From the dark years when medicine taught that neonates feel no pain, we have emerged into an era when, finally, pain and sedation assessment have become as important as any other vital sign in every patient. Sedation and pain management can present challenges for the pediatric practitioner: Many patients are too young to verbalize their discomfort. Practically, there are no truly objective measures of pain: It is a personal, often emotional, experience unique to each patient. Pediatric patients range from the articulate to the noncommunicative, providing unique challenges in the management of their pain.
THE PATHOPHYSIOLOGY OF PAIN
Pain has been defined by the International Association of Pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” Pain can be both an expected physiologic response to a noxious stimulus or an abnormal, pathologic response, as might be the case in chronic pain syndromes.
The classic pain pathway involves nociceptive neurons that respond to painful chemical, mechanical, and thermal stimuli. They are found in their greatest numbers in the skin but are present in many tissues throughout the body. Once stimulated, they transmit signals along peripheral nerve fibers to the lower and midbrain; pain is perceived in the cerebral cortex. Faster A-delta fibers elicit “sharp” initial sensations, while signals along C fibers are perceived as burning, aching sensations of a more chronic nature.
Stimulation of nociceptive neurons causes the release of many local mediators, including histamine, bradykinins, substance P, prostaglandins, growth factors, and H+ and K+ ions. The mere perception of pain, then, is in itself an inflammatory process. Repeated stimulation of peripheral nociceptors, causing repetitive firing of the involved A-delta and C fibers, can lead to hypersensitization of the afferent pathway. This can transform the experience of pain into a neuropathic process, leading to hyperalgesia, an exaggerated response to painful stimuli, or even allodynia, a pain response to otherwise nonpainful stimulation in the tissues surrounding the injury. Factors that predispose patients to the development of neuropathic pain are not well understood.
As defined, pain has an emotional component. Individual patients will have different, yet valid, responses to similar painful stimuli. The assessment and management of pain needs to be tailored to the patient’s level of development, ability to communicate, and ability to tolerate discomfort.
The experience of pain is subjective and its assessment can be challenging, particularly in the young. Adults and mature younger patients can be asked to rank their pain on a scale of 0 to 10, with 10 being the worst imaginable pain. It is important to calibrate both the patient’s and the caregiver’s expectations: Sometimes, a 5 is tolerable, whereas sometimes a 3 is intolerable. Treating pain begins with assessment, and there is therapeutic value in patients ...