Robotic Surgery: Anaesthetic Implications and Management

Overview of the Robotic Platform

• Three-dimensional high-definition visualisation
• Motion scaling (5 mm at the console = 1 mm in the field)
• Software-based tremor filtration
• No haptic feedback - the surgeon cannot "feel" tissue resistance

1. Preoperative Considerations

Patient Assessment

• Assess cardiorespiratory reserve carefully - the steep Trendelenburg position (up to 45°) combined with CO2 pneumoperitoneum creates significant physiological stress
• Identify patients at risk: severe COPD, raised ICP, glaucoma, severe cardiac disease, obesity (BMI >40), obstructive sleep apnoea
• In morbidly obese patients, the Trendelenburg position is particularly challenging and may cause severe respiratory compromise
• Discuss postoperative analgesia plan early; multimodal approaches are preferred

Preoperative Optimisation

• Optimise pulmonary function in patients with significant respiratory disease
• Preoperative fluid loading can partially attenuate the haemodynamic consequences of pneumoperitoneum (higher stroke volume and urine output vs. standard regimens, though outcome benefit is unproven)
• Review medications - anticoagulants, antihypertensives, antiplatelet agents

2. Physiological Implications of the Operative Position and Pneumoperitoneum

The Combination that Drives Anaesthetic Difficulty

Cardiovascular Effects

Respiratory Effects

• Functional residual capacity (FRC) and vital capacity decrease
• Lung compliance decreases - peak airway pressures rise
• V/Q mismatch worsens, predisposing to hypoxia
• CO2 absorption from the peritoneum leads to hypercarbia and respiratory acidosis
• Pulmonary vasoconstriction occurs secondary to hypercarbia and hypoxia
• Compression atelectasis creates intrapulmonary shunting

Central Nervous System Effects

• Steep Trendelenburg + CO2 elevation → increased cerebral blood flow → raised intracranial pressure (ICP)
• Intraocular pressure (IOP) increases progressively with steeper Trendelenburg; longer procedures = greater IOP increases
• CO2-driven cerebrovascular dilation is a separate mechanism from positional ICP elevation
• Caution in patients with pre-existing raised ICP, space-occupying lesions, or glaucoma

Other Effects

• Gastro-oesophageal regurgitation risk
• Venous gas embolism (rare)
• Brachial neuropraxia and other positional nerve injuries
• Tracheal tube displacement (the tube advances with steep Trendelenburg)
• Facial and airway oedema (especially with prolonged cases)
• Activation of renin-angiotensin-aldosterone system

3. Intraoperative Anaesthetic Management

Induction and Airway

• GETT (general endotracheal anaesthesia) is mandatory - LMAs are contraindicated due to aspiration risk and inability to manage high airway pressures
• Secure the ETT meticulously - tube migration is common with steep Trendelenburg
• For TORS (head and neck): use a wire-reinforced or laser-resistant tube secured to the face; induce and intubate at the final bed position (180° from the machine) to avoid a vigilance gap during rotation
• Confirm ETT position with auscultation and capnography after positioning

Vascular Access

• Place at least 2 IV lines before docking - once the robot is docked, the patient's arms are tucked and access is severely restricted
• Arterial line: recommended for long/complex cases, haemodynamically unstable patients, or where beat-to-beat BP monitoring is important
• Consider central venous access where large fluid shifts or vasopressors are anticipated
• All lines must be long enough to reach the anaesthetist, who is often at the patient's feet

Monitoring

• Standard ASA/AAGBI monitoring throughout
• Continuous neuromuscular blockade monitoring - deep NMB is required throughout the docked phase to prevent movement that could tear tissue
• End-tidal CO2 monitoring (NB: EtCO2 may underestimate PaCO2 in the Trendelenburg position; consider ABG in long cases)
• Urine output monitoring - pneumoperitoneum reduces renal perfusion

Ventilation Strategy

• Tidal volume: 6-8 mL/kg IBW (lung-protective)
• PEEP: Moderate levels of 4-8 cmH2O appear to offer better outcomes than low or very high PEEP
• Pressure-controlled ventilation (PCV) preferred over volume-controlled: lower peak airway pressures, better compliance and CO2 clearance
• Recruitment manoeuvres: improve intraoperative oxygenation, end-expiratory lung volume, and distribution of ventilation to dependent (dorsal) lung regions
• Limit insufflation pressure to <12 mmHg to reduce cardiovascular and renal compromise
• Accept permissive hypercarbia if necessary (increase minute ventilation first)
• The oesophageal balloon can clarify transpulmonary pressure for individual PEEP titration

Neuromuscular Blockade

• Deep NMB (TOF count 0, PTC 1-2) is essential during the docked phase
• Patient movement with robot docked is extremely dangerous - can cause catastrophic internal injury
• Sugammadex enables reliable reversal at the end of the case
• Continuous quantitative NMB monitoring is mandatory

Positioning Precautions

• Patient placed on anti-skid foam padding to prevent sliding in steep Trendelenburg
• Both arms tucked at the sides (reduces brachial plexopathy from hyperextension; also gives robot better access)
• Shoulder braces and iliac supports should be avoided - associated with neuropathic injury
• Pad all pressure points thoroughly
• Protect eyes and face from robotic arm movements - anaesthesia team must be vigilant
• For lateral positioning (robotic thoracic, nephrectomy): meticulous padding of the dependent arm, axillary roll, protect peroneal nerve

