CHAPTER 25 Wound pain: impact and assessment
1. Describe the different types of pain experienced by the patient with a wound.
2. Describe the physiologic effect of pain.
3. List the indicators of pain in the conscious and unconscious patient.
4. Describe two methods for assessing wound pain.
5. Identify the common and unique features of three wound pain models.
General pain concepts, as well as wound pain-specific concepts, guidelines, and research are essential underpinnings for all wound care clinicians because painful wounds are so ubiquitous. McCaffery first defined pain in 1972 in her pioneering nursing research in this field as “whatever the experiencing person says it is and exists whenever he says it does” (McCaffery and Pasero, 1999). Today this definition poses a clinical dilemma in the case where an individual is unable to communicate (e.g., patient with severe dementia) and is not able to verbalize his or her pain. However, the inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment (European Wound Management Association [EWMA], 2002; World Union of Wound Healing Societies [WUWHS], 2004). With McCaffery as co-chair, the International Association for the Study of Pain (IASP) and the American Pain Society (APS) subsequently redefined pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” (McCaffery and Pasero, 1999). The National Advisory Council on Aging (2002) describes pain management as “the elimination or control of pain, with a goal of restoring comfort, quality of life, and the capacity to function as well as possible given individual circumstances and the source of pain.”
This chapter discusses pain-related concepts, perception, and consequences of wound pain as well as physiology, classification, assessment of pain, and an introduction to wound models. Chapter 26 provides a detailed discussion of pain management.
Perceptions about pain
A patient’s expectation of pain can be largely dependent on his or her cultural and ethnic background, social support system, medical history, and prior pain experience (Morris, 1991). When a patient cannot communicate in the language of the care provider, effective management of his or her pain becomes more difficult and often leads to undertreatment. Erroneous assumptions and perceptions on the part of the provider about pain tolerance based on traits such as age, gender or ethnic background, can result in inadequate analgesia (Lasch, 2002). However, studies indicate that when patients control their own analgesia (e.g., with patient-controlled analgesia pumps), patients self-administer similar doses for similar injuries independent of race or cultural background. Health care providers must be aware of obstacles such as language and cultural barriers and use more care and time in assessing and treating such patients. Interventions that alter a patient’s expectation of pain may positively affect the pain experienced by that patient.
A long-held myth in wound care is that venous ulcers and pressure ulcers are not painful. Ironically, in a study of patients with venous ulcers, patients often did not request pain medication because they expected their wounds to be painful (Krasner, 1997). Therefore health care professionals often do not even assess for venous ulcer pain, which then contributes to the undertreatment of venous ulcer pain. In a study conducted by Dallam et al (1995) involving 132 patients with pressure ulcers, 68% reported some type of wound pain, yet only 2% were given analgesics for pressure ulcer pain within 4 hours of pain measurement.
In a 2008 review of the literature on pain with pressure ulcers, reported pain prevalence ranged from 37% to 100%, and ulcer stage was reported to most consistently affect pain (Girouard et al, 2008). In 2009, the National Pressure Ulcer Advisory Panel (NPUAP) published a systematic literature review and white paper on pressure ulcer pain advocating the importance of pressure ulcer pain and the need for further research in all populations across all settings (Pieper et al, 2009).
In a qualitative study of nurses providing care to patients with a pressure ulcer who experienced pain, nurse generalists and advanced practice nurses were asked to reflect and write a story about the phenomenon of caring for the patient with wound pain (Krasner, 1996). Text analysis of the reflections from the 42 participants revealed three patterns of responses by the caregivers. By examining and understanding these patterns of response and the examples of behaviors relative to each response, valuable insight can be gained into the delivery of more sensitive care that is patient focused rather than wound focused.
The third and final pattern of response observed by this group of nurses was to “confront the challenge of pain” as exemplified by coping with the frustrations and “being with” the patient. A central benefit to this type of response by the nurse is the insight gained into the meaning of the pain experience to the patient. For example, the challenge of the pain may be triggered more by anxiety rather than pain. This insight then can be used to develop a more individualized plan of care. A hermeneutic phenomenologic study by Kohr and Gibson (2008) suggests that although nurses want to do the right thing and protect the patient from physical and psychic wound pain, many barriers to optimal pain management exist.
