UBP 3.5 (Long Form): Neuro – Transphenoidal Hypophysectomy

Question 1

Intra-Operative Management:

Which monitors would you place for this case?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 1

In addition to the ASA standard monitors, I would place a –

5-lead EKG to monitor for myocardial ischemia.

Given the patient’s hypertension, signs of increased ICP (headache), risk of massive hemorrhage (close proximity of the cavernous sinus and internal carotid artery), and increased risk of end-organ ischemia, I would place an arterial line to more accurately monitor hemodynamic changes.

Since this case is going to be performed with the patient in the sitting position, I would place a –

precordial Doppler to aid in the detection of venous air embolism (place to the right of the sternum, between the 2nd and 4th ribs), and consider placing a central line to provide a means of aspirating embolized air from the heart (a multi-orifice catheter placed with the tip 2 cm below the superior vena caval-atrial junction allows for optimal aspiration of air).

Since the patient is experiencing signs consistent with compression of optic nerves (blurred vision), I would discuss with the surgeon the benefits of monitoring visual evoked potentials.

Due to the length of the surgery, the potential need for drug-induced diuresis, and the risk of diabetes insipidus, I would place – a Foley catheter.

And, finally, given the inaccessibility of the arms after draping, I would consider placing a lower extremity nerve stimulator for monitoring of neuromuscular blockade.

Question 2

Intra-Operative Management:

Do you need an arterial line? Where would you place it?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 2

I believe an arterial line would be indicated in this case for several reasons:

1. the patient’s hypertension places him at increased risk of hemodynamic instability and, if not well controlled, may have caused a right-ward shift of end-organ autoregulation curves;
2. his blurred vision suggests the possibility of increased ICP, which would make the rapid identification of hypotension vital to preventing cerebral ischemia; and
3. the transphenoidal approach places the surgeon in close proximity of the cavernous sinus and internal carotid artery, which increases the risk of massive hemorrhage and hemodynamic instability.

In placing the arterial line, I would utilize the dorsalis pedis or femoral artery, since patients with acromegaly have poor collateral blood flow to the hand, increasing the risk of ischemia with partial or complete obstruction of the radial artery.

Question 3

Intra-Operative Management:

The surgeon suggests monitoring visual evoked potentials.

What do you think?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 3

Visual evoked potentials (VEPs) are sometimes used to monitor the integrity of the optic nerves when the surgeon believes they are at significant risk of surgical trauma during tumor resection.

Unfortunately, VEPs are extremely sensitive to inhalational and intravenous anesthetics, making consistent monitoring very difficult during general anesthesia.

If the surgeon believed that this type of monitoring would be beneficial, I would plan to use a balanced technique with narcotics and a low concentration of volatile agent to minimize anesthetic interference with VEP monitoring.

Question 4

Intra-Operative Management:

Prior to induction, the surgeon injects the nasal mucosa with cocaine and the patient suddenly loses consciousness.

What do you think is going on?

What would you do?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 4

The timing of the event suggests that the local anesthetic injected during topicalization of the nose has spread to the CNS causing –

• a total spinal,
• systemic toxicity, or
• a cocaine associated dysrhythmia.

Therefore, I would intubate the patient, ventilate with 100% oxygen, check the EKG, blood pressure, and administer vasoactive, inotropic and antiarrhythmic agents as indicated.

If I suspected local anesthetic toxicity, I would administer a benzodiazepine and provide hemodynamic support as necessary.

If the local anesthetic toxicity were significant enough to cause cardiovascular collapse, I would start cardiopulmonary resuscitation, begin a lipid emulsion infusion, and call for a surgeon to prepare the patient for cardiopulmonary bypass.

Question 5

Intra-Operative Management:

Assume there were no complications during topicalization of the nose.

How would you induce this patient?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 5

This patient’s obesity, his history of sleep apnea, and the physiologic changes of acromegaly, including the large protruding mandible, large tongue, and hoarse voice (suggestive of acromegalic involvement of the larynx) noted on examination, place him at increased risk of difficult airway management.

Therefore, I would –

• administer metoclopramide and an H2-receptor antagonist (history of GERD);
• apply the appropriate monitors;
• ensure the presence of emergency airway equipment, including smaller ETTs in case there is subglottic stenosis;
• place the patient in the sniff position or 30° reverse trendelenburg position;
• anesthetize the airway;
• provide adequate preoxygenation; and
• attempt an awake fiberoptic intubation.

My goals in developing this plan are to safely secure the airway, while avoiding apnea, hypoxia, aspiration, and a sympathetic surge during laryngoscopy (his hypertension places him at risk for exaggerated hemodynamic responses which could prove harmful in the presence of CAD or elevated intracranial pressure).

Question 6

Intra-Operative Management:

Thirty minutes into the surgery the blood pressure suddenly drops to 62/28 mmHg. What do you think is the cause?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 6

There are many possible causes for his drop in blood pressure, including –

• massive hemorrhage secondary to dissection into the caverous sinus or internal carotid artery,
• venous air embolism,
• myocardial ischemia,
• anesthetic overdose,
• delayed anaphylactic reaction,
• cardiac dysrhythmia, and
• tension pneumothorax.

