Published online September 1, 2006
PEDIATRICS
Vol. 118
No. 3
September 2006, pp.
1070-1077
(doi:10.1542/peds.2006-0719)
Pretransport and Posttransport Characteristics and Outcomes of Neonates Who Were Admitted to a Cardiac Intensive Care Unit
Scott B. Yeager, MDa,
Jeffrey D. Horbar, MDb,
Karla M. Greco, MHSa,
Julianna Duff, MBBSc,
Ravi R. Thiagarajan, MD, MPHc and
Peter C. Laussen, MBBSc
a Department of Pediatrics, University of Vermont School of Medicine, Burlington, Vermont
b Center for Patient Safety in Neonatal Intensive Care, Vermont Oxford Network, Burlington, Vermont
c Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts
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ABSTRACT
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OBJECTIVE. The objective for this study was to characterize the impact and the safety of transporting neonates with known or suspected cardiac abnormalities.
METHODS. We reviewed retrospectively the charts and computerized records of 192 admissions to a cardiac ICU in 2002. Patients were included when they were <28 days of age at admission and were transported from adjacent obstetric facilities (local N = 70) or other inpatient medical facilities (transport N = 122). Demographic, clinical, pharmacologic, laboratory, and diagnostic information was obtained before transport (when available) and within 3 hours of arrival. Arrival status was considered optimal when measured metabolic and clinical parameters all were within range. Outcome variables included days on ventilator, days in ICU, days in hospital, and death.
RESULTS. Of local admissions, 31 (44%) patients had 61 suboptimal arrival values, including pH <7.25 (n = 11), saturation <70% (n = 12), and temperature <36°C (n = 9). There were 69 undocumented values in 39 patients. Of transported patients, 55 (45%) had 86 suboptimal arrival values, including pH <7.25 (n = 8), saturation <70% (n = 14), and temperature <36°C (n = 13). There were 98 undocumented values in 53 patients. No in-transport deaths or catastrophic events occurred. Local admissions were more likely to have a prenatal diagnosis of heart disease and had more complex disease and higher mortality. Other outcome parameters were not significantly different between the 2 groups. Low admission arterial saturation, pH, and core temperature were not correlated with adverse outcome measures.
CONCLUSIONS. Although we did not encounter major transport complications, opportunities exist to optimize arrival status and improve surveillance and documentation.
Key Words: congenital heart defects • transportation of patients • cardiac surgical procedures • cardiac care facilities
Abbreviations: CHB—Children's Hospital Boston • RACHS-1—Risk Adjustment for Congenital Heart Surgery-1 • APV—absent pulmonary valve • CAVC—complete atrioventricular canal
Proponents of regionalization of health care delivery argue that concentrating highly technical and infrequently performed medical procedures in a few geographically selected centers results in improved outcome, lower morbidity, and lower costs.1–3 Neonatal cardiac surgery is an example of a specialty with a long history of regionalization, and there are data to support the medical and economic benefits of this approach.4,5 However, centralizing care necessitates either prenatal or postnatal transport of these infants, often over significant distances. There is little information regarding the systems that are in place for cardiac infant transport or the impact of transport on outcomes. We reviewed the records of all neonates who were admitted to a cardiac ICU during the calendar year 2002 to characterize geographic and demographic distribution of patients, the types of cardiac abnormalities encountered, the metabolic condition of the infants, in-transport events, and the impact, if any, of transport on outcome variables.
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METHODS
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The charts and computer records of all neonates (
28 days) who were admitted to the cardiac ICU at the Children's Hospital Boston (CHB), from January 1, 2002, through December 31, 2002, were reviewed. Patients who were admitted from the emergency department or through outpatient clinics were excluded from analysis.
Patients were considered local when they were born at 1 of 2 hospitals that are located within 1 km of CHB. All others were designated as transport patients. Transport patients were identified further as regional (<50 km from CHB), New England (Connecticut, Rhode Island, New York, Maine, New Hampshire, or Vermont >50 km from CHB), national (non–New England states), or international (outside the United States).
The parameters that were extracted from the charts are listed in Table 1 and generally can be categorized as demographic, diagnostic, transport, support, metabolic, and outcome. Most transported infants did not have the exact time of birth in available records, so patient age and outcome measures were approximated as days rather than hours of life. The pretransport metabolic data were selected to be the measurements that were obtained most proximal in time to the transport. Posttransport metabolic data were selected as the first recorded information after arrival to the ICU. No posttransport data that were collected >3 hours after arrival were included. Time to surgery, time on ventilator, time in the ICU, and time to discharge were approximated as calendar days. Surgical complexity of the primary diagnosis was assessed using the Risk Adjustment for Congenital Heart Surgery-1 scale, a previously described scoring system that is used to characterize congenital heart surgery risk.6 When available, transport records were reviewed for in-transport events or management changes. Data from referring hospitals were obtained from transport notes or copies of records that were included in the CHB chart.
