Screening for carbon monoxide exposure in selected patient groups attending rural and urban emergency departments in England: a prospective observational study

Abstract

ObjectivesCarbon monoxide (CO) exposure does not produce a classical toxidrome and so it is thought that it may easily be missed, allowing patients to continue to be exposed to CO. The aim of this study was to determine the proportion of raised carboxyhaemoglobin (COHb) levels in a targeted population of patients presenting to four emergency departments (EDs) in England.DesignA prospective observational study undertaken over a 9-month period.SettingFour EDs; one in a rural/suburban area and three serving urban populations.Participants1758 patients presenting to the EDs with chest pain, exacerbation of chronic obstructive pulmonary disease (COPD), non-traumatic headache, seizures or flu-like symptoms.Main outcomeMeasures COHb levels measured using a pulse CO-oximeter or venous sample. Patients with COHb levels ≥2.5% (non-smokers) or ≥5% (smokers) completed a questionnaire assessing potential sources. Patients were defined to be positive for CO exposure if they had a positive COHb and either an identified source or no other reason for their raised level.ResultsProportion of positive patients was: overall—4.3%; COPD—7.5%; headache—6.3%; flu-like—4.3%; chest pain—3.3%; seizures—2.1%. A variety of gas and solid (predominantly charcoal) fossil fuel sources were identified.ConclusionsThis study showed that 4.3% of patients presenting to EDs with non-specific symptoms had unexpectedly raised COHb levels 1.4% of patients had a source of CO identified. Study limitations included non-consecutive recruitment, delays in COHb measurements and a lack of ambient CO measurements, which precludes precise determination of incidence. However, this study should alert clinicians to consider CO exposure in patients presenting with non-specific symptoms, in particular headache and exacerbation of COPD, and if necessary refer patients for suitable public-health follow-up, even in the presence of low COHb readings. Further research should include standardised scene assessments.

Analysis of breath carbon monoxide among urban automobile drivers

“…Moreover, COHb often does not correlate with symptoms at presentation according to previous studies. [21] Clinical evaluation with correlation of symptoms and occupational history can prevent misdiagnosis and early treatment.…”

Carbon monoxide poisoning in Beirut, Lebanon: Patient′s characteristics and exposure sources

“…In our study, similar to previously published literature, headache was the most common presenting symptom. [ 9 15 ] None of the patients in our study presented with seizure, flu-like, or chronic obstructive pulmonary disease (COPD) exacerbation symptoms which are commonly reported as presenting symptoms of CO poisoning. [ 15 ] This suggests that CO poisoning might be underdiagnosed or misdiagnosed as another illness in patients presenting to our ED.…”

Assessment of acute headache in adults – what the general physician needs to know

“…Up to 6% of ED attendees with headache may have carbon monoxide toxicity. 23 A high index of suspicion is needed. Toxicity causes non-specific headache, dizziness, nausea and confusion.…”