Peri-operative Management of Diabetes Flashcards
What hormones are released and suppressed in the surgical stress response and what is the overall metabolic result?
Elevation of catecholamines, growth hormone, glucagon and cortisol, ACTH
Depression of insulin levels and insulin resistance
Leads to glycogenolysis and gluconeogenesis with raised blood glucose levels, protein catabolism, lipolysis, free fatty acid production, ketone bodies
How does hyperglycaemia predispose to infection?
Makes neutrophils “sticky”
Bacteria “like sugar”
What are some of the possible complications of hyperglycaemia especially relevant to the peri-operative period?
Increased risk of infection
Impaired wound healing
Worsens outcome after neurologic damage and myocardial ischaemia
Polydipsia, polyuria may lead to osmotic diuresis and cause dehydration and electrolyte disturbance
Hyperosmolar coma (T2DM) or DKA (T1DM), or arrhythmias and cognitive deficits as a result of hypoglycaemia
What is the BGL level at which hypoglycaemia can cause coma, and what are some of the other adverse outcomes associated with severe hypoglycaemia?
Hypoglycaemia less than 2.2 mmol/L may induce coma
May also produce arrhythmias and cognitive defecits
What 7 factors are important in the preoperative assessment of the diabetic patient?
Type of diabetes
When diagnosed
Current management (including insulin type and doses if relevant)
Adequacy of control (via HbA1C or looking at patients recorded sugars)
Complications
Other risk factors for CVD
Plan to manage perioperative glucose
At what level of HbA1C should elective surgery be deferred?
> 9% (patient should be referred to an endocrinologist)
What 7 complications of diabetes need to be considered when preparing the patient for surgery?
Metabolic disturbance (e.g. DKA, HHS) Atherosclerosis Cardiomyopathy Microangiopathy Neuropathy Stiff joints and glycosylation of tissues Infection and reduction in wound healing
What peri-operative management may be required for a patient with diabetes?
Minimally invasive surgery
Fasted for shortest possible time
Epidural anaesthesia (attenuates stress response thereby controlling BSL)
Short-acting insulin infusions (attenuates stress response thereby controlling BSL)
Administration of pre-operative CHOs
Return to normal diet and medication soon after surgery
Within what BGL range is the operative outcome better?
Tight control within 5-10 mmol/L
Management of type 2 diabetic on diet alone
Early morning case if practical (not essential)
No therapy required
Check BGL pre-, intra- and post-operatively
Supplemental short-acting insulin if BGL >10 mmol/L
Management of type 2 diabetic on oral hypoglycaemics (e.g. SU and metformin)
Early morning case
Oral medications ceased 12 hours pre-operatively
Monitor BGL 4 hourly (treat if less than 4 or >10 mmol/L)
May need insulin supplementation for hyperglycaemia
Resume oral agents when back to normal diet
How is a hypoglycaemic episode managed (in order of increasing severity)?
Ingestion of food, drink
Glucagon injections
IV glucose (20mL of 25% concentrated solution)
Management of type 1 diabetic (or type 2 diabetic on insulin) booked for morning procedure
Put first on the list
Measure BGL every 2 hours from 0800
Give usual dose of long-acting insulin or give half-dose of morning insulin and supplemental novorapid or actrapid
IV 5% dextrose infusion (100mL/hr)
What 4 factors may make a diabetic patient more insulin sensitive?
Elderly
Lean type 1 diabetics
Renal failure
Liver failure
What 4 factors may make a diabetic patient more insulin resistant?
Obesity
Patients on glucocorticoids
Guidelines for insulin correction
Under 4: 0 and consider IV glucose
10-14: 4U
14.1-18: 6U
18 mmol/L: 8U and contact endocrinologist
Guidelines for insulin infusion
Requires hourly monitoring 3-7: 0 7.1-10: 2U/hr 10.1-12: 2U/hr + 2U bolus 12.1-16: 3U/hr + 4U bolus 16.1-22: 4U/hr + 10U bolus Must also have fluid infusion of 5% dextrose at 100-200mL/hr
Why is atherosclerosis relevant to the pre-operative assessment?
Increased risk of myocardial ischaemia and (often silent) MI
What may need to be done pre-operatively in the setting of severe atherosclerosis?
Revascularisation
Why is autonomic neuropathy relevant to the pre-operative assessment?
Increases risk of haemodynamic instability, gastroparesis (and therefore regurgitation and aspiration), and silent MI
Why is peripheral neuropathy relevant to the pre-operative assessment?
Important to document pre-existing neurological symptoms if considering regional anaesthesia (may increase risk of intra-operative nerve injury)
May have chronic pain and be on opioids or other analgesics relevant to anaesthetic management
Why are stiff joints and glycosylation of tissues relevant to the pre-operative assessment?
Increased chance of difficult intubation and cannulation
What might retinopathy be indicative of?
Microangiopathy - relevant as this is the process underlying diabetic nephropathy
Why is nephropathy relevant in the pre-operative assessment?
Relevant to drug dosing and metabolism
Surgery may worsen renal failure, tip patient into AKI
