Fig. 4

On-scene time and affecting factors (dichotomous) in subgroups of primary emergency missions with patient encounter (N = 2372). The subgroups included patients with a NACA score of 4–6 only. “Median of all included patients” refers to the median OST, 9 min, in all patients in subgroups except cardiac arrest (top panel). In the cardiac arrest subgroup, 647 (94.7%) patients were classified by a NACA score of 6. Patients suffering cardiac arrest were in most cases transported after ROSC were achieved. In these patients, a low NACA or a high GCS indicates successfully resuscitation before HEMS arrived, as our GCS and NACA variable describes the patient’s condition during HEMS patient care. In a few cases, transported was initiated with continuous CPR using a chest compression device