The key elements that needed to be established for a dedicated aeromedical transfer service to launch are described below:
1. Coordination and activation of a specifically tailored and rehearsed level 3 COVID-19 transfer process.
Transfer requests would be identified via a central process to the South East Coast Ambulance Service (SECAmb) following a daily regional meeting and subsequently passed to the AAKSS Duty Clinical Manager. This would then set off a chain of defined concurrent activity in order to plan the conduct of the tasking. Each individual transfer request would be overseen by the Duty Clinical Manager and an on-call AAKSS HEMS Transfer Consultant (with experience in both pre-hospital emergency medicine and current ICU COVID-19 care). The Duty Transfer crew consisted of a Transfer Doctor (who was an AAKSS HEMS doctor from an ICU-Anaesthesia specialty) and an AAKSS Transfer Paramedic. The temporal nature of identifying and tasking a transfer following the receipt of requests after regional meetings meant that transfers typically occurred in the afternoon and evening. The process overview is shown in Fig. 1.
2. Case “Interrogation” process.
Requests for COVID-19 transfers were coordinated at regional level by the Critical Care Operational Delivery Network and SECAmb. Each request was considered on an individual basis by AAKSS. A patient selection proforma utilised a specifically tailored case interrogation template, as shown in Fig. 2. The complexity, instability and physiological fragility of COVID-19 patients meant that rigorous clinical interrogation, with case-by-case consideration of the challenges posed by moving these patients was required on each occasion.
Prior to deploying on a transfer tasking, a “command huddle” was conducted. At the command huddle the transfer team, duty transfer consultant and duty clinical manager would appraise the clinical and logistic aspects of the case, identify potential risks and pitfalls, discuss mitigation strategies, and decide the most appropriate course of action. Particularly complex or high-risk transfers were escalated to the Medical Director for further review and final decision making.
The crew configuration was delivered by AAKSS PHEM doctors and paramedics. The doctors were all experienced, long-standing AAKSS PHEM doctors and were additionally Consultants in Anaesthesia and Intensive Care Medicine and had recent and regular ongoing exposure to patients who were critically unwell with COVID-19. The AAKSS paramedics had undertaken concurrent training in certain specific elements in critical care and COVID-196. This specific crew-configuration allowed for a familiarity in caring for the critically unwell patient in the out-of-hospital environment. Familiarity between members of the workforce was a particularly important factor in overcoming the additional and significant challenges posed by operating in full Level 3 PPE.
A competency-based critical care transfer training module was developed and instituted to ensure specific training and currency in critical care practice and the management of patients with multi-organ dysfunction. Training built upon the pre-existing PHEM practices and expertise and, as the service developed, was further enhanced, and standardised to a formal training pathway for Critical Care Transfer Medicine. All transfer team members undertook a one-day HEMS Transfer Training Day, along-side a half-day Critical Care COVID Transfer Medicine Package, with a specific focus on the physiology, pharmacology and practical techniques required to manage complex and critically ill patients. Individual crew members were then required to complete a curriculum of core clinical topics, equipment competencies and logistic considerations. It took varying amounts of time for crew members to develop competence and confidence in critical care transfer and while there was no set time to complete the training log, 2–4 weeks was suggested. During this period the Crew Member also undertook at least four transfer shifts under the supervision of a Transfer Consultant. Training culminated in a full-day sign-off assessment, including a clinical viva, equipment OSCE and clinical long-case discussion.
A specific, dedicated set of transfer equipment and bags were carefully assembled. The content was based on the need to maintain the highest standards of intensive care throughout the duration of the transfer. Ventilation was provided with a Dräger Oxylog 3000 ventilator in line with our primary HEMS work and monitoring maintained using the Tempus Pro Monitor (Phillips RDT). This allowed for the added advantage of recording physiological data directly into the electronic clinical record. Infused medicines were delivered via Braun perfusor syringe drivers. Using identical equipment to that used in primary HEMS work was an important consideration in order to enhance the safety of this type of work and minimise the cognitive load that comes with managing patients of this complexity. The transfer kit was physically entirely separate to the HEMS kit and could be deployed onto a land ambulance or helicopter. Personal protective equipment was in-line with standard hospital practice including eye protection, FFP3 masks and surgical gowns. Crews were also given the option of wearing Positive Airway Pressure Respirator hoods.
