A comparison of historical versus proposed physical employment standards for flight paramedics performing helicopter winch rescue

BACKGROUND

Paramedics working in helicopter teams undertake water and land rescues. Historical assessments of role-related fitness were not developed using physical employment standards methodology.

OBJECTIVE

To compare the historical selection tests with new tests developed via contemporary scientific methodology.

METHODS

Candidates undergoing selection to the role of flight paramedic (n = 14; age 37±5 yrs, body mass index [BMI] 26±4 kg.m2) undertook existing paramedic selection tests on land and in water, measurements of task duration, maximum heart rate (HRmax), rate of perceived exertion (RPE6 - 20) and capillary blood lactate (Lacmax) were recorded. These results were compared to the same variables in experienced paramedics (n = 14; age 44±5 yrs, BMI 25±3 kg.m2) who undertook the new tests.

RESULTS

Land task duration (existing 17±2 min vs. proposed 7±2 min, p <  0.05) HRmax (existing 186±13 b.min-1 vs. proposed 173±11 b.min-1, p <  0.05), and Lacmax (existing 23±3 mmol.L-1 vs. proposed 8±2 mmol.L-1, p <  0.05) were higher in the existing test compared to the proposed tests. Water task duration (existing 12±2 min vs. proposed 10±1 min, p <  0.05) was longer in the existing test, but HRmax (existing 166±18 b.min-1 vs. proposed 167±15 b.min-1, p = 0.90), Lacmax (existing 11±4 mmol.L-1 vs. proposed 11±4 mmol.L-1, p = 0.90) did not differ. RPE6 - 20 did not differ between groups for water or land.

CONCLUSIONS

The historical land-based physical tests for paramedics differed from the proposed tests, however the water-based tests had similar duration and physiological demands. Use of tests not developed via established scientific methodologies risks eliminating candidates suitable to work in the role, or including candidates that are not.

Reliability and Validity of a Flume-Based Maximal Oxygen Uptake Swimming Test

A mode-specific swimming protocol to assess maximal aerobic uptake (VO₂max_sw) is vital to accurately evaluate swimming performance. A need exists for reliable and valid swimming protocols that assess VO₂max_sw in a flume environment. The purpose was to assess: (a) reliability and (b) "performance" validity of a VO₂max_sw flume protocol using the 457-m freestyle pool performance swim (PS) test as the criterion. Nineteen males (n = 9) and females (n = 10) (age, 28.5 ± 8.3 years.; height, 174.7 ± 8.2 cm; mass, 72.9 ± 12.5 kg; %body fat, 21.4 ± 5.9) performed two flume VO₂max_sw tests (VO₂max_swA and VO₂max_swB) and one PS test [457 m (469.4 ± 94.7 s)]. For test-retest reliability (Trials A vs. B), moderately strong relationships were established for VO₂max_sw (mL·kg^-1·min^-1)(r= 0.628, p = 0.002), O₂pulse (mL O₂·beat^-1)(r = 0.502, p = 0.014), VEmax (L·min^-1) (r = 0.671, p = 0.001), final test time (sec) (0.608, p = 0.004), and immediate post-test blood lactate (IPE (BLa)) (0.716, p = 0.001). For performance validity, moderately strong relationships (p < 0.05) were found between VO₂max_swA (r =-0.648, p = 0.005), O₂pulse (r= -0.623, p = 0.008), VEmax (r = -0.509 p = 0.037), and 457-m swim times. The swimming flume protocol examined is a reliable and valid assessment of VO₂max_sw., and offers an alternative for military, open water, or those seeking complementary forms of training to improve swimming performance.

The physiological demands of helicopter winch rescue in water and over land

Physically demanding water and over land winch rescues are critical tasks for helicopter paramedics. To assess the physiological demands of winch rescue, 14 intensive care flight paramedics (12 male, 2 female, mean (±SD) age 44.3 (±5.4) years, experience 7.1 (±5.2) years) completed land and water-based task simulations. For the land task, VO₂ was 41.7 (±4.5) mL kg^-1 min^-1, or 86 (±11) % of VO_2peak. Task duration was 7.0 (±3.6) min, or 53 (±27) % of maximal acceptable work duration (MAWD) (13.2 (±9.0) min). For the water task, VO₂ was 36.7 (±4.4) mL kg^-1 min^-1, (81 (±12) % of VO_2peak). Water task duration was 10.2 (±1.1) min, or 47.6 (±4.8) % of calculated MAWD (21.0 (±15.6) min). These results demonstrate that helicopter rescue paramedics work at very high physiological workloads for moderate durations, and these demands should be considered when developing selection tests and when deploying to rescues, to ensure staff are capable of task performance. Practitioner summary: Paramedics performed helicopter winch rescue task simulations in water and over land. Paramedics worked at 81% of VO_2peak for 10.2 min and 86% of VO_2peak for 7 min for swim and land tasks respectively. Rescue organisations should consider these demands when selecting and credentialing staff and when deploying to incidents. Abbreviations: HEMS: helicopter emergency medical service; ICFP: intensive care flight paramedic; MAWD: maximal acceptable work duration; PES: physical employment standards; SAR: search and rescue.

Comparison of swimming versus running maximal aerobic capacity in helicopter rescue paramedics

Swimming is a critical task for helicopter rescue paramedics and aerobic capacity is assessed in this occupation to determine job suitability. We evaluated one treadmill-based and one pool-based assessment of maximal aerobic capacity (V̇O_2peak) in 14 helicopter rescue paramedics. There was a small absolute difference (p = 0.11, d = 0.46) between V̇O_2peak in the swim (45.5 ± 7.8 ml.kg^-1.min^-1) compared to the run (48.5 ± 5.5 ml.kg^-1.min^-1), with a moderate relationship noted (r = 0.74, 95% CI [0.35-, 0.91], p = 0.0023). Whilst not interchangeable, run V̇O_2peak was a predictor of swim V̇O_2peak. Maximal blood lactate was similar (p = 0.93) in swim (13.4 ± 3.8 mmol.L^-1) and run (12.2 ± 3.0 mmol.L^-1), and maximal heart rate 13% lower (p < 0.0001) in the swim (162 ± 11 bpm) versus the run (186 ± 10 bpm). To estimate swimming V̇O_2peak in paramedics a treadmill test is sufficient but does not replace assessment of swimming proficiency. Practitioner Summary: We developed a swim protocol to assess maximal aerobic capacity in helicopter rescue paramedics. Compared to a treadmill-based test, our swim protocol generated 20% lower submaximal V̇O₂ and 6% lower V̇O_2peak. Although not interchangeable, a treadmill V̇O_2peak test is indicative of maximal aerobic capacity in rescue paramedics whilst swimming. Abbreviations: HEMS: helicopter emergency medical service; PES: physical employment standards; ICFP: intensive care flight paramedic; RPE: rating of perceived exertion.