Surgical Principles: Preoperative Evaluation

Preoperative Evaluation

Goal of Preoperative Evaluation

  • Goal: Quantify & Modify Risk Factors to Improve Morbidity
  • Not to “Clear for Surgery”

Wound Classification

ASA Physical Status Classification

  • Classification:
    • Class I: Healthy
    • Class II: Mild-Moderate Systemic Disease, No Impact on Activity
      • Ex: Smoking, Pregnant
      • Unlikely to Affect Anesthesia
    • Class III: Severe Systemic Disease, Limits Activity
      • Ex: Stable Angina, Prior MI, Controlled CHF, CKD
      • Likely to Affect Anesthesia
    • Class IV: Severe Systemic Disease, Incapacitating with Threat to Life
      • Ex: ESRD, On Dialysis, Current MI, Unstable Angina
      • Likely to Significantly Affect Anesthesia
    • Class V: Moribund, Not Expected to Survive 24 Hours
      • With or Without Surgery
    • Class VI: Brain Dead
    • *Add “E” if Emergency Surgery
  • Correlates:
    • Operative Duration
    • Blood Loss
    • Hospital & ICU Stay
    • Wound Infection
    • UTI
    • Cardio-Pulmonary Complications
    • Mortality
  • Not Correlated: Anastomotic Leak

Cormack-Lehane Laryngoscopy Classification

  • View During Direct Laryngoscopy
  • Associated with Risk for Difficult Intubation
  • Grading:
    • Grade 1: Full Glottis
    • Grade 2: Partial Glottis
      • 2a: Partial Glottis
      • 2b: Arytenoids Only
    • Grade 3: Epiglottis, No Glottis
    • Grade 4: No Epiglottis or Glottis
  • Clinical Relevance
Grade Percentage of Patients Percentage with Difficult Intubations
1 74% < 1%
2a 21% 13%
2b 3% 65%
3 2% 80%
4 < 1% 100%

Mallampati Score

  • External View of the Oral Cavity to Estimate Risk for Difficult Intubation
  • Worse Prognostic Value than the Cormack-Lehane Classification
  • Modified Score:
    • Class I: Visualize Soft Palate, Entire Uvula, Fauces & Tonsillar Pillars
    • Class II: Visualize Soft Palate, Partial Uvula & Fauces
    • Class III: Visualize Soft Palate & Base of Uvula
    • Class IV: Visualize Only Hard Palate

Metabolic Equivalent of Task (MET)

  • Serves as an Objective Measure of Energy Expenditure Compared to Body Mass
  • 1 MET = Amount of Oxygen Consumed While Sitting at Rest
    • 1 MET = 1 kcal / (kg x hr)
  • Common Activities:
    • 1: Eating & Sitting
    • 2: Showering & Walking Down Stairs
    • 3: Walking for 1-2 Blocks
    • 4: Walking Up Two Flights of Stairs or Pushing a Power Lawn Mower
    • 5: Social Dancing
    • 6: Nine Holes of Golf While Carrying Clubs
    • 7: Digging Holes, Singles Tennis, Carrying 60 lbs.
    • 8: Moving Heavy Furniture, Rapidly Climbing Stairs
    • 9: Bicycle at a Moderate Pace
    • ≥ 10: Full-Court Basketball, Running, Bicycle Uphill
  • Good Functional Capacity for Surgery Often Defined as Being Able to Perform ≥ 4 METS

Fasting/NPO Timing (ASA Recommendations) Mn

  • Clear Liquids: 2 Hours
  • Breast Milk: 4 Hours
  • Infant Formula/Non-Human Milk: 6 Hours
  • Light Meal: 6 Hours
  • Heavy Meal: Additional Fasting Time (≥ 8 Hours) May Be Needed
    • Fried Foods, Fatty Foods or Meat

Cardiac Evaluation

Estimating Risk of Major Adverse Cardiac Event (MACE)

