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Outcomes of interfacility critical care adult patient transport: a systematic review

Abstract

Introduction

We aimed to determine the adverse events and important prognostic factors associated with interfacility transport of intubated and mechanically ventilated adult patients.

Methods

We performed a systematic review of MEDLINE, CENTRAL, EMBASE, CINAHL, HEALTHSTAR, and Web of Science (from inception until 10 January 2005) for all clinical studies describing the incidence and predictors of adverse events in intubated and mechanically ventilated adult patients undergoing interfacility transport. The bibliographies of selected articles were also examined.

Results

Five studies (245 patients) met the inclusion criteria. All were case-series and two were prospective in design. Due to the paucity of studies and significant heterogeneity in study population, outcome events, and results, we synthesized data in a qualitative manner. Pre-transport severity of illness was reported in only one study. The most common indication for transport was a need for investigations and/or specialist care (three studies, 220 patients). Transport modalities included air (fixed or rotor wing; 66% of patients) and ground (31%) ambulance, and commercial aircraft (3%). Transport teams included a physician in three studies (220 patients). Death during transfer was rare (n = 1). No other adverse events or significant therapeutic interventions during transport were reported. One study reported a 19% (28/145) incidence of respiratory alkalosis on arrival and another study documented a 30% overall intensive care unit mortality, while no adverse events or outcomes were reported after arrival in the three other studies.

Conclusion

Insufficient data exist to draw firm conclusions regarding the mortality, morbidity, or risk factors associated with the interfacility transport of intubated and mechanically ventilated adult patients. Further study is required to define the risks and benefits of interfacility transfer in this patient population. Such information is important for the planning and allocation of resources related to transporting critically ill adults.

Introduction

Regionalization of care and the requirement for specialized resources result in the frequent need for interfacility transport of critically ill patients [1–3]. Although some of these patients may derive significant benefit from such a transfer, they may also be at considerable risk of transport-related morbidity and mortality [4–12]. The decision to initiate the interfacility transport of a critically ill patient must, therefore, be taken carefully. The impact of specific pre-transport and transport-related factors on morbidity and mortality are not well established, however, limiting the ability of clinicians to target particular patients where additional resources and care during transportation might be beneficial. For example, if high-risk patients could be reliably identified, they could undergo additional pre-transport resuscitation [13, 14] and/or be accompanied by specially trained transport personnel with additional equipment in order to anticipate and reduce transport-associated risks [15–21].

Several professional societies have developed guidelines for the inter- and intrafacility transport of critically ill patients [22–25]; however, these guidelines focus primarily on general principles (for example, pre-transport stabilization, minimum transport equipment and medications) and the composition of the transport team, rather than risk stratification. Understanding which patients are most at risk while undergoing interfacility transport and the types of events that occur would be an important step in patient preparation and aligning resources (such as equipment and personnel) at the sending and receiving sites as well as during transportation. To this end, we conducted a systematic review of the literature to determine the adverse events associated with interfacility transport of mechanically ventilated adult patients, along with important pre-transport and transport-related prognostic factors.

Methods

Identification of trials

Our objective was to identify all relevant published clinical studies describing the incidence and predictors of adverse events in mechanically ventilated adults undergoing interfacility transport. We chose to study only intubated and mechanically ventilated patients in order to capture a well-defined group of critically ill patients with significant severity of illness.

A priori, we defined adverse events related to transportation as those that occurred during interfacility transport and up to 24 hours after arrival at the destination. A computerized MEDLINE (1966 to 10 January 2005) search was conducted using the following medical subject headings: 'transportation of patients', 'intubation, intratracheal', and 'respiration, artificial'. In addition, we searched the databases CENTRAL (first quarter 2005), EMBASE (1980 to 10 January 2005), CINAHL (1982 to 10 January 2005), HEALTHSTAR (1975 to 10 January 2005), and Web of Science (1945 to 10 January 2005) using the keywords: 'transport', 'ventilation', and 'intubation'. No language restrictions were applied. Bibliographies of all selected articles and review articles [26, 27] on interfacility patient transport were examined for other relevant studies. This strategy was performed iteratively, until no new clinical trial citations were found on review of the reference lists of retrieved articles. Full details of the searches are available upon request.

Study selection and data abstraction/analysis

The following selection criteria were used to identify published studies for inclusion in our analysis: clinical trial or cohort study or case-series (study design); all patients intubated and mechanically ventilated, and aged ≥ 18 years (study population); and interfacility transport (for example, from one health care facility to another health care facility). Interfacility transports between two sites of the same institution were included if the means of transportation involved air or ground ambulance.

