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Topic: Acute Postoperative Rhabdomyolysis in a Child
A 4-yr-old 16.4 kg healthy male from Mexico underwent surgical closure of an atrial septal defect (ASD). There was no family history of anesthesia-related problems. The anesthetic technique consisted of pentobarbital premedication, followed by sevoflurane, nitrous oxide, fentanyl, and pancuronium. Total CPB and cross-clamp times were 29 and 14 min, respectively. During and after CPB, the patient was not hyperthermic, acidotic, or hyperkalemic, and serum potassium concentrations ranging from 2.94 to 3.71 mEq/L.
On arrival to the cardiac intensive care unit, residual neuromuscular blockade was antagonized with atropine and neostigmine, and the trachea was extubated when the child was strong, awake, and alert. Twenty minutes later, the electrocardiogram showed broad complex bradycardia that rapidly progressed to ventricular tachycardia and fibrillation, and responded to defibrillation (20 J). The patient was reintubated and serum potassium concentration during resuscitation was >9 mEq/L on the first arterial blood gas with a base deficit of -4.3 mmol/L. The child’s esophageal temperature was 37.7°C. The patient received IV calcium gluconate, sodium bicarbonate, and a glucose-insulin infusion. Serum creatine kinase (CK) within an hour of the arrest was 17,821 U/L and peaked at 613,120 mEq/L 48 h postoperatively. The urine was noted to be pale pink in color. Administration of dantrolene was considered and the MH hotline was consulted.
1. Is this clinical syndrome likely to represent acute MH?
a. Yes
b. No
c. Not enough information to make a definitive diagnosis
2. TRUE or FALSE: If this syndrome does not represent MH, administration of dantrolene sodium may still be indicated.
3. What is the proper treatment for acute rhabdomyolysis?
a. Alleviation of hyperkalemia
b. Sodium bicarbonate
c. Furosemide
d. Admission to an intensive care unit
e. All of the above
4. Which additional test is indicated to aid in diagnosis of this patient’s hyperkalemic event?
a. Muscle biopsy
b. Halothane-caffeine muscle contracture test
c. Genetic testing to look for a mutation on the X chromosome
d. Genetic testing to look for a mutation on chromosome 19
Answers:
1. B
Although this patient demonstrated signs of acute rhabdomyolysis, as evidenced by the hyperkalemia and pink urine (representing myoglobinuria), there are no signs of hypermetabolism, such as tachypnea (in the spontaneously breathing patient), tachycardia, metabolic acidosis (prior to the cardiac arrest), and hyperthermia.
2. FALSE
Dantrolene sodium is used to reverse the signs and symptoms of malignant hyperthermia. Dantrolene appears to act by inhibiting further release of calcium into the cytoplasm of the myocyte, thereby halting the process of unregulated muscle contraction and the resulting hypermetabolism. In some cases, dantrolene may treat nonspecific muscle rigidity or hyperthermia, but it is not indicated in the treatment of acute rhabdomyolysis.
3. E
Treatment of rhabdomyolysis consists of lowering serum potassium levels to alleviate the effects of hyperkalemia on the heart and protecting the kidneys against damage from myoglobinuria. Urine flow is promoted by administration of a potent diuretic, such as furosemide, and alkalinization of the urine with sodium bicarbonate. Since rhabdomyolysis may result in life-threatening dysrhythmias, renal failure, and disseminated intravascular coagulation (DIC), the patient should be appropriately monitored in an intensive care unit.
4. C
Several publications in recent years have led to the recognition that exposure to inhalational agents, even without succinylcholine, can lead to life-threatening rhabdomyolysis in patients with undiagnosed Duchenne muscular dystrophy. Although in many children, the diagnosis of Duchenne muscular dystrophy is made clinically, some children do not manifest the classic signs and symptoms until later in life, and therefore, diagnosis is made by demonstrating deletion in the dystrophin gene from at least exon 47 to exon 52.
Narrative:
The MH hotline consultant did not advise administration of dantrolene because there was no evidence of hypermetabolism. The patient was well hydrated with intravenous fluids and bicarbonate, mannitol, and furosemide were administered to protect the kidneys from the toxic effects of myoglobin. He continued to improve and was discharged home on the sixth postoperative day. Questioning the family revealed that the child did not walk until age 2 years of age (upper limit of normal is 15 months). Genetic testing proved a diagnosis of Duchenne muscular dystrophy.
Because of this and other similar cases, on June 27, the FDA approved safety labeling revisions for sevoflurane to warn of the rare risk for perioperative hyperkalemia leading to potentially fatal postoperative cardiac arrhythmias associated with use of this and other inhaled anesthetics in pediatric patients:
“Use of inhaled anesthetic agents has been associated with rare increases in serum potassium levels that have resulted in cardiac arrhythmias and death in pediatric patients during the postoperative period. Patients with latent as well as overt neuromuscular disease, particularly Duchenne muscular dystrophy, appear to be most vulnerable. Concomitant use of succinylcholine has been associated with most, but not all, of these cases. These patients also experienced significant elevations in serum creatinine kinase levels and, in some cases, changes in urine consistent with myoglobinuria. Despite the similarity in presentation to malignant hyperthermia, none of these patients exhibited signs or symptoms of muscle rigidity or hypermetabolic state. Early and aggressive intervention to treat the hyperkalemia and resistant arrhythmias is recommended, as is subsequent evaluation for latent neuromuscular disease.”
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Ronald S. Litman, D.O., F.A.A.P.
Attending Anesthesiologist
The Children's Hospital of Philadelphia
Associate Professor of Anesthesiology and Pediatrics
University of Pennsylvania School of Medicine
Philadelphia, Pennsylvania
