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 (ETCO(2)) 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 ETCO(2) 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 ETCO(2) for all patients on arrival was 29.07 ± 9.96 mmHg. Average ETCO(2) for patients in hypovolemic, cardiogenic and septic shock was 29.64 ± 11.49, 28.60 ± 9.87 and 27.81 ± 7.39 mmHg, respectively. ETCO(2) on arrival was positively correlated with systolic and diastolic BP, MAP, bicarbonate, base excess and lactate when analyzed in all shock patients. Early ETCO(2) measurements were found to be significantly lower in patients who did not survive to hospital admission (p = 0.005). All patients who had ETCO(2) ≤ 12mmHg died in the ED. However, normal ETCO(2) does not ensure patient survival. CONCLUSION: The use of ETCO(2) in the ED has great potential to be used as a method of non-invasive monitoring of patients in shock.