May Case Of The Month

Title: Facelift and Rhinoplasy Procedure under General Anesthesia

A 35 year old healthy woman five feet four inches tall, 70kg is undergoing a facelift and rhinoplasty procedure under general anesthesia. The airway is maintained with an LMA and the anesthesia is being conducted with sevoflurane and nitrous oxide and Oxygen. Baseline blood pressure is 110/70, heart rate 90. During the procedure her end tidal carbon dioxide is 46 with assisted ventilation. During the procedure the surgeon injects 20ml of 1% lidocaine with 1:100,000 epinephrine. In addition cocaine soaked pled gets have been instilled in the nasal passages. Shortly thereafter, the patient develops tachycardia to 120bpm, blood pressure is 195/123. The end tidal carbon dioxide is now 54 and axillary temperature is now 38.5 degrees C. The patient’s rhythm is now V. tach. Metoprolol, 5mg, is administered resulting in bradycardia with a blood pressure of 90/40.

1. At this point what medication should be administered?

dantrolene
phenylephrine
glucose and insulin
atropine
phentolamine

2. What stat laboratory studies are indicated?

ABG
Electrolytes
Blood glucose
None of the above

3. What is the most likely cause of these changes?

a. Malignant hyperthermia

b. Light anesthesia

c. epinephrine/beta blocker interaction

c. lidocaine toxicity

d. hyperkalemia

4. The patient should be advised to consider herself as MH susceptible

a. true

b. false

5. Which laboratory test(s) are indicated:

a. genetic testing for MHS

b. cardiac enzymes

c. plasma metanephrine

d. lidocaine levels

Answers

1. e
2. d
3. c
4. b
5. b

Narrative:
The cause of the cardiovascular changes relate to the unopposed alpha sympathetic stimulation resulting from beta blockade. The combination of epinephrine and cocaine resulted in intense sympathetic stimulation. When beta blockade ensued resulting in relatively upopposed alpha activity, myocardial contractility increased and myoocardial contractility increased dramatically. Some case reports have shown that this might lead to pulmonary edema and cardiac arrest. Vasoconstriction might have led to increased body temperature and mild hypercarbia.
The admonition against using pure beta blockade is also found in treatment of patients with pheochromocytoma for the same reason.

Henry Rosenberg, MD
St. Barnabas Medical Center
Livingston, NJ