Critical care regionalization is becoming more common and studies have supported that the transport of critically ill patients to a tertiary care center leads to better patient outcomes.19 As a result, there is increased interfacility transport of critically ill patients and the need to develop methods for transport of these patients using practices based on the best scientific and management evidence.
Composition of the Transport Team
There are no national data on overall transport volumes or team composition within transport systems. Published guidelines recommend that a minimum of 2 medically qualified people in addition to vehicle operators accompany a critically ill patient, but there are no standard recommendations regarding which patients may be transferred solely with paramedics, which patients require a nurse in attendance, and which patients require a physician in attendance.20
While in urban areas ground transport is most common, in rural areas air transport is more often required because of the distances involved and the difficulties of road travel. In most settings, the emergency medical technician (EMT) is the highest-level care provider on the interfacility transport team, but for critical care transports, it is most often a physician, nurse, or paramedic; many critical care transport programs are using physicians who are still in training on board transport vehicles. However again, there is little information speaking to how the level of experience of the physicians affects outcome. Therefore, current standards for interfacility transport dictate that the decision on transport mode and team composition is based on individual patient requirements, considering minimization of transport time and anticipated treatment requirements during transport.
Medical Management during the Transport
After a literature review concerning medical management in the pre-hospital setting, Ryynänen et al21 concluded that cardiopulmonary resuscitation and early defibrillation are essential for survival, but providing these interventions in the pre-hospital setting has not shown improved survival, so the data regarding their effectiveness are contradictory. Better documentation is available supporting a reduction in mortality in patients with myocardial infarction when pre-hospital thrombolytic treatment is provided. Regarding the trauma patient, it is accepted to provide basic life support (BLS) in the case of penetrating trauma and in cases of short distance to a hospital, but in patients with severe head injuries, advance life support (ALS) provided by paramedics and intubation without anesthesia can even be harmful. There is also some evidence supporting use of ALS among patients with epileptic seizures as well as those with respiratory distress.
Critical care transport often involves advanced airway management that includes establishment of an advanced airway with standard endotracheal tube or backup tools such as laryngeal mask, pharyngotracheal lumen tube, or needle cricothyrotomy with emergency transtracheal jet ventilation. In addition to advanced airway management, ALS transport crews should have equipment available for decompression of tension pneumothorax (ie, either needle or chest tube thoracostomy).20
Mechanical ventilation of intubated patients during transport has been shown to be optimal in comparison with manual ventilation; therefore, several types of ventilators are available for the transport environment. Transport ventilators must be monitored continuously during transport as they are subject to problems such as power failure and disconnection. Pressure-controlled ventilators are used most commonly during transport, and in aircraft they must be adjusted for altitude changes. While providing mechanical ventilation, patients need continuous oximetry and end-tidal carbon dioxide monitoring, to identify clinically unrecognized hypoxia.22
Interfacility critical care transport requires continuous monitoring and clinical management of the patient throughout the transport environment.22 The transporting vehicle should have the necessary power converters for all equipment that could be needed, battery backup in case of electrical failure, and backup oxygen supply in case of vehicle breakdown. In cold climates, provision must be made for maintenance of a warm environment in case of vehicle failure. Transport monitor devices include devices for measuring electrocardiography (ECG), blood pressure, oxygen saturation, and, if necessary, end-tidal carbon dioxide level, pulmonary artery pressure, intra-arterial pressure, and intracranial pressure.20
Defibrillation has been performed safely during flight, and its use does not interfere with other systems on helicopters and fixed-wing aircraft. Medications should be administered by an infusion pump throughout transport to ensure accurate dosing. Many small infusion pumps are available and can be reprogrammed rapidly to manage unstable patients. In addition, new portable intra-aortic balloon pumps and left-ventricular assist devices are available, and can be transported on most ambulances, helicopters, and airplanes.22
Medication lists have been published for the management of the obstetric, neonatal, pediatric, and adult patients during transport.20 Special medications may be required according to patient needs, and protocols should be prepared beforehand for the use of these medications on route. Some common pharmacologic practices include the use of paralytic agents to facilitate endotracheal intubation, and thrombolytic agents for acute cardiac and stroke patients, but in general their use is still controversial.
