Letter to the editors: the potential role for prehospital thrombolysis and time-critical stroke transfers in the northern Norway aeromedical retrieval system; In response to: Norum J, Elsbak TM: Air ambulance services in the Arctic: a Norwegian study. Int J Emerg Med 2011, 4:1

Norum and Elsbak describe the clinical and transfer characteristics of fixed and rotary wing aeromedical retrievals carried out in northern Norway for the 10 years 1999-2009 [1]. Acute cardiovascular diagnoses were encountered in 76/345 (22%) of the transported cohort [1,2], although it is not stated which, if any, of these patients suffered high-risk acute coronary syndromes (ACS) and/or ST elevation acute myocardial infarction (STEMI). With one in five of the transported cohort potentially having a STEMI or high-risk ACS, a lengthy 3 h 33 min one-way transfer time [1] and attendant delays to accessing primary percutaneous reperfusion, Norum and Elsbak's study could have discussed the role of early recognition of ST elevation and prehospital thrombolysis. Prehospital ECG recognition of STEMI is reliable [3], and prehospital thrombolysis is safe [4] and acutely as clinically beneficial as primary angioplasty if transfer times are anticipated to exceed 120 min from onset of chest pain [5-7], a situation that applies to Norum and Elsbak's study cohort. Furthermore, in high-risk ACS, close ECG surveillance for attainment of lysis criteria followed by timely prehospital thrombolysis could mitigate further ST elevation (and the extent of myocardial injury) during transport [8].Despite the apparent absence of neurological/stroke patients in their 10-year retrieval registry, Norum and Elsbak's [1] emphasis on urgent aeromedical transfer to identify stroke patients suitable for thrombolysis is to be applauded. Stroke lysis with intravenous alteplase remains beneficial when administered at up to 4.5 h after symptom onset [9,10], a time range that remains relevant within the approximately 3.5 h mean transfer time encountered in the northern Norwegian aeromedical system. That rapidly aging adult populations in advanced economies will give rise to increased stroke burden is borne out by the transport of 69 stroke patients among 504 patients (14%) recently retrieved by a single