Did the Outpatient have MH?
A 21 year old male, 185 lbs, muscular build, for the first time received anesthesia for plastic surgery in an out patient surgery center. Anesthesia was induced at 08:25 with versed, propofol, fentanyl, rocuronium and isoflurance. Zofran was also given. Monitoring included EKG, noninvasive BP, stethoscope, end-tidal carbon dioxide, pulse oximentry and liquid crystal skin temperature. An endotracheal tube was placed. After surgery about 10:10, when isoflurance was stopped hypercarbia was note. At 10:25 the ET CO2 was 90 mm Hg and there was sinus tachycardia.
QUESTIONS:
1. What do you think is the cause of hypercarbia here?
a. Anesthetic induced respiratory depression
b. Anesthetic apparatus malfunctioning
c. Neuroleptic Malignant Syndrome or Malignant Hyperthermia?
In the PACU rapidly increasing temperature (to 104.6 F) and skin mottling were noted. Respirations were rapid and deep.
2. What lab work would you like to order?
a. Blood gases
b. Liver enzymes
c. Creatine kinase levels
d. Potassium
e. Clotting profile
f. Urine myoglobin
3. Would you give Dantrolene in this case?
a. Yes
b. No
4. Do you transfer the patient in this condition (after the initial treatment) from an outpatient clinic to another hospital? If so, would you accompany him in the ambulance?
a. Yes
b. No
5. What do you want to do after a case like this?
a. Go to www.mhreg.org. Print out an AMRA report, fill out and mail to the MH Registry.
b. Refer the patient to an MH Biopsy Center. See www.mhaus.org for current address.
c. Send the patient for genetic counseling – call 800-454-8155, to seek with Deanna Steele about genetic testing at UPMC.
d. Refer the patients to MH Registry – 888-274-7899.
ANSWERS
1. The answer to questions one is MH, but it is not possible to know that until all the lab tests are performed including the genetic screen.
2. a, c, d, e, & f are all correct.
3. a
4 & 5. Really fit together and have no one simple answer. The patient has to be transferred to a hospital ER & ICU. A physician able to resuscitate and give dantrolene should go with the patient. Active cooling should be continued if the patient has temperature >39 C.
Narrative
MH treatment was begun with bicarbonate, active cooling and hyperventilation with 100% oxygen. Dantrolene, 40 mg, was given at 10.15 and he was transferred to a hospital. It was not possible to perform blood gas or electrolyte measurements in the surgery center. A total dose of 180 mg of dantrolene was given after which heart rate, ETCO2 and temperature decreased. Atropine was given to treat bradycardia of 50/min.
At 11.31 the first ABG that could be obtained showed pH 7.64, pCO2 26 mm Hg, pO2 551 mm Hg, BE +8.0 mEq/l, HCO3 28 mEq/l. Four hours after the incident began creatine kinase was 656 U/L, peak potassium was 6.0 mEq/l, Serum myoglobin was 650 ng/ml.
Nevertheless he recovered without sequelae.
The Hotline Consultant advised further work up to secure the diagnosis of MHS.
The closest MH Diagnostic Biopsy Center was closed so this patient sent blood for genetic screen of RYR1, the ryanodine receptor type one gene, which showed an MH causative RYR1 mutation in EXON 14, p.Tyr522Ser in heterozygous form.
Two asymptomatic family members also have this mutation. The relative with a history of muscle cramps did not have any of the common variants of RYR1
Dr. Barbara Brandom
Children's Hospital and The University of Pittsburgh
Pittsburgh, PA
