As discussed earlier, pain is a complex and personal experience. It is affected by physiological, psychological, and spiritual factors. The evaluation of pain must consider these factors and their interactions that result in the experience of pain. A useful mnemonic in evaluating pain(s) is the acronym: NOPQRST.9
Number of Pains
Although we tend to speak of a patient's pain as an overall experience, in fact, many patients have more than one pain. It would be more appropriate to speak of a patient's pains. These should be individually evaluated.
Origin of Pain
Understanding the cause of a particular pain is immensely helpful. Removal of the underlying cause may eliminate the pain. Even if this is not possible, understanding the origin of the pain may help with consideration of specific therapeutic options.
Palliate and Potentiate
What makes the pain better or worse? Do certain activities or body positions alleviate or worsen the pain? How have previously tried medications affected the pain (partial relief, no relief, etc.)? This may provide an important clue as to the type of pain being experienced, if in doubt. While the focus of this text is on pharmacologic therapy, it is important to point out that nonpharmacologic interventions can have a significant (positive or negative) effect on pain.
Nociceptive pain tends to worsen when stress or pressure is applied to an affected area. Neuropathic pain may be "set off" when usually nonpainful stimuli, such as a light touch, temperature change, or even air movement, provoke a "reverb"-like phenomenon, with paroxysms of pain.
While patients may be able to speak about the effect of medications or body positions, they may be less able to comment on the effect of psychological or spiritual factors. The clinician should be aware that depression, anxiety, confusion, and spiritual distress may all contribute significantly to the experience of pain. If these conditions are present, treating them may result in significant palliation.
A great variety of words are used to describe pain. Nociceptive pain may be sharp, dull, stabbing, or pressurelike. Neuropathic pain descriptions often have an electrical quality: burning, lancinating, buzzing, tingling, zapping, and lightninglike.
Both nociceptive and neuropathic pains may radiate, although we usually associate radiation with neuropathic pain. Neuropathic pain tends to radiate in a distribution that follows nerves. Classic examples include trigeminal neuralgia and herpes zoster pain. The stocking glove distribution of peripheral neuropathies, as in diabetes, also follows a pattern of terminal nerve endings. Nociceptive pain radiates in less obvious ways. Thus, pericarditis, for example, may radiate to the scapula. Cardiac pain may radiate to the arm(s) or neck.
Severity. As mentioned above, it is impossible to accurately gauge the severity of chronic pain by observation alone. You have to ask. The use of pain scales is strongly recommended when patients report having pain. Some patients respond better to certain scales than others. Some scales use nonnumerical images such as faces or colors to represent the range of distress.
Having said this, even numerical scales communicate limited data. On a scale of 0 to 10, is one person's 7 the same as another's? How many of us have really experienced level 10 pain? What is the worst pain we could endure? Hopefully, we will never find out.
If nothing else, pain scales seem to communicate the patient's urgency in wanting their pain addressed. On a scale of 0 to 10, pains of 1 to 3 are often well tolerated. Patients often decline additional interventions at these levels. Levels 3 to 6 usually indicate that some intervention is desired, although it is not an emergency. Pain at 7 to 10 is a serious problem. Not only is the pain seriously distressing, there is usually a fear that it will become a 10 and thus "out of control." Pain at level 10 (or greater) is perceived as an emergency by the patient and should usually be treated as an emergency by the clinician. Such pain is overwhelming. Having said this, some patients will report that pain management is "adequate" with a score as high as 7 to 10. Others will want urgent treatment when the scores rise from 1 to 2.6. Understanding how that patient interprets the pain score is most important. It is strongly advised that the examiner assess whether a given score means treatment is adequate for the individual patient. Individual patients tend to be consistent over time.
Suffering. What impact is the pain having on the patient? The impact may be an internal experience, such as depression or a thought of suicide, or may directly affect the patient's functioning. Sleep disturbances, difficulty walking, inability to work, and impairment of the activities of daily living may all reflect the pain experience. As obvious as this may seem, I am struck by how often we forget to ask how pain (or other symptoms) affect a person's life. Perhaps it is because we assume that pain is simply awful - what more do we need to know? However, hearing how a person is suffering with pain (both the nitty-gritty - "I can't work" - and the deep issues - "I wonder why God did this to me") helps us understand and empathize with what the patient is going through. Personally, I have trouble relating to a number, but if a patient can begin talking to me about how life has changed for them, then I feel I can gain a small glimpse of their experience.
Timing and Trend
Timing. Pain is rarely the same at all times. Pain has a pattern over time. Later, I will explain how matching the patient's pain pattern with therapeutic interventions (pattern matching) enables one to maximize therapeutic efficacy and minimize side effects, especially when treating nociceptive pain. Acute pain comes on rapidly and usually dissipates rapidly. Most chronic pain has a base and occasional spikes of incident pain, which may be predictable or unpredictable. Both need to be addressed. For example, some men may experience predictable trigeminal neuralgia only when shaving. Bed-bound patients often experience pain predictably with turning or cleaning. Wounds may hurt during dressing changes.
Trend. Pain often has momentum. It is very difficult to get a handle on rapidly escalating pain. Therapy is harder and suffering appears to be greater when the trend is worsening. This is true both physiologically and psychologically. Physically, we now know that escalating pain can "rev-up" in the central nervous system, amplifying painful stimuli and resulting in stronger pain signals. Specific receptors in the spinal cord such as those for N-methyl-D-aspartate (NMDA) are involved in this process, and blockading such receptors can be useful in resistant pain syndromes. Psychologically, patients are very aware of their pain trend. If the pain is worsening, patients understandably project into the future that it will become worse and even unendurable. This projection itself contributes to the pain experience and may be communicated as a higher pain score. Likewise, if the trend is good, patients may be able to tolerate more physical pain at any given moment as they project into a more pleasant future. Pain is certainly experienced in the present but is understood in terms of the past and the future.
Perhaps a personal story will help illustrate this point. A few years ago while having a dental cavity filled, I tried to distract myself from the pain I was experiencing by asking myself, "On a scale of 0 to 10, how much pain do you have," as I had asked countless patients. "Hmm, perhaps a 3 or a 4," I thought. With each little whine of the drill I thought, "Only a few moments more, then it will be over." I was to raise my hand if I had too much pain, but I could bear it a bit longer. And then it was over. I wondered - what if that pain had gone on forever? What if I had known it would not only go on, but get worse and worse? My hand would have been up in a flash. The idea of that pain going on and getting worse would have been too much to bear.
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Palliative Care Perspectives
James L. Hallenbeck, M.D.
Copyright © 2003 by Oxford University Press, Inc.
The online version of this book is used with permission of the publisher and author on web sites affiliated with the Inter-Institutional Collaborating Network on End-of-life Care (IICN), sponsored by Growth House, Inc.