Cyclooxygenase inhibition for postoperative analgesia.

T he anesthesiologist has a central role in the management of acute postoperative pain, and effective management has been clearly demonstrated to improve clinical outcomes (1,2). Acute pain can rapidly evolve into chronic pain, and the two should not be viewed as separate entities (3). Failure to achieve effective analgesia is a major predictive factor for the conversion of acute postoperative pain to chronic pain after several different types of surgery (4). Traditionally, opioids and local anesthetics have been the pharmacological foundation for postoperative pain management; however, optimization has been difficult because of anxieties regarding deleterious side effects. Opioids may cause respiratory depression, oversedation, and prolongation of postoperative ileus. Regional anesthetic techniques are limited by the requirement for special monitoring and the irreversibility of neuronal blockade once it is instituted. The effectiveness of nonsteroidal antiinflammatory drugs (NSAIDs) in alleviating pain and reducing requirements for opioids in the postoperative period has been well documented (5–7), but concerns regarding gastropathy, renal dysfunction, and hemostatic defects have limited their use. There is further anxiety because fasting and the frequent prevalence of hypovolemia in the postoperative period may potentiate gastric and renal side effects. Do anesthesiologists underuse NSAIDs as perioperative analgesics because of exaggerated anxieties regarding side effects and inadequate information regarding mode of action? This review article describes prostaglandin (PG) biosynthesis and the central role of cyclooxygenase (COX) expression in pain perception, and then it focuses on the potential side effects of COX inhibition. Goals of Postoperative Analgesia The goal of postoperative pain relief is to achieve optimal analgesia, facilitating a speedy return to normal physiological organ function with minimal side effects. Anesthesiologists must also try to reduce the incidence of chronic pain after surgery by effective treatment of acute postoperative pain. Minimization of opioid and local anesthetic side effects is a major consideration, and here NSAIDs have great potential. This process begins at the preoperative assessment, when the anesthesiologist must identify patients at increased risk of NSAID-induced complications. Although renal failure, allergy, and late pregnancy are absolute contraindications, a history of peptic ulcer disease, congestive cardiac failure, or cirrhosis, previous thrombosis, and concomitant corticosteroid therapy require further consideration before being classed as contraindications. A history of NSAID consumption for other conditions, such as arthritis, is reassuring, and a normal creatinine clearance will allay fears regarding postoperative renal failure.