What is the best method of treating acutely worsened chronic pain?

She should be started on a PCA for rapid pain control and titration. Hydromorphone (Dilaudid) is a better PCA choice than morphine because she has acute renal failure. The equianalgesic dose ratio of oral morphine to IV hydromorphone is approximately 30:1.5. The total 24-hour opioid dose of 280 mg oral morphine is equivalent to 14 mg IV hydromorphone ([280mg morphine per day ÷ 30] x 1.5 = 14).

After adjusting for 60% incomplete cross tolerance, the total 24-hour opioid dose is reduced to 8.4 mg IV hydromorphone (14 mg x 0.6 = 8.4 mg). This is approximately equivalent to 0.4 mg IV hydromorphone/hour (8.4 mg ÷ 24 hours), which is her initial basal rate. The demand dose should be set at 0.2 mg (50% the basal rate) with a lockout interval of 10 minutes.

Over a period of several days, the patient’s pain was controlled and her opioid requirements stabilized. She was on a basal rate of 1.4 mg/hour and a demand dose of 1 mg with a 10-minute lockout. Her total 24-hour opioid requirement was 44 mg of IV hydromorphone. As her renal function improved but did not completely normalize, oxycodone was chosen over morphine when converting her back to oral pain medications (less active renal metabolites). The equianalgesic dose ratio of oral oxycodone to IV hydromorphone is approximately 20:1.5. Her total 24-hour opioid dose of 44 mg IV hydromorphone is equivalent to 587 mg oral oxycodone (44 ÷ 1.5) x 20. After adjusting for 60% incomplete cross tolerance, the total 24-hour opioid dose is reduced to 352 mg oral oxycodone or 180 mg of sustained-release oxycodone twice daily (352 mg ÷ 2 ≈ 180 mg). For breakthrough pain she should receive 40 mg of immediate-release oxycodone every hour as needed (10% to 15% of the 24-hour opioid requirement). TH

Dr. Youngwerth is a hospitalist and instructor of medicine, University of Colorado at Denver, assistant director, Palliative Care Consult Service, associate director, Colorado Palliative Medicine Fellowship Program, and medical director, Hospice of Saint John.

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