the use of the waterpipe , or shisha , for smoking tobacco is an old tradition in the eastern mediterranean region that goes back centuries .
this habit is relatively rare in singapore , a country with a predominantly chinese population .
carbon monoxide ( co ) poisoning can be notoriously deceptive and non - specific in its initial presentation to the emergency department ( ed ) .
its correct diagnosis and eventual management require a high level of suspicion on the part of the emergency physician ( ep ) .
our patient was a 19-year - old gentleman of saudi descent who was a student in singapore and had no past medical history of note .
he had been having dinner with a friend at a restaurant 4  h prior to presentation and had been smoking shisha at that time .
collateral information from his friend revealed that he had been smoking shisha with three other friends and had hit his occiput after a fall .
his vital signs revealed a temperature of 36.7c , blood pressure of 108/61 , pulse rate of 99/min and pulse oximetry reading of 99% on room air .
physical examination revealed that he was alert and orientated to time , place and person .
bedside capillary blood sugar was 5.1  mmol / l , and the baseline electrocardiogram was normal .
the initial working diagnosis was that of stable head injury and a few other possible explanations for the dizziness , including cardiac arrhythmias , transient hypoglycemic episode , viral illness and substance overdose .
he was scheduled for computed tomography ( ct ) of the brain . however , a carboxyhemoglobin ( cohb ) level was taken in view of the shisha smoking .
he was immediately transferred to the critical monitoring area and put on 100% oxygen via a non - rebreather mask .
a bedside arterial blood gas on high flow oxygen revealed respiratory alkalosis with ph of 7.441 , pco2 of 37.3  mmhg and po2 of 501  mmhg .
he was admitted to the medical high dependency unit ( mdu ) for further monitoring and management .
he was placed on 100% oxygen for the next 46  h while he was in the mdu , and his dizziness resolved .
he was discharged 2  days post - admission with a follow - up date for psychometric testing and neurological review at the outpatient clinic .
this case highlights the challenge to emergency physicians regarding the timely diagnosis of co poisoning , a highly treatable condition .
the non - specific neurological complaints can mimic many illnesses , such as viral illness or stable head injury .
it binds to hemoglobin 200300 times more tightly than oxygen , forming cohb . as such
, it inhibits the release of oxygen from hemoglobin to peripheral tissues , causing tissue hypoxia .
the half life of cohb is 4 to 5  h in a person breathing room air and changes to 60 min in the presence of 100% oxygen at sea level . as such
, our index patient would have been symptomatic for a prolonged period of time if the initial suspicion of co poisoning had not been made and he had been managed as a person with stable head injury .
shisha smoking is one form of waterpipe smoking among others , including hookah , nargileh and arguileh .
shisha smoking is relatively rare in singapore , but is common in the mediterranean regions , according to a who report .
the report stated that the overall prevalence of shisha smoking in egypt was estimated at 10% from a national survey in 2002 focusing on hypertension , obesity and diabetes in such smokers .
it has been estimated that smoke exposure could be as much as 100200 cigarettes per session .
co poisoning is difficult to diagnose in the ed as its presenting symptoms are usually non - specific .
undoubtedly , a history of potential co exposure is the most reliable indicator of poisoning .
eps should have a high index of suspicion , even though the exposure can be exotic , as in this case .
it is important to realize that when dizziness occurs in co poisoning , it usually corresponds to a caboxyhemoglobin level of 20% and above , a level considered to be at least moderately severe . making a diagnosis in a timely fashion can expedite the management of such patients .
 carbon monoxide poisoning has been reported as a result of exposure to various sources of smoke , such as car exhaust fumes , home water heaters and tobacco smoke . 
 we describe a case of symptomatic , moderately severe carbon monoxide ( co ) poisoning in a young mediterranean man after smoking a waterpipe , or shisha . 
 this case highlights the importance of considering carbon monoxide exposure in patients presenting with non - specific neurological symptoms to the emergency department ( ed ) . 
Introduction
Case report
Discussion