Perioperative Care

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    Introduction

    • Rather than providing "clearance" for surgery, perioperative medicine should focus on three objectives:
    1. Optimize baseline health and chronic disease mgmt
    2. Assess risk + discussion to ensure informed choice is made
    3. Identify post-op risks

     

    Preoperative Evaluation

    • Routine diagnostic tests are NOT indicated preoperatively.
      • Multiple studies: poor yield + poor risk correlation
      • Choosing wisely: Recommends against routine labs & imaging for healthy patients undergoing low-risk surgery (i.e. eye).
      • Let patient-specific factors guide, examples:
        • Serum electrolytes in patients on diuretics
        • Creatinine in CKD

     

    Medication reconciliation

      • Review all medications and optimize medical therapy
    • Medication  Recommendation
      Anticoagulants

      Continue for minor surgery, d/c for major.

      IV heparin 4-6h pre-op

      LMWH: 24h pre-op (12h if prophylactic dose)

      Warfarin: 5 days

      TSOAC: 1-2d (normal GFR), 3-6d (eGFR < 50)

      Antiplatelet

      Clopidogrel: d/c 5-7d pre-op, continue if cardiac stent

      ASA: Continue if minor OR.  Continue  if recent MI (6mo), stent, high risk CAD.  Or discontinue 7-10d pre-op (other than CABG)

      Cardiovascular

      Continue BB, CCB, nitrates, antiarrhythmics.

      ARB/ACEi controversial (intra-op hypotension), usually continue, diuretics often held on day of OR

      Lipid Lowering Coninue statins (hold other lipid lowering drugs)
      Hypoglycemic

      Oral hypoglycemic agents: d/c 12-72hrs pre-OP (depends on half-life and hypoglycemia risk)

      Short-Acting Insulin: Hold AM of OR

      Intermediate-acting: Reduce to 1/2 (usually)

      Long-acting: coninue, or reduce to 2/3

      Steroids Coninue; Give stress dose if indicated
      Estrogen D/c few weeks pre-op (if continue, increase DVT proph)
      Psych

      Small risk of serotonin syndrome w/ anesthetics (weigh risks/benefits)

      MAOIs d/c 10-14 pre-op, SSRI/TCA decide or taper

      Analgesic NSAIDs and COX-2 inh are d/c 7d preop.
      Immunomodulating

      Transplant recipients: 

      • Keep all meds (Except sirolimus: hold due to wound dehiscence)

      Non-Transplant patients: 

      • DMARDS + biologics: stop > 4 half-lives prior to surgery.  Restart when wounds heal. (2-4w after surgery).
      • Continue methotrexate and hydroxychloroquine (do not impact wound healing)

      Pulmonary

      GI (PPI, H2B)

      Thyroid

      Psych

      Generally continue

     

    Cardiovascular Management

    • See 2014 AHA / ACC perioperative cardiovascular guideline
    • Key Principles:
      • Emergency Surgery: Do not delay for cardiac testing
      • Patients during ACS: Should delay surgery until ACS is assessed and treated
    • IF do not fall in above groups... do they have risk factors?
      • If patient has no risk factors, history, or symptoms --> NO perioperative evaluation required
      • If patient has risk factors:
        • Determine risk for major adverse cardiac event (MACE).
          • RCRI --> most common, easiest to use.
            • Overestimates risk in low-risk or ambulatory surgery
            • Underestimates risk in vascular surgery
    • Calculate MINS
      • Low < 1% risk of MACE 
      • High ≥ 1% risk of MACE
      • Low Risk Surgery: Endoscopic etc.. 
      • High Risk Surgery: Vascular Etc
      • "Intermediate was removed"
    • Risk:
      • RCRI  (underestimates vascular surgery risk)
      • VSG-CRI - For Vascular Surgery group - Cardiac Risk Index
    • Preoperative CV risk summary.png

    • Canadian guidelines include:    

      • BNP screening in high risk patients

      • Removed functional status

     

    Post-MI / Stents

    • Note: premature discontinuation of ASA or second antiplatelet agent post-MI or post-Stent is a strong predictor of peri-op MI and mortality. 
    • 2016 AHA Guidelines for Post-MI and Post-Stent antithrombotic management:

       

      • Do not interrupt dual antiplatelet therapy unless:
        • 30 Days Post Bare Metal Stent
        • 6 Months Post Drug Eluting Stent
        • Unless uncontrolled bleeding or urgent life-saving surgery

       

      • (This is a change from 2014 Guidelines)

