Pain
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We studied if ethnicity influences patient-controlled analgesia (PCA) for the treatment of post-operative pain. Using a retrospective record review, we examined data from all patients treated with PCA for post-operative pain from January to June 1993. We excluded patients who did not have surgery prior to the prescription of PCA or were not prescribed PCA in the immediate post-operative period. ⋯ While there were no differences in the amount of narcotic self-administered, there were significant differences in the amount of narcotic prescribed among Asians, Blacks, Hispanics, and Whites (F--7,352, P < 0.01). The ethnic differences in prescribed analgesic persisted after controlling for age, gender, pre-operative use of narcotics, pain site, and insurance status. Patient's ethnicity has a greater impact on the amount of narcotic prescribed by the physician than on the amount of narcotic self-administered by the patient.
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Heat pain threshold is commonly considered to be an 'absolute' value, which is not dependent on the area stimulated. In contrast, suprathreshold heat pain sensation has been shown to be highly dependent on the area stimulated, with considerable spatial summation demonstrated both within and between dermatomes. The present study sought to reevaluate two major issues: (a) Whether nociceptive thresholds are, indeed, independent of stimulation area. (b) Whether the spatial summation of suprathreshold heat pain sensation is independent of threshold changes. ⋯ Furthermore, when using a stimulus configuration in which stimulation area was increased without changing nociceptive threshold, no spatial summation of perceived pain intensity was seen. Our results suggest that the spatial summation of perceived heat pain intensity can be attributed to reduced heat pain threshold. Furthermore, our findings stress the importance of determining pain thresholds in studies examining the psychophysics of suprathreshold noxious stimuli.
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Accuracy and errors in judges' attempts to differentiate facial expressions that displayed genuine pain, no pain or were dissimulated (i.e., masked and exaggerated) were examined. Judges were informed that misrepresentations in the facial expressions were present and were asked to rate their confidence in classifying these expressions. Detailed, objective coding of the patients' facial reactions (e.g., brow lowering, mouth opening) were related to judges' decisions. ⋯ Judges consistently used rules of thumb based on specific facial cues when making judgments. Certain cues were effectively discriminative. Systematic training in the use of specific cues or the use of articulated decision rules may be helpful in improving judges' accuracy.
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This review is a critical summary of research examining gender variations in clinical pain experience. Gender-comparative pain research was identified through Medline and Psychlit searches and references obtained from bibliographies of pertinent papers and books. Review of this research demonstrates that women are more likely than men to experience a variety of recurrent pains. ⋯ Women may be at greater risk for pain-related disability than men but women also respond more aggressively to pain through health related activities. Women may be more vulnerable than men to unwarranted psychogenic attributions by health care providers for pain. Underlying biological mechanisms of pain and the contribution of psychological and social factors as they contribute to the meaning of pain for women and men warrant greater attention in pain research.
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Randomized Controlled Trial Clinical Trial
Topical capsaicin selectively attenuates heat pain and A delta fiber-mediated laser-evoked potentials.
Cutaneous stimulation with CO2 laser pulses activates A delta of nociceptive afferents and evokes late cerebral potentials (LEPs), the amplitude of which correlates parametrically with the perceived magnitude estimation of laser pulses. Capsaicin is known to desensitize the nociceptive terminals of C fibers. In this double-blind, vehicle-controlled experiment, we tested the hypothesis that topical capsaicin would inactivate A delta afferents and lead to an attenuation of the LEPs. ⋯ It indicated that topical capsaicin caused a definite functional and reversible inactivation of A delta nociceptive afferent transmission. The decline in the magnitude estimation of laser pulses concomitantly with the attenuation of LEP amplitudes supports the hypothesis that some A delta afferents mediate noxious heat in humans. These findings demonstrate the usefulness of LEP in the physiological evaluation of nociceptive pathways and its potential usefulness in objectively documenting the effect of pharmacological treatment on pain perception.