Therefore, I would –

• deliver 100% oxygen,
• verify proper endotracheal tube placement,
• auscultate the chest,
• verify proper function of the arterial line,
• evaluate the EKG,
• reduce my anesthetic agent,
• ask the surgeon about bleeding,
• look at the surgical field,
• listen to the precordial Doppler,
• check the end-tidal CO2, and
• look for hemoglobin in the urine.

Question 7

Intra-Operative Management:

His end-tidal CO2 has decreased.

Does this move venous air embolism to the top of your list?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 7

Since this patient is in the sitting position,

venous air embolism (VAE) is already at the top of my list.

However, a decrease in end-tidal CO2 is not diagnostic for VAE.

While the increased alveolar dead space and/or reduced cardiac output that results from significant VAE does lead to a decrease in end-tidal CO2, this same decrease would be seen with any event that significantly reduced cardiac output.

Unfortunately, any of the items in my differential could lead to decreased cardiac output with subsequently decreased end-tidal CO2.

Similarly, the various complications in my differential would likely produce other clinical signs of VAE, such as tachycardia, cardiac arrhythmias, hypoxia, and cyanosis.

Therefore, to determine if this clinical picture were secondary to VAE, I would – listen for sporadic roaring sounds from the precordial Doppler, auscultate the heart for the characteristic “millwheel” murmur (best heart through an esophageal stethoscope), attempt to aspirate air through the central venous catheter, and/or consider transesophageal echocardiography.

Question 8

Intra-Operative Management:

The Doppler is emitting sporadic roaring sounds. What would you do?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 8

Since this finding is consistent with a venous air embolism, I would –

• immediately ask the surgeon to flood the field with saline;
• discontinue nitrous oxide (probably should be avoided in the first place) and deliver 100% oxygen;
• attempt to aspirate entrained air through the central venous catheter (to remove air that may be interfering with right-sided cardiac output);
• consider the application of direct jugular venous compression to increase venous pressure at the surgical site,
• provide cardiovascular support with fluid, vasoconstrictors, inotropes, and chest compressions, as necessary; and
• treat bronchospasm with B2-adrenergic agonists (reflex bronchospasm may occur with the entry of air into the pulmonary artery).

Clinical Notes:

• PEEP has been recommended to increase venous pressure at the surgical site.
• However, the application of PEEP may not be optimal for several reasons:
  
  1. the potential for impaired systemic venous return in a patient with significant cardiovascular dysfunction;
  2. it is less effective than jugular venous compression in increasing cerebral venous pressure when in the sitting position (where the head is significantly higher than the heart); and
  3. PEEP may reverse the normal trans-atrial (left > right) pressure gradient, increasing the risk of paradoxical embolism with an unrecognized patent foramen ovale.
• Placing the patient in the head down, right-chest-up position (or lateral position with the right side up) has been advocated to move air into the right atrium where it is more easily aspirated through the central venous catheter, and less likely to cause an air lock in the right ventricle. However, this type of positioning is unproven, difficult, or even dangerous during most intracranial operations, and wastes valuable treatment time to achieve.

Question 9

Post-Operative Management:

How do you plan to extubate this patient?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 9

This patient with acromegaly, obesity, and obstructive sleep apnea, remains at risk for difficult airway management.

Given these concerns and the fact that his GERD increases his risk of aspiration during emergence, I would –

• place the patient in the semi-upright position,
• provide 100% oxygen, and
• extubate him only after he was awake and demonstrating full neuromuscular block reversal (especially with history of obstructive sleep apnea), adequate ventilation and oxygenation, hemodynamic stability, and intact airway reflexes.

If I was concerned about the presence of CAD, I would have administered lidocaine prior to extubation to blunt a potential sympathetic response to extubation.

Question 10

Post-Operative Management:

Would your plan for extubation change if the CSF space had been opened intra-operatively?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 10

If the CSF space had been entered intraoperatively,

a smooth emergence (avoiding coughing) is desirable to prevent the reopening of the CSF leak, which would increase the risk of subsequent meningitis.

Although coughing during emergence may increase a CSF leak, I would plan to extubate this patient awake to avoid airway obstruction, laryngospasm, aspiration, and hypoventilation.

I would attempt to prevent coughing by administering intravenous lidocaine just prior to extubation.

Question 11

Post-Operative Management:

After surgery, the PACU nurse calls to inform you that the patient is obtunded and requiring 10 liters of oxygen per facemask to maintain a SpO2 above 90%.

Are you concerned?

What do you think is going on?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 11

This is concerning to me because this obese patient with obstructive sleep apnea is at increased risk of post-operative airway obstruction and apnea, especially with the use of narcotics for post-operative pain management.

