Periop. Cases on Endocrine Disorders Thomas Maniatis Dec. 16, 2010

Conflicts of Interest None

Case 65 female DM2 on glyburide 10 bid, pioglitazone 30 qd, metformin 1g bid Cataract OR Cholecystecomy Colectomy for colon CA

Issues to consider Patient Factors – Type of diabetes – Treatments: Diet, oral agents, insulin – Adequacy of control: loose, optimal, tight Surgical Factors – Minor, major – Timing – NPO starting when and lasting how long

Preop control and periop complications No high-quality data suggesting preop control impacts on periop complications Small study suggested that HbA1c >7% associated with increased wound infections Case-control study showed increased risk for wound infections if sugars > 11 (CABG)

Effects of surgery on glucose control Stress response causing increased glucose levels – glucagon, epi, GH, IL-6 and TNF-alpha

Goals of therapy Prevent ketoacidosis Avoid marked hyper / hypo glycemias Balanced fluids/electrolytes “Tight” vs. “loose” control – Varying evidence for “tight” control Improved outcomes in certain populations at cost of increased hypo’s – In general, “loose” control is acceptable

Case 65 female DM2 on metformin 1 g bid, N Cataract OR Cholecystectomy Colectomy for CA Radical Neck Dissection for neck mass

Case 55 male DM1 on rapid , glargine Cataract OR Neck Biopsy under GA (day surgery) Cholecystectomy CABG for CAD

IV Insulin How to write a protocol preop in stable patients When to transition from IV to SC postop How to transition from IV to SC postop

IV Insulin Protocols vary – Separate insulin/dextrose vs. combined GIK – Targets: tight vs. traditional – See Protocol Calculation of starting dose – Baseline total daily dose/24 – “safety margin” of % – Dextrose depends on fluid sensitivity D5 vs. D10 – Monitoring, NPO, adjustments – Start early to stabilize dose by OR

IV insulin Intraop – Managed by anaesthesia Postop – Continue drips until no longer NPO – Plan transition to SC ahead of time

IV–SC insulin transition post-op Look at baseline dose pre-op Compare with current “needs” and take into account stressors (infection, etc.) and PO intake Hourly dose x 24 = total daily needs if control stable and eating well (and no infection…) Preferred transition to 3 injections of short- acting with meals and 1 intermediate-long acting before bed while in hospital

IV–SC insulin transition post-op Sliding scale – Traditional vs. adaptive sliding scale Monitor transition closely Modify baseline doses daily Closer to discharge, collapse regimen down to patient-appropriate protocol

Case 35 male Pituitary surgery for tumour Panhypopit. subsequently Cort. 25/12.5, thyroxin, testosterone Hernia repair Cholecystecomy Colectomy for mass

Case 65 female PMR on pred. 15/d Cataract Inguinal Hernia Esophageal resection for tumour

Case 50 male Mod-severe COPD on intermittent prednisone 4 x per year, inhaled steroids Exczema on topical steroids Cholecystectomy Pneumonectomy for tumour

Effects of surgery on steroid secretion Basal secretion – 8-10 mg/d of cortisol Minor surgery – 50 mg/d Major surgery – mg/d (up to 200 mg/d in severe stress) Timing – Biggest surge is immediately post-op (reversal of anaesthesia, extubation)

Surgery and steroids Assess reason for steroid exposure – Primary adrenal or pituitary disease vs. other Assess magnitude of exposure – Dose and duration Consider further testing of axis – ACTH stimulation using the 250 microg dose – Uncertain meaning – Need adequate time Assess surgical “stress”

Effects of steroids on adrenal axis Likely not suppressed – Chronic use of < 5 mg of prednisone – Any patient on any dose of steroid for < 3 weeks Likely suppressed – Any patient on > 20 mg of prednisone for > 3 weeks – Any patient with clinical Cushing’s Intermediate – Everyone else!!

Surgery and steroids Supplement limited to immediate periop period – Hydrocortisone mg IV pre-induction of anaesthesia, then mg IV Q8h x 3 doses, then halve dose QD to baseline dose (or d/c) Be aware of risks of steroids periop – Infections – Impaired wound healing

Thyroid disorders and surgery Poor evidence base supporting recommendations Hypothyroidism – associated with intraop. hypotension in retrospective studies – Mild-mod: may choose to postpone elective surgery to optimize – Severe: only emergency surgery, give T4 and T3 urgently – Risk for myxedema coma Hyperthyroidism – Beta blockers to control HR – Thionamides – Risk for thyroid storm

Pheochromocytoma and surgery Medical preparation focuses on avoiding hypertensive crises Alpha blockade starting 7-10 days preop – phenoxybenzamine Followed by beta blockade 2-3 days preop Alternatives: Ca-channel blockers, metyrosine