Two reviewers (EF and RDM) independently applied the selection criteria and abstracted the data using standardized forms. The reviewers abstracted data on description of the cohort, methods, adverse events/outcomes, and transport-related interventions. We report descriptive data from individual trials as mean ± standard deviation, unless otherwise stated. Because of the paucity of studies and the heterogeneity in study populations and reported outcomes, we did not conduct a meta-analysis.

Results

The combined computerized and bibliographic literature search yielded 599 potentially relevant studies, of which 24 articles were identified for more detailed review (Figure 1). Only five studies satisfied our inclusion criteria [28–32]. There was moderate initial agreement between reviewers for study inclusion (raw agreement = 0.80, chance-corrected agreement κ = 0.65 ± 0.16); all disagreements were resolved by consensus.

The five included studies (Tables 1 and 2) enrolled 245 critically ill patients (median 15; range 8 to 146) with a wide variety of diagnoses. All were case-series, two of which were prospective. The most common indication for interfacility transport was the need for investigations and/or specialist care not available at the referring institution (three studies, 220 patients) [28, 29, 31, 32]. The results of the included studies are summarized in Table 3.

Table 1 Characteristics of included studies
Table 2 Transport characteristics of included studies
Table 3 Results of included studies

Pre-transport characteristics

Only 1 study reported severity of illness (Sepsis-related Organ Failure Assessment (SOFA) [33] score of 10 ± 3) prior to transport [31]. Another study reported pre-transport arterial blood gas results from transported burn patients [28]. The other three studies provided little data on pre-transport status that would be useful in standardizing comparisons across patient groups.

Transport characteristics

Modalities used for interfacility transport included air (fixed or rotor wing; 66% of patients) and ground (31%) ambulance, and commercial aircraft (3%). Transport teams included a physician in 3 studies (220 patients) [28, 31, 32]. In one study, 14 patients (21%) were transported in the prone position because of life-threatening hypoxemia [31]. Death during transport was rare (n = 1) [32]. No other adverse events or significant therapeutic interventions during transport were reported in any of the included studies.

Post-transport characteristics

One study (not the same one that described pre-transport characteristics) reported severity of illness on arrival and outcomes following interfacility transport (mean Acute Physiology and Chronic Health Evaluation (APACHE) II [34] score of 17 ± 6; intensive care unit mortality 30%) [29]. The burn study reported the incidence of respiratory alkalosis on arrival (in 19%) and the survival rate to burn unit discharge (71%) [28]. The presence or absence of post-transport adverse events was not reported in the other three included studies.

Discussion

The main finding of this systematic review is the paucity of studies examining adverse events and their associated risk factors in critically ill patients undergoing interfacility transport. The few published studies suggest that significant mortality or morbidity associated with interfacility transport of intubated adult patients is uncommon; however, there are significant limitations to the available data. First, the estimation of the incidence of adverse events is unreliable because all studies were case series (the majority of which were retrospective) that enrolled few transported patients. Second, associations between pre-transport variables and adverse outcomes could not be determined, both because pre-transport status was poorly documented, and because studies lacked standard definitions and methods for ascertaining adverse events. Finally, many studies only examined immediate or short-term adverse events (for example, during transport or on arrival), even though it is possible that later adverse events may also be associated with important transport-related factors (for example, barotrauma from exposure to high ventilatory pressures during transport may go unrecognized for several hours).

A number of factors may have contributed to the low morbidity of interfacility transport documented in this review. These include the possibility that some patients who were less severely ill were intubated and ventilated solely to facilitate safe transportation, thereby lowering the overall acuity of illness and likelihood of adverse events. The extent to which this practice occurred was not reported in any of the included studies. In addition, the composition of the transport teams may have had an influence. In three of the five included studies, the transport teams included a physician; in two of these the physician was a specialist (a burn surgeon and an intensivist). In addition, a nurse accompanied the patient in all four studies that reported transport team composition. Interfacility transport is increasingly becoming the jurisdiction of highly trained and specialized transport personnel [35–38], with at least one paediatric study demonstrating significantly decreased morbidity associated with the use of such teams [36]. Professional guidelines have suggested that transport of unstable critically ill adults should be accompanied by either a physician or a nurse, preferably with additional training and experience in transport medicine [22]. The results of our review may not have been the same if more data were available from transports without such individuals.

