Predictive factors for early requirement of respiratory support through phone call to Emergency Medical Call Centre for dyspnoea: a retrospective cohort study

Abstract

Background Acute dyspnoea is a common symptom in Emergency Medicine, and severity assessment is difficult during the first time the patient calls the Emergency Medical Call Centre. Objective To identify predictive factors regarding the need for early respiratory support in patients who call the Emergency Medical Call Centre for dyspnoea. Design, settings and participants This retrospective cohort study carried out in the Emergency Medical Call Centre of the University Hospital of Toulouse from 1 July to 31 December 2019. Patients over the age of 15 who call the Emergency Medical Call Centre regarding dyspnoea and who were registered at the University Hospital or died before admission were included in our study. Outcome measure and analysis The primary end-point was early requirement of respiratory support [including high-flow oxygen, non-invasive ventilation (NIV) or mechanical ventilation after intubation] that was initiated by the physicians staffed ambulance before admission to the hospital or within 3 h after being admitted. Associations with patients’ characteristics identified during Emergency Medical Call Centre calls were assessed with a backward stepwise logistic regression after multiple imputations for missing values. Main results During the 6-month inclusion period, 1425 patients called the Emergency Medical Call Centre for respiratory issues. After excluding 38 calls, 1387 were analyzed, including 208 (15%) patients requiring respiratory support. The most frequent respiratory support used was NIV (75%). Six independent predictive factors of requirement of respiratory support were identified: chronic β2-mimetics medication [odds ratio (OR) = 2.35, 95% confidence interval (CI) 1.61–3.44], polypnea (OR = 5.78, 95% CI 2.74–12.22), altered ability to speak (OR = 2.35, 95% CI 1.55–3.55), cyanosis (OR = 2.79, 95% CI 1.81–4.32), sweats (OR = 1.93, 95% CI 1.25–3) and altered consciousness (OR = 1.8, 95% CI 1.1–3.08). Conclusion During first calls for dyspnoea, six predictive factors are independently associated with the risk of early requirement of respiratory support.