Anesthesia for transsphenoidal pituitary surgery

INTRODUCTION — Transsphenoidal surgery is the mainstay of treatment for most pituitary adenomas and other sellar masses. Most pituitary lesions amenable to surgery are benign anterior pituitary adenomas.

The most important anesthetic concerns involve the physiologic and anatomic effects of either excess hormone secretion from functional tumors, or hormone deficiency caused by compression of pituitary tissue.

This topic discusses the preoperative evaluation and anesthetic management of patients undergoing transsphenoidal resection of pituitary lesions. The text reflects both publications in the anesthesia literature and our institutional practice.

Surgical technique, results, and complications of transsphenoidal surgery are discussed separately. (See "Transsphenoidal surgery for pituitary adenomas and other sellar masses" and "Primary therapy of Cushing disease: Transsphenoidal surgery and pituitary irradiation", section on 'Transsphenoidal surgery'.)

The endocrine evaluation of pituitary adenomas and other sellar masses and the options for treatment are also discussed separately. (See "Causes, presentation, and evaluation of sellar masses" and "Primary therapy of Cushing disease: Transsphenoidal surgery and pituitary irradiation" and "Treatment of acromegaly", section on 'Overview of approach'.)

PREOPERATIVE EVALUATION — Most transsphenoidal surgical procedures are elective, with ample time for thorough preoperative evaluation and airway assessment. (See "Preoperative evaluation for anesthesia for noncardiac surgery" and "Airway management for induction of general anesthesia", section on 'Airway assessment'.)

For elective surgery, the physiologic and anatomic effects of functioning tumors require particularly careful consideration in consultation with the surgeon and endocrinologist. Anesthetic concerns are most significant for patients with acromegaly and Cushing's disease. Patients with hormonal deficiencies (eg, hypothyroidism, arginine vasopressin deficiency [AVP-D, previously called central diabetes insipidus]) should also be identified and, if necessary, treated preoperatively. (See "Causes, presentation, and evaluation of sellar masses", section on 'Evaluation of a sellar mass'.)

Patients with acromegaly — The clinical manifestations of acromegaly are discussed in detail separately. Manifestations of particular concern for anesthetic management are discussed here. (See "Causes and clinical manifestations of acromegaly".)

Airway changes in patients with acromegaly — Acromegaly is associated with anatomic changes that may increase the difficulty with airway management for anesthesia, and may cause obstructive sleep apnea (OSA). These changes include mandibular and maxillary enlargement; macroglossia; swelling of the soft palate and pharyngeal wall; thickening of true and false vocal cords; vocal cord paresis; tracheal compression; and hypertrophy of the epiglottis and periepiglottic tissues [1]. These changes may cause difficulty with mask ventilation, visualization of the glottis, and/or insertion of the endotracheal tube (ETT).

The reported incidence of difficult direct laryngoscopy in patients with acromegaly varies between 9 and 40 percent [2-6], compared with 2 to 6 percent in patients without acromegaly [6,7], though failed intubation is very rare. Similar to patients without acromegaly, bedside airway assessment tests (eg, Mallampati test, thyromental distance, mouth opening) are relatively insensitive predictors of difficult laryngoscopy, at least for direct laryngoscopy [2,3,8]. (See "Airway management for induction of general anesthesia", section on 'Prediction of the difficult airway'.)

Any available relevant imaging (lateral skull radiograph, computed tomography [CT] or magnetic resonance imaging [MRI] of head and neck) should be reviewed for changes in airway anatomy associated with endocrine dysfunction. In some institutions, preoperative airway assessment includes preoperative flexible nasopharyngoscopy by an otolaryngologist [9].

Soft tissue changes associated with acromegaly may be reversible with medical management (see "Treatment of acromegaly").

However, bony changes are irreversible and can still be present at the time of surgery, and regression of soft tissue changes does not guarantee easier airway management. In a prospective study of 128 patients with acromegaly who underwent transsphenoidal pituitary resection, the incidence of difficult laryngoscopy was similar in patients who received preoperative treatment with octreotide and those who did not, though the numbers were too small to draw definitive conclusions [2].