A patient's posttransport admission status was characterized as optimal when pH was 
7.25, temperature was 36°C, oxygen saturation was 70%, glucose was between 60 and 200 mg/dL, potassium was 3 and 6 mEq/L, sodium was 130 and 150 mEq/L, chloride was 95 and 110 mEq/L, total bicarbonate was 15 and 35 mEq/L, serum urea nitrogen was 30 mg/dL, creatinine was 1 mg/dL, hemoglobin was 10 g%, and hematocrit was 30%. When data were not found through review of both the patient chart and the computerized records, the entry was considered undocumented.
Continuous data were analyzed by using the Mann-Whitney U test, and categorical data were analyzed by using the 
2 method. Patient demographics, pretransport and posttransport physiologic variables in the transport group, and local versus transported patients were compared. P < .05 was considered statistically significant. The study was approved by the scientific review committee of the Department of Cardiology and the institutional review board at CHB.
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RESULTS
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A total of 192 patients met study criteria and were included. Seventy patients were designated as local transports, and 122 were transported from more distant sites. Of transported patients, 38% were regional, 31% were from New England, 27% were national, and 4% were international. The final major diagnoses of both groups are summarized in Table 2.
Thirty-eight (31%) of the transports were performed by the CHB transport service, a nonphysician, specialized nurse team, using both ground and fixed wing methods. The remainder (n = 84 [69%]) were transported by the referring institution, or the details of transport were not found in the CHB chart. There were no documented mechanical failures, such as complete loss of vascular access, exhaustion of oxygen supply, or ventilator malfunction. No patient required intubation or reintubation, and none developed significant airway obstruction during transport. No in-transport deaths occurred. Typical in-transport management included bolus infusions of saline to support blood pressure or improve perfusion, modification of dosage of prostaglandin or vasopressor infusion, and adjustment of ventilator settings or inspired O2 concentration on the basis of cutaneous oximetry. The median duration of transport was 2 hours, with a range of 1 to 28 hours.
The aggregate patient characteristics are summarized in Table 3. Locally born infants were delivered at an earlier gestational age and were smaller than transported infants (P < .001 and P = .006, respectively). Sixty-three (90%) locally born and 8 (7%) transported patients had their cardiac abnormalities diagnosed prenatally (P < .001).
Patients in the 2 groups were equally likely to be admitted on a prostaglandin E1 infusion (63%), with a significantly higher percentage of transported patients on ventilators (54% vs 23%; P = .013) and on vasopressors (30% vs 9%; P = .004). Surgical complexity of the congenital heart abnormalities, as reflected by the RACHS-1 score, was higher in the locally born group (P < .001).
On admission, the locally born infants had a significantly lower mean pH than the transported patients (7.32 vs 7.39; P < .001). Admission temperature and peripheral oxygen saturation were not significantly different. There were small but statistically significant differences between the 2 groups in several parameters measured, probably reflecting, at least in part, the discrepant age at admission between the 2 groups. Analysis of the 2 groups did not show any statistical difference in the likelihood of an out-of-range value for any value measured.
Outcome parameters for the groups also are summarized in Table 3. Locally born infants were younger on admission to the ICU (P < .001) and were younger at the time of intervention (P = .002). Although they also had a longer duration of intubation, stay in ICU, and length of hospitalization, none of these differences reached statistical significance. Locally born infants had a significantly higher mortality (14% vs 4.9%; P = .024).
The patients' arterial pH, oxygen saturation, and core temperature were chosen arbitrarily as commonly measured parameters that are most likely to reflect any adverse in-transport change in status and are summarized in Fig 1. Paired values in the transport group are shown when available, and the locally born patients are included for comparison.
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FIGURE 1 Pretransport and posttransport admission laboratory values for temperature, blood pH, and oxygen saturation. +, Transported patients;  , locally born patients. Paired values in the transport group are joined by a solid line. Unpaired pretransport values are shown on the left, and posttransport unpaired values are on the right.
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Patients who fell out of range and those who arrived with abnormal sentinel laboratory values are shown in Tables 4 and 5. Twenty-one (17%) patients were known to have had normal pretransport values that subsequently fell out of range during transport and are summarized in Table 4. Pretransport and posttransport values, major diagnosis, and in-transport support are shown. There was no significant difference in outcome measures when this group was compared with the transport group as a whole, and there were no deaths among the patients who fell out of range during transport.
