Page 44 - JSOM Fall 2021

are drawn from the larger body of work (not yet published) (e.g., radios, extraction harness, flight helmet, and medical
conducted under the auspices of the aforementioned approvals, gear) to commence the 720-m walk to the patient. The ICFP
with consent from the participant. was clothed in a two-piece fire-retardant Nomex flight suit
(Sisley Clothing, https://www.sisleyclothing.com.au/), with
2
Intensive Care Flight Paramedic (ICFP) Characteristics a jacket fabric weight of 160 g/m (GSM) and pants fabric
The ICFP was 44 years of age. He had 23 years of experience weight of 200 GSM and a cotton undershirt. The ICFP was
as a paramedic, with 12 years in the HEMS SAR role. De- wearing a physical activity monitor watch equipped with
mographics, anthropometric, body composition, and maximal wrist-based heart rate monitor and global positioning system
aerobic capacity are shown in Table 1. (GPS) tracking (https://buy.garmin.com/en-US/US/p/541225).
Recording was started at the commencement of the walk and
TABLE 1 Demographics, Anthropometric, and Physical Activity stopped on arrival at the patient, and data were downloaded
Data for the ICFP to the Garmin Connect web platform after case completion.
Age (years) 44 The ICFP was familiar with the Borg rate of perceived exertion
Sex Male scale (RPE 6-20 ) from involvement in previous research within
Paramedic experience (years) 23 the scope of the PES development and therefore was able to
9
ICFP experience (years) 12 self-rate and record physical exertion after the task.
Height (cm) 183 Physiological Demands of the Task
Body mass (kg) 72 The helicopter remained circling in the area whilw the ICFP
Fat free mass (kg) 60.6 walked to the patient. With limited fuel, timely access to the
Body fat (%) 18.0 patient and a prompt decision regarding extraction was essen-
Body mass index (kg/m ) 21.6 tial. Table 2 summarizes the environmental and physiological
2
•
Run Vo (mL/kg/min) 55.3 characteristics of the walk. The 720-m walk carrying 25 kg of
2
ICFP = intensive care flight paramedic. equipment to the patient took 10 minutes 3 seconds at an av-
erage speed of 4.6 km/h in 37.1°C ambient temperature. These
•
Vo 2peak was determined by incremental treadmill running to vo- conditions, coupled with an average track gradient of 14%, in-
litional exhaustion per the method described in Costa et al. duced substantial physiological strain. The ICFP self-rated the
Influence of timing of postexercise carbohydrate-protein in- task difficulty as RPE 6-20 = 19, and average heart rate (HR) was
gestion on selected immune indices. Int J Sport Nutri Exer 81% of predicted maximum, with the highest recorded HR at
Metabol. 2009;19(4):366–384. 95% of predicted maximum. Relative heart rate (RHR) is one
of a number of reliable indices to determine workload and as-
sociated fatigue, with values > 33% signifying the point of in-
Description of the Task 10
crease of physical workload. It is calculated from the formula
Background RHR = HR work – HR /HR max – HR rest. 11 The RHR of 77.5%
rest
Ambient temperature on the day of the case was 37.1°C, and for this task further demonstrates the substantial physiological
this was the second day in a row of temperatures > 35°C and strain of the walk to the patient. As per the method described by
low relative humidity. The aircrew and ICFP completed a Wu and Wang, we were able to calculate maximum acceptable
13-hour shift in similar conditions the previous day and re- work time (MAWT) for this task from the RHR via the formula
sponded to four cases with ~5 hours of cumulative flight time. MAWT (hours) = 26.12 × e (–4.81 × RHR) , R = 0.87 = 0.6281045;
2
The crew had 11 hours of rest in between shifts, and the case therefore, MAWT (min) = MAWT * 60 (min) = 37.7. 10
described in this report occurred 5.5 hours into the new shift
(with no other strenuous work performed prior). The HEMS TABLE 2 Weather, Climate, Topographic, and Physiological Data
aircraft was dispatched by the AV Flight Coordination Centre for Case
to a remote wilderness environment to retrieve a patient with a Ambient temperature 37.1
medical condition. Ground-based resources would have taken Relative humidity (%) 16
up to 2 hours to reach the patient, and transport of the patient Ambient air pressure (hPa) 999.1
back to ground vehicles would require paramedics and the pa- Equipment weight (kg) 25
tient traversing steep, rocky, and uneven terrain. Delivery of
the ICFP to the scene to assess the patient and recover to the Walk distance (m) 720
helicopter was considered the most rapid method to deliver Average track gradient (%) 14
patient care and transport to a medical facility. Time (min:sec) 10:03
Average speed (km/h) 4.3
On arrival at the scene, the patient was located ~720 m along Average moving speed (km/h) 4.6
a remote walking track from the nearest access point. During Maximum speed (km/h) 5.7
scene reconnaissance, the patient was noted to be located in Maximum heart rate (bpm) 180
an area where there was a significant number of tall trees with % Maximum heart rate 95
dead branches that could be dislodged by the helicopter down- Average heart rate (bpm) 153
wash. Furthermore, there was a steep slope, thus insertion via
helicopter winch was deemed as high risk. Given there was % Average maximum heart rate 81
some risk to the patient and bystanders during winch inser- Perceived exertion (6–20) 19
tion, the aircrew delivered the ICFP and equipment to the Relative heart rate (%) 77.5
nearby clearing via a hover exit (exit from the aircraft while Estimated energy expenditure (kcal) 100
it is still running and wheels touching land). Once the aircraft MAWT (min) 37.7
departed, the ICFP loaded the 25 kg of specialist equipment bpm = beats per minute, MAWT = maximum acceptable work time.

42 | JSOM Volume 21, Edition 3 / Fall 2021