6. Transfer platform and infrastructure
All critical care transfers were considered for transfer via land, air or a land-air hybrid. Given the large geography involved in some of the proposed transfers, the potential opportunity for air or hybrid transfer mission cycles allowed an enhancement in care by decreasing the period a sick COVID-19 patient was out of a hospital ICU environment. This also accelerated the regeneration of the critical care transfer crew. Several transfers, including the long-distance mission cycles, whilst considered for air transfers, often resulted in either pure land or hybrid transfers. This was due to the time of year being winter (December-February), with both light and weather constrictions which made long-distance critical care transfers by air using visual flight rules challenging to undertake.
7. Care of the COVID-19 patient during transfer
Meticulous handling of the COVID-19 patient was required prior, during and after transfer. Respiratory failure was the overwhelming organ failure, requiring multi-faceted management strategies, particularly for refractory hypoxia. Stabilising the patient on the transport ventilator was a particular challenge for some patients and was typically attempted early in the transfer process. The complex implications of COVID-19 on the vascular structure and haematological dynamics, often with a pro-thrombotic propensity, gave these patients a uniquely precarious physiological fragility. The interrogation process between the referring ICU consultant and transfer team was important, but a further dynamic assessment of the patient was essential on transfer team arrival at the referring ICU. Gentle bridging on to transfer specific infusion pumps, ventilator, monitoring and bed was essential followed by careful handling of the patient’s complex pathophysiology. Pre-arrival requests were structured, as shown in Fig. 3.
8. Interpersonal Relationships, Human Factors and Communication
The management of a COVID-19 patient is made harder by the need to work carefully in full PPE. Clear communication was therefore imperative. As a Critical Care Transfer Team, it was important to forge relationships with referring critical care teams, clearly communicate with the receiving ICU and work cohesively alongside a number of new groups of health professionals and team members. The primary PHEM training and practices, particularly in crew-resource-management (CRM) and communication skills, proved a core strength and foundation for the critical care transfer capability response.
9. Aircraft modification
To protect the pilots, a gas-tight curtain was installed between the cockpit and cabin section of the AW169 helicopter. Pilots flew with standard surgical masks, following testing and approval of radio communications whilst wearing them. The size and specification of the AW169 cabin allowed for excellent access to the patients throughout flight, and the ability to maintain monitoring and titrate infusions presented no problems. A closed suction system allowed for in-flight suction of the trachea if required.
10. Clinical Governance
A specific Clinical Governance framework was established that mirrored that of AAKSS primary missions but stood as an independent framework. Whilst this specific process was created de novo to address a specific challenge in the critical care transfer of level 3 COVID-19 patients (Fig. 1), it was embedded in a mature system of standard operating procedures, governance and logistics. A dedicated Transfer Consultant was on-call for remote support and all cases underwent detailed case review.
Analysis of the 50 Critical Care Transfers during the UK COVID-19 second wave
Between 18 December 2020 and 1 February 2021, AAKSS in collaboration with SECAmb performed 50 adult critical care transfers in support of the UK COVID-19 response.
All 50 of these critical care transfers were undertaken to urgently help with ICU capacity across the region. These ICUs were all managing patient numbers significantly beyond their normal footprint. As a result, through a nationally coordinated reconfiguration initiative, other ICUs with capacity were identified to provide mutual aid, often in areas a significant distance away.
Of the 50 critical care transfers, 45 (90%) were critically unwell patients receiving Level 3 multi-organ support. 5 (10%) patients were receiving critical care for non-COVID19 disease processes.
The mean age of these patients was 58 years (29–83). 30 (60%) were male and 20 (40%) were female.
The AAKSS aircraft was used for 3 (6%) transfers and 47 (94%) were moved by road. To our knowledge, this represented the first civilian air transfers of COVID-19 positive patients in the UK.
All of these patients were invasively ventilated with mandatory or pressure support ventilation. 45 (90%) of these patients had an endotracheal tube in situ and 5 (10%) had a tracheostomy sited to facilitate weaning from mechanical ventilation.
The mean FiO2 at referral was 0.45 (0.21–0.8). 17 (34%) patients were established on vasopressor support at the point of referral, versus 33 (66%) on no cardiovascular support. All 17 patients on vasopressor support were receiving noradrenaline, with 1 patient also receiving dobutamine.
The mean total mission cycle (time of referral until the time team declared free at receiving hospital) was 264 minutes (range 149–440 min). The mean time spent at the referring hospital prior to leaving for the receiving unit was 72 minutes (31–158). The mean transfer transit time between referring and receiving units was 72 minutes (9–182).
During this period, no significant adverse events occurred and there were no instances of transfer team members or pilots contracting COVID-19 as a result of a transfer mission.