Upon completion of the chapter, the reader will be able to:
Identify characteristics of the types of pain: nociceptive, inflammatory, neuropathic, and functional.
Explain the mechanisms involved in pain transmission.
Select an appropriate method of pain assessment.
Recommend an appropriate choice of analgesic, dose, and monitoring plan for a patient based on type and severity of pain and other patient-specific parameters.
Perform calculations involving equianalgesic doses, conversion of one opioid to another, rescue doses, and conversion to a continuous infusion.
Educate patients and caregivers about effective pain management, dealing with chronic pain, and the use of nonpharmacologic measures.
Pain is defined by the International Association for the Study of Pain (IASP) as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.”1 KEY CONCEPT Pain is an unpleasant subjective experience that is the net effect of a complex interaction of the ascending and descending neurons involving biochemical, physiologic, psychological, and neocortical processes. Pain can affect all areas of a person’s life including sleep, thought, emotion, and activities of daily living. Because there are no reliable objective markers for pain, the patient is the only person who can describe the intensity and quality of their pain.
Pain is the most common symptom prompting patients to seek medical attention and is reported by more than 80% of individuals who visit their primary care provider.2 Despite the frequency of pain symptoms, individuals often do not obtain satisfactory relief of pain. This has led to initiatives in health care to make pain the fifth vital sign, thus making pain assessment equal in importance to obtaining a patient’s temperature, pulse, blood pressure, and respiratory rate.
EPIDEMIOLOGY AND ETIOLOGY
Most people experience pain at some time in their lives, and pain is a symptom of a variety of diseases. Thus identifying the exact prevalence of pain is a difficult task. According to the American Pain Foundation, more than 76 million people in the United States suffer from chronic pain, and an additional 25 million experience acute pain from injury or surgery.2
Prevalence rates for a variety of different types of pain have been described. Approximately one-fourth of US adults reported having low back pain lasting at least 1 day in the past 3 months.3 Migraine affects more than 28 million Americans, and 78% of Americans experience a tension headache during their lifetime.4 Pain resulting from fibromyalgia affects 10 million Americans.5 Pain ranges in prevalence from 14% to 100% among cancer patients.6 The prevalence of neuropathic pain is unknown because of the lack of epidemiologic studies. Current estimates suggest that approximately 1.5% of the population in the United States might be affected by neuropathic pain.7 Approximately 25% to 50% ...