The Management of Postoperative Pain. Drugs and Anesthetic Techniques

Abstract

Effective pain relief is very important to treat any patient undergoing surgery. This should be achieved not only for ethical and humanitarian reasons, but also in order to obtain a smoother postoperative course, an earlier discharge from hospital, and a reduction of onset of chronic pain syndromes. In fact, there is now evidence that pain relief has significant physiological benefit. Analgesia for postoperative pain relief has traditionally been provided with widespread use of intramuscolar opioids. However, after surgery, patients frequently experience severe pain and a significant portion receive less than adequate analgesia [1, 2, 3]. Furthermore, surveys in the 1980s show that as high as 30%–75% of patients still receive inadequate pain treatment in the postoperative period, in spite of an increasing consciousness of this issue [4, 5, 6, 7]. It is remarkable that Smith, in an editorial, asserted “what is so surprising is that, this deplorable state of affairs has persisted and continues to persist in many hospital, despite considerable advances in the pharmacology of analgesic drugs and description of new and improved methods of relieving pain” [8]. Although recent years have seen the widespread use of modern and effective analgesic techniques such as epidural analgesia, postoperative regional blocks and patient-controlled analgesia (PCA) for the relief of postoperative pain, the most frequently used technique in surgical wards still remains intramuscolar opioids prescribed by ward surgeon and administered by ward nurse on an as-needed basis [9]. Multiple reasons for this undertreatment have been identified, but the primary factors appear to be an exaggerated fear of opioid addiction and respiratory depression [1, 10]. Another primary cause appears to be the perception that pain is a natural, inevitable accompaniment to illness and disease. Indeed, most patients, physicians, and nurses consider moderate to severe postoperative pain, despite the fact that fear of unrelieved pain is a primary concern of patients before surgery, to be an acceptable consequence of surgical intervention. Pain is invisible on most hospital wards and that is another important factor contributing to undertreatment. Severity of pain is not assessed and consequently it cannot be effectively treated. Thus, one of the most-important changes in improving postoperative pain management is to introduce pain assessment as the fifth vital sign in addition to the traditional four vital signs (temperature, pulse, blood pressure, and respiratory rate). Pain, physiologically, signals the presence of damage or disease within the body. Postoperative pain is the result of surgery but the continuous coming in of nociceptive stimuli during the postoperative period may be deleterious for the patient’s outcome [11, 12, 13] and may increase the cost of medical care. For example, pain contributes to the perioperative stress response with elevated cathecolamine levels, hypercoagulability, systemic and coronary vasoconstriction, metabolic shifts to the catabolic, protein-wasting state, and immunosuppression. Pulmonary function can also be compromised in patients undergoing abdominal or thoracic surgery, and pain-induced efferent activity is one possible mechanism of postoperative ileus [14]. Postoperative pain is a subjective experience and the need for each patient to reduce or eliminate pain and discomfort is individual. Thus, the management of postoperative pain has to take into account many factors such as clinical factors, patient-related factors, local factors, and organizational factors. Optimal techniques for acute pain management depend on patient co-morbidity, the magnitude of the surgical procedure, and a variety of other factors (previous opioid use, mental capacity, ethnic customs). Analgesia is best provided by a combination of two or more drugs or techniques, with different sites or through different mechanisms of action, or when analgesic effects are synergistic [15].