The purpose of this study was to determine cardiovascular reactions after the administration of a potent narcotic analgesic, such as fentanyl, in increasing dosages of 0.0025 to 0.16 mg./kg. In addition, comparison was made with meperidine in dosages from 2.5 to 20 mg./kg. The action of a narcotic antagonist (0.4 mg./kg. of naloxone) given in sequence to the analgesic was ascertained also. The data obtained indicate: 1. Increase in LV dP/dt max* was directly proportional to the dose of fentanyl over a low concentration range (0.0025 to 0.03 mg./kg.). 2. Increasing dosages of fentanyl caused a decrease in myocardial oxygen consumption (maximum 30 percent), pressure time index (TTI), and coronary sinus blood flow. 3. High dosages of fentanyl (0.03 to 0.16 mg./kg.) did not affect LV dP/dt max, left ventricular pressure, left ventricular end-diastolic pressure, and central aortic blood pressure. 4. Increasing dosages of fentanyl produced a proportionately greater decrease in mean peripheral blood pressure (maximum 40 percent) and heart rate (maximum 50 percent). Succeeding injection of the same doses had little effect on the two physiologic values, however, suggesting the development of tachyphylaxis. 5. Naloxone given after fentanyl increased all measured values. 6. Meperidine, even in low doses of 2.5 mg./kg., had a depressant effect on the cardiovascular system, particularly in regard to left ventricular pressure. 7. Naloxone alone, up to 5.6 mg./kg., had no effect on the cardiovascular system. The results suggest that sequential analgesia, using in sequence high doses of fentanyl as the sole anesthetic agent and naloxone as the antagonist at the end of the operation, has no depressant effect on the cardiovascular system.
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Enno Freye (1974) studied this question.