Jack J.M. Ligtenberg
Wilma E. Monteban-Kooistra
The authors have no competing financial or other interests.
Immediate Concerns
It is a wet, cold Friday night. Lights flash in the distance. The sound of a siren approaches. An ambulance hurtles through the night carrying a critically ill patient. The nurse and doctor, both inexperienced and sincerely wishing they weren't there, watch the monitor anxiously. They have left the security of one hospital for that of another; like in a circus trapeze act, they hang suspended for a moment. For at that instant the sickest patient in the region is travelling at over 100 km/hour down an unknown highway. Will they catch the trapeze, or will they fall?
--Citation from Philip Haji-Michael (1)
There appears to be little awareness of the problems/adverse events of interfacility movement of critically ill patients. Both national and international guidelines are in place, but appear not to be followed in a considerable number of transfers. Aeromedical transport of patients may have advantages, depending on the distance and the condition of the patient, but also has its specific drawbacks. Interhospital transport of critically ill patients has changed from volunteer work to a specific skill of emergency and intensive care medicine. The intensive care unit (ICU) patient deserves appropriate medical care during the road trip or in the air. Health authorities should be made aware of the fact that an organizational structure guaranteeing safe critical care transferrals requires extensive financial and human investments.
Interhospital Transport of Intensive Care Unit Patients
The number of interhospital transports of critically ill patients gradually expands. Conservative estimates mention more than 11,000 transfers per year in the United Kingdom (2). There are various reasons for this increase, partly due to local or national circumstances such as shortage of ICU beds or insurance motives, but also caused by centralization of patient groups in specialized centers, specific treatment options, second opinions, and new and established services covering extensive areas with people living in remote locations (3,4).
The primary goal of interhospital transport is to get the right patient, with the right personnel and the right equipment, to the right place in the right amount of time (5). This secondary transport should only occur if it is likely to improve the patient's clinical outcome. The transport itself, at least, has to be as safe as possible and should add no extra risk to the patient. Circulatory or ventilatory problems may arise in the ambulance as well as during transportation in the air (6,7,8). Monitoring possibilities are limited during transportation, access to the patient may be limited, and fewer—and sometimes less skilled—“hands” are available compared to the ICU environment. Necessary interventions, if the patient deteriorates, may be difficult during the road or air trip, as may be the physical examination (9).
Ground Transport Using a Standard Ambulance or Mobile Intensive Care Unit
In a recent study evaluating 100 consecutive interhospital transfers of ICU patients over the road, adverse events occurred in more than 30%: Approximately half of these events were graded as being of vital importance (Table 15.1). Recommendations for safe transport made by the intensivist of the receiving ICU were ignored in a considerable number of cases. It is quite worrisome that there appeared to be little awareness of the problems/adverse events that may occur during transportation. A substantial part of the adverse events could have been avoided simply by adhering to protocols. Interestingly, few events were caused by technical problems during transport, such as shortage of oxygen. Other important points for improvement, emerging from several studies, are (a) transparent pretransport communication between professionals; (b) feedback about adverse events; (c) careful preparation of the patient; and, in selected transfers, (d) the utilization of a specialist retrieval team eventually using a mobile intensive care unit (MoICU). Several positive experiences have been described working with specialist retrieval teams (10,11). In the study of Bellingan et al., transports by a specialist retrieval team, compared to standard ambulance with a doctor from the referring hospital, resulted in more stable transports and a reduction in mortality in the first 12 hours from 7.7% to 3% (10). Based on such data, it seems logical to use a specialist retrieving team for critically ill patients (12). However, such a team of specialists will not be available always and at every location. Furthermore, it appears to be difficult to predict which patients will deteriorate during transfer and, therefore, may benefit most from a specialist team (6). It is strongly recommended, in any event, that each referring and tertiary institution have a plan using locally available resources if the referring facility is not able to conduct the transfer. This plan has to address (a) pretransport coordination and communication, (b) transport personnel, and (c) transport equipment and monitoring during transport (13) (Table 15.2). Several excellent papers with practical guidelines for safe ICU transfers that can help in making such a plan have been published (11,13,14,15).
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Table 15.1 Examples of recorded adverse events during interhospital transport |
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Air Medical Transport of Critically Ill Patients
The optimal way of transporting critically ill patients remains controversial. Aeromedical transport (AMT) of patients from the scene or between hospitals may offer advantages but also has its specific drawbacks. The overall benefits of aeromedical services, measured by sound data, remain uncertain and anecdotal, although ample efforts have been made to describe the value of aeromedical transportation to the health system (16). The European HEMS and Air Rescue Committee (EHAC) has put forward the collection of information related to the operation of air ambulances worldwide as a point of interest.