Haemodynamic Management

• Anticipate acute haemodynamic changes at pneumoperitoneum insufflation
• Vasopressors (phenylephrine, noradrenaline) may be needed to maintain MAP during steep Trendelenburg
• Avoid excessive fluid loading - increases risk of facial/airway oedema and pulmonary congestion, especially in long cases
• Goal-directed fluid therapy is preferred

Temperature Management

• Active warming essential - robotic cases are often prolonged
• CO2 insufflation gases are cold and dry; forced air warming devices or resistive heating mattresses recommended

4. Special Procedure-Specific Considerations

Robotic Prostatectomy (RARP)

• The classic steep Trendelenburg (20-45°) + pneumoperitoneum case
• Blood loss is significantly less than open prostatectomy, but haemostasis can be challenging
• A dedicated Miller's box (Box 55.5) highlights: large-bore IV access before docking; monitor for tube displacement; aggressive airway pressure management; plan for undocking emergency

Robotic Hysterectomy / Pelvic Surgery

• Similar physiological concerns as RARP
• Longer cases increase oedema and airway risk
• Postoperative nausea is common - prophylactic antiemetics routinely

Robotic Thoracic Surgery

• One-lung ventilation (OLV) is usually required
• Locoregional anaesthesia (thoracic paravertebral block, serratus anterior plane block, erector spinae plane block) provides effective multimodal analgesia - see La Via et al. (J Clin Med, 2024)
• Lateral decubitus positioning concerns

Robotic Liver/Hepatic Surgery and Transplantation

• Emerging area (Dutta et al., J Cardiothorac Vasc Anesth, 2025)
• Major haemorrhage risk; large-bore access and consider arterial line mandatory
• Hepatic ischaemia-reperfusion physiology applies

Transoral Robotic Surgery (TORS)

• TORS (FDA-approved 2009) for head and neck tumours, sleep surgery, skull base surgery
• The anaesthetist is physically removed from the airway - positioned at the patient's feet
• OR is dark; the surgeon is also remote at the console
• A surgical assistant remains at the patient's head for suction/retraction
• Wire-reinforced tube secured to face; dental guard and eye protection essential
• Difficult airway plan must be discussed pre-induction
• Post-operative: airway assessment before extubation; bleeding may compromise airway

Obese Patients

• Steep Trendelenburg in the morbidly obese carries high risk of severe respiratory compromise
• May require higher PEEP, more aggressive recruitment
• Higher rates of conversion to open surgery
• Prolonged cases increase oedema and recovery time

5. Emergency Scenarios and Safety Protocols

Robot Undocking Emergency

• When a life-threatening emergency occurs (cardiac arrest, catastrophic haemorrhage), the robot must be undocked immediately before CPR or open conversion
• Many institutions now use simulation-based training with the full OR team to practise emergency undocking
• All team members must know the undocking procedure - this should be briefed at each case start

Catastrophic Haemorrhage

• Conversion to open surgery may be necessary
• Have blood available for high-risk cases
• Surgeon/anaesthetist must communicate early regarding deteriorating haemodynamics

Subcutaneous Emphysema / Gas Embolism

• Subcutaneous CO2 can track up to the neck and mediastinum - causes sudden rise in EtCO2
• Venous gas embolism: sudden drop in EtCO2, haemodynamic collapse, "mill wheel" murmur
• Management: desufflate, reposition (left lateral Trendelenburg), 100% O2, consider aspiration via central line

Endobronchial Intubation

• Tube migration with steep Trendelenburg is common
• Always recheck breath sounds and EtCO2 waveform after final positioning

6. Postoperative Care

Extubation

• Ensure full reversal of NMB (TOF ratio >0.9) before extubation
• For TORS: surgical airway assessment mandatory before extubation; post-operative airway swelling can cause obstruction
• Prolonged Trendelenburg cases: upper airway oedema - consider awake extubation protocol
• Monitor closely for laryngospasm/stridor in prolonged cases

Analgesia

• Multimodal analgesia: paracetamol + NSAID (if not contraindicated) + low-dose opioid
• Locoregional techniques where applicable (TAP block, paravertebral block, wound infiltration)
• NSAIDs used cautiously in renal procedures (nephrotoxicity concern)
• Continuous local anaesthetic catheter infusions (rectus sheath, retroperitoneal) shown in small studies to reduce opioid requirement and time to discharge

PONV

• High incidence after robotic pelvic surgery
• Prophylactic dual (or triple) antiemetic therapy: ondansetron + dexamethasone ± droperidol
• TIVA with propofol reduces PONV vs. volatile anaesthetics

PACU Monitoring

• Close observation for respiratory compromise, especially after prolonged Trendelenburg cases
• Urine output monitoring - pneumoperitoneum-related renal compromise may persist
• Nerve injury assessment on recovery

Summary Table: Key Anaesthetic Concerns in Robotic Surgery

• Miller's Anesthesia, 10th ed., Chapter 67 (Robotic Surgery), pp. 9848-9880
• Barash's Clinical Anesthesia, 9th ed., Chapter 50 (Table 50-5: Physiology of CO2 Pneumoperitoneum in Trendelenburg Position)
• Chiumello D et al., Ventilation strategy in robotic-assisted surgery, BJA, 2023 - moderate PEEP 4-8 cmH2O with lung-protective strategy
• Duarte-Medrano G et al., Anaesthesia for robotic urological surgery, J Robot Surg, 2024 - comprehensive guide to patient selection through post-surgical pain management
• La Via L et al., Locoregional anaesthesia for robotic thoracic surgery, J Clin Med, 2024
• Dutta S et al., Anaesthetic considerations for robotic liver transplantation, J Cardiothorac Vasc Anesth, 2025