Although transport methods, distance, and time differ in intra-hospital transfers, the risks and types of adverse events for the patient may be similar to those undergoing inter-hospital transport [24, 39, 40]. Several studies of intra-hospital transfers of critically ill patients have reported transport-related complications [39–42]. In a recent study [42], 191 incidents related to intra-hospital transport were identified over a six year period. The majority of adverse events centered on patient-staff management issues and equipment problems that culminated in serious complications in 31% of reported incidents, including major physiological deterioration in 15% and death in 2% [42]. This relatively high rate of adverse events among reported incidents when intrafacility transport is subjected to close scrutiny further calls into question the validity of the results of our review. It seems likely that the potential for adverse events is significantly higher during air transport between two hospitals than on a trip to another department within the same hospital such as the radiology department. Alternatively, a possible explanation is that patients undergoing intra-hospital transports are sicker and/or the personnel associated with these transports are less experienced than inter-hospital transport teams.

Finally, we acknowledge that a limitation to the generalizability of our results is the restriction of our review to intubated and ventilated patients undergoing interfacility transport. In our attempt to identify and study a well-defined population of critically ill patients, we may have missed other patients at risk for adverse events during interfacility transport.

The lack of informative clinical studies evaluating the interfacility transport of critically ill patients is likely related to a variety of barriers in conducting research in this setting (Table 4). Clearly, deciding if patients will undergo interfacility transport by randomization is infeasible and unethical. Therefore, we believe that a multi-center, prospective observational cohort study is the methodology best suited to address the important questions raised by our review in this rapidly growing field of transit care medicine. In the design of such a study, attention would need to be paid to developing and validating consistent definitions for adverse events. In addition, extensive collaboration between the critical care and transport teams would be essential.

Table 4 Barriers to transport research and recommendations for future studies

Conclusion

Few data document the risks of interfacility transport. Until more robust risk assessment tools become available, common sense and physiological rationale will continue to guide the risk/benefit assessment of interfacility transport for individual patients. We believe that more research is required to document the prevalence of adverse events in critically ill patients during transport, and to elucidate the associated patient- and transport-related risk factors. Such research could form the basis of new strategies to optimize patient safety. In addition, better identification of patients at risk may allow for more efficient and effective alignment of transport-related resources, such as specialist retrieval teams and enhanced pre-transfer stabilization.

Key messages

  • Few data exist regarding the mortality, morbidity, and/or risk factors associated with these outcomes in intubated and mechanically ventilated adult patients undergoing interfacility transport.

  • Further prospective study is required to define the risks and benefits of interfacility transfer in this patient population.

  • Such information is important for the planning and allocation of resources related to transporting critically ill adults.

References

  1. Mackenzie PA, Smith EA, Wallace PGM: Transfer of adults between intensive care units in the UK. Br Med J 1997, 314: 1455-1456.

    Article  CAS  Google Scholar 

  2. Flabouris A: Patient referral and transportation to a regional tertiary ICU: patient demographics, severity of illness and outcome comparison with non-transported patients. Anaesth Intensive Care 1999, 27: 385-390.

    CAS  PubMed  Google Scholar 

  3. Grieve CF, Ferguson ND, Adhikari N, Singh JM, Moneta SL, DeMajo W, Stewart TE, Scales DC: Utilization pattern of Ontario's critical care referral and transfer facilitation program [abstract]. Proc Am Thoracic Soc 2005, 2: A597.

    Google Scholar 

  4. Olson CM, Jastremski MS, Vilogi JP, Madden CM, Beney KM: Stabilization of patients prior to interhospital transport. Am J Emerg Med 1987, 5: 33-39. 10.1016/0735-6757(87)90285-3

    Article  CAS  PubMed  Google Scholar 

  5. Ehrenworth J, Sorbo S, Hackel A: Transport of critically ill adults. Crit Care Med 1986, 14: 543-547.

    Article  Google Scholar 

  6. Kanter R, Tompkins J: Adverse events during interhospital transport: Physiologic deterioration associated with pretransport severity of illness. Pediatrics 1989, 84: 43-48.

    CAS  PubMed  Google Scholar 

  7. Martin G, Cogbill T, Landercasper J, Strutt PJ: Prospective analysis of rural interhospital transfer of injured patients to a referral trauma center. J Trauma 1990, 30: 1014-1020.