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Table 15.2 Equipment recommendations for the mobile intensive care unit |
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The use of AMT differs greatly between various countries, depending, among other things, on health care financing, distances to tertiary hospitals, and the presence of large rural areas. It is difficult to get an overview of AMT in different countries. In the 1990s, for example, there were already more than 170 air medical programs in operation in the United States (17). In the United States, 28% of helicopter transports are scene calls, whereas the remaining 72% are interhospital transfers. In Australia, where experience with AMT is widespread, patients are transported between intensive care units by land ambulance in the metropolitan areas, by helicopter for journeys of less than 400 km, and by fixed wing aircraft for longer distances (18). In Germany more than 50 AMT helicopters are available, having already performed, in the first quarter of 2006, more than 3,000 intensive care transports [source: Allgemeiner Deutscher Automobil Club (ADAC)]. In 1998, in the southern part of Germany, AMT was used in 14% of interhospital transports, ground transport using a MoICU in 16%, and standard ambulance with physician in 59% of cases (19). Table 15.3 shows the top ten patient categories using AMT in the United States. Table 15.4 describes patient categories using helicopter transport in Germany.
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Table 15.3 Top ten patient categories using air medical services in the United States |
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Specific Benefits and Drawbacks of Medical Air Transport
Air medical transport can be divided into two categories: Fixed wing or airplane, and rotor wing or helicopter transport. The most important advantage of helicopter transport is that it is time saving, resultant from the aircraft speed and the ability to avoid traffic delays and ground obstacles. This time benefit must be balanced against organizational delays, flight time from the helicopter base to the referring hospital, and transfer between vehicles/ambulances at the beginning and end (14,20). However, helicopters provide a less comfortable environment than road ambulances or airplanes. Cramped compartments, noise, and turbulence may interfere with patient examination, monitoring, and therapy (21). Helicopters have a poorer safety record compared to ground ambulances and fixed-wing aircrafts (14). The National Transportation Safety Board identified poor weather as the greatest hazard to helicopter air medical transport. Other risk factors of helicopter flights are nighttime flights, disorientation from the lack of visual clues, and pressure to make the flight (22). Airplanes provide increased range, greater speed, and more room for the patient(s), crew, and equipment than helicopters. Less cabin noise and turbulence result in fewer problems, and pressurization can be set in the desired range. Airplane operations are limited, however, to areas that have appropriate runways. Furthermore, airplane patient transfers require multiple means of transportation (i.e., hospital to ambulance to airplane) (21).
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Table 15.4 Interhospital transport using air medical helicopter services in Germany: Per patient category |
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Other aspects that must be dealt with during AMT are as follows:
1. Boyle's law, the impact of which is that with increased altitude and decreasing atmospheric pressure, the volume of a gas expands. This can affect any body cavity or piece of equipment that contains a gas. For this reason, patients with a pneumothorax should have an unclamped chest tube. Similarly, other drains should also be unclamped and monitored. Intravenous bags rather than bottles should be used (air in a bottle will expand) and intravenous lines are best placed on pumps. Endotracheal tube cuffs will also expand, so the cuff pressure should be monitored and adjusted, as needed (8). The cuff can be filled with water, but it has been noted that there may still be a rise in pressure (23).
2. Additional stress of flight: Acceleration/deceleration, dehydration, noise, vibration, anxiety, and motion sickness are frequently encountered in helicopters and small airplanes (24).
3. Hypoxemia: As pressure is reduced, the quantity of oxygen available also decreases at altitude. Although oxygen still constitutes 21% of the atmospheric pressure, each breath brings fewer oxygen molecules to the lungs, resulting in hypoxia. Cabin pressurization has eliminated this problem in most airplanes. Patients with impaired pulmonary function are more at risk for hypoxemia.
Patients who might benefit from AMT are those with a time-dependent disorder, because air transport might save time (25). Good clinical studies defining the benefits of AMT for specific patient groups are needed (26). For some patient categories, for example, acute myocardial infarction and traumatic brain injury, the advantages of AMT seem clear (8,27). For other patient groups, data are lacking. Many investigators try to establish the ideal distance in which air medical transport may be beneficial (28). Helicopter air medical transport can be considered for journeys from about 80 to 400 km or over 2 hours. Airplane medical transport tends to be a more efficient process for patients more distant than approximately 400 km from care (18). On the other hand, interhospital ground transport with a dedicated team, proper patient stabilization before transport, and a transport vehicle with intensive care facilities has been proven to be safe over long distances (29,30).
Approach to the Interhospital Transport of the Critically Ill Patient
Indication for the Transfer
A decision to transfer should be made after communication between professionals of the referring and receiving hospital. It must be clear who is responsible for the preparation and transportation of the patient, following existing local and/or international guidelines.
Mode of Transportation, Accompanying Staff, and Necessary Equipment
Each referring and tertiary institution must have a standard plan using locally available resources if the referring facility is not able to conduct the transfer. This plan has to address mode of transportation (standard ambulance, MoICU, air medical transport), transport personnel (intensive care physician and nurse of the referring or receiving ICU, specialist retrieval team), transport equipment, and monitoring during transport.
Guidelines for Transportation
In the literature, several excellent papers have been published with guidelines for equipment, ambulance requirements, and staffing (13,14,15). Strict adherence to simple protocols and guidelines will increase the quality of transports and minimize the risk for the patient.
Emphasizing the Importance of Safe Transport among Medical Professionals, and Hospital Administrators
This is a very important subject in increasing the quality of interhospital transports, since there appears to be little awareness of the problems/adverse events among medical professionals (6). Interhospital transport of critically ill patients requires specific skills of emergency and intensive care medicine. Health authorities should be made aware of the fact that safe critical care transferrals require extensive financial investments.
References
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