Chapter 42: Pediatric Pain Management

INTRODUCTION

The treatment of pain is a fundamental aspect in caring for children. Management depends on an understanding of developmental pharmacology; the assessment of acute and chronic pain in children; interventional techniques; and the use of nonpharmacologic therapies, including physical, occupational, and cognitive-behavioral therapies.

Pain can be categorized as nociceptive, resulting from activation of nociceptors by actual or threatened damage to tissue, or neuropathic, resulting from dysfunction of the somatosensory nervous system. Pain may present as acute, chronic, or a combination of nociceptive and neuropathic. Acute pain is a physiologic sensation serving as a warning of disease or danger. Chronic pain, whether recurrent or persistent, is defined by the International Association for the Study of Pain (IASP), as pain that has persisted 3 months or more beyond the expected period of healing.^1–5

Children with chronic pain may have significant school absenteeism, and become socially withdrawn. This in turn may have a long-term impact on their health and development.77 There is evidence that childhood pain that is untreated can transition into adult chronic pain conditions. The economic burden from such unmanaged pain conditions has been extrapolated to be a cost of $19.5 billion in the United States annually.^4,5,7,8

ANALGESIC PHARMACOLOGY

Improving pain control necessitates understanding the pharmacodynamic and pharmacokinetic differences between nonopioid and opioid analgesics in the developing pediatric population.⁹ Several factors result in age-related differences in response to analgesics:

• Newborns and young infants have a delay of hepatic enzymes involved in the metabolism of most opioids and amide local anesthetics, resulting in a prolonged half-life. Most infants will have maturation of hepatic enzymes by 6 months of age, although there is individual variation.

• Glomerular filtration and renal tubular function, involved in the clearance of opioids and their metabolites, are reduced in the first few weeks of life and may affect elimination of these drugs.¹⁰

• Newborn and young infants have reduced levels of α-1 acid glycoprotein and albumin proteins. For drugs with high protein binding, such as opioids, reduced plasma protein binding can result in a higher concentration of unbound (active) drug.

• Ventilatory reflexes are immature in infants. Infants therefore do not respond to hypoxia or hypercarbia and thereby have increased the risk of hypoventilation from opioids.¹⁰

PAIN ASSESSMENT

Assessing a child's pain experience is critical in developing a comprehensive treatment plan. Pain measures have been developed for children that are based on developmental age and the child's ability to understand general concepts of pain (Table 42–1).