Clinical presentation
The relationship between clinical features of ethanol intoxication and serum ethanol concentration, in adults and children, is given in Clinical features of intoxication in adults and children associated with serum ethanol concentration. This is only a guide—the clinical features of ethanol intoxication vary widely depending on the patient’s level of ethanol tolerance and the Mellanby effect.
The Mellanby effect is the phenomenon that behavioural impairment due to ethanol is less at the same ethanol concentration when the ethanol concentration is decreasing than when it is increasing.
In children, or in adults who use ethanol infrequently, ethanol tolerance is low and the clinical features of ethanol intoxication are more predictable, with dose-related CNS and cardiovascular effects. For example, an ethanol-naive adult with a serum ethanol concentration of greater than 65 mmol/L (0.30%) is usually comatose. Conversely, in patients with a history of chronic ethanol use who have developed a high level of tolerance to ethanol, clinical features are more unpredictable, and patients may have little clinical evidence of ethanol intoxication, even with serum ethanol concentrations up to 98 mmol/L (0.45%).
In patients presenting with coma and a serum ethanol concentration less than 65 mmol/L (0.30%), consider the possibility of co-ingestants or other causes of CNS depression (eg head injury or infectionMorgan, 2015).
Serum ethanol concentration [NB1] | Clinical features of intoxication | ||
mmol/L | mg/dL | % (g/dL) | |
less than 11 mmol/L | less than 50 mg/dL | less than 0.05% | mild: disinhibition, sociable, euphoria |
11 to 22 mmol/L | 50 to 100 mg/dL | 0.05 to 0.10% | mild: impaired judgement, impaired coordination, and hypoglycaemia (in children) |
22 to 43 mmol/L | 100 to 200 mg/dL | 0.10 to 0.20% | moderate: slurred speech, impaired gait and balance, vomiting, tachycardia, CNS depression or confusion (can be severe in children and ethanol-naive adults) |
43 to 98 mmol/L | 200 to 450 mg/dL | 0.20 to 0.45% | severe: coma, marked ataxia, difficulty sitting upright, hypoglycaemia, seizures, pulmonary aspiration ethanol-tolerant patients can be ambulant |
more than 98 mmol/L | more than 450 mg/dL | more than 0.45% | life-threatening: profound coma, refractory hypotension, metabolic acidosis, respiratory depression, cardiac arrhythmias, death |
Note: CNS = central nervous system NB1: To convert: from mmol/L to mg/dL—multiply by 4.61, from mg/dL to mmol/L—multiply by 0.217, from mmol/L to % (g/dL)—multiply by 0.00461. | |||