Acute cerebral pathology can be due to severe traumatic brain injury (TBI) or stroke, which are potential catastrophic injuries associated with impaired quality of life and high mortality [
1,
2]. Studies in patients with TBI have demonstrated that even brief episodes of hypoxia and hypotension may be associated with secondary brain injury and negative outcomes [
3,
4]. The same may apply to patients with acute non-traumatic intracranial pathology; however, data on the physiological predictors of poor outcome are not available for this group of patients. Accordingly, prehospital treatment of airway obstruction, insufficient oxygenation and unstable haemodynamics is considered essential for a favourable outcome in both groups of patients [
5‐
7]. Current guidelines for the prehospital management of TBI recommend prehospital endotracheal intubation in patients with a Glasgow Coma Score (GCS) < 9, a peripheral blood oxygen saturation (SpO2) maintained above 90%, and systolic blood pressure (SBP) greater than 90 mmHg [
5,
7]. However, new evidence suggests that the threshold for hypotension-induced secondary brain injury in patients with TBI may be as high as an SBP of 110 mmHg [
8] or 120 mmHg [
3,
9]. Consequently, the current standard operating procedure (SOP) for the Danish Helicopter Emergency Medical Service (HEMS) recommends maintaining SBP > 110 mmHg in patients with isolated TBI [
8]. However, no recommendations exist for the prehospital targets for SpO2 and SBP in patients with a clinical diagnosis of acute non-traumatic intracranial pathology. Both traumatic and non-traumatic brain injury share similar pathophysiological mechanisms, including increased intracranial pressure (ICP) and associated compromised cerebral perfusion and oxygenation. In this study, we therefore apply the TBI guideline recommendations above as a measure for the performance of Danish HEMS critical care teams in the prehospital treatment of patients with acute non-traumatic intracranial pathology. Currently, data are not available on the management of patients with suspected acute intracranial pathology by HEMS critical care teams. Thus, the primary objective of this observational study was to assess the extent to which the Danish HEMS critical care teams adhere to the prehospital TBI guideline recommendations for the treatment of patients with a clinical diagnosis of acute non-traumatic intracranial pathology or isolated TBI [
5]. As secondary aims, we assessed the extent to which Danish HEMS critical care teams adhere to more recent blood pressure recommendations of an SBP > 110 mmHg [
8] and > 120 mmHg [
3,
9] in the prehospital management of patients with a clinical diagnosis of non-traumatic intracranial pathology or isolated TBI.