April Case Of The Month

 

Title:  Thyroid Surgery for Tumor

 

A 46 year old 250 pound, six feet 2 inches heavily muscled body builder has undergone thyroid surgery for tumor with sevoflurane anesthesia following propofol induction and suiccinylcholine for intubation. Aside from mild hypercarbia, easily controlled the 3.5 hour case has been uneventful. Following extubation and in the PACU the patient complains of arm weakness and muscle pain. He is normothermic.  There is no history of prior anesthesia related problems in the family.

He relates a history of daily exercise to the point of lactic acidosis. He also takes a testosterone compound for pituitary deficiency, Zetia, fenofibrate both for control of hyperlipidemia, nexium, and vitamins.

 

    1.  What laboratory tests would you order?

    1. calcium
    2. Creatine kinase
    3. ABG
    4. BUN/Creatinine and electrolytes
    5. Urinalysis
    6. None 

    2.  His urine is cola colored. What other tests would you order?

    1. amylase
    2. blood sugar
    3. myoglobin levels
    4. microscopic analysis of urine

    3.  His first CK is 1500 IU. Which drugs may cause increased CK and myoglobinuria?

 

    1. Zetia
    2. Fenofibrate
    3. Nexium
    4. Vitamin B12
    5. Testosterone
    6. succinylcholine 

    4.  Should he be admitted to an ICU ?

       Yes 

       No

 

    5.  Should he receive dantrolene?

       Yes    

       No

 

    6.  Rhabdomyolysis after anesthesia may be caused by:

 

      a.MH

      b.MDMA agonists

      c.Ischemia

      d.Patient position

      e.Sepsis

      f.Renal disease

      g.Hypothermia


 

7.  If his CK rises to > 15,000 , this means:

       a. He definitely is MH susceptible

       b. He may be MH susceptible and needs to have a muscle biopsy contracture test

       c. He need not be tested as the cause of the muscle breakdown is drug related and secondary to his excessive muscle.

       d. He should be tested for a genetic mutation indicative of MH as a first step.

       e. He should be advised to exercise less and reduce muscle bulk.

 

Answers:

1.  B and C.  The patient should at a minimum have a CK, BUN, electrolytes, urinalysis performed. If any are abnormal, particularly the CK calcium should be done along with ABG

 

2.  C and D. If the urine is cola colored this is presumptive evidence of rhabdomyolysis and CK along with myoglobin levels electrolytes, BUN/Creatinine    should be determined.

It should be noted that CK peaks after the appearance of myoglobin in the urine. Hence urinalyss may show indirect evidence of myoglobin release if the urine is hematest positive, but no RBCs are seen.

 

3.  A, B, F  Many drugs may cause rhabdomyolysis. The lipid lowering drugs, MDMA (e.g. Ecstasy)  as might succinylcholine in patients with MH susceptibility, with other muscle disorders and occasionally without neuromuscular problems. Succinlycholine does not regularly  lead to rhabdomyolysis in patients taking statins

 

 

4.  Yes and 5. No..  In the absence of other signs of MH, dantrolene is not indicated. Howevrf, because of the rhabdomyolysis and the possibility of renal failure, the patient should be admitted to an ICU.

 

 

6.  A, B, C, D, E..Rhabdomyolysis may be caused by caused by all of the conditions and drugs mentioned with the exception of hypothermia.

 

7.  B (d is acceptable too)The changes that have been described, i.e. the rhabdomyolysis , is not absolutely predictive of MH. The patient should consider himself to be MH susceptible until proven otherwise. The best test for this purpose is the halothane caffeine contracture test using biopsied muscle  However a case might be made here for genetic testing first since the patient had such strong signs of MH. The genetic test however has a rather low sensitivity even in known MH families. Therefore, the best answer is to have the patient undergo biopsy testing . IF positive, genetic testing should be done and if a known mutation is found other family members should have genetic testing which only involves a blood sample.

 

Narrative:

In this case I would recommend that a blood sample be drawn and with the patient’s permission seek to have the patient enrolled in the study protocol at Uniformed University Hospital which allows for study of mutations in patients with suspected MH clinical episode(s). In addition, a report of the event should be filed with the N American MH Registry in Pittsburgh (an AMRA form)The latter may be downloaded from the web site, www. Mhreg.org.

 

Henry Rosenberg, MD, CPE
Director, Department of Medical Education and Clinical Research
Saint Barnabas Medical Center
Livingston, NJ 07039
Professor of Anesthesiology

Mount Sinai School of Medicine, NY