Surgery (including allied specialties)
What is tested
Surgery tests resuscitation first, then diagnosis: shock and trauma, burns, acute abdomen, hernia, breast and thyroid lumps, and urological emergencies.
Core rules
- ATLS sequence: airway with cervical spine control, breathing, circulation, disability, exposure - treat the greatest threat to life first.
- Tension pneumothorax is a clinical diagnosis: hypotension, absent breath sounds, distended neck veins, tracheal shift. Needle decompression precedes imaging.
- Burns: Parkland formula 4 mL × body weight (kg) × %TBSA of Ringer lactate in 24 hours, half in the first 8 hours counted from the time of the burn, not from admission. Superficial erythema is excluded from the TBSA used for fluids.
- Acute pancreatitis: lipase is more specific than amylase; gallstones and alcohol account for most cases.
- Thyroid surgery: recurrent laryngeal nerve injury causes hoarseness; external branch of the superior laryngeal nerve causes loss of high pitch; hypocalcemia follows parathyroid devascularization.
Worked example
A 70 kg man has 30% TBSA partial-thickness burns and arrives 2 hours after injury. Total fluid = 4 × 70 × 30 = 8,400 mL. Half (4,200 mL) is due in the first 8 hours from the burn, so 4,200 mL over the remaining 6 hours = 700 mL/h; the second half runs over 16 hours (262 mL/h). Urine output of 0.5 mL/kg/h guides titration.
Traps
Timing Parkland from arrival; including superficial erythema in TBSA; and ordering a chest radiograph before decompressing an obvious tension pneumothorax.