Anesthesia for patients with muscular dystrophy (MD) must be administered carefully, as most anesthetic agents act directly on muscles, which are weak and damaged in these people.
A need for special care, including alerting an anesthetist of that the person has MD, is essential whether the anesthetic is local or general.
Doctors should thoroughly evaluate a person diagnosed with MD before administering any anesthetic. Special emphasis must be given to how the anesthetic affects both skeletal and heart muscles. People with muscular dystrophy can respond differently to anesthetics than those without this disease.
The stage of a patient’s disease also needs to be considered. An electromyography, used to evaluate the electrical activity or functioning of skeletal muscles, might be required. Testing the health of the heart and lungs is also recommended.
Serum creatine kinase (CK) levels are elevated in all muscular dystrophies, and measuring levels of CK — an enzyme released in the blood when muscles are damaged — just prior to an operation can be useful for assessing any problems that may occur during or after surgery. These can include rhabdomyolysis, or the breakdown of muscle tissue that releases muscle fiber contents into the blood and can harm the kidneys.
The anesthesiologist will weigh options before considering the type and dose of anesthesia to be administered an MD patient, as these people are at a high risk of rhabdomyolysis and, subsequently, an increased concentration of potassium in the blood (hyperkalemia) due to muscle breakdown and kidney damage.
High potassium levels in the blood, if not treated, can lead to abnormal heart rhythms (arrhythmia) as it affects the electrical signaling in the heart. Therefore, it is important to monitor serum potassium levels before and after giving anesthetics to MD patients.
While there are no definite recommendations for the kind of general or local anesthesia to be used, the U.S. Food and Drug Administration (FDA) recommends against the use of succinylcholine in patients with MD due to high risk of hyperkalemic cardiac arrest (cardiac arrest due to high potassium blood levels).
Assessing heart function before an operation can help anesthesiologists decide the kind of inhaled anesthetic to be administered. Vapors such as ethane and halothane can reduce the effectiveness of heart muscle contraction and worsen conduction defects.
General anesthesia is best when administered as an injection into the bloodstream. Gases such as nitrous oxide can be used as long as cardiac problems are ruled out.
Local, or regional, anesthesia has few reports of major complications associated with its use.
Muscle relaxants block neuromuscular junctions (the point where nerve cells meet muscle cells) for long periods of time; their effect on a patient depends on how advanced the disease is in that person (its stage). Muscle relaxants such as suxamethonium should be avoided as they can cause hyperkalemia.
During and after surgery
Patients must be constantly monitored during the operation for signs of rhabdomyolysis, malignant hyperthermia (severe reaction to medicines used during surgery), respiratory failure, and cardiac arrest.
MD patients do not tolerate changes in body temperature, or the fasting usually associated with surgery. It is important that the patient be kept warm and hydrated using drips.
The extent of post-operative care depends on disease severity and the complexity of the operation. Intensive care with proper ventilatory support immediately following an operation might be required in some cases.
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