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Zhao et al. Vessel Plus 2021;5:10 I http://dx.doi.org/10.20517/2574-1209.2020.77 Page 3 of 12

Further challenges were encountered in the strict no lift policies employed by the local ambulance service
(Ambulance Victoria), where all stretchers are hoisted into the ambulance using an electronic floor-
mounted loader. This is opposed to the more simplistic manual lifting mechanisms for stretcher hoisting
used in some international services. Under normal circumstances the loader mechanism does not allow
the stretcher to be lifted or lowered whilst inside the ambulance. However, due to the need for patient
positioning to align with the CT scanner, a technical workaround was required to manually disengage the
stretcher from the loader whilst inside the MSU. This procedure makes the patient loading workflow more
complex and requires two trained paramedics to operate the stretcher loading sequence.

The staffing composition of the Melbourne MSU, with a neurologist/senior stroke fellow, nurse specialist,
radiographer, and two paramedics (one with airway and cardiac resuscitation training), was chosen to
reflect a standard in-hospital acute stroke team in Australia. The addition of a paramedic with advanced
level training was to cater for stroke patients with unstable conscious state or at risk of neurological
deterioration. In comparison to international services, this is a large and highly experienced team,
especially as some units operate without neurologists or do not have stroke nurse specialists. Many also
utilize CT or emergency technicians who generally have less training than their Australian counterparts.
This level of experience has undoubtedly enabled optimized workflows on the Melbourne MSU, compared
to a typically more junior in-hospital team.

[2]
General operational workflows for the Melbourne MSU have been previously described . The operating
hours (weekdays from 8AM-6PM) was decided in part from modelling and by logistical considerations for
staff. The operational hours were designed to capture approximately 64% of all suspected stroke dispatches
within the 20-kilometre primary co-dispatch radius, whilst simultaneously being able to be broken into two
5 h morning and afternoon shifts. The estimated workload appears to be consistent with the experience of
the first 24 h MSU based in Toledo, USA where the vast majority of dispatches occurred from 7AM-7PM
[6]
and the bulk of the thrombolysis cases occurred between approximately 10AM-6PM .
The primary dispatch radius of the Melbourne MSU was set at 20-kilometres of the home base of Royal
Melbourne Hospital. Within this zone, the MSU transports patients to 9 metropolitan stroke centers, of
which 4 have 24 h capability for endovascular thrombectomy and neurosurgery. This radius was based
on the estimated average on-scene time of 28 min for Ambulance Victoria attending stroke patients in
metropolitan Melbourne (unpublished data, Ambulance Victoria, 2017). As the MSU uses a co-dispatch
model, a closer local ambulance crew would arrive and commence extrication with the expectation that
the MSU would arrive before they were ready to transport to hospital within this timeframe. Compared
to international services, both the Berlin and Houston metropolitan MSUs use a dispatch radius that
approximates a 15 min drive or 7 miles (11.3 kilometres) due to the faster on-scene times of their local
[4,5]
[7]
ambulance services.
Following a period of operation, the Melbourne MSU began accepting suspected stroke cases outside
the 20-kilometre central Melbourne radius where initial attending paramedics had requested the service.
In many of these cases the nearest stroke center was in the direction of the MSU base and there was an
opportunity for the service to rendezvous with the initial ambulance prior to arrival at hospital. This
approach has been successfully by the Houston MSU to double their standard response radius from the
[7]
usual 6 miles to 12 miles . Whilst attending these cases may prevent some concurrent dispatches within
the usual 20-kilometre radius, these paramedic-screened cases have a higher specificity for stroke and
therefore a higher likelihood of benefitting from MSU management. Should Melbourne paramedics also
[8]
identify the patient has having a severe stroke syndrome using the ACT-FAST triage algorithm , there is
a good chance that the patient may require bypass of the peripherally based hospital for an endovascular
thrombectomy (EVT) center that is usually based in central Melbourne.