Patients who were admitted with abnormal pH, oxygen saturation, or core temperature are shown in Table 5 and are compared with the transport group as a whole. One patient in this group had all 3 values abnormal on admission, and 5 others had 2 values out of range. There was no difference in demographics between the groups. Patients who presented with a low systemic saturation also had a lower mean blood pressure when compared with the remainder of the transport group. Patients with a low admission pH also had a lower heart rate, and hypothermic patients were more likely to be on vasopressor support and had a lower saturation, pH, and heart rate than transported patients in general. When the outcome measures were compared, no significant differences were detected except for a longer preoperative period in the ICU for patients who arrived with a core temperature <36°C. This difference did not persist in total ICU days or length of hospital stay.
A summary of optimal arrival status for the 2 groups is shown in Fig 2. Of locally born patients, 31 (44%) had 1 or more clinical parameters or laboratory values out of range. An additional 27 (39%) patients had 1 or more missing values. In the transport group, 55 (45%) patients had 1 or more values out of range, with 33 (27%) patients missing values. Some patients in each group had both out-of-range and missing results.
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FIGURE 2 Admission status of the 192 admissions. Locally born and transported patients are characterized as those who were known to have at least 1 suboptimal admission characteristic versus those who were known to have all optimal values or undocumented values. Those with known suboptimal values are characterized further as patients with an abnormal pH, oxygen saturation, or core temperature versus those with some other abnormal admission value. Some patients in the suboptimal category also had undocumented values.
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Documentation of the pretransport history and laboratory values in many of the transported patients was incomplete or missing altogether. Forty-seven (38%) charts had no documented information about the patient before the arrival of the transport team, and 16 (13%) charts had no transport note.
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DISCUSSION
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Regionalization of some aspects of medical care has been touted as a means of improving outcome and reducing costs. Congenital heart surgery requires very specialized skills and facilities to realize the impressive advances in outcome that have characterized the field in the past 2 decades. Previous studies have suggested improved outcome and lower cost when complex congenital heart surgery is performed by centers and surgeons with high caseloads.4 Consequently, the case for a regional approach to dealing with complex heart disease in the neonate seems compelling. However, few studies have addressed the issues surrounding regionalization and the impact of a transport system on the initial status or outcome in infants with congenital heart disease.7
The prenatal identification of major congenital heart defects clearly has influenced decisions regarding site and timing of elective deliveries. In our study, 90% of local neonates were diagnosed prenatally. Several studies have indicated that prenatal diagnosis selects for infants with more complex anatomic defects or more severe physiologic derangements.8–10 Our experience seems similar, with locally born infants averaging a higher RACHS-1 score as well as showing a trend toward longer duration of ventilator support, ICU care, and hospital stay and statistically higher mortality.
Defects that were diagnosed prenatally were weighted heavily toward univentricular types of anatomy, with hypoplastic left heart representing 27% of locally born patients and other single ventricle–type of defects (eg, single right or left ventricle, heterotaxy syndromes, tricuspid atresia, pulmonary atresia with intact ventricular septum) adding another 26%. This distribution of diagnosis presumably reflects the sensitivity of the standard fetal 4-chamber view in detecting ventricular hypoplasia. Prenatal diagnoses of primarily vascular anomalies (eg, transposition of the great arteries, truncus arteriosus, interrupted aortic arch, totally anomalous pulmonary venous return) usually is more difficult and may not be apparent on the standard 4-chamber view that is used for low-level fetal cardiac screening. These types of diagnoses were represented more commonly among the transported patients (44%), many of whom probably had general prenatal ultrasound evaluation.
Locally born infants demonstrated a lower mean pH on admission but as a group were no more or less likely to be admitted with a pH of <7.25. There were small differences in the 2 groups in most metabolic parameters, but none of the differences seems to be of clinical importance, and they probably stem, in part, from the fact that locally born infants generally were admitted to the ICU shortly after birth, whereas transported infants had undergone a period of stabilization at other medical centers and were older at the time of admission. Many patients electively were intubated and started on vasopressor support for transport, even when their metabolic state at the time did not require these interventions. The justification for this approach would be that in-transport intubation is technically difficult and that metabolic monitoring during the transport is limited. However, prophylactic intubation exposes the infant to the potential for mechanical malfunction such as ventilator failure or tube plugging, and some transport teams elected not to intubate routinely.
