Transsphenoidal surgery and acromegaly
Stem
A 49-year-old man, 108 kg, with acromegaly from a growth-hormone-secreting pituitary macroadenoma presents for endoscopic transsphenoidal resection. He has obstructive sleep apnea on CPAP, hypertension, type 2 diabetes and bilateral carpal tunnel syndrome. His voice is hoarse, his tongue is large, his mandible protrudes, and he is Mallampati 4. Echo shows concentric left ventricular hypertrophy with preserved function. Glucose this morning is 186 mg/dL.
Question
What are your main anesthetic concerns, and how will you manage his airway and the perioperative course?
Ideal answer
HeadlineAirway first: overgrowth makes mask ventilation and intubation difficult,1 so I intubate him awake with a flexible scope.
- Topical anesthesia; a smaller tube, 6 to 6.5. Large tongue, Mallampati 4 and hoarseness suggest glottic narrowing, plus sleep apnea;2 video laryngoscope and surgical airway backup ready.3
- Review ECG and echo; treat his hypertension. Cardiomyopathy and conduction disease are common;1 collaterals checked before the radial line.1
- Stress-dose steroids; glucose closely. Recommended for most pituitary resections;3 diabetes is common, but removing the growth hormone source can drop glucose quickly.1
- Throat pack, oral tube taped aside, remifentanil-based technique.3 A still field, then a fast, smooth wake-up without coughing that could disrupt the sellar repair.
- Fully awake before extubation, because his nose is packed and mask ventilation is worse than at induction.
Watch for: Monitored bed, minimal opioids; urine output and sodium for diabetes insipidus.4
Breaking down the answer
- Why awake — macroglossia, prognathism, and laryngeal mucosal and cartilage hypertrophy can turn a routine view into a grade 4 view;2 Mallampati 3 or 4 predicts difficulty.2
- The cardiac disease — concentric biventricular hypertrophy progresses to dilated failure, and arrhythmias are the leading cause of sudden death.1 A long untreated course raises my concern.
- The hand — an Allen test or ulnar assessment comes before the radial line, because severe carpal tunnel hypertrophy can compromise the radial and ulnar arteries.1
- Glucose both ways — surgical cure of growth hormone excess can cause acute hypoglycemia, so checks continue after the tumor is out.1
- Emergence is a worse airway — nasal packing, residual sedation and sleep apnea combine; mask ventilation is also avoided because it can cause pneumocephalus and infection.3
- Diabetes insipidus is the expected sodium problem — central DI follows 16–34% of sellar operations in the literature, and some cases become permanent.4
Follow-up question
On the evening of surgery he has passed 1,400 mL of urine in 4 hours, he is thirsty, and his serum sodium has risen from 140 to 149 mEq/L. Urine specific gravity is 1.002. What is going on and how do you manage it?
Follow-up answer
HeadlineCentral diabetes insipidus from pituitary stalk manipulation: dilute polyuria above 250 mL/h with a rising sodium.5,3 I tell the neurosurgeon and endocrinologist.
Paired osmolalities confirm it: urine under 300 mOsm/kg with serum over 300 mOsm/kg.5 Awake with an intact thirst, he drinks to thirst; hypotonic fluid replaces losses if he cannot keep up. Desmopressin when output stays high or sodium keeps rising, because it raises urine osmolality in central DI.5 Sodium every few hours, corrected slowly, because rapid swings risk osmotic demyelination.4 Days later, inappropriate ADH release can bring hyponatremia, usually self-limiting and treated with fluid restriction below 130 mmol/L.4
Pitfalls that cost points
- Treating early postoperative polyuria with more isotonic saline without checking sodium and urine concentration.
- Mask ventilating over fresh nasal packing at emergence, which can cause pneumocephalus.
Rapid-fire
Q: What confirms acromegaly biochemically? A: An elevated IGF-1 with growth hormone failing to fall below 1 μg/L after an oral glucose load.1
Q: What fraction of acromegaly is from a pituitary adenoma? A: More than 95%.1
Q: Why are the vocal cords a problem? A: Hypertrophic cords narrow the glottic opening and increase tube resistance.2
Q: Which urine values define diabetes insipidus? A: Urine osmolality below 300 mOsm/kg and specific gravity below 1.005 with serum sodium above 145 mEq/L.5
Q: How long do you watch for DI? A: Monitoring continues to about postoperative day 10; transient DI usually resolves within two weeks.4
Numbers to know
| Item | Value |
|---|---|
| Central DI after sellar surgery | 16–34%4 |
| DI urine osmolality | Below 300 mOsm/kg5 |
| DI urine specific gravity | Below 1.0055 |
| DI serum sodium | Above 145 mEq/L5 |
| DI serum osmolality | Above 300 mOsm/kg5 |
| Urine output that triggers DI workup | Above 200–250 mL/h for 2 h3 |
| GH suppression test | GH not below 1 μg/L confirms1 |
Links
- Obstructive sleep apnea, Awake fiberoptic intubation: topicalization and sedation, Anticipated difficult airway and the ASA algorithm, Diabetes mellitus and perioperative glucose, Adrenal insufficiency and stress-dose steroids
- ASA Practice Guidelines for Management of the Difficult Airway (2022)
Sources
- 1.Acromegaly · OpenAnesthesia, 2026 · openanesthesia.org
- 2.Acromegaly discovered during a routine out-patient surgical procedure: a case report · Journal of Medical Case Reports (Chiaghana et al.), 2017 · pmc.ncbi.nlm.nih.gov
- 3.Anesthesia for Pituitary Surgery · OpenAnesthesia, 2023 · openanesthesia.org
- 4.Diabetes insipidus following neurosurgery at a university hospital in Western Saudi Arabia · Saudi Medical Journal (Qari et al.), 2016 · smj.org.saRetrospective series of 24 patients; cites a 16-34% literature range for central DI after sellar surgery.
- 5.Transsphenoidal surgery: DI treatment (keyword page on diabetes insipidus) · OpenAnesthesia, 2026 · openanesthesia.org
Facts on this page were checked against these sources on Oct 16, 2026. Guidelines change; confirm doses against current institutional protocols.