Prevalence of acute heart failure among unselected non-traumatic emergency department patients admitted with and without need of oxygen

Supplemental oxygen therapy is a routine treatment in the emergency department (ED). In acute heart failure (AHF), oxygen treatment is recommended as part of initial treatment if peripheral oxygen saturation (SpO2) < 90% or PaO2<60 mmHg. However, the clinical evidence in this area is limited.

The purpose of this study was to assess the prevalence of AHF among patients admitted to the ED with and without the need of oxygen. Furthermore, to assess association of oxygen-need with mortality.

In this prospective cohort study, all patients admitted at the medical ED at a large University hospital in Denmark between March 10th, 2020, to March 31st, 2022, were consecutively included. Patients were divided into four groups depending on the presence of AHF and oxygen-need. All patient records were screened by trained cardiologist, to identify patients admitted with AHF.

The cohort consisted of a total of 6290 patients; 1311 (21%) patients in need of oxygen and 4979 (79%) patients without need of oxygen. In the group in need of oxygen, 224 (17%) patients had AHF and in the group without need of oxygen 184 (4%) patients had AHF. The patients with AHF were older and had more comorbidities compared with patients without AHF.

Oxygen-need was associated with higher mortality in both patients with and without AHF (Figure 1). In AHF-patients, higher oxygen-need was associated with higher mortality in a dose-response relationship (HRadjusted 1.04 per L/min oxygen (1.01-1.1), p=0.001), see Figure 2.

Patients with AHF had a higher readmission rate (2 (1-3) times, median (IQR) compared with patients without AHF (1 (0-2) times, p-value < 0.0001). The length of stay in the AHF group was 5 (3-10) days, compared with 1 (0-5, p-value < 0.0001) day in the group without AHF. In AHF-patients, the need of oxygen was associated with increased length of stay (7 (4-12) days, compared with 4 (2-8) days, p-value < 0.0001). Furthermore AHF-patients in need of oxygen were more admitted to the ICU (41(18.3%) versus 18 (9.8%), p-value = 0.02) than patients without need of oxygen. There was a non-significant increase in intubation rate for AHF-patients in need of oxygen compared to those without need of oxygen (26 (11.6%) vs. 14 (7.6%), p-value = 0.18).