Anesth Analg 2007;104:214
© 2007 International Anesthesia Research Society
doi: 10.1213/01.ane.0000249792.37338.cc
LETTER TO THE EDITOR
Editor-in-Chief Steven L. Shafer
Can We Prevent Malignant Hyperthermia After Hypothermic Cardiopulmonary Bypass in a Malignant Hyperthermia-Susceptible Patient?
Sahar M. Siddik-Sayyid, MD, FRCA,
Adib R. Moussa, MD, and
Anis S. Baraka, MD, FRCA
Department of Anesthesiology, American University of Beirut, Beirut, Lebanon, abaraka{at}aub.edu.lb
To the Editor:
We read with interest the report describing a patient with a family history suggestive of malignant hyperthermia (MH) who developed MH after hypothermic cardiopulmonary bypass (CPB), despite the use of a nontriggering anesthetic; the report postulated that systemic rewarming was the triggering factor via a mechanism similar to heat stroke (1).
We report a 75-yr-old male patient whose son had MH confirmed with muscle biopsy. His preoperative creatinine phosphokinase (CPK) was 812 IU/mL (normal reference range in our laboratory is 0–199 IU/mL). When CPK is elevated in a close relative of a person with known MH susceptibility, then this relative may be considered to have MH susceptibility without further testing (2).
The patient was scheduled for coronary artery bypass graft surgery (CABG) under hypothermic CPB. Before surgery, the anesthesia circuit and the CPB machine were flushed with oxygen. General anesthesia was induced with midazolam (2 mg), sodium thiopental (200 mg), sufentanil (25 µg), and cisatracurium (20 mg). Anesthesia was maintained with a propofol infusion 2–4 mg/kg/h, midazolam 0.05 µg/kg/min, sufentanil 0.5–1 µg/kg/h, and cisatracurium 0.15 mg/kg/h. CABG was performed using mild hypothermic CPB (32°C–33°C). Mixed venous oxygen saturation during CPB ranged between 81% and 84%. On bypass, dantrolene 2 mg/kg was infused over 30 min. After CABG, the patient was rewarmed slowly, while maintaining a temperature difference of 1°C between blood and rectum. When the rectal temperature reached 35°C, the patient was weaned from CPB without inotropic support. He was then transferred tracheally intubated and ventilated to the cardiac surgery unit (CSU), while keeping the cooling mattress to maintain his rectal temperature between 35°C and 36°C. His postoperative course was uneventful.
Prevention of MH in our patient may be attributed to the following precautions:
- Avoidance of triggering anesthetics.
- Administration of prophylactic dantrolene.
- Limiting the hypothermia during CPB to 32°C–33°C.
- Slow rewarming of the patient to 35°C by maintaining a temperature gradient difference of 1°C between blood and rectum.
- Transfer of the patient to the CSU while keeping the cooling mattress to maintain his temperature between 35°C and 36°C.
Our report suggests that MH-susceptible individuals can undergo hypothermic CPB whenever indicated provided adequate precautions are taken.
REFERENCES
- Lichtman A, Oribabor C. Malignant hyperthermia following systemic rewarming after cardiopulmonary bypass. Anesth Analg 2006;102:372–5.[Abstract/Free Full Text]
- Gronert G, Antognini J, Pessah I. Malignant hyperthermia. In: Miller RD, ed. Anesthesia. Philadelphia: Churchill Livingstone, 2000;1033–52.
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A. D. Lichtman and C. Oribabor
Can We Prevent Malignant Hyperthermia After Hypothermic Cardiopulmonary Bypass in a Malignant Hyperthermia-Susceptible Patient?
Anesth. Analg.,
January 1, 2007;
104(1):
214 - 215.
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