The Patient Undergoing Surgery:Proven Steps to Better Outcomes

Ariel U. Spencer, MD

Lafayette Surgical Clinic

Lafayette, Indiana

Disclosures

• No conflicts of interest to disclose

Risk Factor Modification

• What specific steps have been proven to improve outcomes?

• What guidelines are supported by current literature?

Hyperglycemia

• Stress and fasting

• Relative insulin deficiency

• Increased insulin resistance

• Decreased insulin production

• Free fatty acids

Hyperglycemia

• Fluid shifts

• Increased inflammatory response

• Endothelial dysfunction

• Thrombotic complications

Effects of Hyperglycemia on Immune System

• Decreased granulocyte adhesion

• Impairment of chemotaxis

• Impaired intracellular killing

• Compromised phagocytosis

• Superoxide formation

• At what blood sugar level do harmful effects of hyperglycemia begin to occur?

• Clinical signs appear after cellular and tissue damage has already happened

Conventional Therapy

• No perioperative insulin administration• NPO status• Postoperative management with sliding

scale insulin; inclusion of oral hypoglycemic agents as diet is advanced

• No standardization for target blood glucose levels (? , 200 mg/dl, etc.)

Intensive Insulin Therapy(IIT)

• Very influential study in 2001 (large randomized controlled trial, > 1500 critically ill, intubated surgical ICU patients)

• Underlying concept: maintain total normoglycemia in the perioperative period

Van den Berghe G, N Engl J Med 2001; 345:1359-1367)

Intensive Insulin Therapy

• Average blood glucose in study group of 101 mg/dl was achieved

• Control group (treatment threshold at glucose = 220 mg/dl) achieved an average blood glucose of 152 mg/dl

• 42% reduction in mortality risk

Intensive Insulin Therapy

• Serum insulin levels in patients receiving IIT were similar to levels in patients receiving conventional insulin therapy, despite much higher doses of insulin

• Conclusion that normoglycemia can be achieved without significantly elevating insulinemia

• Evidence for improved insulin sensitivity

Mode of Insulin Delivery

• Decreased sternal wound infections

• 69% reduction in death, myocardial infarction, and CHF

(continuous IV insulin therapy; blood sugar maintained between 100 - 150)

Subramaniam B, Anesthesiology 2009; 110:970-977

Tight glucose control

• AACE (2007)

• ADA (2008)

• Institute for Healthcare Improvement (2009)

• Protocols began to be instituted across the nation

• Some concerns expressed

Problems with IIT

• RCT testing IIT in the intra-operative setting (on-pump cardiac surgery, n= 201) with a very aggressive BG goal (80-100)

• This study found an increased risk of death and stroke in the IIT group

• Conclusion: IIT implemented during surgery may actually worsen outcomes

Gandhi GY, et al., Ann Int Med 2007;146:233-43.

Hypoglycemia Dilemma

• Considerable variability between studies in the target blood glucose achieved

• With IIT-driven protocols, significantly increased rate of episodes of profound hypoglycemia (rates from 5 - 29%)

• Termination of two large European studies

NICE-SUGAR

• Normoglycemia in Intensive Care Evaluation - Survival Using Glucose Algorithm Regulation

• Largest trial of IIT thus far

• IIT group: target glucose 80-108

• Control group: target glucose 144-180N Engl J Med 2009; 360:1283-97

NICE-SUGAR

• INCREASED mortality in the group receiving tighter blood glucose control

• 3% higher absolute mortality rate

• Increased rate of cardiovascular death

Avoiding hypoglycemia

• Fluctuation in an individual’s blood glucose may be more critical than the average glucose level

• Using computer-driven models to predict an individual patient’s insulin resistance and requirements

• Careful monitoring