Carbon monoxide exposure is potentially deadly and has been used in suicidal attempt. We present a case in which such poisoning occured accidentally in a faulty car exhaust system.
A 43-year-old gentleman was found unresponsive in his car around noon. Passers-by alerted the ambulance. On paramedic assessment, he was unconscious with GCS of 11/15 (E3V3M5) and appeared flushed. The BP and heart rate were normal. Pulse oxymetry showed 100% under room air. Nevertheless, he was put on a high flow mask oxygen at 15L/min. His GCS became full on arrival to hospital but still groggy. He complained of lethargy, sleepiness and giddy for the last 3 days. He drives a Kancil (a compact car produced locally between 1994 and 2009 which name means ‘mousedeer’) and for the preceding 3 days has been driving car more than usual. He admitted smelling exhaust fume within the cabin. He also napped in the car twice in those days for half an hour each time. At the emergency department, vital signs were stable and the SPO2 was 99% with random blood sugar level of 10.7mmol/L. The arterial blood gas showed carboxyhemoglobin level of 46.5% (normal value for nonsmokers < 3%, for smokers < 10 %). Patient was put on a non-rebreathable high flow mask and the level came down to 20.3% and 12% at 30 minutes and 60 minutes respectively. Patient was admitted for observation and after 2 hours, the level had normalized to less than 3%. He was discharged well the next day.
LESSONS LEARNT & CONCLUSION
Consider carbon monoxide poisoning in an unconscious person with high oxygen saturation and reddish skin. Accidental poisoning should be suspected in patients present being unconscious in old vehicle with presence of fume smell within the cabin or car that rattles.