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Background End-tidal carbon dioxide pressure (etCO 2 ) is widely used in anaesthesia and critical care in intubated patients. The aim of our preliminary study was to evaluate the feasibility of a simple device to predict capnia in spontaneously breathing patients in an emergency department (ED). Patients and methods This study was a prospective, nonblind study performed in our teaching hospital ED. We included nonintubated patients with dyspnea (≥18 years) requiring measurement of arterial blood gases, as ordered by the emergency physician in charge. There were no exclusion criteria. End-tidal CO 2 was measured by an easy-to-use device connected to a microstream capnometer, which gave a continuous measurement and graphical display of the etCO 2 level of a patient's exhaled breath. Results A total of 43 patients (48 measurements) were included, and the majority had pneumonia (n = 12), acute cardiac failure (n = 8), asthma (n = 7), or chronic obstructive pulmonary disease exacerbation (n = 6). Using simple linear regression, the correlation between etCO 2 and Paco 2 was good ( R = 0.82). However, 18 measurements (38%) had a difference between etCO 2 and Paco 2 of 10 mm Hg or more. The mean difference between the Paco 2 and etCO 2 levels was 8 mm Hg. Using the Bland and Altman matrix, the limits of agreement were −10 to +26 mm Hg. Conclusion In our preliminary study, etCO 2 using a microstream method does not seem to accurately predict Paco 2 in patients presenting to an ED for acute dyspnea.

Introduction The prognostic value of cardiac troponin I (cTnI) in patients having a heat-related illness during a heat wave has been poorly documented. Methods In a post hoc analysis, we evaluated 514 patients admitted to emergency departments during the August 2003 heat wave in Paris, having a core temperature >38.5°C and who had analysis of cTnI levels. cTnI was considered as normal, moderately elevated (abnormality threshold to 1.5 ng.mL-1), or severely elevated (>1.5 ng.mL-1). Patients were classified according to our previously described risk score (high, intermediate, and low-risk of death). Results Mean age was 84 ± 12 years, mean body temperature 40.3 ± 1.2°C. cTnI was moderately elevated in 165 (32%) and severely elevated in 97 (19%) patients. One-year survival was significantly decreased in patients with moderate or severe increase in cTnI (24 and 46% vs 58%, all P < 0.05). Using logistic regression, four independent variables were associated with an elevated cTnI: previous coronary artery disease, Glasgow coma scale 120 μmol.L-1, and heart rate >110 bpm. Using Cox regression, only severely elevated cTnI was an independent prognostic factor (hazard ratio 1.93, 95% confidence interval 1.35 to 2.77) when risk score was taken into account. One-year survival was decreased in patients with elevated cTnI only in high risk patients (17 vs 31%, P = 0.04). Conclusions cTnI is frequently elevated in patients with non-exertional heat-related illnesses during a heat wave and is an independent risk factor only in high risk patients where severe increase (>1.5 ng.mL-1) indicates severe myocardial damage.