Management of Diabetes in Surgery

1. Management of Diabetes in Surgery

2. Diabetes • Diabetes is a metabolic disorder resulting from insulin deficiency or intolerance • Associated with acute and long term systemic problems • Diagnosed by a random plasma glucose >11.1mmol/l and a fasting glucose>7.0mmol/l (WHO criteria) • The two most common forms of diabetes are Insulin Dependant Diabetes Mellitus (Type 1) and Non Insulin Dependant Diabetes Mellitus (Type 2)

3. Type 1 Diabetes Mellitus • Polygenic disorder thought to be of auto immune aetiology • Results in destruction of β cells in the Islets of Langerhans in the Pancreas, with subsequent insulin deficiency • Young onset • 0.4% prevalence • Endogenous insulin is required to maintain plasma glucose levels to within physiological levels

4. Type 2 Diabetes Mellitus • Hypoglycaemia resulting from reduced insulin secretion and peripheral insulin resistance • Some genetic concordance • Older onset, associated with central obesity • Depending on severity, may be controlled with: • diet and exercise to lose weight • oral hypoglycaemics • insulin

5. Diabetes and Surgery • Surgery is a form of physical trauma • It results in catabolism, increased metabolic rate, increased fat and protein breakdown, glucose intolerance and starvation. • In a diabetic patient, the pre existing metabolic disturbances are exacerbated by surgery • The type of diabetes, amount of insulin dose, diet or oral hypoglycaemic agents must be considered as this will change the overall management plan • The risk of significant end-organ damage increases with the duration of diabetes, although the quality of glucose control is more important than the absolute time

6. Factors Adversely Affecting Diabetic Control Perioperatively • Anxiety • Starvation • Anaesthetic drugs • Infection • Metabolic response to trauma • Diseases underlying need for surgery • Other drugs e.g. steroids

7. Hormonal Secretion of stress hormones Cortisol Catecholamines Glucagon Growth Hormone Cytokines Relative decrease in insulin secretion Peripheral insulin resistance Metabolic Increased gluconeogenesis and glycogenolysis Hyperglycaemia Lipolysis Protein breakdown Metabolic Responses to Surgery

8. Metabolic Response to Surgery and Diabetes • Hypoglycaemia • May develop perioperatively due to the residual effects of preoperative long acting oral hypoglycaemic agents or insulin. • Exacerbated by preoperative fast or insufficient glucose administration • Counter-regulatory mechanisms may be defective because of autonomic dysfunction • Can lead to irreversible neurological deficits • Dangerous in anaesthetised or neuropathic patient as the warning signs may be absent • Management • Give i.v dextrose and monitor glucose levels

9. Metabolic Response to Surgery and Diabetes • Hyperglycaemia • Glucagon, cortisol and adrenaline secretion as part of the neuroendocrine response to trauma, combined with iatrogenic insulin deficiency or glucose overadministration may result in hyperglycaemia • Causes osmotic diuresis, making volume status difficult to determine and risking profound dehydration and organ hypoperfusion, and increased risk of UTI • osmotic diuresis, delayed wound healing, exacerbation of brain, spinal cord and renal damage by ischaemia • Results in hyperosmolality with hyperviscocity, thrombogenesis and cerebral oedema • Management • Frequently measure blood glucose and administer insulin

10. Metabolic Response to Surgery and Diabetes • Ketoacidosis • Any patient who is in a severe catabolic state and has an insulin deficiency (absolute or relative) can decompensate into keto-acidosis • Most common in type 1 patients • Increased risk postoperatively, often precipitated by the stress response, infection, MI, failure to continue insulin therapy. • characterised by hyperglycaemia, hyperosmolarity, dehydration (may lead to shock and hypotension) and excess ketone body production resulting in an anion gap metabolic acidosis.

11. Metabolic Response to Surgery and Diabetes • Management • restore intravascular volume • eliminate ketonaemia • control blood glucose • replace electrolytes • monitor glucose and ketone levels • Mortality from DKA –5-10% • Electrolyte abnormalities • Anticipate imbalances in potassium, magnesium and phosphate

12. Underlying Cardiac Complications of Diabetes and Surgery • Cardiovascular problems frequently present in long standing diabetics • Ischaemic Heart Disease - Often silent ischaemia • Coronary artery disease • Hypertension • Diabetic patients must be considered as being at high risk of MI • Silent MI in autonomic neuropathy as Cardiac Autonomic Neuropathy may abolish the hearts response to stress • Induction of anaesthesia and tracheal intubation can lead to a reduction in cardiac output

13. Underlying Cardiac Complications of Diabetes and Surgery • Management • Most cardiac and antihypertensive drugs should be continued throughout the perioperative period except, aspirin, diuretics and anticoagulants • History to determine effort tolerance, clinical examination for cardiac failure and an electrocardiogram in all patients. • Echocardiography can help in assessing an ejection fraction in borderline cases

14. Underlying Renal Complications of Diabetes and Surgery • Renal • Renal dysfunction • Intrinsic renal disease including glomerulosclerosis and renal papillary necrosis enhance the risk of acute renal failure perioperatively • Proteinuria is an early manifestation • Dialysis should optimally be done the day before surgery. • Urinary infection • Management • Urea and electrolyte determination. • Dipstix urinalysis for proteinuria

