Case 28 - Parathyroidectomy

Question 1

What is the physiology of calcium regulation?

Answer 1

Vitamin D

• absorption of Ca2+ from GI

PTH

• absorption of Ca2+ from bone, intestines, vit D production, decrease renal excretion

Calcitonin (produced by thyroid)

• decrease Ca2+ plasma concentrations

Ca2+

• ionized Ca = active and free form
• alkalosis –> increases binding of Ca2+ to albumin –> decrease ionized plasma conc

Question 2

clinical features of hypercalcemia?

Answer 2

Bones, stones, groans, and psych overtones

Muscukloskeletal (bones)

• weak/atrophy
• bone fx

Renal (stones)

• kidney stones / polyuria

GI (Groans)

• n/v
• abd pain / stomach ulcer
• pancreatitis
• constipation

CNS (psych overtones)

• seizures
• disorientation
• altered mental status
• lethardy/sedation

Cards

• htn
• conduction abnormalities / arrhythmias

Question 3

how do you treat hypercalcemia?

Answer 3

• stop administration of calcium (limit intake)
• 0.9% NS administration
• diuresis with furosemide
  
  • do not give thiazide diuretics –> they save calcium in renal tubules –> increase levels
• consider dialysis (if patient has pre-existing renal failure or CHF)
  
  • CHF can be exacerbated with fluid administration
• bisphosphonates (pamidronate)
  
  • tx for ​life threatening hpercalcemia

Question 4

what are pre-op anesthetic considerations for parathyroidectomy?

Answer 4

• fluid management
  
  • life threatening hypercalemia requires fluid admin
    
    • at risk for hypervolemia, CHF**​
• diuretic use
  
  • risk of hypokalemia
• muscle relaxation
  
  • hypercalcemia antagonizes muscle relaxation (need frequent dosing)
• conduction abnormal / arrhythmias
• parathyroid hyperplasia assoc with MEN (MEN 2 involves pheochromocytoma)

Question 5

are there important aspects to consider during anesthetic managment for a patient undergoing parathyroidectomy?

Answer 5

general anes straightforward

1) muscle relaxation vs intraop nerve monitoring

• consider opioid infusions to maintain relaxation
  
  • benefits of opioids: provides deeper anesthesia, depress laryngeal reflexes –> avoid coughing during surgery and emergence
  • coughing can cause neck hematoma

2) frequent lab draw for PTH levels

• PTH half life of 5 minutes
• frequent intraop lab draws to assess surgical success (low PTH = successful surgery, correct gland excised)

Question 6

What regional anesthesia technique could you use for parathyoridectomy?

Answer 6

superficial and deep cervical plexus block

• superficial = sensory to surgical site
• deep = motor to surgical site
  
  • risks: vertebral A. injection, phrenic nerve paralysis, neck hematoma, epidural or subdural block

Question 7

what are the complications of parathyroidecotmy?

Answer 7

similar to thyroidectomy - complications resulting in respiratory distress

Resp Distress

• recurrently laryngel N. injury (uni vs b/l)
• neck hematoma
• tracheomalacia
• Hypocalacemia - laryngeal muscle tetany
  
  • ​occurs 24-72 hours after surgery

Other complications

• coagulopathy
• neuromuscular irritability
  
  • muscle cramps
  • chvostek’s sign (facial n irritability) /trousseau’s sign (carpal spasm)
• paresthesia
• CNS
  
  • psychosis
  • seziures
    *