a retrospective cohort study using medical chart review of children presenting to free-standing, American College of Surgeons – verified, level 1 pediatric trauma center for injury care between March 2012 and December 2013.
Population and Setting
We identified subjects through a query of the hospital's trauma registry. Patients were eligible for inclusion in the study if they were <18 years of age, were transferred from an outside hospital to hospital's Emergency Department (ED), and met criteria for inclusion in the hospital's trauma registry (trauma team activation or admission for > 24 hours of injury care) during March 1, 2012 through December 31, 2013. We excluded patients who presented to the ED before March 1, 2012 due to lack of electronic records for inter-hospital Emergency Medical Services (EMS) run sheets. Additional exclusion criteria related to patients who were transported to the ED directly from the scene of injury, were admitted to an outside hospital before being transferred to the ED, were not transported to the ED by an EMS transport team (i.e., private vehicle, ambulation), or were directly admitted to the hospital. Prior to data analyses, we excluded cases with incorrect transportation times and unknown transport types.
Human Subjects Protection
The Washington University in St. Louis Institutional Review Board reviewed and approved the study. The study was deemed minimal risk and was conducted under waiver of written informed consent.
Data Collection and Processing
Study data were collected and managed using Research Electronic Data Capture (REDCap) electronic data capture tools hosted at Washington University in St. Louis.Citation20 REDCap is a secure, web-based application designed to support data capture for research studies, providing 1) an intuitive interface for validated data entry; 2) audit trails for tracking data manipulation and export procedures; 3) automated export procedures for seamless data downloads to common statistical packages; and 4) procedures for importing data from external sources. All study personnel attended a training meeting to review study procedures, to learn how to use the REDCap software, and to practice data abstraction using sample medical records. After training, we conducted structured data abstraction, verified by the study principal investigator (a pediatric emergency physician) by review of the medical record. We monitored data abstraction periodically throughout the study.
We adhered to an explicit abstraction protocol, which outlined the source hierarchy for chart abstraction within each medical record. We first abstracted data from the inter-hospital EMS run sheet, Consolidated Omnibus Budget Reconciliation Act of 1986/ Emergency Medical Treatment and Active Labor Act Transfer Form, and the trauma flow sheet. If these forms were missing or incomplete, we abstracted data from the referring ED record and the physician and nursing notes.
The primary comparison groups for this study were based on care team type and mode of transportation: ground or air pediatric transport team (PTT), ground advanced life support (ALS), and air critical care (ACC). The categorical variables used to describe each transfer care/mode included: age, gender, race, Injury Severity Score (ISS), payor, injury type, Glasgow Coma Score (GCS), and ED disposition. The continuous variables, consisting of transport times calculated for each comparison group included: time (min) preparing for transport (time transport en route to referring hospital – time transport notified), time (min) en route to patient (time transport arrived at patient at referring hospital – time transport en route to referring hospital) time (min) spent at referring hospital (time patient departed referring hospital – time transport arrived at patient at referring hospital), time (min) spent en route to the ED from referring hospital (time transport arrived the ED – time transport departed referring hospital), time (min) to the first surgical intervention (intraoperative hemorrhage control, traumatic wound repair, decompressive neurological procedure, or limb salvaging surgery) (surgical start time – time transport team notified), total transport time (min) (time transport arrived ED – time transport notified), distance between hospitals (mile), and transport team time per mile that the patient traveled in minutes per mile (total transport time/distance between hospitals).
Key Outcome Measures
The primary outcome for this study was hospital LOS compared between care team type (PTT, ALS, and ACC). During the study period, there were four PTTs, more than ten ACC services, and more than forty ALS services within the St. Louis Children's Hospital (SLCH) catchment area. The SLCH PTT was the exclusive PTT for this study and at the time included 75 registered nurses (RNs) and critical care paramedics. SLCH team members held current certifications in: Basic Life Support, Pediatric Advanced Life Support, Neonatal Resuscitation Program, Advanced Cardiac Life Support, Trauma Nursing Core Course (RNs), Advanced Trauma Life Support or Prehospital Trauma Life Support and Neonatal Pediatric Transport. Team members are required to pass an advanced certification exam for the transport and care of pediatric and neonatal patients after three years of employment. Team members were also required to participate in a structured continuing education program which includes simulation training sessions for four hours each month, and two days per year in the SLCH operating rooms focusing purely on airway management. Team member proficiency was demonstrated quarterly for direct laryngoscopy and bi-annually for GlideScope. SLCH PTT trauma transports were staffed with a RN and either another RN or critical care paramedic.
We analyzed hospital LOS for all children in our cohort, followed by a sub-group analysis of the children with moderate and severe injuries. These children had ISS of 9-75, with 9-15 indicating a moderate injury and 16-75 indicating a severe injury. We analyzed several secondary outcomes including transport team interventions (administration of blood products, pressors, pain medications, and antiemetics) and adverse conditions on ED arrival (acidosis, hypocarbia or hypercarbia, hypoxia, nonfunctioning vascular access, dislodged endotracheal tubes, and hypothermia).
