Preoperative Assessment Framework

Goals & Scope - Setting the Stage

• Primary Goal: Enhance patient safety by minimizing perioperative morbidity and mortality.
• Core Purpose:
  • Systematically identify patient-specific risk factors (e.g., comorbidities, allergies, medications).
  • Optimize the patient's physiological status pre-surgery.
  • Develop a tailored anesthetic and perioperative management plan.
• Scope of Assessment:
  • Comprehensive medical history and focused physical examination.
  • Judicious selection of preoperative investigations.
  • Risk stratification to guide clinical decisions.

⭐ The primary aim of preoperative assessment is risk identification and mitigation, not merely surgical "clearance."

History & Examination - The Detective Work

• Key History:
  • Surgical indication, comorbidities (cardiac, respiratory, renal, endocrine).
  • Prior anesthetic issues (malignant hyperthermia, difficult airway).
  • Medications (anticoagulants, antiplatelets, steroids). Note other significant drugs.
  • 📌 AMPLE History:
    • Allergies
    • Medications (current)
    • Past medical Hx (including anesthesia)
    • Last meal (NPO: solids 6-8h, clear fluids 2h)
    • Events leading to admission/surgery
  • Exercise tolerance (>4 METs).
• Focused Examination:
  • Vitals, BMI.
  • Airway: Mouth opening (>3 fingers), Mallampati Score (I-IV), Thyromental Distance (TMD >6.5 cm), neck mobility, dentition.
  • Systemic: Focused CVS, RS.

⭐ A thyromental distance < 6 cm, sternomental distance < 12.5 cm, or Mallampati Class III/IV often predict difficult laryngoscopy.

Risk Assessment & ASA - Grading the Challenge

• ASA Physical Status Classification: Assesses overall patient health.

  • ASA I: Normal healthy patient.
  • ASA II: Mild systemic disease, no significant functional limitation.
  • ASA III: Severe systemic disease, significant functional limitation.
  • ASA IV: Severe systemic disease that is a constant threat to life.
  • ASA V: Moribund patient not expected to survive without the operation.
  • ASA VI: Declared brain-dead patient, organ procurement.
  • Suffix 'E': Emergency procedure.

• Revised Cardiac Risk Index (RCRI): Predicts Major Adverse Cardiac Events (MACE). 1 point per factor:

  • High-risk surgery (e.g., vascular, intraperitoneal, intrathoracic).
  • History of Ischemic Heart Disease (IHD).
  • History of Congestive Heart Failure (CHF).
  • History of Cerebrovascular Disease (CVA/TIA).
  • Diabetes Mellitus requiring Insulin.
  • Preoperative Serum Creatinine >2.0 mg/dL.
  • MACE Risk: 0 pts (0.4%); 1 pt (0.9%); 2 pts (6.6%); ≥3 pts (>11%).

⭐ ASA physical status is a strong independent predictor of perioperative mortality; risk approximately doubles with each increasing class.

Fasting & Medications - Pre-Flight Checks

• NPO Guidelines (ASA): 📌 "2-4-6-8 Rule"
  • Clear liquids: 2 hrs
  • Breast milk: 4 hrs
  • Infant formula/Light meal (toast & clear liquids): 6 hrs
  • Fatty/Fried/Meat meal: 8 hrs
• Medication Management:
  • Continue: β-blockers, statins, most antihypertensives (ACEi/ARBs often held day of surgery), anti-epileptics, thyroid medications.
  • Hold/Adjust:
    • Oral hypoglycemics: Hold AM dose.
    • Insulin: Adjust (e.g., ½ to ⅔ of long-acting, hold short-acting).
    • Anticoagulants: Warfarin (stop 3-5 days, target INR <1.5), DOACs (stop 1-5 days based on drug/renal function).
    • Antiplatelets: Aspirin (often continued for high CV risk; stop 5-7 days if elective/high bleed risk), Clopidogrel (stop 5-7 days).
    • Diuretics: Hold AM dose.
    • MAOIs: Stop 2 weeks prior.

⭐ Beta-blockers should be continued perioperatively in patients chronically taking them to prevent adverse cardiac events; abrupt withdrawal can be harmful.

High‑Yield Points - ⚡ Biggest Takeaways

• ASA Physical Status Classification is key for perioperative risk stratification.
• A thorough history (medical, surgical, medications, allergies) is fundamental.
• Focused airway assessment (e.g., Mallampati) and cardiovascular examination are vital.
• Investigations must be selective, guided by clinical findings, not routine.
• Assessing functional capacity (METs) helps predict perioperative cardiac events.
• Informed consent detailing risks, benefits, and alternatives is mandatory.
• Preoperative optimization of comorbidities (e.g., diabetes, HTN) improves outcomes.