Intraosseous (IO) access is an accepted method for providing vascular access in the out-of-hospital critically ill patients when traditional intravenous access is difficult or impossible. Different IO techniques have been used showing overall success rates of 50% using the manual needle, 55% using the bone injection gun, and 96% using the EZ-IO.23
Controversies in Management
Blood product transfusion during interfacility transport is controversial. It has been shown that in HEMS using flight nurses, the transfusion of blood can be performed safely and is feasible during transport,24 but the use of blood product transfusions is still limited to the length of the transport during which crystalloid infusion alone will not stabilize a patient. Use of blood products during transport requires adherence to strict standard blood transfusion protocols, with blood administered by properly trained transport personnel.
Current options for mode of transport are the ground ambulance, either a helicopter or a fixed-wing aircraft, and watercraft.20 In many urban centers, all options are available, and in more remote rural areas the airplane is essential. Factors that will influence the mode of transport include the distance and duration of transport, the diagnosis and complications that may arise during transport, the level of training and techniques the transporting personnel can provide, the urgency of access to tertiary care, and local weather conditions and geography. In the United States, helicopters are used frequently for the transportation of trauma patients; a 2007 overview estimated that 753 helicopters and 150 dedicated fixed-wing aircraft are in EMS.25
Ground ambulances have the advantage of rapid deployment, high mobility, and lower cost. However, patients and equipment are subject to significant deceleration and vibration forces.20 Ground ambulance vehicles are usually most readily available and should be considered for transport distances of 30 miles or less. They are categorized as vehicles for BLS or ALS. BLS ambulances are most often staffed with 2 EMTs whereas ALS ambulances are staffed with a paramedic, nurse, or physician as the highest-level provider. Ground ambulances are limited by surface conditions or traffic congestion. All of them should have a backup equipment supply (ie, batteries or oxygen tanks), and ALS ambulances, particularly, must have the necessary outlets for managing ventilators or balloon pumps for interfacility critical transfers. The US Department of Transportation (DOT) has published standards that have been adopted by most states that relate to minimum ambulance configuration and equipment requirements.26 Communication between the ground ambulance and the receiving facility or designated medical control center can be considered during transport.
Fixed-wing or rotary aeromedical transport may be necessary during disasters to extricate victims via air.20 Helicopters should be considered for transports over distances of 30 to 150 miles. They travel at ground speeds of 120 to 180 miles/h and often are dispatched from the receiving tertiary facility or urban area emergency service providers. The physical location of the helicopter at the time of dispatch is important to consider because an inflight round trip to transport a patient may not offer advantages over a 1-way trip by an available ground vehicle. Helicopters usually require a warm-up time of 2 to 3 minutes before liftoff and, allowing for communication time, can be launched within 5 to 6 minutes of receipt of the flight request. Medical transport helicopters are usually staffed by critical care crews, and the number of patients who can be transported is determined by aircraft capacity. Under normal weather conditions, helicopters can fly point to point and land at accident scenes or sending facilities; the liftoff capability depends on the type of helicopter used. Helicopter transports are limited by adverse weather conditions and available landing sites (often a problem in densely populated areas).
Fixed-wing aircraft should be considered for transport over distances exceeding 100 to 150 miles. Being faster, they have the advantage of having a greater range and the ability to fly in difficult weather conditions, but they are limited by the need for ground transportation at both ends.20 Though there is reduced noise, significant forces (fore/aft) are exerted on the patient and may affect critically ill patients who have a decreased physiologic reserve. Aircraft cabins are normally pressurized at altitudes between 6000 and 8000 ft, and this may have effects not only on the patient's clinical condition but also on medical devices.
Watercrafts are rarely used for interfacility critical care transport. However, in special environments, such as offshore islands and oil platforms, watercrafts play a role in medical transport.20 Their use usually comes into play in situations where inclement weather does not allow for helicopter transport. Because of problems with water damage to electric equipment and dangers of staff electric shock from defibrillators, the monitoring and ALS activities that can be supported on watercraft are limited.