Data Analyses
Data for our study were analyzed using SAS® software (Copyright © 2011, SAS Institute Inc., Cary, NC, USA). The final cohort was described with categorical variables for ground PTT, air PTT, ALS and ACC. We calculated frequency and percentages for categorical variables and made pairwise comparisons between these groups by performing chi-square tests. Pairwise comparisons were made by performing Tukey's honest significance difference test. A p-value of less than 0.05 was considered significant. For continuous variables, medians, and inter-quartile ranges were calculated.
To analyze our primary outcome, we fit a multiple linear regression model of LOS between transport team types for all children in our cohort, followed by a subgroup analysis of children with an ISS of 9-75. Only patients who were admitted to the hospital and survived to discharge were included. We analyzed each of our secondary outcomes using multivariable logistic regression modeling in order to adjust for potential confounders. We calculated adjusted odds ratio, confidence intervals, and p-values for each secondary outcome variable.
Sample Size Determination
It was estimated that 100 children per transport team type would be needed to have 90% power to detect a 10% difference with alpha equal to 5%. Given the distribution of children between team types, it was estimated that at least 1000 injured children undergoing inter-hospital transfer would be required.
Figure 1. Subject identification. SLCH: St. Louis Children's Hospital; ED: Emergency Department; EMS: Emergency Medical Services.
Results
There were 1,177 children who fit the inclusion criteria for this study (Figure ). The characteristics of the total cohort of children are described in Table based on transport team type. ALS transported the majority of injured children (68%) followed by ACC (13%), ground PTT (11%), and air PTT (9%). The majority of children, regardless of mode of transport and care team type, were injured by blunt force trauma (87% of the total cohort). Children transported by ACC and ground/air PTT had higher ISS and lower GCS. Though the majority of children were admitted to the hospital, ALS had the highest percentage (35%) of children discharged home from the ED while air PTT had the highest percentage of children admitted to the intensive care unit (36%). Ground and air PTT also transported the highest percentage of younger children between the ages of 0–4 (51% and 38%, respectively). Fourteen children in our cohort did not survive to hospital discharge, four of whom expired in the ED and are noted in Table .
Table 1. Description of categorical variables by transport team type/mode.
Table compares the time spent in the various phases of trauma transport for our total cohort of 1,177 children by transport team type. For phases of transport that were independent of the distance traveled and mode of transport, PTT took longer. PTT spent more time preparing for departure and at the referring hospital when compared to ACC and ALS respectively (median time in minutes (interquartile range)): ALS 4 (1–13) versus ground PTT 25 (19–37) and ACC 11 (6–15) versus air PTT 30 (22–40); time at referring hospital: ALS 11 (8–15) versus ground PTT 26 (17–33) and ACC 19 (15–22) versus air PTT 35 (27–45). There were insufficient children with surgical interventions to analyze differences in the time to first surgical intervention. When accounting for distance traveled, the overall transport was longer for PTT whether by ground (median transport team time per mile that the patient traveled in minutes per mile (interquartile range)): 3 (2–5) versus ALS 3 (2–4) or air 2 (1–4) versus ACC 1 (0–1). For the subgroup of the 316 children with ISS 9-75, the differences in transport times between PTT versus ALS and ACC were even greater. Transport team time per mile that the patient traveled (median in minutes per mile (interquartile range)) for ground PTT was 3 (2–5) versus ALS 2 (1–4) or air PTT 2 (1–5) versus 1 (0–1).
Table 2. Description of continuous variables by transport team type/mode.
Table presents the analysis of our primary outcome, hospital LOS, across our total cohort and for the subgroup of severely injured children. Fourteen children did not survive to hospital discharge and were excluded from the analysis (1 transported by ground PTT, 7 transported by air PTT, 0 transported by ALS, and 6 transported by ACC). Hospital LOS was skewed, thus we performed a logarithmic transformation of LOS and compared the ratio of LOS with the reference group for our categorical variables and one unit higher for our continuous variables. ISS, GCS, distance transported, total transport time, injury mechanism (blunt, penetrating, burn, other), and payor status were included as independent covariables in the regression analysis. This analysis demonstrated that hospital LOS was not related to transport care team type for the total cohort. However, we found that among the subgroup of moderate to severely injured children, hospital LOS did differ between transport team types. Children transported by ACC had a 65% longer LOS versus PTT.
Table 3. Differences in hospital length of stay among transport team type, mode, age, and injury.
Table 4. Differences in secondary clinical outcomes among transport team type.
Table presents the analysis of our secondary outcomes for our total cohort. For the total cohort, there were an insufficient number of children with several outcomes of interest (administration of blood and pressors en route, hypoxia, and hypothermia on arrival, and dislodged endotracheal tubes en route or on arrival) precluding statistical comparison. After adjusting for important covariates (age, ISS, GCS, transport mode, distance between hospitals and total transport time) children transported by ACC and PTT were more likely to receive pain medications (vs. ALS) and anti-emetics (vs. ALS). There were no differences by transport team type for intact vascular access, acidosis, or hypocarbia or hypercarbia on arrival. In addition, there were no statistically significant differences found among transport team types for the subgroup of moderate to severely injured children.
