Sickle Cell Pain
Sickle cell disease (SCD) afflicts 70,000 Americans. On average, sufferers have one significantly painful episode each year, although more fortunate people with SCD may go for years between painful crises. The cause of sickle cell pain is thought to be tissue ischemia due to occlusion of vascular beds with sickled erythrocytes. A vicious process leads to pain caused by hemoglobin S in erythrocytes that react to form rigid polymers, producing erythrocyte distortion, polymorphonuclear (PMN) leukocyte cytokine release, and endothelium adhesion molecule induction. Erythrocyte binding causes the vessel caliber to narrow, which in turn traps more cells and creates more hypoxia and more sickling. Erythrocyte and endothelial interaction releases vasoconstrictors, which worsen regional blood flow. Areas commonly involved with SCD include vascular beds in vertebrae, femurs, hips, and ribs, and the resulting pain manifests in the back, thigh, hip, and chest.
Pain with acute SCD may be more severe than postoperative pain or even pain caused by cancer. SCD pain may be provoked by temperature extremes, physical and emotional stress, dehydration, menstruation, fatigue, or infection. For many patients, pain recurs in the same areas from one attack to the next, and often affects two or more sites at the same time.
Most healthcare professionals treating those with SCD-evoked pain use intravenous analgesics administered around-the-clock. Patient-controlled analgesia (PCA) relieves pain and avoids intermittent dosing, but typically decreases the time between pain perception and administration of medication. Oral and transdermal pain relievers have not been fully evaluated, but they do offer alternatives to parenteral agents. Oral opioids may be used for mild-to-moderate pain; however, opioids are often used later in recovery, when the patient’s pain intensity is improving. Transdermal delivery may be effective, but not as effective as intravenous medication, because 12 or more hours are needed to reach steady state; with titration, dosing can be challenging when pain fluctuates.
Patients with sickle cell pain encounter barriers to appropriate care, especially because of poor continuity of care and perceived possible opiate dependence. Even though pain triggers hospitalization, not all patients experience pain with the same frequency or intensity. Five percent of patients have 3 or more painful episodes per year, and those who are at risk for poor pain control also have poor coping strategies, are poorly adjusted, live in adverse social situations, and are more profoundly affected by pain. Unfortunately, health professionals remain reluctant to prescribe adequate doses of opioids because of their own fear about potential addiction and side effects. Adequate pain control is not commonly noted because of insufficiently assessed pain, inappropriate opioid selection or dose, and lack of knowledge about SCD and its concomitant pain. Protocol-guided management of pain crises improves patient satisfaction.