[Systemic analgesia for postoperative pain management in the adult]

Severe postsurgical pain contributes to prolonged hospital stay and is also believed to be a risk factor for the development of chronic pain. Locoregional anesthesia, which results in faster patient recovery with fewer side effects, is favored wherever feasible, but is not applicable to every patient. Systemic analgesics are the most widely used method for providing pain relief in the postoperative period. Improvements in postoperative systemic analgesia for pain management should be applied and predictive factors for severe postoperative pain should be anticipated in order to control pain while minimizing opioid side effects. Predictive factors for severe postoperative pain include severity of preoperative pain, prior use of opiates, female gender, non-laparoscopic surgery, and surgeries involving the knee and shoulder. Pre- and intraoperative use of small doses of ketamine has a preventive effect on postoperative pain. Multimodal or balanced analgesia (the combined use of various analgesic agents) such as NSAID/morphine, NSAID/nefopam, morphine/ketamine improves analgesia with morphine-sparing effects. Nausea and vomiting, the principle side effects of morphine, can be predicted using Apfel's simplified score; patients with a high Apfel score risk should receive preemptive antiemetic agents aimed at different receptor sites, such as preoperative dexamethasone and intraoperative droperidol. Droperidol can be combined with morphine for postoperative patient-controlled anesthesia (PCA). When PCA is used, dosage parameters should be adjusted every day based on pain evaluation. Patients with presurgical opioid requirements will require preoperative administration of their daily opioid maintenance dose before induction of anesthesia: PCA offers useful options for effective postsurgical analgesia using a basal rate equivalent to the patient's hourly oral usage plus bolus doses as required.