We chose admission with a peripheral oxygen saturation of <70%, a pH of <7.25, or a core body temperature of <36°C as possible indicators of physiologic instability during transport and compared outcomes between those subgroups and the remaining transported patients. The only difference in outcome was a longer preoperative period in the ICU for the hypothermic admissions. However, it would be necessary to apply more subtle and sensitive outcome evaluation to these patients before concluding that this level of metabolic derangement is entirely benign.
The absence of significant in-transport events is encouraging. Other reports of pediatric transports consistently have highlighted mechanical problems, such as loss of intravenous access or endotracheal tube plugging.11–13 However, these studies have included a different and probably less stable patient group, including trauma victims, severe infections including respiratory infections, and neurologic injury. They also were not confined to neonates. The majority of patients in our study were transported from level III nurseries after diagnosis and stabilization by local neonatal teams with input from pediatric cardiologists.
In-transport metabolic "deterioration" has been reported to occur in 4% to 12% of pediatric transports, although relatively limited posttransport metabolic evaluation was performed in those studies.11–14 In this review, 21 (17%) patients had 1 or more metabolic measurements that were known to be normal before transport and were abnormal shortly after arrival. Four of these could be considered to be a major deterioration. In 2 patients, the pH fell to <7.15. One was a patient who had transposition of the great arteries and intact ventricular septum and was appropriately on a prostaglandin infusion, and the other was a patient who had myocarditis and was on a ventilator with vasopressor support. Two other patients arrived with a saturation of <50% despite having a normal saturation level before transport. One was a patient who had hypoplastic left heart syndrome and was on a prostaglandin infusion, and the other had totally anomalous pulmonary venous return. Neither patient had been intubated for transport. The remaining patients had less dramatic changes in status or laboratory values of less immediate concern. Thirty-four other patients arrived after transport with 1 or more abnormal initial findings but with no pretransport assessment available, so it is impossible to know whether these values changed during the interhospital period.
It is surprising to note that the large majority of patients in both groups had either a suboptimal variable on arrival or some missing clinical or laboratory value after review of the chart and computer records (Fig 2). Suboptimal values in the local patients might be explained by the fact that most were only a few minutes or hours old at admission. Most patients in the transport group, however, were stabilized in nursery settings and evaluated by transport teams. More uniform protocols for evaluation and intervention before transport might result in fewer arrivals with metabolic abnormalities, and such a strategy deserves additional investigation. Missing values might be explained if some tests were not done because the patient's status was believed not to warrant them, and there may be variability among admitting physicians in how comprehensive an initial metabolic profile was performed. An alternative explanation might be that some patients were known to have had recent, normal values at the referring hospital, but a review of the data indicates that few patients had unpaired, pretransport values.
It also was discouraging to find that pretransport information so often was missing in the patients' charts. Unfortunately, records from referring hospitals frequently lack a clear status after patient transfer. Although they may be reviewed at the time of admission, they often are stored separately and can be difficult or impossible to retrieve at a later time. Likewise, transport records were not located consistently during the chart review. A possible solution to this problem is offered by electronic transfer of records or a Web-based transport data collection system so that pretransport or in-transport information could be incorporated directly into the records of the receiving institution. Such a system also could reduce the duplication of tests in patients in whom there is no clinical indication for repeating them.
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CONCLUSIONS
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This study demonstrates that neonates with a wide range of cardiac diagnoses can be transported safely and effectively without adverse consequences on measured outcome parameters. No catastrophic in-transport events were documented, and serious deterioration of patient status was uncommon. Nonetheless, almost one half of patients were admitted with at least 1 abnormal metabolic or clinical parameter, and many others had 1 or more undocumented values.
Clearly, opportunities exist to improve this regional system of neonatal cardiac management. The need for patient transport could be reduced through improved prenatal diagnoses, particularly of conotruncal anomalies. In addition, more uniform protocols for pretransport and posttransport assessment could highlight in-transport support issues and provide a more reliable means of identifying potentially dangerous practices or omissions. Finally, the development of interinstitutional electronic record-keeping offers the prospect of a relatively seamless document of patient care across multiple centers.
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ACKNOWLEDGMENTS
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This study was supported in part by the Rochelle E. Rose Fund and the Champlain Valley Area Health Education Center.
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FOOTNOTES
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Accepted May 4, 2006.
Address correspondence to Scott B. Yeager, MD, Division of Pediatric Cardiology, University of Vermont School of Medicine, FAHC Patrick 581, Burlington, VT 05401. E-mail: scott.yeager{at}vtmednet.org
The authors have indicated they have no financial relationships relevant to this article to disclose.
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PEDIATRICS (ISSN 1098-4275). ©2006 by the American Academy of Pediatrics
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ABSTRACT
METHODS
