Preanesthetic Evaluation and Perioperative Assessment
What you must understand
Preoperative evaluation is risk stratification plus optimization, not clearance. Know the components: focused history and physical, airway assessment (Mallampati, thyromental distance, mouth opening, neck mobility, dentition), functional capacity (metabolic equivalents; <4 METs is poor), and comorbidity-specific risk (cardiac, pulmonary, renal, hepatic, endocrine, OSA). Understand the Revised Cardiac Risk Index and when stress testing or cardiology consultation changes management. Learn fasting guidelines (clear fluids 2 h, breast milk 4 h, light meal 6 h), the rationale for each, and when to delay surgery. Understand anticoagulant and antiplatelet perioperative management and neuraxial bleeding risk. Recognize informed consent elements and when surrogate consent is needed.
Traps in questions
A common trap is treating an abnormal test as automatically canceling surgery - the question usually wants optimization and proceeding when risk is acceptable. Another is assuming all patients need an ECG or chest X-ray; routine testing without indication rarely changes management. Watch fasting questions: the 2-hour clear-fluid rule is often misremembered as 6 or 8 hours. Also distinguish "NPO" from "adequate fasting" - the goal is minimizing aspiration risk, not absolute emptiness.
Rule of thumb
Ask "will this test or consult change what I do today?" If no, it is not indicated. For METs, if a patient can climb a flight of stairs without symptoms, functional capacity is generally adequate.
Worked example: A diabetic patient on metformin and an SGLT2 inhibitor presents for elective surgery. SGLT2 inhibitors should be held (euglycemic DKA risk); metformin is typically held per institutional protocol. This is a management change, not just a lab value.