Analgesic therapy in acute myocardial infarction.

Parenterally administered narcotic analgesics are a critically important part of therapy for the patient with acute myocardial ischemic syndromes. These agents are very effective and, when used with appropriate caution and monitoring, are also generally safe. They not only relieve the sensation of severe pain but also reduce the effective and physiologic reaction to pain and thus reduce patient anxiety. Because these agents all depress respiratory drive to some degree in the doses used for adequate analgesia, close attention to respiratory status is mandatory. In patients with underlying pulmonary disease or significant congestive heart failure, this monitoring should be even more intensive and include arterial blood gas measurements and preparations for possible narcotic antagonist administration and ventilatory assistance. With regard to the hemodynamic changes produced by these agents, several important points are worth noting. It must be remembered that the conclusions regarding hemodynamic effects of these agents are derived from studies involving patient groups that were generally hemodynamically stable, usually pain-free, and almost always at least several hours following acute presentation. Thus, the hemodynamic effects of these agents may be quite different in patients with active pain during a period of acute ischemia, or in patients that are hemodynamically unstable. Hemodynamic studies during these acute settings, however, are extremely difficult to perform because the patient's acute distress mandates rapid administration of an analgesic agent prior to the institution of invasive monitoring. With these cautions relating to data interpretation in mind, it is still possible to make certain recommendations regarding the use of analgesic therapy in acute MI.(ABSTRACT TRUNCATED AT 250 WORDS)