Measurement of end-tidal carbon dioxide in spontaneously breathing patients in the pre-hospital setting. A prospective evaluation of 350 patients.

Objective: Monitoring of end-tidal carbon dioxide (EtCO(2)) is good clinical practice in the patient who is intubated and ventilated. This study investigated the EtCO(2) values in spontaneously breathing patients treated in a physician-staffed mobile intensive care unit (MICU). This article also discusses whether EtCO(2) monitoring may have an influence on therapeutic decisions by emergency physicians by providing additional information.

Methods: Over a period of 6 months, 350 spontaneously breathing patients (162 males, 137 females) were treated and transported in our MICU and monitored using a LifePak 12 monitor (EtCO(2), respiratory rate, pO(2), blood pressure, heart rate). Only 299 were enrolled in the study.

Results: Pathological EtCO(2) values were detected in 19 patients (6.3%). EtCO(2) levels of >55 mmHg (7.3 kPa) were found in nine of 12 (75%) patients with asthma, in one of 23 patients with hypoglycaemia (4.3%), and in all patients with subarachnoid hemorrhage, acute seizures and drug intoxications. With the exception of the asthma patients, all patients had an initial Glasgow Coma Score <8. EtCO(2) levels <20 mmHg (2.7 kPa) were found in all patients with hyperventilation or shock due to volume deficiency. Errors in EtCO(2) measurement occurred in 5% of cases.

Conclusion: Although EtCO(2) monitoring may be a useful additional variable in spontaneously breathing patients. Consideration of the respective disease and the cost to benefit ratio suggests that this method should only be used for selected indications.