Other potential causes or contributing factors include –

• atelectasis (hypoventilation of this obese patient),
• pulmonary edema (secondary to congestive heart failure and/or air entering the pulmonary artery during VAE),
• aspiration (leading to bronchospasm or atelectasis),
• inadequate reversal of neuromuscular blockade,
• hypo/hyperglycemia (diabetic patient),
• electrolyte abnormalities,
• arrhythmia,
• myocardial infarction, or
• stroke (paradoxical emboli, ischemia).

Question 12

Post-Operative Management:

Assuming this patient had significant OSA, how would you manage him postoperatively?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 12

Postoperatively, I would maintain the patient in a seated or lateral position (avoiding supine positioning) and provide supplemental oxygen until the patient was able to maintain his baseline oxygen saturation on room air and in a quiet peaceful environment.

Additionally, I would apply his home CPAP machine as soon as possible;

administer NSAIDs for analgesia with the goal of avoiding sedatives and narcotics, if possible; and

utilize continuous pulse-oximetry until his oxygen saturation remained above 90% during sleep.

I would continue to monitor this patient for airway obstruction, hypoxemia, dysrhythmias, and hypertension for a median of 3 hours longer than a non-OSA patient and for at least 7 hours after the last episode of airway obstruction or hypoxemia while breathing room air in a non-stimulating environment.

Question 13

Post-Operative Management:

On the second postoperative day, the nurse reports over two liters of urine output in the last hour.

What do you think is the cause?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 13

This patient’s postoperative polyuria could be due to –

• central diabetes insipidus (DI),
• mobilization of third-spaced fluid,
• diuretic use, or
• osmotic diuresis from hyperglycemia.

Therefore, I would –

• review the fluids and medications administered;
• rule out hyperglycemia; and
• further evaluate the patient for DI, a condition that occurs in as many as 40% of patients following hypophysectomy
  
  • (tests: urine specific gravity, serum osmolality, serum/urine electrolytes).

DI is characterized by marked impairment in renal concentrating ability secondary to decreased ADH secretion, and usually occurs 4-12 hours postoperatively (but may develop intraoperatively).

This condition is suspected when a patient produces copious amounts of urine despite rising serum sodium levels (increased serum osmolality).

The diagnosis is confirmed when –

• hyperglycemia is ruled out,
• the patient’s urine specific gravity is < 1.005 (some sources say = 1.002), and
• the urine osmolality increases with the administration of exogenous ADH.

Question 14

Post-Operative Management:

(On POD #2, nurse reports over two liters of urine output in the last hour.)

How would you treat this patient?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 14

The form of diabetes insipidus that occurs following transphenoidal hypophysectomy is almost always central diabetes insipidus (decreased ADH production) rather than nephrogenic diabetes insipidus (abnormal response of renal tubules to circulating ADH).

Therefore, I would –

• replace the urinary loss of hypo-osmolar, low sodium fluids with 1/2 normal saline (while D5W is sometimes used in this situation, I would avoid it in this diabetic patient) at a rate equal to hourly maintenance requirements plus two thirds of the previous hour’s urine output (alternatively, replacement could be based on maintenance requirements plus the previous hour’s urine output less 50 mL).

If the hourly fluid requirements exceeded 350 mL, I would–

• administer aqueous vasopressin or desmopressin (DDAVP) to replace the patient’s ADH.

Question 15

Post-Operative Management:

On the fourth postoperative day, the patient gradually develops hypotension that is refractory to fluid boluses and vasopressors.

What do you think?

• (A 34-year-old, 98 kg, male presents for transphenoidal resection of a pituitary adenoma in the sitting position. He complains of progressive headache, blurred vision, and rhinorrhea over the last 3 months.*
• PMHx: Hypertension, GERD, Obstructive Sleep Apnea - on CPAP, Diabetes mellitus - diet controlled*
• Meds: Propranolol, HCTZ, Omeprazole, Octreotide, and Bromocriptine*
• Allergies: NKDA*
• PE: Vital Signs: HR = 54, BP = 140/62 mmHg, RR = 18, Temp = 37.1 °C, Weight = 98 kg, Height = 176 cm*
• Airway: Mallampati II, large protruding mandible, large tongue, TMD > 9cm, hoarse voice*
• General: large hands and feet, broad prominent frontal bone*
• Lungs: Clear to auscultation*
• Cardiovascular: regular rate and rhythm*
• Labs: Hgb = 12.1 gm/dl, glucose = 201 mg/dL, cortisol = 4 mcg/dL, K+ = 4.2 mEq/L*
• EKG: left ventricular hypertrophy*
• CT: 10 mm anterior pituitary mass without suprasellar extension, diffuse skeletal overgrowth)*

Answer 15

This patient’s refractory hypotension is concerning because it may be associated with adrenal insufficiency secondary to panhypopituitarism or pituitary apoplexy, a known complication of surgical hypophysectomy.

This diagnosis could be confirmed by –

• identifying decreased cortisol and ACTH plasma concentrations, and

would require specific hormone replacement therapy, including glucocorticoids, mineralocorticoids, and thyroid hormone.