chapter 19 - transsphenoidal hypophysectomy Flashcards
what is the cause of acromegaly? what is the most common cause of death in acromegaly patients?
Acromegaly
- GH-secreting tumor 2/2 pituitary adenoma (ant pituitary)
Death
- Most common cause = cardiac
- etiology: HTN, accelerated CAD, HTN induced LVH leading to L CHF
What are airway changes associated with acromegaly?
airway changes
- enlarged nasal turbinates
- difficult to place nasal airways
-
enlarged tonsils
- **OSA**
- enlarged and floppy epiglottis
-
glottic stenosis
- enlargement of soft tissue around larynx, as well as enlarge vocal cords –> narrow glottic opening
-
compression of recurrent laryngeal nerves
- connective tissue overgrowth
- limitation in head and neck movement
Overall - DIFFICULT AIRWAY
How can acromegaly be treated surgically, how can it be treated medically?
Surgical tx
- transsphenoidal approach
- compared to crani, this approach assoc with less morbidiity (hypopituitarism, Diabetes insipidus)
Medical
- bromocriptine or levodopa - dopamine agonists
- DA agonists bind to receptors on the GH-producing cells in the pituitary gland and decrease GH production
what are anesthetic considerations for patients with acromegaly?
1) Difficult Airway
* enlarged tonsils, floppy and enlarged epiglottis, enlarged vocal cords with glottic narrowing, limited head and neck movement, enlarged nasal turbinates
2) Cardiac disease
- CAD, HTN, LV dysfuction (LVH -> diastolic dysfunction)
- intranasal epi containing LA or cocaine administered for anes and vasoconstrict during scope placement for sx
3) OSA
* polycythemia vera, pulm HTN, RVH
describe airway management concerns for patients with acromegaly?
airway concerns - Difficult ventilation and intubation
- floppy and enalrged epiglottis
- enlarged tonsils
- large tongue
- distortion of larynx
- increase vocal cord size -> narrow glottic opening and laryngeal airway narrowing
- OSA
- cannot use nasal passages 2/2 sx surgical site
how would you proceed intubating an acromegalic patient who appears to have a difficult airway?
1) AWAKE FOB
- minimize mechanical trauma to upper airway and vocal cords -> edema -> airway obstruction
- may be dificult to do FOB 2/2 excessive soft tissue in oropharynx
- can consider awake DL or awake glidescope assisted FOB (probably best choice)
2) awake tracheostomy
3) asleep intubation -> glidescope assisted FOB
what structures lie within transphenoidal surgical field?
anatomy
- sella turcica provides bony protection for pitutatry gland
- diaphragama sella = roof of dura
- pierced by pituitatry stalk (connects hypothalams to pituitary gland)
structures
- cavernous sinus surrounds walls of the sella
- contains inter carotid artery
- CN III, IV, VI
- sinus = contains venous blood
-
Optic nerve
- above diaphragm to form chiasm
bleeding
- from cartoid artery or venous bleeding
What is the etiology, symptoms, ddx, and tx of central Diabetes insipidus?
define - decrease ADH secretion
etiology
- direct hypothalamic injury
- pituitary stalk edema or dissection
symptoms
- polydipsia
- poorly controlled polyruia
- high serum osmolarity (hypernatremia 2/2 hemoconcentration)
- decrease ADH -> loss of water
ddx
- mannitol or hyperglycemia induced diuresis
Tx
- increase oral intake
- 0.45% NS (hypoosmotic) -> replace water and dec sodium levels
- DDAVP (desmopressin)
what are post-op concerns for patients with acromegaly?
post-op concerns
1) CSF rhinorrhea
* can place a lumbar drain post-op to divert CSF until diaphragma sella has healed
2) bleeding
- copious bleeding can be from carotid artery or cavernous snus
- requires excessive pressure and packing for control
3) pressure or packing during bleeding -> induce CN injury
* packing or pressure of cavernous sinus can lead to compression of CN III, IV, VI
4) smooth emergence
* avoid coughing, bucking and HTN during emergence -> can disrupt surgical repair
