Describe the options for postoperative analgesia.
Intravenous narcotic administration has the advantage of rapid uptake and attainment of therapeutic levels. However, this mode of administration is also associated with rapid declines in drug concentration during which patients may experience pain. Although using larger doses of narcotics may increase the duration of analgesia, higher doses may be associated with a greater number of adverse side-effects. To minimize these side-effects, small frequent doses of narcotic may be administered via a patient-controlled pump, i.e., patient controlled analgesia (PCA). This technique allows patients greater comfort control during their hospital course and may prevent overmed-ication. Although this technique is safe, respiratory depres-sion may occur, so routine postoperative nursing care should include careful monitoring of respiratory status.
An attractive alternative to the use of intravenous narcotics is epidural administration of analgesics. Local anesthetics, narcotics, and other agents such as α2-agonists have been described as effective in significantly decreasing the intensity of postoperative pain. Although this method can provide profound pain relief, it may be associated with significant side-effects. Local anesthetics may cause sympa-thetic blockade (with resultant decreases in preload and afterload that may result in hypotension and tachycardia), motor blockade, and local anesthetic toxicities. Epidural narcotics may cause pruritus, nausea, vomiting, urinary retention, or respiratory depression. These side-effects can usually be treated with conventional therapy (e.g., antihis-tamines or antiemetics) or specific narcotic antagonists. Epidural narcotics have the advantage of specificity of action, without the major hemodynamic changes and motor blockade that may be associated with local anesthetics.
Preoperative epidural catheter insertion for postoperative analgesia is probably safe when perioperative anticoagulation is anticipated. Epidural anesthesia may increase coronary blood flow, but there is contradictory evidence on the effect of epidural anesthesia on myocardial ischemia dur-ing noncardiac surgery. There have been multiple reports of attenuation in the stress response with peri- and post-operative epidural anesthesia and analgesia during vascular surgery. Supplemental epidural anesthesia may signifi-cantly attenuate catecholamine release during aortic occlu-sion and reperfusion. This reduction in the stress response by epidural anesthesia/analgesia may decrease postopera-tive hypercoagulability.