The use of exhaled carbon monoxide for the diagnosis of carbon monoxide poisoning. A case report.

INTRODUCTION

Carbon monoxide (CO) poisoning is difficult to confirm in small rural hospitals that lack easy access to a cooximeter. A small hand held device can be used to assess exhaled CO (ECO) in parts per million. This device is often used in smoking cessation clinics to confirm that a person has abstained from smoking.

CASE SUMMARY

A 47-year-old white male became dizzy and had a near syncopal episode while working on his boat in the local marina. He was brought to the ER and was found to have an exhaled CO level of 180 ppm. The presence carboxyhemoglobin (HbCO) was confirmed later by an independent reference laboratory and the result was 26% HbCO.

DISCUSSION

The patient's exhaled CO level dropped slower than expected while breathing oxygen delivered by a non-rebreather mask. This could be due to inadequate compliance to oxygen therapy and a fiO2 somewhat less than 1.0. Another limitation of the technique is the calibration gas (50-ppm CO). This concentration may be too low to assess ER patients. Therefore a confirmatory ABG with cooximetry should be obtained if available. Clinicians are cautioned that there is no safe level of HbCO (6). There is a simple formula to convert ECO to HbCO. The use of exhaled CO monitoring may be a promising alternative that is relatively less expensive than cooximetry in the ER setting, but more research is clearly indicated.