    Article  CAS  PubMed  Google Scholar 

  8. Valenzuela T, Criss E, Copass M, Luna GK, Rice CL: Critical care air transportation of the severely injured: Does long distance transport adversely affect survival? Ann Emerg Med 1990, 19: 169-172. 10.1016/S0196-0644(05)81803-7

    Article  CAS  PubMed  Google Scholar 

  9. Kerr HD, Byrd JC: Community hospital transfers to a VA Medical Center. J Am Med Assoc 1989, 262: 70-73. 10.1001/jama.262.1.70

    Article  CAS  Google Scholar 

  10. Dragsted L, Jorgensen J, Jensen NH, Bonsing E, Jacobsen E, Knaus WA, Qvist J: Interhospital comparisons of patient outcomes from intensive care: Importance of lead-time bias. Crit Care Med 1989, 17: 418-422.

    Article  CAS  PubMed  Google Scholar 

  11. Borlase BC, Baxter JK, Kennedy PR, Forse RA, Benotti PN, Blackburn GL: Elective intrahospital admissions versus acute interhospital transfers to a surgical intensive care unit: Cost and outcome prediction. J Trauma 1991, 31: 915-918.

    Article  CAS  PubMed  Google Scholar 

  12. Durairaj L, Will JG, Torner JC, Doebbeling BN: Prognostic factors for mortality following interhospital transfers to the medical intensive care unit of a tertiary referral center. Crit Care Med 2003, 31: 1981-1986. 10.1097/01.CCM.0000069730.02769.16

    Article  PubMed  Google Scholar 

  13. Henderson A, Coyne T, Wall D, Miller B: A survey on interhospital transfer of head-injured patients with inadequately treated life-threatening extracranial injuries. Aust N Z J Surg 1992, 62: 759-762.

    Article  CAS  PubMed  Google Scholar 

  14. Lambert SM, Willett K: Transfer of multiply-injured patients for neurosurgical opinion: A study of the adequacy of assessment and resuscitation. Injury 1993, 24: 333-336. 10.1016/0020-1383(93)90058-E

    Article  CAS  PubMed  Google Scholar 

  15. Harrahil M, Bartkus E: Preparing the trauma patient for transfer. J Emerg Nurs 1990, 16: 25-28.

    Google Scholar 

  16. Gore JM: Feasibility and safety of emergency interhospital transport of patients during the early hours of acute myocardial infarction. Arch Intern Med 1989, 149: 353-355. 10.1001/archinte.149.2.353

    Article  CAS  PubMed  Google Scholar 

  17. Anderson C: Preparing patients for aeromedical transport. J Emerg Nurs 1987, 13: 229-231.

    Google Scholar 

  18. Greco A: Development of an interfacility transport program for critically ill cardiovascular patients. Clin Issues Crit Care Nurs 1990, 1: 3-12.

    CAS  Google Scholar 

  19. Fromm RE, Dellinger RP: Transport of critically ill patients. J Int Care Med 1992, 7: 223-233.

    Article  Google Scholar 

  20. Runcie CJ, Reeve W, Reidy J, Wallace PG: Secondary transport of the critically ill adult. Clin Intensive Care 1991, 2: 217-225.

    CAS  PubMed  Google Scholar 

  21. Selevan JS, Fields WW, Chen W, Petitti DB, Wolde-Tsadik G: Critical care transport: Outcome evaluation after interfacility transfer and hospitalization. Ann Emerg Med 1999, 33: 33-43. 10.1016/S0196-0644(99)70414-2

    Article  CAS  PubMed  Google Scholar 

  22. Warren J, Fromm RE, Orr RA, Rotello LC, Horst HM: Guidelines for the inter- and intrahospital transport of critically ill patients. Crit Care Med 2004, 32: 256-262. 10.1097/01.CCM.0000104917.39204.0A

    Article  PubMed  Google Scholar 

  23. Faculty of Intensive Care of the Australian and New Zealand College of Anaesthetists and Australasian College for Emergency Medicine: Minimum standards for transport of the critically ill[http://www.acem.org.au/open/documents/crit_ill.pdf]

  24. Faculty of Intensive Care of the Australian and New Zealand College of Anaesthetists and Australasian College for Emergency Medicine: Minimum standards for intrahospital transport of the critically ill[http://www.acem.org.au/open/documents/intrahosp_crit_ill.pdf]

  25. Intensive Care Society 2002: Guidelines for the transport of the critically ill adult (UK)[http://www.ics.ac.uk/downloads/icstransport2002mem.pdf]

  26. Gray A, Bush S, Whiteley S: Secondary transport of the critically ill and injured adult. Emerg Med J 2004, 21: 281-285. 10.1136/emj.2003.005975

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  27. Fromm RE, Varon J: Critical care transport. Crit Care Clin 2000, 16: 695-705. 10.1016/S0749-0704(05)70141-X

    Article  PubMed  Google Scholar 

  28. Barillo DJ, Dickerson EE, Cioffi WG, Mozingo DW, Pruit BA Jr: Pressure-controlled ventilation for the long-range aeromedical transport of patients with burns. J Burn Care Rehabil 1997, 18: 200-205.

