Ch15: Organ Transplantation & Laparoscopic Surgery（器官移植与腹腔镜外科）

Preparatory Mindset

Two shorter S1 topics: organ transplantation (16 Surgery transplantation.ppt — legacy binary, covered by 外科学笔记 + prep) and laparoscopic surgery (18 laparoscopic surgery.pptx, 3.1KB). The exam covers: transplant concepts (allograft types, rejection, immunosuppression, organ sources, common transplants — kidney/liver), and laparoscopy (CO2 pneumoperitoneum, port placement, advantages/disadvantages, complications, the "learning curve").

Exam mindset: know the transplant immunology basics (rejection types: hyperacute/acute/chronic), the immunosuppressive drugs, and the laparoscopic advantages (less pain, faster recovery, smaller scars) vs disadvantages (cost, learning curve, CO2 effects, contraindications).

Core Concepts

1. Organ transplantation — basics (MUST KNOW)

- Autograft (自体移植): same person (skin graft, vein graft) — no rejection - Isograft (同系移植): identical twins — no rejection - Allograft (同种异体移植): same species, different genetic makeup (most human transplants) — immune rejection - Xenograft (异种移植): different species (e.g., pig valves) — severe rejection

• Definition: surgical transfer of an organ/tissue from a donor to a recipient to replace a failed organ
• Types by donor-recipient relationship:
• Common transplants: kidney (most common), liver, heart, lung, pancreas, corneal, bone marrow, skin

2. Rejection (MUST KNOW)

1. Hyperacute rejection: minutes-hours; preformed antibodies (ABO incompatibility, previous sensitization) → intravascular thrombosis → immediate graft failure (prevent by cross-match; irreversible) 2. Acute rejection: days-weeks; T-cell mediated (cellular) ± antibody; treatable with increased immunosuppression (steroids, antilymphocyte therapy) 3. Chronic rejection: months-years; gradual fibrosis/vasculopathy (obliterative arteriopathy) → progressive graft loss; poorly reversible

• Mechanism: recipient immune system recognizes donor HLA antigens as foreign → T-cell & antibody-mediated attack
• Types:
• Prevention: ABO compatibility, HLA matching, cross-match (negative required), immunosuppression

3. Immunosuppression (MUST KNOW)

- Calcineurin inhibitors: tacrolimus, cyclosporine — mainstays (nephrotoxicity, hypertension, diabetes, tremor) - Antimetabolites: mycophenolate mofetil (MMF), azathioprine — myelosuppression - Corticosteroids (prednisone) — taper; many side effects - mTOR inhibitors: sirolimus — alternative

• Induction (early, high-dose): antilymphocyte antibodies (ATG), IL-2 receptor antagonists (basiliximab)
• Maintenance:
• Side effects of immunosuppression: infection (CMV, PCP, fungal), malignancy (skin cancer, PTLD — post-transplant lymphoproliferative disease, EBV-related), diabetes, nephrotoxicity, hypertension
• Infections to know: CMV (most common opportunistic), Pneumocystis jirovecii (prophylaxis TMP-SMX), BK virus nephropathy (kidney), EBV/PTLD

4. Organ-specific transplant notes

• Kidney transplant: most common; for ESRD; donor = living related or deceased; place in the iliac fossa (not orthotopic); monitor urine output, creatinine, US for vascular issues
• Liver transplant: for end-stage liver disease (cirrhosis, acute liver failure, HCC within Milan criteria); replace the native liver; vena cava & portal vein anastomoses
• Heart transplant: orthotopic; denervated heart (no vagal response — rest HR ~90-110, no response to atropine)
• Donor criteria: brain death donation (heart-beating) vs cardiac death donation (DCD); living donation (kidney, liver lobe)
• Brain death diagnosis: coma, absent brainstem reflexes, apnea test, confirmatory tests — declared by two doctors; legally required for organ donation
• Organ preservation: cold ischemia (UW solution), cold storage; minimize cold ischemia time

