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September 13, 1976

Nitrous Oxide in Myocardial Infarction

Author Affiliations

Monterey Park, Calif

JAMA. 1976;236(11):1237-1238. doi:10.1001/jama.1976.03270120015011

To the Editor.—  I would agree, in general, with the conclusion of Thompson and Lown (235:924,1976) that nitrous oxide 35% mixed with oxygen is an effective and safe analgesic for patients with acute myocardial infarction; however, clinicians should be aware that concentrations of nitrous oxide as low as 30% may rarely cause loss of consciousness1 and that more recent studies indicate that nitrous oxide directly and significantly depresses myocardial function.2On the other hand, I disagree strongly with the suggestion that for severe pain, nitrous oxide has any use as an adjunct to potent narcotic analgesics in the coronary care unit. In the first place, this combination can produce complete anesthesia that could present considerable danger to the patient, and in the second place, the combination of nitrous oxide and morphine has been shown to cause significant, and in some cases, severe depression in cardiac output and mean