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  The transport of critically ill patients should be undertaken by appropriately trained and supported staff.

  
  
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  All critically ill patients undergoing transport are at risk of complications.

  
  
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  Preparation for transfer requires a systematic approach to assessment, physiological stabilization before departure, and communication between centers.

  
  
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  Adverse event recording and audit may improve the quality of transport systems.

The transport of critically ill patients dates back to the Napoleonic wars, with Baron Dominique Larrey’s invention of the “ambulance volante” to transport injured soldiers rapidly to the surgeon. In the modern era transport with ongoing intensive care support can be dated to Pantridge and Geddes’ 1967 description in The Lancet of the successful transport of over 300 myocardial infarction patients to hospital by mobile intensive care unit with a high success rate for resuscitation.¹

Transport of critically ill patients is a common element in their care, encompassing journeys lasting from a few minutes to many hours. These may include transfer from the scene of injury or illness to the hospital, transport from the emergency department to the radiology department and the operating room, and from there to the intensive care unit. Transport across much greater distances may be necessary in rural areas, for tertiary referrals, and in repatriation from overseas for both civilian and military patients. The main determinants of risk common to all patient movements are dependence on organ system support, physiological instability and limited reserve, and separation from sophisticated diagnostic and therapeutic interventions.

PRIOR TO TRANSFER

Timing: Most transfers within the hospital occur at the convenience of the intensive care, imaging or operating room staff departments, and are contingent on the urgency of the intervention. Critical care transfers between hospitals can be classified as either time critical or nontime critical. An example of a time critical transfer would be that of an acute intracranial bleed requiring urgent neurosurgical intervention.² Transfers outside working hours should be avoided if possible and, if aeromedical transfer is required, transfer during daylight hours is preferable. Duration of both intrahospital and interhospital transfers varies widely; dedicated transfer teams may reduce transfer times by reducing the time required for patient preparation.³

Team Composition: To optimize efficiency and safety, a team leader should assume responsibility for patient preparation, communication between all relevant parties, and team coordination. The composition of the transfer team will depend on the requirements of the patient, specialist equipment in use, such as an intra-aortic balloon pump, and the duration and mode of travel. Team composition will also depend on local protocols, regional systems, and team member experience and training. A 2-year cohort study of 1169 patients transferred by air demonstrated no difference in outcomes between nurse-lead and physician-lead transfer teams.⁴ Indeed, nurse- or paramedic-lead teams may be appropriate for less severely ill patients regardless of the mode of transport.⁵ Longer distance transfers of patients requiring cardiovascular or respiratory support almost certainly benefit from the presence of an appropriately trained doctor as part of the team.^6,7 They should be experienced in anesthesia, intensive care, or an acute care specialty and be proficient in airway management, resuscitation, and organ support.^8,9 Papson et al demonstrated that unexpected or adverse events were common during intrahospital transfers between the emergency department and the intensive care unit. The frequency of these events was negatively correlated with the experience level of the escorting doctor.¹⁰ This effect may be ameliorated by training.¹¹

Some units and organizations will advocate the use of specialist retrieval teams trained to manage patients according to particular protocols.^12-18 This applies to pediatric hospitals and those providing highly specialized services. It has been suggested that use of specialized teams results in fewer adverse events, improved patient outcome, improved staff satisfaction, and an increase in cost effectiveness.^3,18-19 A minimum of two escorts should accompany the patient.^9,20 One of those should be an experienced medical practitioner who is competent at managing the airway as well as providing organ support and resuscitation. All clinical members of the team should be familiar with the patient’s condition and management to date.²¹ They should have received training in patient transportation and be familiar with the transport equipment and environment.^8,9

In some jurisdictions, some of the above provisions are mandated by law. For example, in the United States among other requirements, transfer team members must be appropriately qualified and the relevant documentation must accompany the patient. Medical staff responsible for organizing or undertaking transfers should be familiar with local legal requirements and the recommendations of their national medical bodies.

Mode of Transport: The chosen mode of transport for interhospital transfers will depend not only on the distance to be traveled, but also on the stability and physiology of the patient, urgency of transfer, vehicle and staff availability, weather conditions, cost, and time of day.^21,22 Each mode of transport carries its own advantages and disadvantages (Table 11-1). Smaller countries, such as the United Kingdom, predominantly use a road ambulance system for critical care transfers, with air transport used to transfer patients longer distances from isolated areas or to specialist centers,^22,23 or for trauma retrieval. Larger countries, such as the United States and Australia, rely more heavily on air transport rather than road ambulances. Both the military and private aeromedical companies provide long-distance transportation by air, bridging continents if required.^24-28 Regulatory bodies such as the Federal Aviation Authority (US), Joint Aviation Authority (Europe), and Civil Aviation Authority (UK) stipulate standards for operation of air ambulances.

