Transport of COVID-19 and other highly contagious patients by helicopter and fixed-wing air ambulance: a narrative review and experience of the Swiss air rescue Rega

Every air rescue provider should develop precise SOPs for the use and handling of PPE during HEMS missions. Especially during the current pandemic, with high numbers of infected patients (and individuals with unknown COVID-19 status), strict adherence to these standards on every mission is essential. Simulation training of these special measures to prevent infection is highly recommended for every crew member, as this is known to improve adherence to the SOPs [2, 3].

Table 1 provides an example of an SOP for infection prevention measures in primary (and secondary) HEMS missions during the COVID-19 pandemic, as used by Rega.

During the COVID-19 pandemic, Rega has not used closed suction catheters on primary missions or for transfers between hospitals (secondary transport), and their use is avoided even if they are pre-installed, due to the risk of aerosol production from mobile suction units. Furthermore, most patients with COVID-19 (without bacterial superinfection) have only minor production of bronchial secretions.

Air rescue providers use different concepts for the secondary transport of COVID-19 patients: open transport systems that allow direct patient management through the medical crew wearing PPE (e.g., FFP2/3 mask, goggles or face shield, gloves and protective gown) throughout the transport [4], or closed transport systems (so-called air transport isolator systems) that were originally developed for the fixed-wing transport of patients with other highly contagious and dangerous diseases, such as viral hemorrhagic fever.

There are two basic designs of these isolator systems: closed patient isolation units (PIU), which separate the patient from the medical crew (e.g., EpiShuttle®, EpiGuard HQ, Oslo Norway); Stretcher-Air Transport Isolators (S-ATI), and the larger Trexler Air Transport Isolator (T-ATI; Trexler Air Transport Isolator, UK, United Kingdom and the Rega PIU (Fig. 1). Alternatively, there are open systems which provide a portable isolation facility large enough for both the patient and attending medical staff wearing personal protective equipment (e.g., multi patient transport unit, the Containerized Biological Containment System, CBCS, Phoenix Arizona, USA). In the case of COVID-19, open PIUs do not offer an additional benefit.

Table 2 provides an overview of current concepts used by different air rescue providers in Europe for transporting COVID-19 patients (as of April 5th, 2020; only providers with verified information are listed). Although the authors have made considerable efforts to collect information about transported COVID-19 patients and their operational backgrounds, the table is not exhaustive. Additional patients might have been transported by additional operators or in different aircraft; operational orders may have been modified by the date of publication, etc. Furthermore, not all operators provided the requested information, and there are certainly additional operators who might have transported COVID-19 patients. Nonetheless, the table provides insight into patients transported and the range of operators, as well as into the operational infection control mechanisms involved. At the moment, there is no pan-European register for reporting numbers of transported COVID-19 patients.

For secondary missions that often last several hours, it must be taken into account that working in full PPE during the transport of COVID-19 patients – especially in fixed-wing ambulances or helicopters – is very exhausting and physically stressful for the medical team, which may result in medical errors [3]. Furthermore, close attention must be paid to every movement, in order to avoid accidental disease transmission (e.g., by touching your own face with contaminated gloves). Therefore, for the aeromedical transport of patients with possible or confirmed COVID-19 on secondary missions (fixed-wing ambulances or long-lasting secondary HEMS missions), the use of a PIU offers substantial benefits, in spite of the higher costs and logistical requirements [5].

Closed PIUs also allow patients to be airlifted faster, as fixed-wing ambulances or helicopters do not require additional decontamination between transports (Fig. 2). Another advantage of using small PIUs is the easy transfer from an airplane to an ambulance or rescue helicopter, or vice versa. Thus, all teams involved in transporting these patients can be effectively protected, and the available FFP2/3 respirators can be reserved for use in hospitals. Both commonly used, small, closed PIUs (EpiShuttle® and Rega PIUs) offer these advantages.

However, at present the overall number of PIUs available for Rega is actually limited because they are normally manufactured in Italy (Lombardy). With regard to possible future epidemics or pandemics, to keep a minimum number of PIUs on hand for use in the case of a pandemic might be reasonable.

The Rega PIU (Fig. 3) comprises a flexible safety hull stabilized by arched wires mounted on a hard floor plate. It is maintained under negative pressure by a High Efficiency Particulate Air (HEPA) filtered ventilation system that uses aircraft power within the aircraft and battery power when outside, while the cabin pressure is maintained at a standard cabin altitude of 8000 ft. During development, it was successfully tested against infectious agents and liquid penetration using the EN 14126 test method and the EN ISO 17491-3 fixed-wing test, respectively. Altogether, PIU barrier performance proved equal to that provided by protective clothing. Its fixation system allows transportation on any commonly available patient stretcher. The PIU is designed to fit in a fixed-wing ambulance, a medium-sized helicopter, and ground-based ambulances (Fig. 4). Its dimensions are 200 cm*58 cm*63.5 cm. Power for the PIU ventilation is supplied by a rechargeable battery pack (runtime of 8 h) and a 220 V connector.

Albrecht et al. showed in 2015 [6] that a PIU undergoing sudden loss of cabin pressure at a flight level of 30,000 ft. would lose leak tightness. Consequently, the Rega PIU features a built-in “air bag” that allows for additional air volume expansion encountered with sudden loss of cabin pressure [6]. Therefore, it is currently the only available PIU that allows patient transport in pressurized fixed-wing cabins at usual flight levels.

Plazikowski et al. compared airway management in the Rega PIU with airway management under standard protective measures [7]. The study compared intubation of mannequins using a standard laryngoscope, a video laryngoscope, or cricothyrotomy. Overall, intubation of a patient in the PIU was rated subjectively more difficult compared to standard measures (Visual Analogue Scale 76 vs. 9, p < 0.01). However, success rates in both groups were comparable. Thus, emergency airway management was shown to be achievable even inside the PIU.

Since the beginning of the current pandemic in Switzerland, in March 2020, eighty-three seriously ill patients (55 men, 28 women) infected with COVID-19 were transported. The majority of patients were classified as NACA 4 or 5 (NACA 4: 30 and NACA 5: 42). Thirty-seven patients were spontaneously breathing, forty-six were intubated and ventilated predominantly in IPPV mode (37 IPPV, 3 CPPV, 6 PCV). Eighteen patients needed noradrenaline support for the transport. Flight duration ranged between 5 and 59 min.