Cardiovascular disease — Cardiovascular abnormalities associated with acromegaly include hypertension, left ventricular hypertrophy, arrhythmias, and cardiomyopathy [1,10]. Heart failure and valvular heart disease are also more common in patients with acromegaly. (See "Causes and clinical manifestations of acromegaly", section on 'Cardiovascular disease'.)

Preoperative cardiac evaluation should be similar to patients without acromegaly. Preoperative medical therapy with a somatostatin analog can improve cardiac function in patients with cardiovascular dysfunction related to acromegaly, and should be considered in consultation with the surgeon, neuro-endocrinologist, and cardiologist [11,12].

Obstructive sleep apnea — Sleep apnea occurs in up to 50 percent of patients with acromegaly, primarily related to the airway changes discussed above [13]. (See 'Airway changes in patients with acromegaly' above.)

Patients with OSA are more sensitive to the respiratory depressant effects of sedatives and opioids, and are at increased risk of perioperative complications. Perioperative management of patients with OSA is discussed separately in several topics. (See "Surgical risk and the preoperative evaluation and management of adults with obstructive sleep apnea" and "Intraoperative management of adults with obstructive sleep apnea" and "Postoperative management of adults with obstructive sleep apnea".)

For patients with OSA who use positive airway pressure therapy (PAP; ie, continuous positive airway pressure [CPAP] or bilevel positive airway pressure [BPAP]), the need for postoperative PAP should be discussed preoperatively with the surgeon. Postoperative PAP therapy is generally recommended for patients with OSA who use it preoperatively (see "Postoperative management of adults with obstructive sleep apnea", section on 'Positive airway pressure therapy'). However, PAP has been associated with development of pneumocephalus after transsphenoidal therapy, and some surgeons prohibit its use [14]. The incidence of pneumocephalus, risk factors, and optimal timing for resumption of PAP after this type of surgery have not been defined.

Diabetes mellitus — Diabetes mellitus occurs in up to 15 percent of patients with acromegaly. Perioperative management of diabetes mellitus is discussed separately. (See "Perioperative management of blood glucose in adults with diabetes mellitus" and "Anesthesia for patients with diabetes mellitus and/ or hyperglycemia".)

Patients with Cushing's disease — There is a wide spectrum of manifestations of Cushing's disease, ranging from subclinical to the overt Cushing's syndrome, depending on duration and intensity of excess steroid production. (See "Epidemiology and clinical manifestations of Cushing syndrome", section on 'Frequency and severity of symptoms'.)

Major manifestations of Cushing's disease that may affect anesthetic management include the following:

●Central obesity, which often includes a moon facies and a buffalo hump, that may increase difficulty with airway management (see "Epidemiology and clinical manifestations of Cushing syndrome", section on 'Progressive obesity' and "Anesthesia for the patient with obesity", section on 'Airway management')

●Sleep apnea, likely related to obesity and possibly myopathy of airway muscles (see "Epidemiology and clinical manifestations of Cushing syndrome", section on 'Sleep apnea' and "Intraoperative management of adults with obstructive sleep apnea")

●Cardiovascular disease including hypertension, dyslipidemia, and increased risk of myocardial infarction, stroke, and thromboembolism (see "Epidemiology and clinical manifestations of Cushing syndrome", section on 'Cardiovascular')

●Glucose intolerance, possible overt hyperglycemia, and possible electrolyte abnormalities (see "Epidemiology and clinical manifestations of Cushing syndrome", section on 'Metabolic')

Other preoperative concerns — In addition to acromegaly and Cushing's disease, other issues that may affect anesthetic management and should be considered preoperatively include the following:

●Clinically nonfunctioning tumors – Clinically nonfunctioning tumors (which include gonadotroph tumors) tend to be larger at the time of diagnosis than functioning tumors, and therefore increase the risk of invasion of surrounding vascular structures including internal carotid arteries and cavernous sinuses. Available imaging should be reviewed; larger bore intravenous (IV) access and/or intra-arterial blood pressure monitoring may be indicated.

