This experience was led in very good condition for patients, with no adverse effect during transport. It provided valuable information regarding collective evacuation by bus.
A) Safety Of Transport
As stated above, some minor equipment dysfunctions were experienced, hinting at the need of additional spare peripheral items (connectors…) of every sensitive device.
There is no existing literature related to COVID-19 patients interhospital transportation so far. A 2016 review noticed that safety issues of interhospital transports were only recently the focus of some research [2]. Moreover, Droogh et al. [3] signalling that literature was addressing more often medical problems than technical ones, inventoried 55 types of such problems. Authors insisted as well on the ability of the transport team to resolve critical events, the rate of which was measured as concerning 16% of all patients in a 298 cases study [4], but a less worrisome 6.4% in another study involving 368 transports [5]. A 2020 evaluation of short-term mortality after 42,188 interhospital transports [6] advocates for transportation by ALS ambulance to minimize risks, as well as another study [7].
In summary, apart from having ample redundant spare items, the safety of such an interhospital transport relies essentially on the experience of assigned personnel. Specialized retrieval teams comprised of Emergency Medical Services (EMS) regular professionals (and not personnel whose work is restricted to the ICU) must be in charge, because of their specific knowledge of transport technical issues. The CALSA trial run personnel complied with this recommendation.
B) Patients Triage
When the aim of an interhospital transfer is to debottleneck a healthcare system, risks must be reduced as much as possible.
Strauch et al. evaluated short-term outcomes and mortality after interhospital transports by using the Sequential Organ Failure Assessment (SOFA) score [5]. An Experts’ Opinion [8] also recommended the SOFA score for pre-transport evaluation of patients, preferentially to the Simplified Acute Physiology Score (SAPS II) or the Acute Physiology and Chronic Health Evaluation Score (APACHE II). In this publication, patients were excluded if they met one of the following criteria: PaO2/FiO2 ratio < 100 with PEEP > 15 cmH2O, or mean arterial pressure < 60 mmHg despite adequate fluid therapy and vasoactive medication, or after cardiopulmonary resuscitation within 24 h prior to transport.
In the CALSA trial run, the SAMU zonal did provide the exclusion rules: patients with FiO2 > 0.6, or Norepinephrine > 0.2 mg/h, or PEEP > 15 cm H2O were excluded.
C) Stretcher Technique
Commonly, patients transported in ALS ambulance are “packaged” in a VM. Undoubtedly useful for immobilization of trauma patients [9], the VM is not so convenient when moving patients through a narrow corridor because it needs to be handled from the sides.
The entrance of a bus is such a narrow pass. To facilitate access on board, the VM could be associated with a Scoop Stretcher, the former being anchored on the latter. This way, the whole “package” could be handled from both extremities, making the operation smoother.
Consequently, a Scoop Stretcher must be added to the CALSA equipment.
D) Handover Of Patients
SAMU of Hauts-de-Seine achieves annually 2,200 interhospital transports. Its experience leads to emphasize the importance of a stage which interestingly was not stressed upon by the reviewed publications: the moment when devices connected to the patient in its ICU of origin, or in a given vector, have to be changed for other ones because of a handover. This coincides with the patient being moved from bed-to-stretcher (or stretcher-to-stretcher, or stretcher-to-bed) and generally also with a change of the healthcare team in charge.
The trial run showed that a considerable lapse of time was spent for this procedure, compared to the loading and unloading times.
1. Equipment changes
During these bed/stretcher change movements, accidental extubation or catheter disinsertion are likely incidents.
Other sensitive operations during handover of patients are:
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Ventilator change with parameters potentially differing from one model to another;
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Invasive blood pressure to be reinitialised (for zero-level);
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Syringe pumps to be changed with the risk of infusion irregularities;
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And a more or less brutal relocation of the patient onto a new surface.
Thus, limiting these equipment changes in interhospital transports is a safety matter, advocating for door-to-door capability of the vector.
2. Crew changes
When the responsibility of a critically ill patient is being transferred from a healthcare team to another, a comprehensive data transmission is mandatory [10]. A 2019 qualitative study of interhospital transports pointed out the discrepancy between the time spent on the road and the total time of the mission, explaining this by how time-consuming it was to prepare for a transport, collect information, etc. [11]
Again, limiting these crew changes in interhospital transfers pleads for door-to-door capability of the vector.
E) Door-to Door Capability
In their very comprehensive synthesis about methods and issues of interhospital individual transports of patients with ARDS, Jahn et al. [12] outlined the need for not losing time, particularly because of the inability to escalate the therapeutic while en route. They notably insisted on the two necessary intermediate legs of a transport by fixed-wings aircraft, i.e.: from airport to hospital and from hospital to airport, by comparison with helicopters which may land at the hospital itself.
Considering collective transportation vectors, fixed-wings aircrafts and trains require these two intermediate legs between airport or station and hospitals, implying 4 crew changes/equipment changes.
For short distances, because of its door-to-door capability, a bus could be a suitable alternative to reduce these crew changes/equipment changes from 4 to 2. The CALSA accommodating only up to 6 patients, a balanced study between vectors capacities and transport length has to be made on a case-by-case basis.
F) Safeguarding From Contamination
Lockhart et al. [13] highlighted the risks associated with COVID-19 PPE doffing process, when healthcare workers “let their guard down”.
During the “hospital train” trip subsequent to the first leg transport by CALSA, CBRN referent instructors set up a decontamination/doffing pass-through at the bottom of the staircase to the upper deck of the wagon (considered as a “safe area”), the “contaminated area” being by definition the lower deck. This allowed healthcare workers to have a rest during an extended period of work under PPE. This pass-through has to be added to the CALSA configuration for future long-distance transports.
Finally, the air-conditioning system (A/C) was set at the lowest pace because it could not be shut down, the quality of A/C filters being unknown. Healthcare workers being under PPE, this was likely inconsequential for a short trip. For long-distance transports, completely shutting down A/C or considering high efficiency filters will be necessary.
G) Military Vs Civilian Concept For Collective Evacuations
The French Army’s Health Service has been developing since 2006 a collective strategic air medical evacuation capability known as Morphée (Module de Réanimation Pour Haute Élongation d’Évacuation) [14]. Aboard an Airbus A330 MRTT Phénix, it may accommodate 6 to 12 patients over a 10,000 km range.
There is a doctrinal difference between these military collective evacuation resources and the CALSA civilian solution: whereas the civilian vectors are a one-off and engineered for a specific situation, the military have been developing a medical support concept based on early strategic aeromedical evacuation (MEDEVAC) [15]. This strategic MEDEVAC itself is the third leg of a survival chain from the point of injury to homeland [16]. Obviously, these military evacuations have to be performed for patients whose clinical status is not in a stable condition and en route stabilization capabilities are mandatory [17], offering a distinct survival advantage [18].
Civilian-organised collective evacuations cannot address the wartime tactical or strategic situations, hence must be devoted to stabilized (triaged) patients, even if under critical care support, patients eligibility through an appropriate application of risk scores [8] must be evaluated.
During civilian disasters, it is conceivable that stabilized patients may be evacuated by a collective civilian-organised transport such as a CALSA, from the scene to remote hospitals. Another conceivable circumstance is a sudden important need of a sparse specific capability such as burn intensive care beds.