Consequences of wound pain
Quality of life
Chronic pain has been well documented to affect a patient’s physical, psychological, and spiritual well-being and social concerns. Patients experience lack of sleep, fatigue, anxiety, depression, and fear of future pain. Chronic pain increases caregiver burden and greatly affects roles and relationships (Ferrell, 2005). Patients with wounds are at high risk for acute and chronic pain that tends to be moderately severe to severe in intensity. Uncontrolled pain is considered the most significant predictor of impaired quality of life (Dallam et al, 1995; Szor and Bourguignon, 1999). Pressure ulcer pain, specifically, affects activities of daily living because the pain could limit the patient’s mobility and ability to reposition, thus increasing the risk for wound deterioration (Popescu and Salcido, 2004).
Specific to venous ulcer pain, Hofman et al (1997) found that for 69% of the patients in their study, pain was “the worst thing about having an ulcer,” disrupting sleep and negatively affecting quality of life. Previous studies reported similar findings in patients with venous ulcers (Phillips et al, 1994; Walshe, 1995). Using a Heideggerian hermeneutic phenomenologic approach, Krasner (1997, 1998a, 1998b) described the experience of patients with venous ulcer pain. The common pattern that emerged from the study was “carrying on despite the pain.” Eight themes provide a glimpse at the impact of venous ulcer pain on quality of life and activities of daily living were identified (Box 25-1).
Physiologic
Acute pain increases circulating catecholamines, including epinephrine and, leads to peripheral vasoconstriction, decreased perfusion of blood to the skin and extremities, and, consequently, reduced oxygen availability in the tissues (Franz et al, 2008). As tissue oxygen decreases, leukocyte activity is progressively impaired so that bacteria have a greater likelihood of remaining viable and cause wound infections (Hopf and Holm, 2008). To function properly (i.e., to remove cellular debris and kill bacteria in the wound), leukocytes require oxygen. A major mechanism by which leukocytes kill bacteria is oxidative bacterial killing. The membrane-bound enzyme phagosomal oxygenase or primary oxidase converts oxygen to superoxide, which itself is bactericidal. Superoxide is then converted to multiple other bactericidal oxidants within the phagosome, including hydrogen peroxide, hypochlorite (bleach), and hydroxyl radical (Allen et al, 1997). An hypoxic wound environment will further impair wound healing by disrupting fibroblast activity and angiogenesis, thereby impacting negatively on collagen synthesis and migration and the delivery of oxygen to the wound cells.
Pain physiology
Although pain is a subjective experience, objective physiologic mechanisms control how pain is initiated, transmitted, and perceived. The objective neural response to a painful stimulus (e.g., at the wound) is called nociception. Nociception is defined as the detection of impending or actual tissue damage and is accomplished by specialized sensory nerve terminals (nociceptors) derived from Aδ (delta) and C fibers. All nerve endings in the epidermis are considered nociceptors (Popescu and Salcido, 2004). When cells are damaged, chemicals are released, triggering the nerve fibers to transmit the pain impulses along nerve sheaths to the spinal cord. The spinal cord transmits the information to the brain, where it is centrally processed. Synaptic junctions in the spinal cord and brain will either attenuate or amplify the pain signal and thus affect how the intensity of the pain signal will be perceived or interpreted.
In addition to the actual tissue injury that triggers the pain episode, psychological, physical, emotional, and cultural factors as well as the patient’s expectations collectively define an individual’s pain experience. Thus the same type of injury in two different individuals often generates a very different pain experience in terms of severity, quality, and impact (Turk, 1993). Reported pain may appear to be either less than expected or excessive given the degree of tissue injury. Distress out of proportion to the injury is often ascribed to anxiety as well as “catastrophizing” (Sullivan and Neish, 1999; Sullivan et al, 1998).
Catastrophizing is significantly correlated with mood and personality variables such as depression, fear of pain, coping strategies, and state and trait anxiety (Rosenstiel and Keefe, 1983; Sullivan et al, 1995). These variables have been shown to be important predictors of the pain experience. Preoperative levels of anxiety and catastrophizing can be predictive of postoperative pain intensity. A study by Granot and Ferber (2005) found that moderately anxious surgical patients are at greater risk for developing greater postoperative pain.