Case 42 - typanomastoidectomy

Question 1

why is typanomastoidectomy performed?

Answer 1

• eustachian tube malfunctions, vacuum created in middle ear
• vacuum assoc with chronic upper resp infections
• cholesteatoma - abnormal growth of primarily skin cells
  
  • grows behind a perf tympanic membrane (perf due to recurrent infections)
  • cholesteatoma assoc with progressive hearing loss, facial nerve damage
• Typanomastoidectomy - remove cholesteatoma and infected bone of middle ear

Question 2

any preop considerations assoc with tympanomastoidectomy?

Answer 2

• pts usually manfiest middle ear diseaes: nystagmus, vertigo, n/v
• PONV is important issue to address in these pts
  
  • combo therapy is effective

Question 3

What are the intraop requirements for tympanomastoidectomy?

Answer 3

1) surgical anatomy is small, need mangnifying scope
* cruicial to minimize introp bleeding to allow surgical view under scope
2) injury to facial nerve

• facial nerve electromyography may be used
• avoid NMBDs

3) patient position 90 to 180 degree away from anesthesiologist

• long extension circuits
• neck not hyperextended
• eye and ear free of pressure

Question 4

Is nitrous oxide contraindicated during tympanomastoidectomy?

Answer 4

Best to avoid nitrous oxide for two reasons:

1) expansion of middle ear air space

• nitrous oxide is more soluble in blood than nitrogen. nitrous oxide will enter middle ear space quicker than nitrogen can diffuse into blood –> expansion of air space.
• typanic membrane graft can be dislodged

2) PONV