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Walter et al. Vessel Plus 2021;5:27 https://dx.doi.org/10.20517/2574-1209.2020.102 Page 5 of 10

connection to a stroke specialised centre so that stroke patients in remote regions could obtain diagnosis
and treatment at the emergency site. The large Victorian Stroke Telemedicine project, a state-wide
programme to establish access to acute stroke thrombolysis in non-specialised regional hospitals has
[31]
demonstrated that the delivery of acute remote stroke specialist support can be safely implemented .

The advantage of a helicopter solution is the potential for rapid activation (no runway needed) and the
direct landing possibilities on hospital helipads. A fixed-wing aircraft, however, would be able to cover a
much wider area of approximately 5000 km in radius with a shorter flying time.

There are different settings in which such an Air-MSU could be beneficial and it can be assumed that the
daily operation of such an Air-MSU would need to have a high level of flexibility, mainly because constant
changes are likely to occur in the setting depending on the actual emergency call and situation on scene. An
Air-MSU could be used in a similar way to a road MSU as a first responding ambulance directly dispatched
to the patient. The team would then function as first emergency medical team for the patient, independent
of the actual medical condition. The disadvantage of this arrangement is that the crew is then locked into
the current event and therefore might not be available for other even more deserving calls. For example, a
stroke patient who may be suitable for early therapeutic intervention appears while the current call turns
out to be a stroke-mimic.

Alternatively, the Air-MSU could operate in a rendezvous system and meet the patients en-route once a first
local emergency medical service crew has clinically confirmed the stroke diagnosis. This setting is
dependent on the availability of the local emergency medical service and might vary from day to day. The
advantage is not only that the diagnosis accuracy of the stroke call is higher for the Air-MSU team but also
that there would be additional help available to manage a difficult scene.

In both scenarios an acute stroke treatment with intravenous thrombolysis, could be initiated at the
emergency site, saving crucial time for the patient.

A third scenario would be an inter-hospital transfer of patients from local hospitals/health care centres to
stroke specialised centres. A recent publication of the RFDS stroke retrieval calls in rural Australia describes
more than 1700 retrieval flights for acute stroke patients in a period of 4 years with a median flight distance
of 291 km per patient and a median transfer time of 238 min. The subtype of the stroke was not categorised
[32]
for most of these patients as CT scanners were not available so that a specific therapy such as intravenous
thrombolysis could not be started. Most of these transfers were time consuming with an attendant delay
such that patients were usually outside their treatment time window once arriving at the stroke centre . In
[15]
this situation, the Air-MSU could provide immediate stroke diagnostic assessment and treatment initiation
before transferring the patient to the required level of stroke care.

However, all these scenarios depend on an accurate direct dispatch of the Air-MSU and the first team
involved to develop a likely working diagnosis of an acute stroke including treatment eligibility. This is one
of the significant hurdles in the delivery of acute stroke care, as well as in standard stroke management.
Inappropriate activation of a specialised stroke team reduces its targeted capacity for those likely to benefit.
This is even more relevant when the specialised stroke team has long distances to travel for patient retrieval
as would be the case with an Air-MSU approach. Hence, an appropriate implementation of such a novel
system of care would require an optimised pathway to identify relevant patients. This would include an
embedded, country- and region-specific education programme, not only for the dispatch centres, but also
for the local emergency medical service, healthcare centres and every other link in the chain. Specialised