    Article  CAS  PubMed  Google Scholar 

  29. Remond C, Jimeno MT, Dubouloz F: Mesures du CO 2 expire en transport extrahospitalier: Interets et limites. Jeur 1998, 4: 179-186.

    Google Scholar 

  30. Orf J, Thomas SH, Wedel SK: Ventilation rates in intubated head injury patients undergoing helicopter EMS (HEMS) transport [abstract]. Crit Care Med 2000, 28: A208.

    Google Scholar 

  31. Uusaro A, Parviainen I, Takula J, Ruokonen E: Safe long-distance interhospital ground transfer of critically ill patients with acute severe unstable respiratory and circulatory failure. Intensive Care Med 2002, 28: 1122-1125. 10.1007/s00134-002-1348-9

    Article  PubMed  Google Scholar 

  32. Veldman A, Diefenbach M, Fischer D, Benton A, Bloch R: Long-distance transport of ventilated patients: advantages and limitations of air medical repatriation on commercial airlines. Air Med J 2004, 23: 24-28. 10.1016/j.amj.2003.12.009

    Article  PubMed  Google Scholar 

  33. Vincent JL, Moreno R, Takala J, Willatts S, De Mendonca A, Bruining H, Reinhart CK, Suter PM, Thijs LG: The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. Intensive Care Med 1996, 22: 707-710.

    Article  CAS  PubMed  Google Scholar 

  34. Knaus WA, Zimmerman JE, Wagner DP, Draper EA, Lawrence DE: APACHE – acute physiology and chronic health evaluation: a physiologically based classification system. Crit Care Med 1981, 9: 591-597.

    Article  CAS  PubMed  Google Scholar 

  35. Burtnyk S: Secondary transportation of critically ill people – implications for nurses and the need for specialist training. Intensive Crit Care Nurs 1992, 8: 234-239. 10.1016/0964-3397(92)90055-O

    Article  CAS  PubMed  Google Scholar 

  36. Edge WE, Kanter RK, Weigle CG, Walsh RF: Reduction of morbidity in interhospital transport by specialized pediatric staff. Crit Care Med 1994, 22: 1186-1191.

    Article  CAS  PubMed  Google Scholar 

  37. Gebremichael M, Borg U, Habashi NM, Cottingham C, Cunsolo L, McCunn M, Reynolds HN: Interhospital transport of the extremely ill patient: the mobile intensive care unit. Crit Care Med 2000, 28: 79-85. 10.1097/00003246-200001000-00013

    Article  CAS  PubMed  Google Scholar 

  38. Beyer AJD, Land G, Zaritsky A: Nonphysician transport of intubated pediatric patients: a system evaluation. Crit Care Med 1992, 20: 961-966.

    Article  PubMed  Google Scholar 

  39. Braman SS, Dunn SM, Amico CA, Millman RP: Complications during intrahospital transport in critically ill patients. Ann Intern Med 1987, 107: 469-473.

    Article  CAS  PubMed  Google Scholar 

  40. Lovell MA, Mudaliar MY, Klineberg PL: Intrahospital transport of critically ill patients: complications and difficulties. Anaesth Intensive Care 2001, 29: 400-405.

    CAS  PubMed  Google Scholar 

  41. Shirley PJ, Stott SA: Clinical and organizational problems in patients transferred from the intensive care unit to other areas within the hospital for diagnostic procedures. Br J Anaesth 2001, 87: 346-347.

    Google Scholar 

  42. Beckmann U, Gillies DM, Berenholtz SM, Wu AW, Pronovost P: Incidents relating to the intra-hospital transfer of critically ill patients. Intensive Care Med 2004, 30: 1579-1585. 10.1007/s00134-004-2177-9

    Article  PubMed  Google Scholar 

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Correspondence to Niall D Ferguson.

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The authors declare that they have no competing interests.

Authors' contributions

EF, RDM, DCS, TES, and NDF conceived the study. All authors contributed to the study design and interpretation of the data. EF and RDM performed the literature search and abstracted the data. EF wrote the first draft of the manuscript, which was then revised for intellectually important content by all authors. All authors read and approved the final manuscript.

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Fan, E., MacDonald, R.D., Adhikari, N.K. et al. Outcomes of interfacility critical care adult patient transport: a systematic review. Crit Care 10, R6 (2005). https://doi.org/10.1186/cc3924

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