●Thyroid stimulating hormone-secreting tumors – Patients with thyroid stimulating hormone (TSH)-secreting tumors may present for surgery in hypothyroid (after thyroid ablation), hyperthyroid, or euthyroid states [15]. Anesthesia for patients with thyroid disease is discussed separately. (See "Anesthesia for patients with thyroid disease and for patients who undergo thyroid or parathyroid surgery".)

Some patients with TSH-secreting tumors are misdiagnosed with primary hyperthyroidism (which is much more common), and undergo thyroid ablation. Thyroid ablation can reduce negative feedback on the tumor and allow it to grow rapidly and invade locally.

●Prolactin-secreting tumors – Lactotroph tumors, particularly in males, tend to be large and potentially locally invasive at the time of diagnosis. Lactotroph macroadenomas are routinely treated initially with dopamine agonists (eg, cabergoline, bromocriptine), which can cause orthostatic hypotension. (See "Management of hyperprolactinemia", section on 'Overview of dopamine agonists'.)

●Disorders of water metabolism – Both arginine vasopressin deficiency (AVP-D, previously called central diabetes insipidus) and, very rarely, the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) [16,17] may be associated with pituitary tumors. AVP-D is associated with tumors of the pituitary stalk or hypothalamus, and is a recognized complication of transsphenoidal pituitary resection. The pathogenesis of SIADH related to pituitary adenomas is unknown. Patients with either condition may present with fluid balance and electrolyte abnormalities, which should be corrected prior to surgery. Medications used to treat DI should be continued up to and including the day of surgery.

Treatment of DI and SIADH is discussed separately. (See "Arginine vasopressin deficiency (central diabetes insipidus): Treatment" and "Treatment of hyponatremia: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and reset osmostat".)

Preoperative testing — In addition to any preoperative laboratory testing based on patient comorbidities, we perform preoperative testing for pituitary surgery as follows:

●We order a complete blood count and blood typing and antibody screen (ie, type and screen). Significant bleeding is rare. However, there is potential for catastrophic bleeding because the cavernous sinus forms the lateral border of the sella turcica and contains, in addition to venous structures, the intra-cavernous portion of the internal carotid artery. Depending on the size and location of the tumor and the expected response time of the blood bank, preoperative crossmatch of one or more units of red blood cells may be indicated.

●Patients with endocrine abnormalities (ie, with functioning tumors or hormone deficiencies) should have glucose and electrolytes measured in the week before surgery.

Most patients have extensive preoperative visual field and endocrine testing prior to surgery. This testing does not need to be repeated if recent, and any repeat testing should be ordered in consultation with the surgeon and endocrinologist. Concurrent endocrinopathies, such as hypothyroidism, adrenal insufficiency, or sex steroid deficiency have usually been treated before the patient presents for elective surgery.

Further testing should be performed based on comorbidities, and is discussed separately. (See "Preoperative evaluation for anesthesia for noncardiac surgery", section on 'Preoperative testing'.)

ANESTHETIC MANAGEMENT — General anesthesia is required for all transsphenoidal pituitary surgical procedures. Operative time with experienced surgeons operating on well-defined adenomas is typically between 90 and 120 minutes. Larger lesions, especially those with extra-sellar extensions requiring extended access through the sphenoid bone, can occasionally last over five hours.

Vascular access — Intravenous (IV) access is typically placed in the upper extremity on the side that will be opposite the surgeon. At our institution, this means we prefer to place the IV in the left arm, since the right arm is tucked at the patient's right side, where the surgeon will stand once the operating table is turned 90 degrees after induction of anesthesia.

