GC196 Minimally Invasive Thoracic Surgery

This is a critical exam discriminator. If asked "What is minimally invasive surgery?", do NOT simply say "small incisions." The correct framework is:

Surgery simultaneously cures disease AND causes surgical trauma. ^[1] The goal of MIS is to maintain the curative intent while reducing the trauma component as much as possible.

VATS replaced open thoracotomy (posterolateral thoracotomy with large incision, rib spreading, significant muscle division) with small port-site incisions and camera-assisted surgery. The evolution from "Past" (large open incisions) to "Present" (VATS) represents a paradigm shift.

Advantages of VATS: ^[1]

• Less post-operative pain
• Fast recovery
• Early discharge
• Less complication
• Less inflammatory response
• Same oncological outcome

The last point is crucial: VATS achieves the same oncological clearance (lymph node harvest, R0 resection rates, survival) as open thoracotomy for lung cancer — this satisfies the "Adulthood" evidence threshold.

Traditional thoracic surgery requires general anaesthesia with a double-lumen endotracheal tube for one-lung ventilation (the operative lung is deflated while the contralateral lung is ventilated). ^[1]

This carries specific harms:

• Airway injury from double-lumen tube placement
• Ventilator-induced lung injury (VILI)
• Systemic inflammatory response from mechanical ventilation
• Need for muscle relaxants (problematic in myasthenia gravis patients)
• Side effects of deep general anaesthesia

Non-intubated VATS technique: ^[1]

• Spontaneous breathing (the patient breathes on their own)
• Avoids airway injury
• Avoids mechanical ventilation
• Reduces systemic inflammatory response
• Dependent lung benefits: perfusion is better, lung recruitment is maintained by preserved diaphragmatic function, intrapulmonary shunt and hypoxaemia are reduced
• Regional/local anaesthesia (e.g. thoracic epidural, paravertebral block, intercostal nerve block)
• Avoids deep sedation
• Avoids muscle relaxant (especially important for myasthenia gravis patients undergoing thymectomy)
• Reduces side effects of GA

Applications include: ^[1]

• Pleural biopsy
• Lung wedge resection
• Sympathectomy
• Bullectomy
• Thymectomy
• Anatomical lung resection
• Segmentectomy
• Sleeve resection
• Carinal reconstruction

The range is impressively broad — NIVATS has moved well beyond simple diagnostic procedures to complex anatomical resections.

Non-intubated VATS: ^[1]

• Safe procedure
• Technically feasible
• Alternative for selected patients
• Early recovery demonstrated
• Long-term benefit unclear

This places NIVATS at the "Childhood" to early "Adolescence" stage of the evidence hierarchy.

Advantages of robotic-assisted surgery: ^[1]

• 10x magnified 3D view
• Camera stability
• 360° range of motion vs 47° for conventional instruments
• Seventh degree of freedom (the robotic wrist can articulate in ways the human hand through a port cannot)
• Improved dexterity
• Better ergonomics (surgeon sits at a console, reducing fatigue)
• Motion scaling (large hand movements translate to fine instrument movements)
• Filters hand tremor

Disadvantages: ^[1]

• Higher cost (startup and maintenance)
• Docking time (time to set up the robot adds to total OT time)
• Lack of tactile feedback (surgeon cannot "feel" tissue tension — must rely on visual cues)

The lecture specifically highlights thymectomy as a key application of RATS:

First reported robotic-assisted thymectomy: Yoshino et al., J Thorac Cardiovasc Surg 2001 ^[1]

Subxiphoid approach for robotic-assisted thymectomy is emphasized:

Advantages of subxiphoid approach: ^[1]

• Better visualize both phrenic nerves
• Better clearance of both cervical poles (important for complete thymectomy in myasthenia gravis)
• Less painful (avoids intercostal nerves entirely — the incision is below the xiphoid process)
• Enables reconstruction if necessary (e.g. vein and pericardium)

All procedures that can be done by VATS can be done by RATS. ^[1]

RATS vs VATS for lobectomy/segmentectomy (meta-analysis, Ma et al. BMC Cancer 2021):

18 studies, 11,247 patients (5,114 RATS vs 6,133 VATS): ^[1]

RATS showed:

