The subarachnoid space is the space in the brain between the pia and arachnoid mater. It contains the blood vessels that supply various regions of the brain and the cerebrospinal fluid [1].

Aneurysms are bulges or weakenings in the walls of blood vessels, commonly where the vessels split. These weakenings can eventually cause the aneurysm to burst and bleed into the subarachnoid space, leading to a subarachnoid hemorrhage (SAH), the third most common subtype of stroke [1,2,3]. Intracerebral hemorrhage comprises 15% of all strokes, of which 54% are subarachnoid hemorrhages. A SAH is often a catastrophic clinical event with significant morbidity and mortality. Approximately 25% of SAH patients die before reaching the hospital, and of the survivors, 50% suffer permanent disability. The 30-day mortality rate for SAH is 50%, and 15% die before reaching the hospital because there is a particular risk of early and devastating re-bleeding [4, 5].

Treatment for SAH can include coiling or clipping for aneurysms, or specific reversal agents for those on anticoagulants. In patients on anticoagulation with a subarachnoid hemorrhage, reversal agents are used to counteract the effects of anticoagulant (blood-thinning) treatment, reducing the risk of future bleeding [6]. An endovascular coiling method involves inserting a catheter into the femoral artery and guiding it to the location of the brain aneurysm. The aneurysm is then sealed off to stop additional bleeding by deploying small platinum coils, forming a blood clot.

Aneurysm clipping, an invasive surgical method, entails opening the skull to access the aneurysm directly. The aneurysm is isolated from the regular blood circulation with a tiny metal clip that a neurosurgeon inserts at its neck to stop it from rupturing or bleeding again [7]. These treatments unfortunately are only available at comprehensive stroke centers (CSCs) and are not provided at all hospitals [6, 7]. Therefore, a patient with SAH has the best outcome at a facility that can provide specific treatment. This necessitates urgent assessment, where the shorter the time from symptom onset to diagnosis and therefore treatment, the better.

There are several types of stroke center designations. Primary stroke centers, or PSCs provide stroke patients with specialized care paths and protocols, and can administer thrombolytics for ischemic stroke and supportive care for intracerebral hemorrhage [8]. Thrombectomy Capable Stroke Centers (TSC) can provide endovascular therapy in addition to tissue plasminogen activators (tPA) for ischemic stroke [9]. A comprehensive stroke center (CSC).

can do all of the above, and provide coiling or clipping of aneurysms in cases of intracerebral hemorrhage. Essentially, a CSC can provide care for all types of stroke patients [8, 9].

Prehospital treatment is crucial and includes transferring the patient to a hospital with neurocritical/neurosurgical expertise after considering breathing, circulation, and airway during triage. Diagnosing subarachnoid hemorrhage can be nuanced [2]. In fact, 33% of patients present no symptoms except for a headache [1]. This makes it particularly challenging for Emergency Medical Services (EMS). Therefore, developing and adhering to protocols is crucial for EMS to be able to accurately identify SAH cases. This takes a great deal of discipline as the traditional teaching is that the presentation of a SAH is a sudden, severe headache, often referred to as the “worst headache of [the patient’s] life” [1].

Over the past few decades, the incidence rate of subarachnoid strokes has declined, which can be attributed to improvements in lifestyle habits, such as lower rates of smoking and methods of controlling hypertension [4]. Additionally, there are country-specific variations in incidence, ranging from a 59% decline in Japan to a 14% decrease in North America. These variations are likely associated with variations in the prevalence of smoking [4].

In response to the lack of sufficient prehospital research and consensus on effectively detecting subarachnoid hemorrhages in the field, Polk County Fire Rescue (PCFR) designed and implemented a three-step SAH protocol. In this paper, the authors describe their experience with using this protocol to identify patients likely to experience SAH, thereby minimizing the risk of treatment delay with interhospital transfers.