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Topic: Pediatric circumcision - postop fever, tachycardia, lethargy
An 11 kg 16-month-old male is scheduled for circumcision at 0730. He is induced with sevoflurane inhalation; an LMA is placed. The child is maintained with sevoflurane and nitrous oxide. Prior to emergence, he is given 5 mg Demerol IV and 10 mg IM. No intraoperative problems are noted. The child has postoperative bleeding and is taken back to the OR. He is intubated because of interval po intake. He is induced with intravenous propofol and mivacurium; sevoflurane is used for maintenance. 10 cc 0.25% bupivacaine is given as a single-shot caudal injection prior to starting the second procedure. To ensure that the child will not be agitated upon emergence, additional IV Demerol given despite evidence that the caudal is effective. In the recovery room, the child is somewhat lethargic. Three hours after the second procedure, the child is noted to be febrile (103.3° F. axillary), pale, mottled, with intermittent “twitching.” Additional vital signs: BP 120/63 and HR 178/minute.
1. Which of the following statements is correct?
A) Anesthetic-induced MH can have its onset at any time during the first
24 hours following emergence from general anesthesia.
B) Anesthetic-induced MH has its onset during general anesthesia, or
during emergence and the 1st hour following emergence.
2. When evaluating a non-intubated patient for acute MH who is in the recovery room, which diagnostic test should be performed ASAP?
A) Serum ionized calcium level
B) Serum CK level
C) Arterial or venous blood gas
D) Blood cultures
3. A decrease in body temperature following IV dantrolene is specific for MH.
A) True
B) False
4. The reason that succinylcholine is not recommended for elective airway management in children is:
A) Possibility of prolonged paralysis
B) Possible masseter muscle rigidity
C) It is an MH trigger
D) The rare occurrence of unanticipated hyperkalemic cardiac arrest
A femoral venous blood gas is obtained: pH 7.40 PaCO2 34 PaO2 68, base excess –3 mEq/L; SpO2 100% on room air. Hct 31%. The child is given Tylenol 12 mg/kg pr. His temperature decreases to 102.1° F. The child is now alert and taking oral Pedialyte.
5. The anesthesia care professional should:
A) Discharge the child home.
B) Ask a pediatrician to evaluate the child for an acute infectious process
(e.g. otitis media or aspiration pneumonia).
C) Give the parents a letter stating that the child has had an adverse
reaction to general anesthesia.
Answers:
1. B
2. C
3. B
4. D
5. B
Narrative:
1. B is correct documented by Dr. Pollock’s careful review of the literature. The statement that MH can have its onset any time during the 24 hours following general anesthesia is, unfortunately, a popular myth.
2. The uncontrolled release of calcium within the myocyte, not into serum, is the fundamental pathologic process during an MH crisis. Blood cultures should be performed if suspicious of bacteremia, but the results cannot guide immediate management. Serum CK peaks 8-12 hours following skeletal muscle injury; initial values may be minimally elevated despite significant muscle injury. Acute MH is characterized by hypermetabolism marked by respiratory acidosis, usually (but not always) combined with lactic acidosis. Shortly after onset of an MH crisis, femoral venous blood will show more severe hypercarbia and metabolic acidosis than femoral arterial blood, because it drains a large mass of affected skeletal muscle. A benign blood gas result excludes the diagnosis of MH.
3. Because dantrolene will decrease heat generated by skeletal muscle activity, it can cause a non-specific decrease in temperature.
4. Succinylcholine has rarely caused unanticipated hyperkalemic cardiac arrest in children with undiagnosed myopathies, especially dystrophinopathies (i.e. Duchenne or Becker).
5. The child should be evaluated for an infectious cause of postoperative fever. Giving the parents a letter suggesting that the fever was caused by “general anesthesia” does not accurately describe the course of events or provide any benefit to the patient and his family.
_____________________________________________
MH Hotline Consultant
Professor of Anesthesiology
UCLA School of Medicine
Los Angeles CA 90095-1778