    Landmark Trials

    • POISE Trial: Post-OP MI is 5% at 30 days.
      • Defined as: troponin elevation. (problem)
    • MINS Trial: 
    • Peri-OP MI: supply/demand mismatch (catecholamines, stress, reduced fibrinolytic activity, hypercoagulability, BP shifts, induction agents and labile BP, tahycardia).
      • Study: plaque rupture 50% of cases. 
    • Landmark trials:
      • CARP (Like COURAGE TRIAL for stable coronary disease, but same for peri-operative).
        • Elective major vascular surgery (highest risk surgery) randomized to revascularization with cath or CABG. (50% prevalence of CAD)
        • If >70% stenosis --> randomized to revasc vs. not.   (excluded prev revasc, if L-main disease, or LAD w/ LV dysfxn).
        • No difference, so if stable coronary disease, no need to revasc (just delays surgery due to antiplts).
      • POISE I (2008 - McMaster)
        • 8000pts, multicenter RCT, RCRI (intermediate/high risk pts).
        • metoprolol 100mg 2-4hrs pre-op then 200mg po x30d. (criticism: high doses!)
        • CV death, nonfatal MI, fatal MI --> LESS EVENTS IN CV GROUP.
          • Stroke risk was higher likely due to hypotension (significantly).  So Risk vs. Benefit 
        • CONCLUSION: Continue BB if on them chronically.  In patients with intermediate/high risk of ischemia may be reasonable to begin BB, but start few weeks before (>1w).  Do not give BB on day of surgery.
      • POISE II
        • ASA on day of CV surgery.
          • 200mg of ASA on day of surgery, followed by 100mg daily for 30d. (if on asa previously, stop for 72hrs, then do this).
            • Excluded recent stents, excluded endarterectomy (on ASA already)
          • Post-op trop 6-12hrs, day 1 and day 3.  
          • NO DIFFERENCE in MI, death, non-fatal MI. INCREASED bleeding risk.
            • Increased bleeding risk can drive MI risk. 
          • Restart 8-10 days post-op when bleeding risk is lower.
      • POISEII - SECOND 2X2 ARM
        • Perioperative low-dose clonidine (discontinue usual anti-hypertensives the morning of surgery, given clonidine).
          • Did not reduce MI, but more non-fatal cardiac arrests in clonidine group. 
          • More hypotension and bradycardia in clonidine group. 
      • VISION trial
        • Background; Troponin elevation worsens outcomes.  Most pts on analgesics, and don't feel MI.
        • 15,000pts undergoing non-cardiac surgery >45yo WITH OVERNIGHT STAY!
        • Measured Troponin on days 1 & 3 and evaluated 30d mortality  (most didn't meet MI standards)
        • Results: Troponin predicts mortality and morbidity post-surgery.
        • Supports post-op surveillance 
        • Data:
          • MINS (criteria TnT ≥ 0.03 ng/mL or Tn > 30)
            • No MINS: 1.1% death at 30 days
            • MINS 9.8% death at 30 days (>3 times increase mortality)
            • 84% asymptomatic
      • Rodseth 2014
        • 2179pts - 18 studies
        • Pre-op BNP independentlyl associated with death or nonfatal MI at 30 days after NCS
        • NT-proBNP < 300 ng/L (or BNP < 92 ng/L) - 4.5% risk
        • NT-proBNP ≥ 300 ng/L or BNP ≥ 92 ng/L - 21% risk
          • recommend daily troponin for 48-72hrs. 
    •  
    • Statins:
      • DECREASE III trial
        • Excluded if on statin already.
        • Used fluvastatin 37d prior to surgery.  (fluvastatin = long half-life).  
        • Outcome: MI, ischemia on ECG, trop elevation etc,, 
        • Fewer MIs in fluvastatin group. 
        • Conclusion: DO NOT stop statins, continue.
        • Conclusion: if vascular patient not on statins, can start one.
    • DO NOT workup/treat conditions that would not be worked up or treated if they were not going for surgery.

     

    Hypertension

    • Pre-Op delay surgery if BP > 180-200/110 -- until better BP control
      • During induction of anesthesia about 90mmHg BP variations (up or down), and can be dangerous.
    • Post-Op:
      • Generally control BP if > 180/110
        • Causes: MANY!  (Pain, Alcohol Withdrawal!!!!)

     

     

    Anticoagulation Management

    Patient thrombosis risk should be weighed with bleeding risk - based on both patient and surgery/procedure factors

     

     

    2012 Periprocedural Management of Oral Anticoagulants

    VKAs

    • Low risk of TE- no bridging
    • Intermediate risk of TE
      • Low risk of bleed - consider bridging
      • High risk of bleed - no bridging
    • High risk of TE - bridging

    *** BRIDGE trial (2015) suggests that both low and all intermediate risk groups for TE should not be bridged, but guidelines do not reflect this yet ***

    DOACs

    • Recommended to hold 4 half lives prior to high-risk of bleed procedure (~3 days prior)
      • May be able to hold only 2 days prior for low-risk of bleed procedures

     

     

    UNDER CONSTRUCTION

    • No need to stop anticoagulant therapy for minor dental procedures (includes extractions) [Source: NEJM K+]

    Components of Peri-Op Assessment

    Cardiac Risk

    • Identify RF's of complications.
    • Establish risk profile, help make informed decision about surgery.
    • MACE = Major Adverse Coronary Event
    • Surgery Risk Factors
      • Low < 1% risk of MACE
        • Endoscopic, superficial, cataract, breast, ambulatory
      • High ≥ 1% MACE
        • Vascular, intraperitoneal, intrathoracic, head&neck, suprainguinal.
    • Patient Risk Factors:
      • Functional Capacity: METs
      • LEE Index/RCRI
        • Most common
        • Underestimates risk of vasc surgery (use VSG-CRI)
        • Not Surgery sapecific.
        • Score 0-3: risk 0.4% - 11%)
        • Score ≥ 2 = >1% risk of MACE = high risk. 
      • VSG-CRI:  If Vascular surgery (Vascular Surgery Group)
        • Carotid en
      • Gupta
        • ASA class, procedure type, etc.. 
        • Easy to use.
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