Step 2 Surgery Study Lecture

Jul 4, 2024

Step 2 Surgery Study Lecture Notes

Lecture Goal: Review key surgery concepts for Step 2 and Surgery Shelf Exam

Pre-operative Evaluation

  • Absolute Contraindications to Surgery:
    • Diabetic coma (DKA)
    • Sky-high glucose (infection risk)
  • Indicators of Poor Nutritional Status:
    • Albumin < 3
    • Transferrin < 200
    • Weight loss > 20% of body weight
  • Maximizing Nutrition:
    • Prefer enteral feedings over TPN
  • Reasons to Delay Surgery:
    • Severe liver failure
      • Check: Bilirubin, PT, Ammonia, signs of encephalopathy
    • Smoking
      • Quit 2 months before surgery to aid wound healing

Goldman’s Index & Cardiac Risks

  • Key Factors:
    • CHF: Biggest predictor of perioperative mortality (Check ejection fraction with echo; < 35% means no surgery)
    • Recent MI: Within 6 months (Check EKG, stress test, revascularization)
    • Arrhythmias, age, emergent surgery, and aortic stenosis are also important

Ventilator Management

  • Settings:
    • Assist Control: Predefined volume and rate; matches patient’s own breaths
    • Pressure Support: Patient controls rate; machine helps with volume
    • CPAP: Continuous positive airway pressure for spontaneous breathing
    • PEEP: Positive end-expiratory pressure to keep alveoli open (use in ARDS)
  • ABG Analysis:
    • Low PaO2: Increase FiO2
    • High PaO2: Decrease FiO2 (avoid free radical damage)
    • ABG corrections involve adjusting rate and tidal volume (prefer tidal volume)

Acid-Base Disorders

  • Steps:
    • Check pH < 7.4: Acidosis
    • Check HCO3 and PCO2 for metabolic vs. respiratory
    • Calculate anion gap: Na - (Cl + HCO3)
      • High anion gap: MUDPILES causes
      • Normal anion gap: Diarrhea, RTA
    • Treatment: Fluid restriction, diuretics, hypertonic saline for severe cases

Electrolyte Imbalances

  • Hyponatremia:
    • Causes: Fluid overload, CHF, nephrotic syndrome, cirrhosis, SIADH
    • Treatment: Fluid restriction, diuretics, hypertonic saline for symptomatic hyponatremia
  • Hypernatremia: Replace with hypotonic fluids
  • Hypocalcemia: Numbness, prolonged QT interval
    • Treat underlying cause
  • Hypercalcemia: Shortened QT interval, psychiatric overtones
    • Treat hypercalcemia crisis
  • Hypokalemia: Paralysis, ileus, EKG changes (give K)
  • Hyperkalemia: Peaked T waves (treat with Ca gluconate, insulin + glucose, dialysis)

Burns

  • Degrees:
    • 1st: Epidermis, erythematous, painful
    • 2nd: Epidermis and part of dermis, painful
    • 3rd: Full thickness, painless where nerves are destroyed
  • Complications: Circumferential burns can cause compartment syndrome
  • Treatment: Surgical escharotomy for compartment syndrome, intubation for inhalational injury, 100% O2 for CO poisoning

Trauma and Shock

  • Airway:
    • Intubate for GCS < 8, facial trauma, emphysema, expanding neck mass
    • Cricothyroidotomy if severe facial trauma
  • Breathing: Listen to breath sounds, Chest x-ray
  • Circulation and Shock:
    • Hypovolemic: Flat neck veins (resuscitation with fluids and blood)
    • Cardiac tamponade: Muffled heart sounds, JVD (needle decompression)
    • Tension pneumothorax: Needle decompression without waiting for x-ray

Head Trauma

  • Diagnosis: CT scan for anyone unconscious
  • Signs of ICP: Headache, vomiting, altered mental status
  • Treatment: Elevate bed, mannitol, hyperventilation

Neck and Abdominal Trauma

  • Neck zones:
    • Zone 3: Above mandible (check aorta and endoscopy)
    • Zone 2: Mandible to cricoid (2D doppler)
    • Zone 1: Below cricoid (check aorta)
  • Abdominal:
    • Gunshot wounds: Straight to OR
    • Stab wounds: OR if unstable/rebound; otherwise FAST/DPL for assessment

Post-Operative Care and Complications

  • Early fever: Atelectasis
  • High fever (104°F): Necrotizing fasciitis or malignant hyperthermia
  • Post-op day 3-5: Pneumonia (antibiotics), UTI (antibiotics)
  • Post-op day 7+ with IV site tenderness: Line infection (remove line)
  • Wound Issues:
    • Cellulitis: Red, swollen, no drainage (antibiotics)
    • Wound infection: Red, draining (open and pack)
    • Dehiscence: Salmon-colored fluid (requires OR)

Electrolyte and Fluid Management in Surgery

  • Fluid Calculations:
    • Maintenance: D5 1/2 NS + 20 mEq KCl
    • Volume based on weight
  • Electrolyte Repletion: Hypokalemia (monitor renal function), Hyperkalemia (calcium gluconate, insulin, glucose)

Common Ortho-trauma and Management

  • Fractures:
    • Skull, severely displaced, angulated, intra-articular, femoral neck (OR)
    • Common fractures with characteristic signs: Posterior (seizure), anterior (deltoid sensation), Colle's (outstretched hand), scaphoid (anatomic snuff box)

Quick Reference for Abdominal Pathology

  • Appendicitis: Peri-umbilical pain moving to RLQ, surgery if clinical signs present
  • Carcinoid tumor: Most common in appendix, >2cm or with lymph nodes = hemicolectomy

Last Points

  • When to Go to Surgery for Obstruction:
    • SBO with peritoneal signs or >48hrs conservative treatment ineffective
  • Post-op Ileus vs Ogilvie Syndrome: Tire-dialed loops through all intestines (ileus) vs massive cecum (Ogilvie's)
  • Identification of Key X-ray Findings: Free air under diaphragm (perforation), volvulus (bird beak or coffee bean sign)