Porphyria and Anesthesia
Porphyria is the name given a group of rare genetic disorders that result in a buildup of porphyrins and a lack of heme, a protein necessary for the production of hemoglobin. Hemoglobin is the molecule in red blood cells that carries oxygen throughout the body.
Anesthesia can lead to uncomfortable and potentially dangerous acute attacks in some types of porphyria.
What is anesthesia?
Anesthesia is the use of medications to prevent patients from feeling pain, usually during medical procedures such as surgery. There are four main classes of anesthesia: general, sedation, regional, and local.
General anesthesia is given to put patients in a sleep-like state, so they don’t respond to pain signals. Patients either inhale general anesthetics as gases, or an anesthesiologist injects these medications into the bloodstream.
With sedation, patients can remain awake and may be able to answer questions. Or, they may feel drowsy enough to fall asleep, or not remember the procedure. Sedation is typically given for more minor surgeries, like less intrusive biopsies or procedures like a scope of the throat.
Regional anesthesia affects a large part of the body, such as an arm or leg, or the entire lower half of the body. A common anesthesia given women during labor, it allows a patient to stay awake and responsive. Regional anesthetics, such as an epidural, are typically injected around or into the spine.
Local anesthesia eliminates pain in a small and specific part of the body while the patient is fully awake. Local anesthetics can be given as injections, topical ointment, or spray.
Can anesthesia cause problems if I have porphyria?
Patients with acute porphyria are prone to acute attacks. Many different triggers can cause an attack, including fasting, infections, hormone imbalances, stress, dehydration, smoking, alcohol consumption, and medications such as anesthetics. Attack symptoms require medical attention, and can range from abdominal pain, and nausea and vomiting, to psychiatric changes such as confusion and psychosis, muscle pain or weakness, cardiovascular irregularities, and seizures.
Cutaneous porphyria is related to the skin and does not involve acute attacks. People with this type of porphyria are not at an increased risk with anesthesia’s use.
How can anesthesia cause attacks?
Scientists are still learning more about the exact cause of acute attacks in porphyria patients. They think that certain medications, including some anesthetics, cause the attacks through a complex feedback mechanism. The body creates an enzyme known as cytochrome P450 (CYP450) in order to metabolize, or break down, many medications. But to produce CYP450, the body uses heme.
Heme levels decline because of this need, which signals the liver to produce more delta-aminolevulinic acid (ALA), a precursor used in the production of heme.
People with acute porphyria have unusually lower amounts of functional enzymes along the pathway that converts ALA to heme, causing a rise in ALA levels. Increased levels of ALA can cause neuronal damage, and could lead to pain and other symptoms of an acute porphyria attack.
What precautions should doctors take?
Be sure to inform your physician and/or anesthesiologist about your disease prior to any procedure.
If general anesthesia is necessary, the anesthesiologist must be careful to choose an anesthetic that is regarded as safe and avoid those which could trigger an acute attack in people with porphyria. Regional and local anesthetics are generally considered safe, although some doctors prefer not to use regional anesthetics. This is because complications that could follow a surgery could be similar to symptoms signaling an acute attack.
Physicians must also be careful with patients who have the cutaneous porphyria, as their skin can be sensitive to excessive pressure and irritation during surgery.
Last updated: Sept. 22, 2020
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