Background: Erroneous diffusing capacity of the lung for carbon monoxide (Dlco) values as measured by spectrophotometry were observed at our facility in ethanol-intoxicated subjects. An atypical methane curve tracing was noted in these subjects.
Study objectives: We hypothesized that ethanol intoxication interferes with Dlco measurements obtained using methane and designed a study to assess the blood ethanol level at which this occurs.
Study design: Dlco and breath ethanol levels were measured at baseline and after escalating doses of ethanol in seven healthy subjects.
Setting: Pulmonary function testing laboratory of a university hospital.
Participants: Seven healthy volunteers.
Interventions: Dlco measurement at baseline and after escalating doses of ethanol.
Measurements and results: We found no significant change in measured Dlco values for a wide range of blood ethanol levels (from 0.006 to 0.12 mg/dL). However, subsequently, an abnormal methane curve and Dlco were again observed in an intoxicated subject whose ethanol blood level was 0.22 mg/dL.
Conclusions: We conclude that interference between breath ethanol level and Dlco measurement exists only for blood ethanol levels well above the legal limit for intoxication. Based on our observations, we suggest that ethanol intoxication should be suspected when an abnormal Dlco measurement occurs along with an abnormal methane curve tracing. If intoxication is confirmed, precautions should be taken and referral for treatment of possible ethanol dependence should be offered.