Comparison of Helicopter Emergency Medical Services Transport Types and Delays on Patient Outcomes at Two Level I Trauma Centers

Figures & data

Figure 1. Study flow diagram detailing selection and categorization by transport method for all trauma patients between January 1st, 2012–December 31st, 2014.

Table 1. Baseline characteristics of patients transported by helicopter emergency medical services

	Overall (n = 911)
Age, n (%)
15–55	615 (67.5)
>55–65	125 (13.7)
>65	171 (18.8)
Sex, n (%)
Male	678 (74.4)
MOI, n (%)
Blunt	864 (94.8)
Penetrating	47 (5.2)
MOI Detailed, n (%)
Motor vehicle collision	323 (35.5)
Fall	187 (20.5)
Motorcycle collision	86 (9.4)
Pedestrian struck	57 (6.3)
Stab wound	21 (2.3)
Gunshot injuries	13 (1.4)
Other	224 (24.6)
Injury Severity Score, n (%)
<15	249 (27.4)
15–24	310 (34.0)
25–34	238 (26.1)
35–44	71 (7.8)
>45	43 (4.7)
Admission vital signs, mean (SD)
Heart rate, beats/min	90 (22.7)
Systolic blood pressure, mmHg	135 (29.8)
Respiratory rate, breaths/min	19 (4.1)
Glasgow Coma Scale, n (%)^*
13–15	574 (64.0)
9–12	37 (4.1)
<8	286 (31.9)
Outcomes
Discharged home from ED, n (%)	39 (4.3)
ICU admission (%)	464 (50.9)
Placed on ventilator (%)	448 (49.2)
Ventilator days, d median (IQR)	4.0 (2.0–12.0)
Hospital LOS, d median (IQR)	9.5 (4.0–18.0)
Overall mortality, n (%)	99 (10.9)

^* 14 missing values.

Table 2. Comparison of patient characteristics of helicopter emergency medical services by method of transport

	Scene Call	Modified Scene	Interfacility Transfer
	(n = 139)	Call (n = 333)	(n = 439)	P-value
Age, n (%)
15–55	96 (69.1)	252 (75.7)	267 (60.8)	<0.01
>55–65	23 (16.5)	46 (13.8)	56 (12.8)
>65	20 (14.4)	35 (10.5)	116 (26.4)
Sex, n (%)
Male	101 (72.7)	250 (75.1)	327 (74.5)	0.86
MOI, n (%)
Blunt	135 (97.1)	317 (95.2)	412 (93.9)	0.29
Penetrating	4 (2.9)	16 (4.8)	27 (6.1)
Injury Severity Score, n (%)
<15	51 (36.7)	79 (23.7)	119 (27.1)	<0.01
15–24	37 (26.6)	98 (29.5)	175 (39.9)
25–34	26 (18.7)	92 (27.6)	120 (27.3)
35–44	13 (9.4)	44 (13.2)	14 (3.2)
>45	12 (8.6)	20 (6.0)	11 (2.5)
Admission vital signs, mean (SD)
Heart rate, beats/min	92 (23.6)	93 (24.8)	89 (20.7)	0.05
Systolic blood pressure, mmHg	136 (29.2)	131 (34.0)	139 (26.0)	<0.01
Respiratory rate, breaths/min	20 (3.8)	19 (4.8)	18 (3.5)	0.01
Glasgow Coma Scale, n (%)^*
13–15	104 (75.9)	185 (55.9)	285 (66.4)	<0.01
9–12	7 (5.1)	18 (5.4)	12 (2.8)
<8	26 (19.0)	128 (38.7)	132 (30.8)
Outcomes
Discharged home from ED, n (%)	12 (8.6)	13 (3.9)	14 (3.2)	0.02
ICU admission (%)	58 (41.7)	171 (51.4)	235 (53.5)	0.05
Placed on ventilator (%)	57 (41.0)	200 (60.1)	191 (43.5)	<0.01
Ventilator days, d median (IQR)	4.0 (2.0–14.0)	5.0 (2.0–13.0)	3.0 (2.0–9.0)	0.11
Hospital LOS, d median (IQR)	10.0 (4.0–18.0)	11.0 (4.0–25.0)	9.0 (5.0–17.0)	0.09
Overall mortality, n (%)	11 (7.9)	46 (13.8)	42 (9.6)	0.08

^* 14 missing values.

Table 3. Transport times for different methods of transport for helicopter emergency medical services

	Scene	Modified	Interfacility
	Call	Scene Call	Transfer
Time in minutes, median (IQR)
Call accepted to HEMS launched	9 (5–11)	10 (6–12)	10 (6–14)
HEMS launched to arrival at landing site	20 (14–28)	26 (16–37)	30 (22–41)
Arriving at landing site to patient contact	3 (2–5)	8 (5–12)	9 (5–13)
Time on scene or in hospital	10 (6–12)	20 (10–33)	30 (20–42)
Departing scene/hospital to arriving at landing site	5 (2–8)	10 (5–13)	11 (7–15)
Departing landing site to arriving at trauma center	17 (11–29)	25 (16–34)	30 (23–40)
Arriving at trauma center to handover to trauma team	10 (8–15)	11 (9–15)	14 (9–19)
Total transport time in minutes, median (IQR)	80 (61–100)	118 (91–153)	145 (116–175)

Table 4. Identified delays to helicopter emergency medical services transport of trauma patients

	Percent of time
	responsible (%)
Delays arriving at patient (n = 50)
Refuel^*	34.0
Mechanical or medical check of aircraft	20.0
Crew change^*	14.0
Weather check/poor weather	12.0
Cancelled from call then called back^*	10.0
HEMS crew busy on another call	6.0
Dispatching issues^*	4.0
Delays on scene or in hospital (n = 85)
Sending physician doing procedure^*	24.7
Waiting to meet land EMS^*	16.5
Delays for diagnostic imaging^*	14.1
Prolonged extraction	12.9
Confirming disposition or destination^*	12.9
Needed urgent resuscitation or intubation by HEMS crew	11.8
Waiting for aircraft to return from refuel^*	4.7
HEMS crew waiting to speak to patch physician^*	1.2
Multiple injured patients needing triage for HEMS transport	1.2
Delays arriving at trauma center or handing over to team (n = 27)
Waiting for land EMS escort^*	37.1
Poor weather	18.5
Trauma team not assembled^*	14.8
Patient arrested en route	7.4
Unclear who receiving team was^*	7.4
Transfer care to another HEMS crew^*	3.7
Other HEMS crew had to depart with more seriously injured patient	3.7
Patient driven by land EMS to avoid pilot duty out^*	3.7
Refuel^*	3.7

^* Considered modifiable delay.