The use of end-tidal carbon dioxide monitoring in patients with hypotension in the emergency department

BACKGROUND The aim of this study was to determine the usefulness of end tidal carbon dioxide (ETCO2) monitoring in hypotensive shock patients presenting to the ED. METHODS This was a prospective observational study in a tertiary ED. One hundred three adults in shock with hypotension presenting to the ED were recruited into the study. They were grouped according to different types of shock, hypovolemic, cardiogenic, septic and others. Vital signs and ETCO2 were measured on presentation and at 30-min intervals up to 120 min. Blood gases and serum lactate levels were obtained on arrival. All patients were managed according to standard protocols and treatment regimes. Patient survival up to hospital admission and at 30 days was recorded. RESULTS Mean ETCO2 for all patients on arrival was 29.07 ± 9.96 mmHg. Average ETCO2 for patients in hypovolemic, cardiogenic and septic shock was 29.64 ± 11.49, 28.60 ± 9.87 and 27.81 ± 7.39 mmHg, respectively. ETCO2 on arrival was positively correlated with systolic and diastolic BP, MAP, bicarbonate, base excess and lactate when analyzed in all shock patients. Early ETCO2 measurements were found to be significantly lower in patients who did not survive to hospital admission (p = 0.005). All patients who had ETCO2 ≤ 12mmHg died in the ED. However, normal ETCO2 does not ensure patient survival. CONCLUSION The use of ETCO2 in the ED has great potential to be used as a method of non-invasive monitoring of patients in shock.