  • Strongest Risk Factor for Major Adverse Cardiac Event (MACE): CHF
  • ACC/AHA Guideline on Perioperative Cardiac Risk
    • Estimates Risk for Major Adverse Cardiac Event (MACE) Based Only on the Procedure Being Performed
    • Risk:
      • Low Risk (< 1%): Others (Breast, Endoscopic, Cataract)
      • Intermediate Risk (1-5%): Abdominal, Thoracic, CEA, H&N, Ortho & Prostate
      • High Risk (> 5%): Vascular (Aortic & Peripheral Vascular – Not CEA)
  • Revised Cardiac Risk Index (RCRI/Lee Criteria)
    • Estimates Risk for Major Adverse Cardiac Event (MACE) Based on Patient Factors & the Surgery Being Performed
    • It is a Modification of the Original Cardiac Risk Index System (CRIS)
    • Factors (+1 Each):
      • High Risk Surgery (Intraperitoneal, Intrathoracic or Supra-Inguinal Vascular Procedures)
      • Congestive Heart Failure (CHF)
      • Coronary Artery Disease (CAD)
      • Diabetes on Insulin Therapy
      • Past CVA/TIA
      • Serum Creatinine ≥ 2 mg/dL
    • Risk:
      • 0 Points: Class I (0.5%)
      • 1 Point: Class II (1%)
      • 2 Points: Class III (7%)
      • ≥ 3 Points: Class IV (11%)

Delaying Elective Surgery After Cardiac Intervention

  • Angioplasty: 2 Weeks
  • Bare Metal Stent (BMS): 1 Month
  • Drug Eluding Stent (DES): 6-12 Months

Preoperative Orders

  • Excellent Functional Status (Able to Perform ≥ 4 METS):
    • No Past Cardiac History: None
    • Past Cardiac Disease: EKG
  • Poor Functional Status (Unable to Perform ≥ 4 METS):
    • No Signs of ACS: Echo
      • Also Obtain Echo for an Aortic Stenosis Murmur
    • Signs of ACS: Stress Test & Possibly Angiogram

Pulmonary Evaluation

Risk Factors

  • Risk Factors: CHF (#1) > Low Albumin > Age Over 60 > COPD > Smoking
    • Not Obesity or Mild/Moderate Asthma
  • Routine Nasogastric Tube Postoperatively Increases Risk
    • Keeps Lower Esophageal Sphincter Patent

Modalities to Reduce Risk

  • Postoperative Deep Breathing Exercises and Incentive Spirometry
  • Postoperative CPAP
  • Smoking Cessation
    • Goal: 4-8 Weeks
    • *Historically Thought that Cessation Soon Before Surgery Increased Risk Due to Increased Sputum & Impaired Clearance, Now Disproven > Advise Cessation at Anytime

Pacemaker Management

Settings

  • Described As a 4-Letter Abbreviation (ex: DDDR)
I – Paced Chambers II – Sensed Chambers III – Sense Response IV – Rate Adaptation
O = None O = None O = None O = None
A = Atrium A = Atrium I = Inhibited R = Rate Adaptive
V = Ventricle V = Ventricle T = Triggered
D = Dual D = Dual D = Dual

Preoperative Management

  • Electrocautery Can Interfere with Conduction Sensing
    • Highest Risk: Monopolar Electrocautery
  • If Using Electrocautery: Set to an Asynchronous Mode (-OOO) & Turn of Defibrillator
    • Asynchronous Mode Fires Independent of Input Minimizing Arrhythmia Risk
      • If Pacemaker Dependent, Completely Turning Off Can Cause Bradycardia & Hemodynamic Instability
    • Defibrillator Can Cause Accidental Discharge

Mnemonics

NPO Timing

  • “2-4-6-8”
    • Clear Liquids: 2 Hours
    • Breast Milk: 4 Hours
    • Light Meal: 6 Hours
    • HeHeavy Meal: Additional Fasting Time (≥ 8 Hours) May Be Needed