Hyperkalemia and emergency surgery
A patient with end-stage renal failure is scheduled for exploratory laparotomy secondary to ruptured appendix. The potassium is 6.8 mEq/l.
1. How will you proceed?
The potassium must be lowered urgently. Emergent treatment is to include calcium chloride to reverse cardiotoxicity, insulin, and glucose if the patient is normovolemic. Dialysis should be instituted if he is hyperkalemic and hypervolemic. Additional measures to decrease potassium include hyperventilation, beta-adrenergic stimulation, sodium bicarbonate, diuretics, and kayexalate.
2. Must the potassium be lowered preoperatively?
Yes. The risks of hyperkalemia include arrhythmias to include ventricular premature contractions, ventricular tachycardia, fibrillation, and cardiac arrest. The effects of hyperkalemia are aggravated by hypoventilation and acidosis, and the potassium must be lowered preoperatively.
3. Can succinylcholine be used?
The use of succinylcholine can dangerously aggravate hyperkalemia, leading to cardiac arrest upon induction of anesthesia.
4. How does succinylcholine work?
It mimics acetylcholine, depolarizing the neuromuscular membrane. Instead of being hydrolyzed at the neuromuscular junction like acetylcholine is, plasma cholinesterase hydrolyses succinylcholine, and therefore the muscle contraction is prolonged, as it is a diffusion-dependent metabolism.
4. If not, what relaxant will you use for rapid sequence induction?
5. What are other causes of hyperkalemia?
It may be drug-induced, may be found in diabetes mellitus, massive transfusion, and acidosis.
Anesthesia and hepatitis
A 20-year old man is to have elective knee surgery. He has resolving hepatitis A with mildly elevated liver function tests.
1. Would you cancel the case until liver enzymes return to normal?
2. Suppose this was an emergency case on the lower extremity. What type of anesthetic would you choose?
3. What is the effect of your choice on hepatic blood flow?
4. What is the clinical importance?
Open eye and full stomach
A 46-year old woman presents for removal of a piece of metal from her eye, sustained while mowing the lawn after eating breakfast.
1. What are your major anesthetic concerns?
2. How would you manage the airway during induction?
3. Which muscle relaxant would you use? Discuss your rationale.