Types of Pain
Pain is categorized according to its duration, location, and etiol-ogy. Three basic categories of pain are generally recognized: acute pain, chronic (nonmalignant) pain, and cancer-related pain.
Usually of recent onset and commonly associated with a specific injury, acute pain indicates that damage or injury has occurred. Pain is significant in that it draws attention to its existence and teaches the person to avoid similar potentially painful situations. If no lasting damage occurs and no systemic disease exists, acute pain usually decreases along with healing. For purposes of definition, acute pain can be described as lasting from seconds to 6 months. However, the 6-month time frame has been criticized (Brookoff, 2000) as inaccurate since many acute injuries heal within a few weeks and most heal by 6 weeks. In a situation where healing is expected in 3 weeks and the patient continues to suffer pain, it should be considered chronic and treated with interventions used for chronic pain. Waiting for the full 6-month time frame in this example could cause needless suffering.
Chronic pain is constant or intermittent pain that persists beyond the expected healing time and that can seldom be attributed to a specific cause or injury. It may have a poorly defined onset, and it is often difficult to treat because the cause or origin may be un-clear. Although acute pain may be a useful signal that something is wrong, chronic pain usually becomes a problem in its own right.
Chronic pain may be defined as pain that lasts for 6 months or longer, although 6 months is an arbitrary period for differen-tiating between acute and chronic pain. An episode of pain may assume the characteristics of chronic pain before 6 months have elapsed, or some types of pain may remain primarily acute in na-ture for longer than 6 months. Nevertheless, after 6 months, most pain experiences are accompanied by problems related to the pain itself. Chronic pain serves no useful purpose. If it persists, it may become the patientâ€™s primary disorder.
The nurse may come in contact with patients with chronic pain when they are admitted to the hospital for treatment or when they are seen out of the hospital for home care. Frequently the nurse is called on in community-based settings to assist pa-tients in managing pain. For more information on common pain syndromes, see Chart 13-1.
Pain associated with cancer may be acute or chronic. Pain result-ing from cancer is so ubiquitous that after fear of dying, it is the second most common fear of newly diagnosed cancer patients (Lema, 1997). More than half of the 1,308 cancer patients in-cluded in a study conducted by Foley (1999) reported being in moderate to severe pain 50% of the time. Pain in the patient suf-fering from cancer can be directly associated with the cancer (eg, bony infiltration with tumor cells or nerve compression), a result of cancer treatment (eg, surgery or radiation), or not associ-ated with the cancer (eg, trauma). Most pain associated with can-cer, however, is a direct result of tumor involvement. An approach to cancer pain management is illustrated in Figure 13-1. This three-step approach illustrates the types of analgesic medications used for various levels of pain. A cancer pain algorithm developed as a set of analgesic guiding principles appears in Figure 13-2.
The previous discussion of acute and chronic pain is an example of the categorization of pain according to duration. Pain is some-times categorized according to location, such as pelvic pain, headache, and chest pain. This type of categorization is helpful in communicating and treating pain. For example, chest pain sug-gests angina or a myocardial infarction and indicates the need for treatment according to cardiac care standards.
Categorizing pain according to etiology is another way to think about pain and its management. Burn pain and postherpetic neu-ralgia are examples of pain described by their etiology. Clinicians often can predict the course of pain and plan effective treatment using this categorization.