Robotic Surgery — Pneumoperitoneum + Steep Trendelenburg Physiology

CO2 absorbs across peritoneal surfaces and raises ETCO2 25-30%; respond by increasing minute ventilation (typically rate, not tidal volume — TV often constrained by high airway pressures).

The diaphragm is pushed cephalad → decreased FRC, atelectasis, reduced lung compliance.

Expect peak inspiratory pressures 30-40 cmH2O and plateau pressures 25-30 — use pressure-controlled or volume-controlled with low TV (6 mL/kg IBW) + PEEP 8-10 + recruitment maneuvers.

End-expiratory atelectasis is universal; deep recruitment before extubation reduces post-op hypoxemia.

Consequences: cephalad shift of mediastinal contents (further reduces FRC + compliance), increased CVP/PA pressures (filling pressures rise but TRUE preload often decreased from venous compression — vasopressors common), increased ICP (relative contraindication for unrepaired intracranial aneurysm, recent stroke, severe AVM), increased intraocular pressure (caution in glaucoma, recent vitreoretinal surgery; IOP can double — postop visual loss risk), facial + airway edema, conjunctival edema (chemosis).

Airway edema can require post-op intubation — always check cuff-leak before extubation in long steep-T cases.

Tucked arms with hands palm-in along the body — beware of ulnar compression.

Corneal abrasion risk from facial edema + prep solutions running into eyes — tape eyes, consider goggles.

Padding + frequent reassessment (impossible mid-procedure with the robot docked).

The robot CANNOT be moved emergently — any code requires undocking before any manipulation, which takes minutes.

Pre-position EVERYTHING (IV lines, monitors, OG tube, foley, art line if used) before docking; mid-case access is essentially impossible.

⚡The combination of pneumoperitoneum + steep Trendelenburg produces a counterintuitive picture: high CVP + high PA pressures from external compression + cephalad shift, but reduced effective preload from compressed IVC.

Cardiac output typically falls 10-30% at induction of pneumoperitoneum + recovers partially as compensation occurs.

MAP often rises from increased SVR (catecholamine response to CO2 + position).

Vasopressors (phenylephrine, ephedrine, sometimes norepi infusion) commonly needed; aggressive crystalloid loading just contributes to airway/facial edema without restoring true preload.

Use balanced crystalloid 4-6 mL/kg/hr maintenance, treat hypotension with pressors first.

Subcutaneous emphysema is common (palpable crepitus over chest + neck + scrotum) and usually self-limited — but watch for pneumothorax + pneumomediastinum, especially if airway pressures suddenly rise or oxygenation deteriorates.

Aggressive recruitment + PEEP for atelectasis resolution.

Check cuff leak (deflate ETT cuff with positive pressure applied — audible leak suggests airway lumen patent; absent leak in a long steep-T case may warrant leaving the tube).

Avoid coughing (Valsalva → bleeding at port sites).

PONV is common — multimodal antiemetic.

Facial + conjunctival edema typically resolves in 12-24 hr; warn patient + family preop.