Patient transportation by any mode subjects the patient to physiological changes. All modes, including simple bed movement during an intrahospital transfer, expose the patient to the effects of acceleration and deceleration, as well as motion sickness, vibration, temperature change, noise, and anxiety.²⁹ Air transport can pose hazards to both the patient and the escorting team.³⁰ Studies evaluating the efficacy of air transport show conflicting results, probably due to geographical factors and differences between systems. A number of studies have concluded that while transfer times may be shorter by air, this does not always correlate with improved patient outcome.^31-33 Gunnarsson concluded that there were no more adverse events associated with air transport when compared to road transportation of pediatric patients³⁴ whereas Mann et al concluded that the removal of a rotary aircraft transfer system for rural intrahospital transfers had increased mortality associated with traumatic injuries.³⁵ When conducted appropriately, transfers by rotary aircraft have been shown to be as safe as road transfers.²² While major adverse events during helicopter transfers are rare, minor physiological events are more common, especially in those patients requiring ventilatory and inotropic support.³⁶ Air transport causes changes in ambient atmospheric pressure, partial pressure of oxygen, and relative humidity.²⁷ Most commercial fixed wing aircraft have their cabins pressurized to 8000 ft above sea level with a total ambient pressure of 565 mm Hg (75.3 kPa).³⁷ At this altitude, the partial pressure of oxygen falls to 65 mm Hg (8.7 kPa). Oxygen saturations in a normal subject will fall to 93% to 94% at this altitude, placing them on the steep part of the hemoglobin-oxygen dissociation curve. In the nonintubated patient, this reduces the oxygen-carrying capacity of blood and increases oxygen requirements. Team members may also feel the effects of reduced oxygen tension with increased fatigue, dehydration, and poor concentration.

According to Boyle’s law, gases increase in volume as pressure decreases (at a fixed temperature). At 8000 ft, gas expands by a factor of 1.35. Gas is normally found in a number of body cavities including the middle ear, sinuses, and bowel. Expansion of such gas can cause discomfort and barotrauma. In the critically ill patient, there may be unwanted gas in the thorax, peritoneal cavity, or skull. Expansion of such gas may have serious consequences. A nasogastric tube should be inserted and placed on free drainage and any pneumothorax should be treated with a chest drain with a one-way valve prior to departure. If air transfer is necessary, some aircraft can pressurize their cabins to sea level, at the expense of speed, increased turbulence, and reduced fuel efficiency.

Whichever vehicle is chosen, it must be appropriately equipped to transfer a critically ill patient. The vehicle should allow unobstructed access to the patient, with seating for staff members within close proximity. The patient, stretcher, and escorting staff must be provided with appropriate fixing points, harnesses, or seatbelts. Oxygen and suction should be available as well as a power supply compatible with the equipment used. Patient and staff comfort should be optimized with adequate heating, air conditioning, and lighting.⁸ Once the vehicle is selected, contact should be made with the relevant control center to book the transport according to the timings required.

Communication: Poor communication is associated with adverse events during transportation.⁴⁰ The team leader is responsible for ensuring there has been clear communication with all relevant parties.

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  Patient: If feasible, consent for the transfer should be obtained from the patient following a discussion of risks and benefits.⁹ The patient should be kept informed of the progress of their transfer at all times.

  
  
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  Patient’s next of kin: An explanation of the risks and benefits of the transfer as well as the contact details for the receiving unit should be provided, particularly when this involves a transfer of responsibility of care.

  
  
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  Transferring specialist: The decision to transfer the patient lies with the specialist with overall responsibility for the patient’s care.⁹ Any other specialists involved in the patient’s care must be made aware of the transfer and timings. A comprehensive summary of the patient’s condition should accompany them.

  
  
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  Receiving specialist: The final decision to accept the patient lies with the receiving critical care specialist.⁸ Once the patient has been accepted by the receiving specialist the following information should be confirmed to them:

  
  
  
  
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    Reason for transfer

    
    
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    Patient name, age, sex

    
    
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    Medical history

    
    
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    Details of current clinical condition

    
    
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    Details of current therapy

    
    
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    Change in therapy to be undertaken for transfer

    
    
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    Infection risk

    
    
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    State of family communication

    
    
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    Mode of transfer

    
    
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    Time frame of transfer

    
    
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    Contact details for referring team

  
  
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  Other specialties involved: Handover should be provided between all the teams involved in the patient’s care at the discharging unit and the receiving unit, including details of nursing care.

  
  
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  Critical care network: Depending on the location, there may be central coordination of critical care beds, thus transfers should usually be arranged with the approval of the critical care network administrator.^8,41,42

  
  
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  Ambulance control/aeromedical control center.

  
  
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  Hospital porters/orderlies.

This can be delegated to another team member if required. All communication should be documented clearly, with copies kept by the discharging and receiving units.

Preparing the Patient: A number of risks associated with patient transfer can be attributed to inadequate patient stabilization prior to departure. Patients transferred with cardiovascular or respiratory instability have higher overall mortality than those who are stable during transfer.⁴³ In a survey of 100 consecutive interhospital transfers, Olson et al identified 45 errors in stabilization in 28 patients, many resulting in morbidity or mortality.⁴⁴ A thorough, systematic approach must therefore be taken when preparing the patient for transfer. Equipment and drug requirements will depend on the duration of the transfer (Table 11-2). Hazards of intrahospital transfer are almost identical to those of interhospital transfer.²¹ Standardization and homogeneity of such an approach reduces transfer-related risks.⁴⁵ The discharging team should be involved in patient preparation, facilitated by local guidelines provided by the transportation team or unit.⁴⁶ All body systems should be examined carefully. In all but the most spacious of vehicles, access to the patient is likely to be limited, and procedures such as line insertion and tracheal intubation can be particularly difficult. The patient may undergo physiologic changes in any organ system, and appropriate monitoring and medication to deal with such changes should be available during transfer. The advent of transportable monitoring in the 1970s resulted in early recognition and management of patient deterioration during transfer.⁴⁷ The monitoring used during transfer should have the same capabilities as that used on the intensive care unit and, ideally, should be capable of data recording, although this does not obviate the requirement for written documentation.²⁰ Charts and results for the previous 12 hours should be reviewed to assess patient stability and suitability for transfer.