• Less blood loss (p = 0.010)
• Lower conversion rate (p < 0.001)
• More harvested lymph nodes (p = 0.002)
• Shorter chest drain duration (p < 0.001)
• Shorter LOS (p < 0.001)

No significant difference in:

• Operative time, mortality, overall survival (OS), and disease-free survival

Different lung resections (from most to least tissue removed): ^[1]

1. Pneumonectomy — entire lung
2. Lobectomy — one lobe
3. Sublobar resection
   • Segmentectomy — anatomical segment with its bronchus, artery, and vein
   • Wedge resection — non-anatomical removal of a peripheral wedge of lung

Key milestones: ^[1]

• 1933: Graham performed the first pneumonectomy
• 1962: Cahan proposed "Radical lobectomy" (~30 years later)
• 1995: LCSG trial (Ginsberg RJ) — RCT of lobectomy vs limited resection for T1N0 NSCLC (~30 years later)

The 1995 LCSG trial showed lobectomy was superior to limited resection (higher local recurrence with limited resection). This established lobectomy as the gold standard for early-stage NSCLC for decades.

Background for segmentectomy: ^[1]

• Small-sized early-stage lung cancer is increasing (due to CT screening)
• Specific group of adenocarcinoma with low risk of nodal metastasis and recurrence
• Multiple synchronous primary lung cancers are increasing
• Limitations of the previous LCSG trial (small sample, older staging, no CT screening era tumours)
• Goals: Oncological clearance + Functional preservation

The lecture shows survival curves stratified by tumour size:

For tumours ≤ 2cm: equivalent disease-free and overall survival ^[1] For tumours 2-3cm and > 3cm: lobectomy remains standard ^[1]

The MIS approach applies equally to oesophagectomy. As covered in GC 189, approaches include Open, VATS, Total MIE (minimally invasive oesophagectomy), and Robotic. QMH performs 80-90% of oesophagectomies as total MIE. ^[2] The same principles apply: reduced wound trauma, equivalent oncological outcomes, faster recovery.

Cardiac surgery similarly uses MIS approaches: paramedian approach, hemisternotomy, thoracotomy approach, and robotic-assisted approach for valvular surgery. ^[3] The principle is the same — median sternotomy requires 10 weeks for bone healing and carries wound infection risk; MIS approaches reduce this.

The broader categories of MIS in surgery include: laparoscopic, robotic, endoscopic, NOTES (Natural Orifice Transluminal Endoscopic Surgery), and endovascular. ^[4] Thoracic MIS fits within this larger framework.

Post-VATS chest drain management follows standard principles: insertion in the safety triangle (5th ICS, bordered by pectoralis major laterally and latissimus dorsi anteriorly), underwater seal with 2cm H₂O, monitoring for swinging and bubbling. ^[5]

"List three advantages of minimally invasive surgery." (6 marks) ^[6]

Markscheme answer (based on this lecture):

1. Less post-operative pain (reduced wound trauma, fewer intercostal nerves injured)
2. Faster recovery / early discharge (shorter hospital stay)
3. Fewer post-operative complications (less inflammatory response, less wound infection)

Additional acceptable answers: better cosmesis, reduced blood loss, same oncological outcome (for cancer surgery), reduced healthcare costs.

Discriminator: The question asks for "advantages," not "definition." You should list concrete benefits, not describe the philosophy. Each advantage should be a distinct point — "faster recovery" and "early discharge" can count as one if the examiner is strict, so include "less pain" and "fewer complications" as separate items.

"An 89-year-old gentleman undergoes laparoscopic cholecystectomy under GA. He develops hypotension right after the surgeon insufflates the peritoneal cavity with CO₂. Which of the following is a physiological effect of pneumoperitoneum?" ^[7]

A. Decrease in airway resistance B. Decrease in functional residual capacity ✓ C. Increase in renal perfusion D. Increase in venous return

Rationale: This is a general MIS/laparoscopic surgery question. CO₂ pneumoperitoneum increases intra-abdominal pressure → diaphragm pushed up → decreased FRC and pulmonary compliance. It also causes decreased venous return (IVC compression initially), decreased renal perfusion, and increased airway resistance. The immediate hypotension is from IVC compression reducing venous return (but D says "increase" so it's wrong).

Connection to this lecture: The same MIS principles apply — understanding the physiological consequences of the surgical approach is part of comprehensive MIS knowledge.