Management of Acute Pain in Children: Pharmacologic

Patient Controlled Analgesia

PCA is widely used for postoperative pain relief in both children and adults. With appropriate preoperative teaching and encouragement, children as young as 6 to 7 years of age can independently use the PCA pump to provide good postoperative pain relief.³⁴ Children between the ages of 4 and 6, however, generally require encouragement from their parents and nursing staff to push the button before anticipated painful movements or procedures. Even with encouragement, the failure rate among 4 and 5 year olds with PCA appears quite high. For younger children, NCA has recently gained popularity to permit small titrated dosing of opioids for infants and children unable to use the PCA button.³⁵

Typical Starting Parameters for PCA
Drug	Bolus dose (mcg/kg)	Continuous rate (mcg/kg/hour)	4 hour limit (mcg/kg)
Morphine	20	4-15	300
Hydromorphone	5	1-3	60
Fentanyl	0.25	0.15	4
Lockout interval = 5 to 7 minutes. The lockout interval is the period during which the PCA unit is refractory to further demands by the patient, and is necessary to prevent patients from taking an additional dose before appreciating the effect of the preceding dose.

PCA may be administered either alone or in conjunction with a low-dose continuous infusion. Initial parameters for the most commonly used agents can be found in the table (see above), Typical Starting Parameters for PCA. Morphine, hydromorphone and fentanyl have all been used and there are no data to suggest that one is inherently better than another. There is large individual variation across drugs, however, and it may be necessary to shift from one to another to find the most beneficial agent. Morphine has been the most extensively studied in children and often is tried first. Basal infusions improve sleep quality, but have been associated with episodes of hypoxemia when used for postoperative pain management in children.³⁶ One solution for this has been to combine PCA in bolus-only mode with round-the-clock administration of NSAIDs and/or acetaminophen. For children with acute pain associated with chronic illness, most of whom have developed some tolerance to opioid analgesics, a larger basal infusion is preferred to adequately control disease-related pain. For tumor- related pain or palliative care, roughly two-thirds of the overall requirement is provided from the basal infusion.

Although PCA is widely available in the U.S., it is useful to have options when considering strategies for the management of inpatients with acute severe pain. By delivering very small boluses of drug at a very short interval, PCA eliminates the problem of fluctuating effects associated with bolus injections of a short-acting opioid at an interval of several hours. The use of a simple regimen involving intravenous methadone can accomplish the same outcome.³⁷ In this approach, loading doses (usually 0.1 to 0.2 mg/kg) are given and the nursing staff evaluates pain at intervals not exceeding 4 hours (reverse “PRN” method). The drug is administered via a “sliding scale”. If the pain is rated as severe, 0.07 mg/kg is administered; 0.05 mg/kg is given for moderate pain or 0.03 mg/kg if the pain is considered mild. This method can be safe and effective, but is dependent on an available, well-trained staff.

Children who have chronic pain related to cancer or other serious illness can be treated with long-term opioid therapy, typically with oral or transdermal delivery. The guidelines to optimize outcomes mirror those of adults.