Insulin and Glucose in Obstructive Jaundice - 10-Mark Anesthesia Exam Answer

Introduction

Why Glucose Metabolism is Disturbed in Obstructive Jaundice

• Prolonged biliary obstruction leads to progressive hepatocyte damage from the direct toxic effects of retained bile acids, bilirubin, and cholesterol.
• Damaged hepatocytes have reduced capacity for glycogen storage, glycogen breakdown (glycogenolysis), and de novo glucose synthesis (gluconeogenesis).
• The net result is a tendency toward hypoglycemia, especially during prolonged fasting or surgery.

• Patients with obstructive jaundice are frequently malnourished due to anorexia, malabsorption of fat-soluble nutrients (due to absence of bile in the gut), and the underlying disease (e.g., pancreatic carcinoma, cholangiocarcinoma).
• Malnutrition depletes hepatic glycogen stores. When these patients are fasted pre-operatively, their ability to mount a counter-regulatory hyperglycemic response is blunted, placing them at risk of intraoperative hypoglycemia.

• The liver is responsible for about 50% of first-pass insulin degradation.
• In hepatocellular dysfunction from biliary obstruction, insulin is not adequately cleared, leading to relative hyperinsulinemia.
• Elevated circulating insulin suppresses gluconeogenesis and glycogenolysis further, compounding the hypoglycemic tendency.

• Lack of bile in the gut disrupts the intestinal mucosal barrier, facilitating bacterial translocation and endotoxin absorption (endotoxemia).
• Endotoxin triggers cytokine release (TNF-α, IL-6), which can cause insulin resistance - particularly in the peripheral tissues and skeletal muscle.
• This paradoxically creates a situation of simultaneous insulin resistance (in muscles/fat) and insulin excess (due to impaired hepatic degradation), making glucose control unpredictable.

• Surgery itself, combined with the existing stress of jaundice, causes catecholamine and cortisol release, suppressing insulin secretion and promoting glycogenolysis and gluconeogenesis.
• However, with depleted glycogen stores and impaired hepatic function, this counter-regulatory response is blunted and unreliable.

Clinical Consequences

Role of Insulin-Glucose Infusion (Dextrose-Insulin Regimen)

Rationale

1. Prevents hypoglycemia from depleted glycogen stores.
2. Provides a protein-sparing caloric substrate.
3. Reduces catabolism and amino acid release (which would otherwise worsen nitrogen balance in an already malnourished patient).

Regimen Used

• 5% or 10% Dextrose infusion started from the time the patient goes nil by mouth (NBM/NPO), continued throughout surgery and into the postoperative period.
• Regular monitoring of blood glucose every 1-2 hours intraoperatively, every 2-4 hours postoperatively.
• If glucose rises above 180-200 mg/dL (a common threshold), short-acting insulin is added (either as sliding scale subcutaneous or as a low-dose IV infusion).
• If glucose falls below 80 mg/dL, the dextrose infusion rate is increased and insulin is withheld.

Target Blood Glucose Range

• Target: 140-180 mg/dL (avoid both hypoglycemia and marked hyperglycemia)
• Tight control (80-110 mg/dL) is NOT recommended due to increased hypoglycemia risk, especially with impaired hepatic counter-regulation.

Additional Relevant Considerations for the Anesthesiologist

• Assess nutritional status; consider pre-operative enteral/parenteral nutrition if severely malnourished (serum albumin <30 g/L, >10% weight loss).
• Correct coagulopathy (Vitamin K deficiency is common due to fat malabsorption; give IV/IM Vitamin K or FFP).
• Check preoperative blood glucose and establish a baseline.

• Avoid prolonged fasting without glucose supplementation.
• Use glucose-containing IV fluids (not saline-only regimens) from time of NBM.
• Monitor blood glucose at induction, every hour intraoperatively, and on emergence.
• Avoid hypotonic fluids (risk of hyponatremia).
• Be alert for hypoglycemia signs that may be masked: unexplained tachycardia, hypertension, diaphoresis, delayed awakening.

• Impaired hepatic metabolism alters the pharmacokinetics of many anesthetic agents.
• Insulin itself has a half-life of ~35 minutes; in hepatic dysfunction, clearance of insulin is reduced, prolonging its effect.
• Avoid exogenous insulin unless blood glucose clearly exceeds 180 mg/dL; use conservative doses.

• Continue glucose monitoring for 24-48 hours after surgery.
• Reintroduce enteral feeding as soon as feasible.
• Blood glucose instability may persist for several days post-operatively in patients with severe pre-existing liver dysfunction.

Summary

1. Depleted hepatic glycogen stores (malnutrition)
2. Impaired gluconeogenesis (hepatocyte dysfunction)
3. Hyperinsulinism from reduced hepatic insulin degradation
4. Endotoxemia-driven insulin resistance

• Wang L, Yu WF. "Obstructive jaundice and perioperative management." Acta Anaesthesiologica Taiwanica, 2014 [PMID: 24999215]
• Pavlidis ET, Pavlidis TE. "Pathophysiological consequences of obstructive jaundice and perioperative management." Hepatobiliary & Pancreatic Diseases International, 2018 [PMID: 29428098]