Historically, people with Duchenne have been told that using inhaled anesthetics can cause malignant hyperthermia (“MH”; extremely high body temperature), a condition causing rhabdomyolysis (breakdown of skeletal muscle tissue causing the release of myoglobin, a muscle protein that damages the kidneys) and hyperkalemia (the release of too much potassium into the bloodstream), that results in life-threatening heart rhythms.
New evidence suggests that while rhabdomyolysis may still be possible with inhaled anesthetics, it is rare, and unrelated to MH. This information is explained below.
These recommendations have clarified several issues:
New Evidence: Increased Risk of Rhabdomyolysis in Duchenne; Unrelated to Malignant Hyperthermia
Among anesthesiologists, it is established knowledge that patients with Duchenne muscular dystrophy may develop unique complications when undergoing medical or surgical procedures that require administration of certain anesthetic agents. Medical reports that date as far back as the 1970s, indicated that patients with Duchenne have a propensity to develop rhabdomyolysis (muscle breakdown and damage) when exposed to inhalational (gas) anesthetics, or when administered a muscle relaxant called succinylcholine. This muscle damage may result in life-threatening increases in blood potassium (hyperkalemia), and myoglobin, a protein released from muscle that has the potential to cause kidney damage when present in large amounts in the blood.
These important complications are nearly indistinguishable from those seen when a patient develops a rare anesthetic-related complication called malignant hyperthermia (MH). Although clinically similar in appearance to the complications that may occur in Duchenne patients, they are actually two separate entities. MH is primarily caused by an inherited mutation in a gene product called the ryanodine receptor (RYR1), which regulates calcium control in the muscle cell. Patients with these MH-causing mutations may or may not develop muscle disease or weakness during their lifetime.
Because of the similar clinical presentation of these two complications, there was a time when many clinicians (as a result of reports in medical journals) believed that the complications in Duchenne patients were, in fact, MH. However, with the passage of time, and with incorporation of new knowledge, especially in the area of medical genetics, we now know that this isn’t true. MH occurs in patients who have inherited MH-causing mutations, which are not more prevalent in patients with Duchenne when compared with the general population.
Therefore, experts in muscle disease and anesthesia have joined with Parent Project Muscular Dystrophy to clarify its guidelines on administration of general anesthesia for patients with Duchenne. These clarified guidelines make it clear that Duchenne patients are not at an increased risk of developing MH, but may continue to be at increased risk of rhabdomyolysis when administered inhaled anesthetic gases. These guidelines have been reviewed and approved by the Professional Advisory Council of the Malignant Hyperthermia Association of the U.S. (MHAUS).
2015 Revised Duchenne Anesthesia Guidelines
These new guidelines can also be found in the Surgery and Anesthesia section of PPMD's website.
Do Not Use Succinylcholine
Patients with known or suspected Duchenne should not receive the drug succinylcholine. Succinylcholine is sometimes used in emergencies to relieve breathing difficulties in anesthetized patients, but when administered to patients with any kind of ongoing muscle atrophy, no matter the underlying cause, succinylcholine can cause severe, life-threatening (and sometimes fatal) increases in blood potassium. Instead of succinylcholine there are other commonly available muscle relaxants (e.g., any non-depolarizing neuromuscular blocker) that can be used in emergency situations if necessary (see list here). It is possible, however, that there exists a rare situation (such as life-threatening airway obstruction that requires immediate treatment) where an anesthesiologist may be justified in administering succinylcholine to a patient with Duchenne whose life is in imminent danger.
If Possible, Avoid Use of Inhalational Anesthetic Gases
There are known cases of serious (and sometimes fatal) muscle breakdown (rhabdomyolysis) in Duchenne patients when exposed to inhalation anesthetic gases even when succinylcholine was avoided. There are at least 31 such reported cases dating as far back as 1970, and thus, this complication seems to be a tangible risk to Duchenne patients. Therefore, we recommend, that when possible, inhaled anesthetic gases should be avoided in patients with Duchenne.
Nevertheless, despite the fact that rhabdomyolysis has not been reported with IV anesthetic agents, there exists a mixed practice nationally in children’s hospitals that anesthetize Duchenne patients. While some centers will completely avoid inhaled anesthetic gases in patients with Duchenne, in others it is the standard of care to use an anesthetic gas to begin general anesthesia in children (for reasons discussed below), and then switch over to an IV anesthetic medication (propofol is the IV anesthetic agent most commonly used) for the remainder of the case. Furthermore, some experts in pediatric anesthesia may choose to use only inhaled anesthetic gases because of a specific reason on a case-by-case basis.
Why not just completely avoid inhalational gas anesthesia in all Duchenne patients? Inhalation anesthesia may be suggested for the following reasons:
Overall the most important recommendation is that if possible, these complex patients should be managed in medical centers with expertise in the anesthetic management of patients with neuromuscular disease, even for relatively minor procedures. A pre-anesthetic evaluation of cardiac and pulmonary function is very important, and careful attention to these organ systems during and following the surgical procedure is probably more important in determining a good outcome than the chosen anesthetic technique.
These recommendations have been reviewed and approved by the Professional Advisory Council of the Malignant Hyperthermia Association of the U.S. (MHAUS).