Sickle cell anemia is an inherited disease that is caused by an abnormal version of hemoglobin, known as hemoglobin S or sickle hemoglobin.
Patients with the disease often experience acute or chronic pain. Opioids sometimes may be used to manage this pain. However, some clinicians have biases against opioid use. As a result, the patient’s pain is sometimes not efficiently managed.
To address this problem, public authorities have developed guidelines for pain management. In the U.S., the National Heart, Lung and Blood Institute (NHLBI) provides guidelines based on recommendations developed by the American Pain Society (APS). In the U.K., guidelines are provided by the National Health Services (NHS) and the National Institute for Health and Care Excellence (NICE).
Types of pain in sickle cell anemia
Acute pain
Acute painful episodes in sickle cell anemia patients usually develop as a result of a vaso-occlusive crisis (VOC) and should be treated as a medical emergency. VOC occurs when sickle-shaped red blood cells block small blood vessels so that the blood cannot flow normally. This leads to tissue damage and causes pain.
Chronic pain
Pain is defined as chronic if it lasts three to six months or more. The cause of chronic pain in sickle cell anemia is unclear, but it may be an extension of recurrent painful episodes.
Chronic pain often is associated with neuropathic pain, which is caused by nerve damage. It often is described as tingling, burning, numbing, or lancinating (sharp) and may be described as a sensation of pins and needles. In sickle cell anemia patients, neuropathic pain is either caused by the occlusion of blood vessels that supply nerves, resulting in nerve cell damage, or by persistent chronic pain that results in inflammation.
Pain management guidelines
Acute pain
First, the cause of the pain should be evaluated. Acute pain is usually the result of VOC, but might be of different origin.
If the pain is caused by VOC, analgesic therapy should be started as soon as possible. The goal is to start with pain relief within 30 minutes of arrival at the hospital. The dose and type of painkiller to be used is based on the patient’s recent painkiller use, the location and intensity of the pain, other symptoms associated with the pain, and what agents and doses effectively worked in the past.
When VOC-associated pain is mild to moderate, non-steroidal anti-inflammatory drugs (NSAIDs) might be sufficient to control it. Diclofenac and ibuprofen are commonly used NSAIDs in sickle cell anemia patients. If the pain persists, an opioid can be added.
Moderate-to-severe pain usually is treated with opioids. For moderate pain, a weaker opioid such as codeine may be sufficient. For severe pain, a stronger opioid such as morphine, or equivalent opioid such as levorphanol, methadone, oxymorphone, or fentanyl may be used.
Since sickle cell anemia patients often have poor vein access, so under-the-skin (subcutaneous) rather than intravenous administration is recommended. The pain should be re-assessed every 15-30 minutes and opioids should be re-administered if necessary until the pain is under control.
To avoid repeated injections, a continuous infusion is recommended, which may allow the patient to better control their pain, known as patient-controlled analgesia (PCA). A PCA pump provides a constant background infusion rate, and the patient can add single controlled doses of the painkiller when needed.
While the patient is receiving opioids, their respiratory function and sedation level should be carefully monitored.
Non-pharmacologic approaches, such as distraction, local heat application, massage, and positioning might provide additional pain relief.
As the VOC resolves, opioids should be gradually adjusted down.
Chronic pain
For chronic pain management, the cause and type of the pain should be determined. The chosen treatment mainly depends on the patient’s response.
Pain relief, side effects, and functional outcomes should guide the type and dose of opioid used.
Massage and muscle relaxation therapy may be used to support pharmacological pain therapy.
Chronic pain should be assessed at least annually, and treatment adapted as needed.
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