Improving Postoperative Pain Outcomes
Over 23 million surgical procedures are performed in the United States each year and are often associated with pain. Surgical pain is often inadequately treated and may persist long after the tissue heals.1 In certain cases the presence of intolerance to opioid analgesics, sedatives and non-steroidal anti-inflammatory drugs (NSAIDs) can limit the options for perioperative pain management, increasing the role of regional and local anesthesia. Understanding perioperative pathophysiology and planning the care of patients in order to reduce the associated stress can help to accelerate rehabilitation and contribute to decreased length of stays and increased patient satisfaction and safety after discharge.2
Consequences of poor planning for pain management perioperatively may not only affect the immediate well-being of the patient but also have negative socioeconomic implications.3 An aggressive approach to assessment and management of pain leads to increased patient comfort and satisfaction. Rigidity in this aspect, however, is inappropriate as patients differ in level of tolerance and perception of pain. Contributing factors include underlying conditions, social circumstances and personal preferences. Surgical stress can lead to a variety of responses including increase in catabolism, glycogenolysis, gluconeogenesis and lipolysis. Inadequate blunting of these responses can lead to tachycardia, hypertension, respiratory compromise and intraventricular hemorrhage. Increase in myocardial oxygen consumption and myocardial ischemia may also result.
Pre-emptive analgesia is an evolving clinical concept that specifies that an analgesic regimen be administered before the onset of noxious stimuli. This prevents the development of central sensitization caused by incisional and inflammatory injuries during both the surgical and initial postoperative periods.4 Though there has been conflicting trial results since the latter half of the 1990s, there is evidence that the use of non-opioids could play a role and — through this mechanism — reduce postoperative opioid requirements. The uniqueness of patients presenting for surgery also requires optimizing patients on an individual basis to improve their postoperative outcome. Examples of a unique patient group include sickle cell patients presenting for surgery. Hydrating such patients, transfusing to hemoglobin> 9g/dl perioperatively, intraoperative body temperature conservation and monitoring for early recognition of ventilation to perfusion mismatch or acid base balance will help reduce incidents of acute painful vaso-occlusive crisis and acute chest syndromes5 and hence contribute to better postoperative conditions.
Regional analgesia and anesthesia are increasing in popularity for perioperative management. Epidural catheters are now being placed for pain management prior to surgical procedures and continued intraoperatively — either as total epidural anesthesia or as supplementation for general anesthesia. Peripheral nerve blocks and wound infiltrations are commonly used as adjuvant to monitored anesthesia care and general anesthetic techniques because they can provide intra- and postoperative analgesia.6
Postoperative pain is often under-treated with routine orders of intramuscular ‘as needed’ medications failing to relieve pain in about half of postoperative patients. Aside from potential side effects, factors such as timing of onset of action, duration of action, maximum pain relief, use of rescue medication, as well as other factors relevant to a given pain model, are important in determining overall analgesic efficacy.7 Post-operative patients in pain manifest shallow breathing and decreased cough with the potential for pulmonary atelectasis. These patients may also experience delayed return of bowel function. Inability to provide adequate analgesia after many of these surgical procedures impedes effective physical therapy and rehabilitation. In cases of procedures like joint or lower extremity surgery, proper pain management is critical to achieving acceptable joint range of motion. Under-treatment of postoperative pain potentially delays discharges and adversely affects quality of life.
The authors have reviewed literature examining all stages of perioperative care, including the various modalities that have been shown to improve patient outcome postoperatively. The literature search was conducted of applicable studies and trials over a five-year period 1997-2002. Resources searched included the National Library of Medicine (PubMed), Medscape, and popular Internet search engines such as Yahoo and Google. Searches utilized terms such as “perioperative analgesia”, “pain management”, “regional anesthesia”, “perioperative outcome” — alone or in combination. Materials analyzed included abstracts, full-length articles, systematic reviews, meta-analyses randomized controlled trials, controlled trials, cohort, case-control analytic studies, descriptive case series, and narrative reviews. Preference was given to studies comparing at least two modes of administering perioperative pain management with at least one of them being a regional anesthetic or analgesic technique. Articles analyzing patient outcome and satisfaction with perioperative care, as well as placebo-controlled studies involving one modality, were included in this study.
Most studies in this review involved a small number of patients ranging from 30 to 112. Table 1 shows results from 11 studies examining some of the established techniques and methods such as regional blocks, subarachnoid blocks, and epidural analgesia/anesthesia employed at different times during the perioperative period.