5. Laparoscopic surgery (MUST KNOW)

- Smaller incisions → less postoperative pain, less wound infection, better cosmesis - Faster recovery & shorter hospital stay (ERAS synergy) - Less ileus, less blood loss (magnified view), fewer adhesions

- Cost (equipment, disposables) - Learning curve (loss of depth perception, limited haptics, ergonomics) - Longer operative time initially - CO2 effects: hypercapnia, shoulder-tip pain (diaphragm irritation), venous return changes (pneumoperitoneum compresses IVC)

- Veress needle/trocar injury (bowel, vessels — entry is the dangerous step; use open (Hasson) technique or optical entry) - Gas embolism (rare, fatal — CO2 in vein) - Thermal injury (monopolar/bipolar — lateral spread to bowel) - Subcutaneous emphysema, port-site hernia, port-site infection - Conversion to open (bleeding, adhesions, injury, difficult anatomy — not a complication, good judgment)

• Definition: minimally invasive surgery using a camera (laparoscope) & long instruments through small ports, with CO2 pneumoperitoneum (usually 12-15 mmHg) to create working space
• Advantages:
• Disadvantages/limitations:
• Physiologic effects of pneumoperitoneum: ↑ intra-abdominal pressure → ↓ venous return (in hypovolemia), ↑ SVR/BP, diaphragmatic splinting (↓ lung compliance), CO2 absorption → respiratory acidosis (hyperventilate)
• Complications:
• Absolute/relative contraindications: severe cardiopulmonary disease (CO2/positioning intolerance), severe coagulopathy, diffuse peritonitis (relative), massive abdominal distension, multiple prior surgeries (adhesions — relative), pregnancy (relative), morbid obesity (relative)
• Common laparoscopic procedures: cholecystectomy (gold standard), appendectomy, hernia repair (TAPP/TEP), sleeve gastrectomy/gastric bypass, colorectal resection, adrenalectomy, splenectomy, diagnostic laparoscopy, Nissen fundoplication
• Patient positioning & access: supine/lithotomy/Trendelenburg/reverse-Trendelenburg per surgery; ports placed for triangulation; insufflation via Veress (closed) or Hasson (open) entry

High-Yield Points

• Allograft = same species (most transplants); autograft = self; rejection: hyperacute (minutes, preformed antibodies), acute (T-cell, treatable), chronic (fibrosis, irreversible)
• Cross-match must be negative; ABO & HLA matching
• Immunosuppression: tacrolimus/cyclosporine (calcineurin inhibitors) + MMF + steroids; watch infection (CMV), malignancy (PTLD), nephrotoxicity
• Kidney = most common transplant; liver for end-stage disease/HCC (Milan)
• Laparoscopy: CO2 pneumoperitoneum 12-15 mmHg; less pain/faster recovery; learning curve & cost
• Entry injury (Veress/trocar) = most feared complication; thermal bowel injury; gas embolism
• Contraindications: severe cardiopulmonary disease, coagulopathy, diffuse peritonitis (relative)
• Cholecystectomy = most common laparoscopic procedure
• Brain death: coma + absent brainstem reflexes + apnea test

Topic Summary

Transplantation: allografts (same species, most transplants) trigger rejection — hyperacute (minutes, preformed antibodies, irreversible), acute (days-weeks, T-cell, treatable with immunosuppression), chronic (fibrosis, irreversible). Prevention: ABO/HLA matching + negative cross-match + immunosuppression (tacrolimus/cyclosporine + MMF + steroids), watching for infection (CMV), malignancy (PTLD), nephrotoxicity. Kidney is the most common transplant; liver for end-stage/HCC. Laparoscopy uses CO2 pneumoperitoneum (12-15 mmHg) — advantages (less pain, faster recovery, better cosmesis) vs disadvantages (cost, learning curve, CO2/physiologic effects); complications (entry injury, thermal injury, gas embolism); contraindications (severe cardiopulmonary disease, coagulopathy); common procedures (cholecystectomy, appendectomy, hernia repair, bariatric, colorectal).