Acute vasoocclusive events, or painful “crisis,” are the most common complication of SCD and are the most frequent cause of ED visits.2 Pain episodes result from the obstruction of blood flow in the microcirculation leading to tissue ischemia and microinfarction. Vasoocclusion occurs via a combination of sickle cell interactions with endothelial cells and obstruction from nondeformable sickle cells.
Dactylitis, or hand–foot syndrome, is vasoocclusion in the marrow of the metacarpal or metatarsal bones (Fig. 104-1). This is often the earliest presentation of SCD, usually occurring between 6 and 18 months of life. Infants present with hand and foot swelling and tenderness, which may lead to refusal to walk and irritability. Dactylitis declines with age as hematopoiesis shifts to the long bones.
Child with sickle cell anemia and dactylitis.
Older patients typically experience vasoocclusive events in the long bones, back, joints, and abdomen. Pain events may be precipitated by dehydration, hypoxia, cold exposure, or infection. However, often no instigating factor is identified. There is a great deal of individual variation in number and severity of painful crises. On average, patients with SCD experience 0.8 hospitalizations per patient-year, but 5% of patients have frequent pain crises and account for approximately one-third of all medical contacts for painful crisis.2 Figure 104-2 outlines an approach to the management of severe acute pain in the ED.
Algorithm for the management of sickle cell disease.
As there is no diagnostic test or clinical finding that will identify patients in vasoocclusive crisis, the diagnosis is made on the basis of history alone. Patients with SCD and pain should be evaluated for other disease processes such as traumatic injuries, osteomyelitis, septic arthritis, and surgical abdominal problems. The formation of gallstones due to chronic hemolysis may lead to cholecystitis or pancreatitis and abdominal pain. A complete blood count (CBC) and reticulocyte count is indicated in every encounter with SCD patients. Typically, patients remain at baseline levels of Hgb during a painful event. Hydration at maintenance rate should be initiated to correct and prevent dehydration. Overhydration may lead to ACS and should be avoided. Oxygen has not been shown to be beneficial in the management of pain crises unless hypoxemia is present.
Pain should be assessed at least every 30 minutes using standardized pain scales. Prompt initiation of appropriate pain control is important. Pain relief is achieved with a variety of analgesics, depending on the severity of the crisis and what the patient has required in past crises. Oral agents such as acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), and codeine used separately or in combination are the mainstays of treatment for mild-to-moderate pain. Usually, patients have unsuccessfully tried these therapies on a scheduled basis at home prior to presenting to the ED. For patients who have not attempted oral therapy at home, this should be initiated first. Parenteral opioids, preferably morphine or hydromorphone, are often necessary for severe pain. Anxiety about giving children narcotics leads to undertreatment of pain, which should be avoided. Meperidine is a poor choice for SCD pain. Its use results in the buildup of normeperidine, a toxic metabolite with poor analgesic effect, which can cause dysphoria, and increases the risk of seizures.3
Typically, patients in the ED receive scheduled oral opioid and NSAIDs and parenteral opioid analgesics and are observed for 3 or 4 hours. Patients will often require further doses of parenteral opioid. If the patient remains comfortable without further need for parenteral opioid, he or she may be discharged with continued scheduled oral opioid and NSAIDs at home. If adequate pain relief is not achieved, the patient is admitted for further parenteral analgesia. Analgesia should be provided at frequent regular time intervals to avoid breakthrough pain. In a crisis prn pain medications should be avoided. When pain recurs between doses, the recurring pain is more difficult to control. Hypoventilation as a result of opiate use may increase the risk of developing ACS. Incentive spirometry should be encouraged in order to decrease this risk.