Minimal Access Surgery Principles

Minimal Access Surgery Principles - Keyhole Revolution

• Concept: "Keyhole surgery"; utilizes small incisions, specialized instruments, and camera (laparoscope) for visualization.
• Pioneer: Dr. Philippe Mouret (first laparoscopic cholecystectomy, 1987).
• Core Principles:
  • Magnified 2D/3D vision on monitor.
  • Triangulation: optimal port placement for instrument maneuverability.
  • Pneumoperitoneum: insufflation of CO2 (non-combustible, high blood solubility) to create working space.
    • Standard intra-abdominal pressure: 12-15 mmHg in adults.
  • Ergonomics: surgeon and team positioning for comfort and efficiency.
• Advantages: ↓ Post-operative pain, ↓ hospital stay, faster recovery, improved cosmesis, ↓ adhesions.
• Disadvantages: Steep learning curve, loss of direct tactile sensation, potential for longer initial operative times, specific complications (e.g., trocar injuries, CO2 embolism, port-site hernias).

⭐ Veress needle entry: Two audible clicks often indicate correct entry into the peritoneal cavity (fascia and peritoneum). Initial pressure should be < 10 mmHg.

Minimal Access Surgery Principles - Tiny Tech Titans

• Core Equipment:
  • Insufflator (CO₂): Maintains pneumoperitoneum (pressure 12-15 mmHg).
  • Light Source: Xenon or LED.
  • Camera System: HD/4K, Hopkins rod-lens or chip-on-tip.
  • Monitor: High resolution, ergonomic placement.
• Instrumentation:
  • Trocars: Access ports (e.g., Hasson, optical, bladed, bladeless). Sizes 5-12 mm.
  • Hand Instruments: Graspers, dissectors, scissors, needle holders (various tips).
  • Energy Devices: Monopolar/bipolar diathermy, ultrasonic (Harmonic Scalpel), advanced bipolar (LigaSure).
• Physiological Effects: ↑ Intra-abdominal pressure → ↓ venous return, ↑ SVR, ↑ peak airway pressure.

⭐ Veress needle placement: Audible clicks (fascia, peritoneum), saline drop test, aspiration test, and low initial pressure (<8 mmHg) confirm correct placement before insufflation.

• Key Principles: Triangulation, fulcrum effect, depth perception challenges, ergonomic instrument handling.
• 📌 Mnemonic (CO₂ advantages): Cheap, Odorless, Non-flammable, Easily absorbed (C.O.N.E. but CO₂ is the one!)

Minimal Access Surgery Principles - Pneumo Effects & Perils

• Physiological Effects of CO2 Pneumoperitoneum (IAP target 12-15 mmHg):
  • Cardiovascular: ↑MAP, ↑SVR, ↑HR. ↑IAP → ↓venous return, ↓CO. Hypercapnia, acidosis, arrhythmias risk.
  • Respiratory: ↓Lung compliance, ↓FRC, ↑Peak airway pressure. V/Q mismatch, atelectasis risk.
  • Renal: ↓Renal blood flow, ↓GFR, transient oliguria.
  • Cerebral: ↑ICP, especially in Trendelenburg position.
• Potential Complications:
  • Access: Injury (vascular, visceral) from Veress needle/trocar.
  • Gas-related:
    • CO2 embolism (⚠️ sudden ↓ETCO2, hypotension, "mill-wheel" murmur).
    • Subcutaneous emphysema, pneumothorax, pneumomediastinum.
  • Positioning: Nerve injury (e.g., brachial plexus, common peroneal), compartment syndrome.
  • Other: Port-site issues (hernia, infection, metastasis), hypothermia (due to cold, dry CO2 insufflation).

⭐ > CO2 is the preferred gas for insufflation; its high solubility in blood reduces the risk and severity of gas embolism compared to air or N2O.

Minimal Access Surgery Principles - Access & Ergonomics

• Access Methods:
  • Veress Needle (Closed): Blind insertion; saline drop/aspiration tests.
  • Hasson Technique (Open): Direct visualization entry; safer with prior surgery/adhesions.
• Pneumoperitoneum:
  • Gas: CO2 (standard).
  • Pressure: 12-15 mmHg (adults).
  • Palmer's Point: Left subcostal, mid-clavicular line; alternative primary access.
• Ergonomics & Port Setup:
  • Surgeon: Neutral posture, elbows 90-120°.
  • Monitor: Eye level, 0-15° downward gaze, opposite surgeon.
  • Ports: Triangulation principle; instrument working angles 60-90°.

⭐ Standard insufflation pressure for CO2 pneumoperitoneum is 12-15 mmHg; exceeding this significantly increases risk of cardiopulmonary compromise and gas embolism.

High‑Yield Points - ⚡ Biggest Takeaways

• CO2 is the preferred gas for pneumoperitoneum; typical pressure 12-15 mmHg.
• Access techniques: Veress needle (closed) or Hasson cannula (open).
• Physiological effects: ↑ intra-abdominal pressure, ↑ PaCO2, potential ↓ venous return.
• Major complications: vascular injury, bowel injury, gas embolism.
• Commonest post-op issue: shoulder tip pain (phrenic nerve irritation).
• Advantages: ↓ post-op pain, ↓ hospital stay, better cosmesis.
• Port-site hernia is a known late complication of laparoscopic surgery.