Assessment of the breath alcohol concentration in emergency care patients with different level of consciousness.

Abstract

BackgroundMany patients seeking emergency care are under the influence of alcohol, which in many cases implies a differential diagnostic problem. For this reason early objective alcohol screening is of importance not to falsely assign the medical condition to intake of alcohol and thus secure a correct medical assessment.ObjectiveAt two emergency departments, demonstrate the feasibility of accurate breath alcohol testing in emergency patients with different levels of cooperation.MethodAssessment of the correlation and ratio between the venous blood alcohol concentration (BAC) and the breath alcohol concentration (BrAC) measured in adult emergency care patients. The BrAC was measured with a breathalyzer prototype based on infrared spectroscopy, which uses the partial pressure of carbon dioxide (pCO2) in the exhaled air as a quality indicator.ResultEighty-eight patients enrolled (mean 45 years, 53 men, 35 women) performed 201 breath tests in total. For 51% of the patients intoxication from alcohol or tablets was considered to be the main reason for seeking medical care. Twenty-seven percent of the patients were found to have a BAC of <0.04 mg/g. With use of a common conversion factor of 2100:1 between BAC and BrAC an increased agreement with BAC was found when the level of pCO2 was used to estimate the end-expiratory BrAC (underestimation of 6%, r = 0.94), as compared to the BrAC measured in the expired breath (underestimation of 26%, r = 0.94). Performance of a forced or a non-forced expiration was not found to have a significant effect (p = 0.09) on the bias between the BAC and the BrAC estimated with use of the level of CO2. A variation corresponding to a BAC of 0.3 mg/g was found between two sequential breath tests, which is not considered to be of clinical significance.ConclusionWith use of the expired pCO2 as a quality marker the BrAC can be reliably assessed in emergency care patients regardless of their cooperation, and type and length of the expiration.