Monitoring — All patients who undergo anesthesia will have American Society of Anesthesiologists standard monitors applied. Advanced monitoring (eg, continuous intra-arterial blood pressure monitoring) may be used, based on patient comorbidities. Intra-arterial catheters may also be placed if the need for multiple blood samples is anticipated (eg, invasive tumors, diabetes mellitus, arginine vasopressin deficiency [previously called central diabetes insipidus] or syndrome of inappropriate antidiuretic hormone, elevated intracranial pressure). Larger arteries (eg, brachial, axillary, or femoral arteries) may be used as alternatives for patients in whom radial arterial access is not possible or appropriate (see "Arterial blood gases", section on 'Ensure collateral circulation'). Bladder catheterization should be considered for longer procedures, in consultation with the surgical team. A bladder catheter should also be considered for patients with DI.

Premedication — Premedication should be individualized based on the patient's level of anxiety and comorbidities, including sensitivity to sedatives as a result of obstructive sleep apnea (OSA), which is common in patients with acromegaly and Cushing's disease. For patients with OSA, sedatives and opioids should not be administered routinely.

The decision to administer a sedative should be balanced against the need to have a prompt emergence. If premedication is necessary, short-acting sedatives (eg, midazolam) should be administered in small doses, titrated to effect, with continuous pulse oximetry monitoring. Sedative and opioid antagonist medications (eg, flumazenil, naloxone) should be immediately available (see "Intraoperative management of adults with obstructive sleep apnea", section on 'Premedication').

Lumbar spinal drain — In some institutions, the neurosurgeon places a lumbar cerebrospinal fluid (CSF) drain or requests that the anesthesiologist place a drain, either to improve surgical exposure, or to reduce CSF pressure for patients at high risk of CSF leak. Lumbar catheters may be used to move the tumor up or down within the surgical field, by draining CSF to lower CSF pressure or injecting saline or air to increase pressure. Drains that are placed to prevent or treat CSF leak may be left in for several days postoperatively [18]. The technique for placement of a lumbar drain is similar to the technique for continuous spinal anesthesia. (See "Spinal anesthesia: Technique", section on 'Continuous spinal' and "Anesthesia for open descending thoracic aortic surgery", section on 'Cerebrospinal fluid (CSF) pressure monitoring'.)

Important considerations for lumbar drains include the following:

●Lumbar drains are optimally inserted with the patient awake or lightly sedated, to allow patient feedback and minimize the risk of neurologic injury during placement [19].

●Lumbar drains can be placed with the patient sitting or in lateral decubitus position.

●Lumbar drains must be placed and managed using strict aseptic technique. (See "Spinal anesthesia: Technique", section on 'Aseptic technique'.)

●Lumbar drains should not be allowed to drain freely. The volume and timing of CSF drainage should be discussed with the neurosurgeon. Drainage rate should be established in discussion with the neurosurgeon.

●If air is injected through the lumbar catheter, nitrous oxide should not be used, as it diffuses into air bubbles and cause unintended increase in pressure. (See "Inhalation anesthetic agents: Clinical effects and uses", section on 'Disadvantages and adverse effects'.)

●There is a relatively high risk of post dural puncture headache (PDPH) after placement of lumbar drains [20]. If PDPH occurs, treatment options, including epidural blood patch, should be discussed with the neurosurgeon. (See "Post dural puncture headache".)

Complications of neuraxial procedures and of lumbar drain placement are discussed separately. (See "Overview of neuraxial anesthesia", section on 'Adverse effects and complications' and "Anesthesia for open descending thoracic aortic surgery", section on 'Cerebrospinal fluid (CSF) pressure monitoring'.)

Perioperative glucocorticoids — Perioperative glucocorticoids may be administered according to institutional protocol and/or surgical preference. At the authors' institution, we administer dexamethasone 4 to 10 mg IV to reduce swelling, prevent nausea, cover the stress of surgery, and avoid early postoperative hypotension from transient adrenal insufficiency associated with temporary disturbance of corticotroph function. Other institutions administer hydrocortisone in this setting selectively, for patients with demonstrated adrenal insufficiency. We withhold steroids in Cushing's disease patients.

