A person who has been in a drug-induced coma for several hours may develop skin necrosis secondary to prolonged pressure without relief. Similar findings can be found with other forms of coma (diabetic ketoacidosis, cardiac arrest, etc).
Mechanisms: Some changes are due to compression of blood supply with ischemia. Some drugs may exert a toxic effect. Impaired breathing can result in hypoxemia.
Examples of drugs causing prolonged coma:
(1) barbiturates
(2) glutethimide
(3) heroin
(4) methadone
(5) morphine
(6) imipramine
(7) nitrazepam
Clinical features:
(1) history of prolonged coma
(2) skin lesions at pressure points
(2a) bullae
(2b) reddish-blue plaques
(2c) macular erythema
where:
• The time required to produce the injury may vary. In theory it could develop within a few hours.
A biopsy of affected skin shows ischemic necrosis, which can involve sweat glands. Later an inflammatory cell infiltrate will develop. Hemorrhage may occur around small blood vessels.
Differential diagnosis:
(1) thrombotic ischemia
(2) skin breakdown due to vomit or urine
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