What is the recommended anesthesia management for patients with insulinoma?

Anesthesia Management for Insulinoma

Preoperative Glucose Stabilization

The most critical preoperative priority is stabilizing glucose levels with dietary management and diazoxide, while avoiding somatostatin analogs which can precipitously worsen hypoglycemia and cause fatal complications. 1

• Diazoxide is the first-line medical therapy for managing hypoglycemia due to hyperinsulinism before surgery 1
• Everolimus can be considered as an alternative for preoperative stabilization 1
• Somatostatin analogs (octreotide, lanreotide) must be used with extreme caution or avoided entirely in insulinoma patients, as they suppress counterregulatory hormones (particularly glucagon) and can precipitously worsen hypoglycemia 1, 2
• Patients requiring splenectomy should receive preoperative trivalent vaccine (pneumococcus, haemophilus influenzae b, meningococcus group C) 2, 1

Intraoperative Glucose Management

Continuous intravenous glucose infusion with frequent monitoring (or continuous glucose monitoring) is mandatory throughout the perioperative period to maintain plasma glucose >60 mg/dL. 3, 4

• 10% glucose infusion is typically required until tumor resection to prevent hypoglycemia 3
• Severe hypoglycemia can occur during tumor manipulation, with symptoms masked under general anesthesia 4
• Frequent blood glucose measurements or continuous glucose monitoring is mandatory during the perioperative period 3
• After tumor resection, insulin infusion may be needed to control rebound hyperglycemia, targeting blood glucose around 150 mg/dL 3

Anesthetic Technique

Propofol-based general anesthesia combined with epidural analgesia is a safe and effective approach for insulinoma surgery. 5

• Propofol for induction (80-100 mg) and maintenance via continuous infusion, combined with epidural block, has been successfully used 5
• Epidural catheter placement (typically T9/10) provides excellent analgesia and reduces anesthetic requirements 5
• Standard neuromuscular blockade (vecuronium 6 mg) facilitates intubation 5
• Opioids (fentanyl 200 mcg) can be used as part of balanced anesthesia 5

Intraoperative Tumor Localization

Intraoperative ultrasound (IOUS) is mandatory and achieves 92-97% sensitivity for identifying insulinomas, particularly small lesions in the pancreatic head. 1

• IOUS enhances detection beyond all preoperative imaging modalities and serves as a useful adjunct to surgical palpation 1
• Rapid immunoreactive insulin (IRI) measurements during surgery are useful for confirming tumor localization 5
• IRI levels should decrease after successful tumor removal 5

Critical Perioperative Pitfalls

The most dangerous period is tumor manipulation, when severe hypoglycemia can occur suddenly, and immediately post-resection, when rebound hyperglycemia develops. 3, 4

• Blood glucose can change dramatically during the perioperative period, requiring vigilant monitoring 3
• Hypoglycemic symptoms remain masked under general anesthesia, making frequent glucose checks essential 4
• Do not rely on somatostatin receptor scintigraphy (SSRS) for preoperative localization, as sensitivity is only 50-60% for insulinomas (compared to 75% for other pancreatic NETs) 1
• Proton pump inhibitors can cause spuriously elevated chromogranin A levels, complicating diagnosis 1

Postoperative Management

Monitor for both persistent hypoglycemia (indicating incomplete resection or multiple tumors) and rebound hyperglycemia (indicating successful tumor removal). 3

• Glucose infusion requirements typically decrease dramatically after successful tumor resection 5
• IRI levels should normalize after tumor removal 5
• In malignant cases (approximately 5% of insulinomas), ongoing medical management may be required 6