Discussion
In this retrospective cohort study, we evaluated the inter-hospital transport of injured children to a pediatric trauma center with the goal of determining whether there were differences in outcome between children transported by a pediatric specialized team compared to general teams. Our study found that children transported by PTT were younger, with the majority of children transported being 0–4 years of age, and sicker (higher ISS and lower GCS). Transport by pediatric teams also took longer after accounting for mode and distance transported. No difference in LOS was demonstrated across the entire cohort, but a subanalysis of the children with moderate to severe injuries (ISS 9 to 75) demonstrated a 65% longer LOS for children transported by ACC compared to by PTT. These findings suggest that for children with minor injuries (ISS less than 9), transport team type did not affect hospital LOS. However, for children with moderate to severe injuries, hospital LOS was affected by transport team type.
Our study did not find a significant difference in adverse clinical events among transport team types. Prior literature supports the use of pediatric transport teams versus generalized adult transport teams from the referring hospital for critically ill children.Citation12, Citation14–16 Studies showed a decrease in adverse outcomes related to equipment malfunction, such as occluded or misplaced endotracheal tube, loss of intravenous access, loss of monitoring, malfunctioning of ventilator, or exhaustion of oxygen supply. Children transported by PTT were also found to have a decrease in mortality and adverse and unplanned physiological events during transport, such as death, respiratory or cardiac arrest, hypothermia, and loss of consciousness. One study found that children transported by generalized adult transport had a higher need for interventions and a higher incidence of critical complications upon arrival at the pediatric intensive care unit (PICU) compared to those transported by PTT. Citation13 These studies, while examining the same comparison groups of PTT vs. generalized transport teams, differed from our study in that they evaluated only critically ill children being transported directly to the PICU. Our study evaluated injured children being transferred to the ED of a pediatric trauma center, many of whom had no need for airway support and were not sick enough to be at risk for physiological events such as respiratory or cardiac arrest. In fact, over one quarter of children in our study were discharged home from the ED. Had our study examined a greater number of critically ill injured children, we may have found differences in outcomes or adverse events.
Our study did find that PTT and ACC significantly differ from ALS for the administration of pain medications and anti-emetics. Pain has long been recognized as undertreated and mismanaged in the pediatric population.Citation22 Studies have shown that there is less provider comfort when treating pediatric pain and that EMS providers measure and treat pain in children less rigorously than in adults.Citation23 Qualitative studies found that adult paramedics have provider anxiety, discomfort, and unfamiliarity with pediatric patients, therefore contributing to a delay in pain treatment in the prehospital setting.Citation24 Other studies have shown that EMS providers have difficulty accurately assessing and documenting pain in children, a significant barrier to effective pediatric pain management.Citation25 The medical staffs of PTT and ACC receive advanced pediatric training and deal with higher acuity patients, which likely leads to a higher degree of confidence in administering anti-emetics and pain medications to children.
PTT had longer transport times than ACC or ALS. One prospective cohort study analyzed transport of traumatically injured patients and found that a scene transport time exceeding twenty minutes increased odds of mortality in penetrating injuries.Citation17 Although this study showed that faster scene transport times produce better outcomes in injured children, our study did not demonstrate the same relationship to be true for inter-hospital transport. Although PTT had a longer transport time, it did not adversely affect the outcomes of the children. In fact for children with moderate to severe injuries, the hospital LOS was 65% longer for those transported by ACC as compared to PTT. It may be that faster transport during and after the “golden hour” does not always equate to better outcomes.Citation26,27 It is also possible that transport teams are providing important care during the time spent en route to the pediatric tertiary center. PTT may be better equipped to render care for children during this critical time, which is the trade-off to a quicker transfer.
One of the largest limitations to our study was sample size. We were unable to analyze several variables due to insufficient numbers of children. Other study limitations were inherent to retrospective chart reviews, such as missing data in medical records and chart abstraction errors. We used several measures to alleviate these limitations. Our chart abstraction followed a highly structured and precise protocol and was periodically monitored by the principal investigator.
Conclusion
Although PTT inter-hospital transport times for injured children were significantly longer, we were unable to detect differences in outcomes between those transported by PTT versus ACC and ALS. However, a sub-analysis of the moderate to severely injured children demonstrated that those transported by ACC had a 65% longer hospital LOS than those transported by PTT. These findings suggest that the longer transport time does not compromise patient outcomes and that having pediatric specialized transport teams for the moderate to severely injured children, particularly the very young, may make a difference. It may be that PTT have the ability to mobilize patient resources in advance of pediatric trauma center arrival or provide important inter-hospital interventions that were not measured in this study. Prospective larger-scale studies are necessary to fully investigate the benefits of using PTT for inter-hospital transport of injured children and to determine which injured children are optimally cared for by PTT during inter-hospital transport.
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