The treatment of pain in the acute phase of a suspected acute myocardial infarction is often insufficient and has remained unchanged during recent years. The introduction of substances with a potential to limit the infarct size, such as thrombolysis and beta-blockade, have, however, decreased the requirement for narcotic analgesics (which are still the drugs of choice in many hospitals). Knowledge is still lacking regarding the duration of pain relief, the time between drug administration and pain relief, and optimal doses for various analgesics. Future research should aim at the development of drugs with a more rapid onset of action, less side effects and more complete analgesia.
[Show abstract][Hide abstract] ABSTRACT: The characteristics of chest pain due to suspected acute myocardial infarction and morphine use during the first 3 hospital days are described in a population of 2988 consecutive patients admitted to hospital. The duration of pain was usually less than 24 h (mean 20.9+/-0.55 h), and only 24.8% of patients experienced chest pain of longer duration. The majority of patients had only one attack of pain, but 34.4% experienced four or more attacks during hospitalization. A mean morphine dose of 6.7+/-0.2 mg was administered over the 3 hospitalization days, but surprisingly 52.4% of all patients required no morphine analgesia at all. Independent predictors of an increased morphine consumption were initial degree of suspicion of acute myocardial infarction, ST changes on admission ECG, male sex, a history of angina pectoris and a history of congestive heart failure. In a separate pharmacokinetic/pharmacodynamic study in 10 patients, plasma concentrations of morphine and its major metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), were measured after intravenous administration of morphine. In this patient group, terminal half-life of unchanged morphine ranged from 0.77 to 3.22 h. M3G and M6G plasma concentrations increased gradually up to 60-90 min after the intravenous morphine injection. Initial pain intensity by numerical rating scale was 6.6+/-0.6 (arbitrary units), and after morphine administration, there was a rapid and significant decrease in pain intensity. After 20 min, pain relief was 69+/-11% and remained at this level during the following 8 h observation period. It is concluded that the need for morphine administration in patients with suspected or definite acute myocardial infarction, differs among subgroups of patients and, in particular, higher doses are needed in those with a strong suspicion of myocardial infarction at arrival. When intravenous morphine is given, it attains full effect 20 min after injection. Furthermore, the active morphine metabolites M3G and M6G appear rapidly in the circulation, which could influence the analgesic response to morphine treatment. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
European journal of pain (London, England) 02/1998; 2(2):115-125. DOI:10.1016/S1090-3801(98)90004-0 · 2.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To compare the analgesic effect of metoprolol and morphine in patients with chest pain due to suspected or definite acute myocardial infarction after initial treatment with intravenous metoprolol.
All patients, regardless of age, admitted to the coronary care unit at Uddevalla Central Hospital due to suspected acute myocardial infarction were evaluated for inclusion in the MEMO study (metoprolol-morphine). The effects on chest pain and side-effects of the two treatments were followed during 24 h. Pain was assessed by a numerical rating scale.
A total of 265 patients were randomized in this prospective double-blind study and 59% developed a confirmed acute myocardial infarction. In both treatment groups, there were rapid reductions of pain intensity. However, in the patient group treated with morphine, there was a more pronounced pain relief during the first 80 min after start of double-blind treatment. The side-effects were few and were those expected from each therapeutic regimen. During the first 24 h, nausea requiring anti-emetics was more common in the morphine-treated patients.
In suspected acute myocardial infarction, if chest pain persists after intravenous beta-adrenergic blockade treatment, standard doses of an opioid analgesic such as morphine will offer better pain relief than increased dosages of metoprolol.
Journal of Internal Medicine 03/1999; 245(2):133-41. DOI:10.1046/j.1365-2796.1999.00415.x · 6.06 Impact Factor
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