Combined spinal/general anesthesia with postoperative femoral nerve block for total knee replacement in a patient with familial hyperkalemic periodic paralysis: a case report.

Familial hyperkalemic periodic paralysis (HYPP) is a rare genetic disorder in which the sodium channels in skeletal muscle cells have altered structure and function. Small elevations in serum potassium lead to inactivation of sodium channels, causing episodic weakness or paralysis. Exposure to cold, anesthesia, fasting, emotional stress, potassium ingestion, and rest after exercise can stimulate an attack. This case report describes a 65-year-old man with HYPP who was admitted for a right total knee arthroplasty. He had a history of arteriosclerotic heart disease and stenting 8 years earlier, previous inferior wall myocardial infarction with ejection fraction of 65%, anxiety, degenerative joint disease, well-controlled type 2 diabetes mellitus, and a body mass index of 53.3 kg/m2. A combined spinal/general anesthetic with a femoral nerve block for postoperative pain control was chosen. Careful attention was given to monitoring and maintenance of core temperature, use of insulin and glucose to maintain normokalemia, and carbohydrate loading the night before surgery. The patient recovered from the anesthetic without complication and had pain relief for approximately 22 hours postoperatively because of the femoral nerve block. The patient was without weakness or paralysis related to HYPP in the postanesthesia care unit or throughout his hospitalization.