The use of glucocorticoids should be discussed with the surgeon prior to administration for any patient having pituitary surgery. Standard doses of dexamethasone used for the management of postoperative nausea and vomiting (PONV) inhibit the hypothalamic-pituitary-adrenal axis for over 24 hours [21]. In practices in which a serum cortisol is drawn on the morning following surgery to screen for hypopituitarism, dexamethasone used in the perioperative period can suppress cortisol levels and may result in a false diagnosis of pituitary insufficiency [22].

Induction of anesthesia — A variety of medications and techniques can be used for induction of anesthesia and are chosen based on patient factors. There are no requirements specific to transsphenoidal surgery. For most adults, IV induction is performed and is discussed separately. (See "Induction of general anesthesia: Overview".)

Airway management — Endotracheal intubation with an oral endotracheal tube (ETT) is required. Nasotracheal tubes are contraindicated as they would be in the surgical field. Extra-large anesthesia face masks, oral airways, and laryngoscope blades are often required for patients with acromegaly, and should be immediately available before induction.

Patients with acromegaly and Cushing's disease may be at increased risk for difficulty with airway management. (See 'Airway changes in patients with acromegaly' above and 'Patients with Cushing's disease' above.)

●Preoxygenation should be performed for all patients who undergo anesthesia, and is particularly important for patients with potential difficulty with mask ventilation and intubation, such as patients with acromegaly or obesity. Apneic oxygenation during attempts at securing the airway may also be beneficial. These issues are discussed separately. (See "Airway management for induction of general anesthesia", section on 'Preoxygenation' and "Preoxygenation and apneic oxygenation for airway management for anesthesia".)

●Equipment and personnel for difficult airway management should be immediately available during induction of anesthesia for patients with acromegaly. Videolaryngoscopy and/or a bougie may be useful as primary or secondary devices for intubation [6]. If careful preoperative airway evaluation reveals potential for difficult airway management or there is previously known difficulty with intubation, awake flexible scope intubation should be considered, using a smaller ETT than would typically be used. (See "Flexible scope intubation for anesthesia", section on 'Preparation for awake intubation' and "Management of the difficult airway for general anesthesia in adults", section on 'Planning the anesthetic approach'.)

●Optimal positioning for airway management may be more difficult for patients with obesity and for those with buffalo humps. Airway management for patients with obesity is discussed separately. (See "Anesthesia for the patient with obesity", section on 'Airway management'.)

The ETT should be taped to the side opposite the surgeon and to the lower lip to allow surgical access to the nares, and to facilitate insertion of the throat pack (if used) without displacing the ETT.

ETTs must be appropriately sized and adequately secured to avoid extubation or displacement, which would cause a leak of anesthetic gases or oxygen out of the airway. Leak of oxygen may increase the risk of airway fire if the surgeon uses electrocautery in the surgical field. (See "Fire safety in the operating room".)

In optimal surgical position, the head may be moderately extended. Extending the head can inadvertently extubate the patient or cause the ETT cuff to herniate through the vocal cords. After turning the bed and head positioning, the anesthesiologist should ensure bilateral breath sounds, end-tidal carbon dioxide return, and a lack of excessive cuff leak, prior to draping for surgery, as the anesthesia team does not have access to the head during the surgery.

A throat pack, typically made of moistened gauze, may be placed by the surgeon to protect the airway from blood and debris, and to prevent blood from entering the stomach, which can cause PONV.

The anesthesia breathing circuit should be routed to allow surgical access, and in cases in which fluoroscopy is used, unimpeded access for the radiology equipment.

Positioning — After anesthesia is induced and the airway secured, the operating table is typically turned 90 degrees with respect to the anesthesia machine. The head may be secured in Mayfield pins or supported on a headrest. The arm on the side on which the surgeon will stand is padded and tucked along the patient's side. The anesthesia clinician typically has access to the opposite upper and lower extremities.

