General Surgical Principles and Perioperative Care
General Surgical Principles and Perioperative Care covers asepsis, wound classification and healing, haemorrhagic shock, fluids, nutrition and surgical infection. It is the highest-yield domain for safety questions because most answers are protocol-driven and unambiguous.
Wound classification and infection
- Clean: elective operation with no viscus entered (hernia repair, thyroidectomy).
- Clean-contaminated: viscus opened under control (elective cholecystectomy, colectomy).
- Contaminated: acute inflammation without pus, or gross spillage.
- Dirty: pus, perforation or old traumatic wound.
- Give prophylactic antibiotic within 60 minutes of incision; redose every two half-lives and after blood loss above 1500 mL. Chlorhexidine-alcohol skin preparation, normothermia, euglycaemia and supplemental oxygen reduce surgical site infection.
Wound healing
Haemostasis, then inflammation (0-3 days), proliferation (3-21 days: fibroblasts lay down type III collagen), then remodelling for up to a year as type I collagen replaces type III. Vitamin C is required for hydroxylation of proline; deficiency produces fragile capillaries and poor collagen cross-linking.
Shock and fluids
ATLS classes: class I under 15% blood loss; class II 15-30% (tachycardia, narrowed pulse pressure); class III 30-40% (hypotension, confusion); class IV over 40%. Damage-control resuscitation uses balanced blood products in a 1:1:1 ratio rather than large crystalloid boluses, with permissive hypotension until haemorrhage control.
Nutrition
Enteral before parenteral. Feed around 25 kcal/kg/day and watch for refeeding syndrome (hypophosphataemia) in the severely malnourished.
Worked example
A 65-year-old has an elective laparoscopic cholecystectomy. The case is clean-contaminated, so cefazolin 2 g IV is given 30-60 minutes before incision and repeated if the operation exceeds 4 hours or blood loss exceeds 1500 mL.
Traps
Calling an elective cholecystectomy 'clean'; giving prophylaxis after the incision; treating class II haemorrhage with crystalloid alone; forgetting to adjust renally cleared antibiotic doses.