Haemodynamic effects of a 10-min treatment with a high inspired oxygen concentration in the emergency department: a prospective observational study

Abstract

Objectives To investigate the haemodynamic effects of a high FiO2 administered for a limited duration of time in patients who receive preoxygenation for procedural sedation and analgesia (PSA) in the ED.Design, settings and participants In a prospective cohort study, cardiac output (CO), stroke volume (SV) and systemic vascular resistance (SVR) were measured using the Clearsight non-invasive CO monitoring system in patients who received preoxygenation for PSA in the ED. Measurements were performed at baseline, after 5 min of preoxygenation via a non-rebreathing mask at 15 /L min and after 5 min of flush rate oxygen administration.Outcomes measures The primary outcome was defined as the change in CO (L/min) from baseline after subsequent preoxygenation with 15 L/min and flush rate.Results Sixty patients were included. Mean CO at baseline was 6.5 (6.0–6.9) L/min and decreased to 6.3 (5.8–6.8) L/min after 5 min of oxygen administration at a rate of 15 L/min, and to 6.2 (5.7–6.70) L/min after another 5 min at flush rate (p=0.037). Mean SV remained relatively constant during this period, whereas mean SVR increased markedly (from 781 (649–1067), to 1244 (936–1695) to 1337 (988–1738) dyn/s/cm–5, p<0.001. Sixteen (27%) patients experienced a>10% decrease in CO.Conclusion Exposure of patients to a high FiO2 for 5–10 min results in a significant drop in CO in one out of four patients. Therefore, even in the ED and in prehospital care, where oxygen is administered for a limited amount of time, FiO2 should be titrated based on deficit whenever this is feasible and high flow oxygen should not be given as a routine treatment.