Forensic Science

McEwan’s Sign : Alcohol Poisoning & Intoxication



In case of alcohol intoxication, pupils are contracted, but on external painful stimulation of the person, e.g. by pinching or slapping, causes pupil to dilate followed by slow constriction again. This is called as McEwan’s sign and if this is positive, it is suggestive of alcoholic coma.



  • Acute alcohol poisoning is considered when blood alcohol concentration exceeds 150 mg/100 ml beyond his/
    her capacity consumed by any preparation containing alcohol either in small doses at short intervals, or in one big dose.


1. Stage of Excitement

  • Blood level: 50–150 mg/100 ml of blood
  • Blood alcohol concentration (BAC): 0.05-0.1%

2. Stage of In-coordination

  • Blood level: 150–250 mg/100 ml of blood
  • Blood alcohol concentration (BAC): 0.15-0.25%

3. Stage of Coma

  • Blood level: >250 mg/100 ml of blood
  • Blood alcohol concentration (BAC): > 0.25%

The physiologic effects of alcohol are more pronounced & severe when the blood alcohol level is rising, as compared to levels attained at peak or plateau, or when the level is falling. This is known as the Mellanby effect and is believed to result from an acute tolerance to alcohol that develops during intoxication.


The most important single factor in the treatment of the acutely alcohol-intoxicated patient is to provide cardio respiratory support.

  • Patient must be kept warm and placed in a quiet environment, and emphasized to lie on the side to minimize risk of aspiration.
  • Gastric lavage with alkaline solution within 2 hours of ingestion.
  • 1 liter of NS with 10% glucose and 15 units of insulin or 50% dextrose (50 in 100 ml) is given IV.
  • Thiamine 100 mg in 500 ml glucose solution IV.
  • Respiratory support and O2 therapy.
  • Hemodialysis and peritoneal dialysis may be used.
  • Vitamin B6 is said to accelerate the metabolism of alcohol, is administered intravenously in a dose of 50-100 mg may effect a rapid recovery.
  • Coramine 3-5 ml by slow intravenously may render amazing results.
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