15. Underlying Nervous System Complications of Diabetes and Surgery • Nervous System • Counter-regulatory response to hypoglycaemia • Peripheral glove and stocking neuropathy with an increased susceptibility to iatrogenic nerve injuries • Cardiac Autonomic Neuropathy • Management • History of postural dizziness, post gustatory sweating, nocturnal diarrhoea and impotence. • Careful documentation of peripheral sensation

16. Underlying Orthopaedic Complications of Diabetes and Surgery • Small Joint Disease • Non-enzymatic glycosylation causing abnormal cross-linking of collagen may lead to joint rigidity • At the atlanto-occipital joint, it may result in difficult intubation • The small joints of the fingers and hands are also affected • failure to approximate the palmar surfaces of the interphalangeal joints are indicators of a difficult laryngoscopy (positive prayer sign) • Management • Clinical assessment of neck extension, examination of the small joints of the hand and a good evaluation of the ease of intubation

17. Underlying Immune Complications of Diabetes and Surgery • Immune and infectious risk • Diabetics are susceptible to infection and have delayed wound healing • Hyperglycaemia • facilitates proliferation of bacteria and fungi • depresses the immune system management • Proteolysis and decreased amino acid transport retards wound healing. • Loss of phagocytic function increases the risks of post-operative infection • Management • Need very strict sterile techniques and need to assess risk/benefit ratio for procedures e.g catheterisation

18. Underlying Gastrointestinal and Opthamological Complications of Diabetes and Surgery • Gastrointestinal • Gastroparesis • Management • History of early satiety and reflux • H2 blocker and metoclopramide • Ophthalmology • Cataracts, glaucoma and retinopathy decrease visual acuity and increase the unpleasantness of the perioperative period • Management • Increase the amount of explanation and reassurance to the patient.

19. Principles of Managing Diabetics During Surgery • Management of preoperative insulin therapy depends on baseline blood glucose, level of diabetic control, severity of illness and the proposed surgical procedure • However, aims for all diabetic patients are: • No excess mortality • No increase in post-op complications • Normal wound healing • No increase in duration of hospitalisation • No hypoglycaemia, hyperglycaemia or ketoacidosis

20. Pre-operative Assessment • This is the most important step in the management of the diabetic patient • Involves a thorough history and physical examination • Review prior anaesthetic records to determine whether there were any difficulties with intubation or anaesthetics • Lab investigations • blood glucose - K+ • BUN - creatinine • ketones - proteinuria • HbA1c (to assess how well controlled diabetes is)

21. Pre-Operative Management • Admit as early as possible prior to surgery • Avoid long-acting glucose lowering agents • chlorpropamide –glibenclamide • ultralente insulins • Avoid metformin • Closely monitor blood glucose levels • 2 hourly for Type 1 • 4 hourly for type 2 • Test urine every 8 hours for ketones • Place first on morning operating list if possible • Aim for a blood glucose of 5-10mmol/L

22. Surgical Management of Insulin Dependant Diabetes Mellitus • Aim to keep blood glucose 5 to10mmol/L • Pre operative • NBM for 6 hrs prior to surgery (4 hrs for clear fluids) • Anti aspiration prophylaxis • Initiate glucose/ potassium/ insulin regime after commencing NBM (check K+ as well) • 500ml 10% glucose solution with 20mmol K+ at 1ml.kg-1.hr-1 connected to Y piece with insulin syringe • Make up insulin syringe as 50 units insulin in 50 ml saline in a 50 ml syringe pump and run through Y piece with 10% glucose at between 1 to 5 u hr-1 (1 – 5 ml). • Base on existing insulin regime • Use sliding scale e.g. 1 u hr-1 if BG between 5 to 10 • Hourly capillary glucose is measured until operation

23. Surgical Management of Insulin Dependant Diabetes Mellitus • Intra-operative • Hourly glucose monitoring • keep between 5-10 mmol/L • Two hourly potassium monitoring • keep between 3.5-4.5 mmol/L • Anaesthesia determined by patient physiology and surgical requirements • Set up additional IV for resuscitation fluids

24. Surgical Management of Insulin Dependant Diabetes Mellitus • Post-operative • Continue Glucose/Potassium/Insulin regime until patient can take orally • Oral medication with first meal • Allow for pain resulting in increased insulin requirements

25. Surgical Management of Non Insulin Dependant Diabetes Mellitus • Treat as insulin dependant if: • poorly controlled (blood glucose >10 mmo/L) • major surgery • Pre-operative • Biguanides must be stopped 48 hours before hand for fear of lactic acidosis • NBM for 12 hours prior to operation • Start i.v maintenance fluid • 0.18% NaCl with glucose 4% • Hourly capillary glucose is measured until operation

26. Surgical Management of Non Insulin Dependant Diabetes Mellitus • Hourly glucose monitoring • Aim to keep within 5-10mmol/L • if blood glucose >10 mmol/L, switch to treating as insulin dependant • Post-operative • Restart oral hypoglycaemics with first meal

27. Other Considerations with Anaesthesia in Diabetic Patients • Usual intra-operative monitoring • record BP and pulse every 5 minutes • watch skin colour and temp • suspect hypoglycaemia if patient is cold and sweaty • give IV glucose • No contraindications to standard anaesthetic induction or inhalational agents • If the patient is dehydrated then hypotension will occur and i.v. fluids will be needed

28. Conclusion • The diabetic patient presents numerous challenges to management during surgery • Awareness of the complications should enable tight metabolic control • Correct management of the diabetic patient during surgery reduces morbidity and length of admission, as well as resulting in better wound healing