Emergency Point-of-Care Blood Gas Analysis During Mass Gathering Events: Experiences of the Vienna City Marathon

<b>Background</b>: Long-distance running impacts many organ systems. Aside from musculoskeletal and cardiopulmonary events, the gastrointestinal and renal system as well as metabolic homeostasis and electrolyte balance can be affected. A respective medical support strategy enabling rapid diagnosis, triage, and treatment in the context of large sports events is thus of utmost importance. Incidents can be assessed and graded via point-of-care (POC) blood gas analysis (BGA). We thus aimed to evaluate the feasibility and benefits of its use during a large sports event. <b>Methods</b>: All documented patient contacts during the race of the Vienna City Marathon (VCM) 2023 were retrospectively assessed. Additionally, the BGAs conducted in all patients requiring intravenous access were analyzed. Data are presented in a descriptive manner. <b>Results</b>: There were 39,871 participants at the VCM 2023. Of these, 277 (0.7%) required medical support, localized most commonly in the finishing area of the race (n = 239, 86% of all incidents). Fifty-eight (20.9%) patients had to be hospitalized. The most frequent chief complaints were syncope or collapse (24.9%), followed by general pain (20.6%) and trauma (14.8%). Five patients (1.8%) suffered from seizures, and one experienced (0.4%) from spontaneous pneumothorax. Thirty-one patients (11.2%) received venous blood gas analyses, showing mean creatinine levels of 1.82 (±0.517) mg/dL, mean lactate concentrations of 6.03 (±4.5) mmol/L, mean pH of 7.42 (±0.0721), and a mean base excess of -0.72 (±3.72) mmol/L. No cases of hyponatremia occurred in the documented samples. In eight cases (25.8%), sodium concentrations were above 145 mmol/L, with a maximum of 149 mmol/L. No cardiac arrests occurred. <b>Conclusions</b>: The physical exertion during the assessed long-distance running race resulted in numerous contacts with the medical support teams. The use of POC BGA at a large-scale marathon event was shown to be easy and feasible, allowing for more extensive diagnostics on-site. It can be integrated into a medical support strategy and might be beneficial for decision-making regarding patient triage, treatment, hospitalization, or patient discharge.