Postoperative Pain Relief

Chapter 7 Postoperative Pain Relief

Introduction and background

The goal of postoperative pain relief is to achieve optimal analgesia, facilitating a quick return to normal activities with minimal side effects. In addition, the effective treatment of acute postoperative pain may reduce the incidence of chronic pain after surgery. Acute postoperative pain differs from chronic or cancer pain because it is more transitory and there may be an affective component relating to anxiety about the outcome of the surgical procedure and concern for suboptimal analgesia. Studies have shown that for patients awaiting surgery the possibility of severe acute postoperative pain is a major concern.1 In addition, uncontrolled postoperative pain can lead to delayed recovery from surgery, pulmonary dysfunction and hypoxia, together with restriction of mobility and subsequent increased risk of thromboembolism. Surveys in the UK, the USA and Europe have identified an unacceptable prevalence of poor pain control after surgery.2,3 However, in recent years the introduction of acute pain management services in hospitals has promoted improvements in postoperative pain.4 In addition, the use of ‘multimodal’ or ‘balanced’ analgesia – a combination of opiates, non-steroidal antiinflammatory drugs (NSAIDs), local anaesthetics and other adjuvants have been recommended to manage postoperative pain. Recently, White and Power reviewed the evidence for such pain management. They showed that multimodal analgesia improves the efficacy of pain relief, decreases the risk of side effects and is an evidence-based, established effective strategy for postoperative pain management.5,6

Measurement of pain

In adults, three common methods of self-reported pain measurement are used.

Each of these methods of measurement is reasonably reliable as long as the endpoints and adjectives employed are carefully selected and standardized.

Available methods of pain relief


Paracetamol (acetaminophen) is an acetanilide derivative with the molecular formula C8H9NO2. It is one of the most commonly used drugs worldwide, owing in part to its excellent safety record. Paracetamol has analgesic and antipyretic but not antiinflammatory activity. It is believed to be a centrally acting cyclooxygenase (COX) inhibitor with weak peripheral effects. Current evidence points to multi-site activity in the central nervous system, involving inhibition of prostaglandin synthesis and interaction with both serotonergic and cannabinoid pathways. Paracetamol can be given orally and rectally. An intravenous formulation is now available and has become widely used in the UK as it provides rapid and predictable therapeutic plasma concentrations. Rectal administration is restricted by slow onset time and unpredictable bioavailability and is becoming less popular.

Adverse effects/complications

Cox-2 inhibitors

In an effort to minimize the potential for bleeding at the surgical site and to reduce the incidence of serious gastrointestinal adverse effects and renal dysfunction associated with traditional NSAIDs, selective COX-2 inhibitors, also named ‘coxibs’, such as rofecoxib and celecoxib, were developed . Other novel COX-2 inhibitors with improved biochemical selectivity recently developed include etoricoxib, valdecoxib, parecoxib and lumiracoxib. These ‘coxibs’ have similar analgesic efficacy to that of NSAIDs, with reduced risk of bleeding and less gastrointestinal toxicity. However, large outcome and epidemiological studies suggest that while COX-2 inhibitors do confer improved gastrointestinal safety, they are not devoid of gastrointestinal effects during long-term use. Two of these drugs have already been withdrawn because of safety concerns: rofecoxib because of cardiovascular problems and valdecoxib because of serious subcutaneous adverse reactions.12

Concerns have also been raised regarding the increased incidence of thrombotic complications (leading to myocardial infarction and stroke) associated with selective COX-2 compounds.13 COX-2 inhibition with coxibs may increase the risk of vascular thrombus formation by upsetting the balance between pro- and anti-platelet aggregation effects: thromboxane A2 synthesis is primarily a COX-1-induced effect, and prostaglandin I2 synthesis a COX-2 effect.

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Sep 8, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Postoperative Pain Relief

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