During positioning, meticulous attention should be paid to padding joints and pressure points, particularly for patients with functioning pituitary tumors, who may be at increased risk of positioning-related injuries. Excess cortisol secretion in Cushing's disease leads to skin fragility and osteoporosis, while tissue enlargement in acromegaly can increase the risk of nerve compression. (See "Patient positioning for surgery and anesthesia in adults".)

Maintenance of anesthesia — A variety of medications and techniques can be used for maintenance of anesthesia and are chosen based on patient factors. Maintenance of anesthesia is discussed in detail separately. (See "Maintenance of general anesthesia: Overview" and "Maintenance of general anesthesia: Overview", section on 'Selection of maintenance techniques'.)

Considerations specific to transsphenoidal surgery are discussed here.

Much of the surgery is not particularly stimulating, aside from drilling of the sphenoid bone, which may require transiently deepening anesthesia (eg, with short-acting opioid or propofol), or administration of short-acting beta blocker (ie, esmolol). Transsphenoidal surgery involves delicate dissection that requires an immobile patient. In particular, patient motion during tumor dissection can result in injury to the cavernous sinus or internal carotid artery. Immobility can be achieved with neuromuscular blocking agents, deep inhalation anesthesia, and/or remifentanil infusion, and practice among the contributors to this topic varies.

Neuromuscular blocking agents — Transsphenoidal surgery ends quickly following reconstruction of the skull base defect, so the depth of relaxation should be monitored closely to allow rapid and full reversal for emergence and extubation. Sugammadex may be used to rapidly reverse vecuronium or rocuronium. (See "Clinical use of neuromuscular blocking agents in anesthesia", section on 'Reversal of neuromuscular block'.)

Hemodynamic management — There is no consensus regarding optimal blood pressure targets during surgery (see "Anesthesia for patients with hypertension", section on 'Determination of target blood pressure values'). We aim for normotension in patients without hypertension. In patients with hypertension, we aim to maintain mean arterial pressure (MAP) within 20 percent of baseline, as determined at previous clinical encounters. Hypertension beyond these goals should generally be avoided, since much of the intraoperative bleeding is from cut bone edges, with limited surgical options for control. The decision to maintain a higher MAP must be balanced against risks of greater bleeding.

The surgeon applies a vasoconstrictor topically or injects it into the nasal mucosa before initial incision to minimize bleeding. Patients who undergo transsphenoidal surgery often experience significant hypertension and arrhythmias after intranasal injection of epinephrine-containing solutions and during emergence from anesthesia. In a single institution retrospective review of 100 patients who underwent transsphenoidal hypophysectomy, 58 percent of patients experienced a >50 percent increase in systolic blood pressure with intranasal injection, and 33 percent experienced a >50 percent increase in systolic blood pressure upon emergence from anesthesia [23]. There was no difference in the hemodynamic response of patients with Cushing's disease or acromegaly, compared with patients without endocrinopathy. The mechanism for such an exaggerated blood pressure response is unknown, but may relate to underlying hypertension, which is common in patients who undergo these procedures.

Even transient tachycardia and/or hypertension may be poorly tolerated in patients with cardiac disease [24]. Titrated boluses of short-acting beta blocker (ie, esmolol), ultrashort-acting opioid (ie, remifentanil), or propofol, are options for treating these hemodynamic effects.

Glycemic management — For patients with known diabetes, perioperative glucose levels should be monitored and treated as needed with IV regular insulin boluses or an insulin infusion. There are no established guidelines for glucose management in the setting of transsphenoidal surgery. A reasonable goal is to maintain blood glucose between 110 and 180 mg/dL. (See "Perioperative management of blood glucose in adults with diabetes mellitus", section on 'Glycemic targets'.)

Prophylaxis for postoperative nausea and vomiting — We administer multimodal prophylaxis for PONV for all patients who undergo transsphenoidal surgery; postoperative retching or vomiting can increase venous pressure, cause epistaxis, and disrupt the surgical wound.

