Helicopter-based emergency medical services for a sparsely populated region: A study of 42,500 dispatches

Abstract

Background: The Helicopter Emergency Medical Service (HEMS) in Norway is operated day and night, despite challenging geography and weather. In Western Norway, three ambulance helicopters, with a rapid response car as an alternative, cover close to 1 million inhabitants in an area of 45,000 km(2) . Our objective was to assess patterns of emergency medical problems and treatments in HEMS in a geographically large, but sparsely populated region.

Methods: Data from all HEMS dispatches during 2004-2013 were assessed retrospectively. Information was analyzed with respect to patient treatment and characteristics, in addition to variations in services use during the day, week, and seasons.

Results: A total of 42,456 dispatches were analyzed. One third of the patients encountered were severely ill or injured, and two thirds of these received advanced treatment. Median activation time and on-scene time in primary helicopter missions were 5 and 11 min, respectively. Most patients (95%) were reached within 45 min by helicopter or rapid response car. Patterns of use did not change. More than one third of all dispatches were declined or aborted, mostly due to no longer medical indication, bad weather conditions, or competing missions.

Conclusion: One third of the patients encountered were severely ill or injured, and more than two thirds of these received advanced treatment. HEMS use did not change over the 10-year period, however HEMS use peaked during daytime, weekends, and the summer. More than one third of all dispatches were declined or aborted.

Figure 1

Flowchart showing all HEMS missions, with excluded and declined dispatches, aborted and completed missions, and the proportion of completed primary and secondary missions with patient encounter. Primary missions were defined as responses to patients outside hospitals. Secondary missions were defined as inter‐hospital transfers, transporting patients to a higher level of care. Search and Rescue (SAR) missions include searching for the patient or a missing person, or when rescue techniques were used (e.g., rope rescue operation). Examples of other missions are inter‐hospital transportation of a patient to a lower level of care, and transporting blood products, surgeons, or fire crew. *470 declined, and 117 aborted missions (total 1.4% of all HEMS missions) were transferred to other HEMS in the area; hence, these incidents are counted as two dispatches. Some dispatches were declined or aborted with helicopter but completed (with patient encounter) using a rapid response car. ^#1/3 of the completed SAR missions included patient encounter (n = 175).

Figure 2

Distribution of NACA in primary missions with patient encounter and level of treatment performed in the different NACA groups. Basic treatment: Basic airway procedures (manual airway opening/ oropharyngeal airway), suction, oxygen therapy, assisted ventilation, CPAP, defibrillation/electro‐conversion, CPR, naso‐gastric tube, ECG, immobilization (stiff neck collar, backboard, pelvic‐sling, splint), or use of drugs available in the ground ambulance service; epinephrine (only during CPR), cyclizine, metoclopramide, glucose, sublingual glycerol nitrate, acetylsalicylic acid, crystalloids, inhalational ipratropium bromide and salbutamol, naloxone, flumazenil, and paracetamol. Advanced treatment: Intubation/tracheostomy, mechanical ventilation, thoracostomy, chest compression device, thoracic needle decompression, external cardiac pacing, anesthesia, central venous/arterial/intraosseus cannulation, use of neonatal incubator, nerve blocks, ultrasound, use of blood products, and use of drugs not mentioned in the basic treatment. NACA 4 are patients with a condition that can possibly lead to deterioration of vital signs, while NACA 5 and 6 are patients with deranged vital signs and a confirmed life‐threatening injury or disease.19 NACA scoring was missing (not reported) in 706 missions.

Figure 3

Temporal distribution of reasons for declining or aborting primary HEMS dispatches with respect to time of day. *P‐value < 0.05 for difference between observed “no indication,” competing missions, and bad weather, for declining and aborting dispatches (for time of day) and the total of the others compared by Chi‐square test. “No indication” describes when HEMS was dispatched by the EMCC, but the HEMS physician on call decided no indication for advanced medical treatment or helicopter transport, and also includes “coordination” (e.g., other suitable ambulance/resource available). Competing mission specifies a dispatch occurring simultaneously with another mission. “Other reasons” for declining or aborting a dispatch includes patient deceased before arrival, technical problems, crew out of service due to flight regulations, or patient not suitable for transport.