The choice of antiemetics should be discussed with the surgeon. In some institutions, dexamethasone is avoided because it can interfere with postoperative cortisol testing [22] (see 'Perioperative glucocorticoids' above). The authors administer ondansetron 4 mg IV, in addition to routine intraoperative dexamethasone, and use total IV anesthesia for patients who are felt to be at particularly high risk of PONV. Risk factors for PONV and options for prophylaxis are discussed separately. (See "Postoperative nausea and vomiting".)

Plan for postoperative pain control — Transsphenoidal surgery is associated with low to moderate postoperative pain. We routinely administer acetaminophen, 1000 mg orally, in the preoperative holding area, to supplement intraoperative opioids.

A small intraoperative dose of a long-acting opioid (eg, morphine 0.05 mg/kg IV or hydromorphone 0.01 mg/kg IV, modified for patient factors) usually provides adequate control of immediate postoperative pain.

Similar to other intracranial procedures, nonsteroidal antiinflammatory drugs (NSAIDs) are typically avoided because of the potential for intracranial bleeding.

An abdominal site is sometimes chosen to harvest a small quantity of subcutaneous fat for closure of the surgical site. The small skin incision can be an additional source of mild discomfort.

Emergence and extubation — After removal of the throat pack at the end of surgery, the oropharynx should be thoroughly suctioned to remove any accumulated blood. In some circumstances, we consider emptying the stomach with an orogastric tube.

The ideal emergence should be smooth, with avoidance of cough, straining, and hypertension, and with the patient rapidly awake enough for an adequate neurologic examination and vision assessment. Coughing and straining increase venous pressure and can cause epistaxis, and can also force nasopharyngeal flora into the wound, and therefore potentially increase the risk of meningitis.

Extubation in a patient with a difficult airway is considered a high risk extubation (see "Extubation following anesthesia", section on 'Higher-risk extubation'). After transsphenoidal surgery, high risk extubation occurs most commonly in the patient with acromegaly who was difficult to intubate, or had an awake flexible scope intubation. For these patients, we administer a remifentanil infusion (0.02 to 0.05 mcg/kg/min IV) during extubation. This allows the patient to spontaneously breathe while reducing the response to the presence of the ETT in the airway. We extubate once airway reflexes return, the patient follows commands, and appears able to maintain his or her own airway. We agree with recommendations from airway management organizations that the use of an airway exchange catheter should be considered when extubating such high-risk patients, to facilitate rapid reintubation if necessary. (See "Extubation following anesthesia", section on 'Airway exchange catheters'.)

Extubating a patient who is unlikely to be able to maintain a patent airway or ventilation is inadvisable. Positive pressure mask ventilation to rescue such a situation can predispose to disrupting surgical closure or introduce nasopharyngeal flora into the surgical site. Techniques for minimizing the physiologic effects of extubation (eg, administration of IV lidocaine or opioids, a no-touch technique) are discussed separately. (See "Extubation following anesthesia", section on 'Minimizing physiologic response to extubation'.)

INTRAOPERATIVE MRI — In selected cases intraoperative magnetic resonance imaging (iMRI) may be used to facilitate more complete resection of pituitary adenomas [25,26]. (See "Transport of surgical patients".)

The surgical site is closed and drapes are removed in preparation for iMRI. If the MRI confirms sufficient resection, the procedure is over and the patient is awakened immediately. Thus, the anesthetic should be tailored to allow rapid emergence and extubation. We aim for a stable general anesthetic before the MRI, ideally with paralysis that can be effectively reversed if a decision to conclude the surgical procedure is made soon after the MRI scan is finished.

Anesthesia in the MRI environment, including the necessary equipment and safety concerns, is discussed separately. (See "Anesthesia for magnetic resonance imaging and computed tomography procedures", section on 'Anesthetic challenges for magnetic resonance imaging'.)

CONVERSION TO OPEN PITUITARY SURGERY — Injury to the carotid artery is a rare and potentially catastrophic complication of transsphenoidal pituitary surgery. Bleeding from a previously undiagnosed aneurysm is also possible [27].

Uncontrolled hemorrhage may be managed in the angiography suite or may require an emergency open craniotomy. Anesthetic management in this setting would be similar to management for a ruptured intracranial aneurysm prior to aneurysm exposure. (See "Anesthesia for craniotomy in adults" and "Anesthesia for intracranial neurovascular procedures in adults", section on 'Rupture prior to aneurysm exposure'.)

EMERGENCY PITUITARY SURGERY — Although very rare, urgent or emergency pituitary surgery may be indicated in patients with threatened visual loss as a result of acute pituitary hemorrhage (pituitary apoplexy) or infarction (Sheehan syndrome) (see "Causes of hypopituitarism", section on 'Pituitary infarction (Sheehan syndrome)' and "Causes of hypopituitarism", section on 'Pituitary apoplexy'). Efforts should be made to allow for expedient surgical decompression, which may be performed via the transsphenoidal route or via craniotomy. Patients with pituitary apoplexy may exhibit hypotension that is poorly responsive to systemic vasoconstrictors, due to acute cortisol deficiency. In this circumstance, treatment with glucocorticoids (eg, hydrocortisone 100 to 200 mg intravenous [IV], or dexamethasone 4 mg IV) will help to restore vascular responsiveness. (See "Clinical manifestations of adrenal insufficiency in adults", section on 'Secondary/tertiary adrenal insufficiency'.)

Management of other aspects of hypopituitarism is discussed separately. (See "Treatment of hypopituitarism".)

POSTOPERATIVE CARE — Most patients recover in the postanesthesia care unit and are then transferred to a postoperative floor, without intensive monitoring.

Monitoring for postoperative hormonal deficiencies and other complications of surgery are discussed separately. (See "Transsphenoidal surgery for pituitary adenomas and other sellar masses", section on 'Hormonal deficiencies' and "Transsphenoidal surgery for pituitary adenomas and other sellar masses", section on 'Damage to parasellar structures'.)

SUMMARY AND RECOMMENDATIONS

●Preoperative evaluation

•For patients who undergo transsphenoidal pituitary surgery, the most important anesthetic concerns involve the anatomic and physiologic changes that result from hormone abnormalities, particularly from functioning tumors that cause acromegaly or Cushing's disease. (See 'Preoperative evaluation' above.)

•Patients with acromegaly are at increased risk of unanticipated difficulty with airway management, cardiovascular disease, obstructive sleep apnea (OSA), and diabetes. (See 'Patients with acromegaly' above.)

•For patients with Cushing's disease, anesthetic concerns include associated cardiovascular disease, impaired glucose control, OSA, and obesity-related difficulty with airway management. (See 'Patients with Cushing's disease' above.)

●Anesthetic management – General anesthesia with an oral endotracheal tube (ETT) is required for transsphenoidal pituitary surgery. (See 'Anesthetic management' above.)

•For patients with acromegaly, difficulty with airway management should be anticipated with preoxygenation and possible apneic oxygenation and immediate availability of personnel and equipment for difficult airway management. Awake flexible scope intubation should be considered for patients who are felt to be at particularly high risk. (See 'Airway management' above.)

•Prophylaxis for postoperative nausea and vomiting should be administered for all patients who undergo transsphenoidal pituitary resection. (See 'Prophylaxis for postoperative nausea and vomiting' above.)

•Optimal resection of the tumor may require intraoperative magnetic resonance imaging (iMRI). (See 'Intraoperative MRI' above.)

●Postoperative pain control – Transsphenoidal surgery is associated with low to moderate postoperative pain. We administer acetaminophen 1000 mg orally, and a low dose of long-acting opioid (eg, morphine 0.05 mg/kg intravenous [IV], or hydromorphone 0.01 mg/kg IV, modified for patient factors) during surgery to prevent immediate postoperative pain. (See 'Plan for postoperative pain control' above.)

●Emergence from anesthesia – The ideal emergence should be smooth, with avoidance of cough, straining, and hypertension, and with the patient rapidly awake enough for an adequate neurologic examination and vision assessment. (See 'Emergence and extubation' above.)