Robotic surgery and steep Trendelenburg
Stem
A 68-year-old man, 96 kg, BMI 32, is scheduled for robotic-assisted radical prostatectomy, expected to last four hours in steep Trendelenburg with CO2 pneumoperitoneum. He has treated hypertension, mild COPD and open-angle glaucoma on latanoprost drops. Baseline SpO2 is 95% on room air, and he has no cardiac symptoms.
Question
How will steep Trendelenburg and pneumoperitoneum affect him, and what is your plan?
Ideal answer
HeadlineTilt and pneumoperitoneum threaten his lungs, eyes and brain, and I cannot reach him once docked: protective ventilation, the least tilt and pressure, and an undocking plan.
- Low tidal volumes and PEEP, a higher rate for CO2, because compliance during robotic prostatectomy has been measured falling from about 60 to 28 mL/cmH2O, with more atelectasis and V/Q mismatch.1
- Recheck tube position after he is tilted, because the carina rises toward the tube tip.
- Lowest effective insufflation pressure, steep tilt only as needed: 25 degrees raises intraocular pressure less than 30 without harder surgery,1 and his glaucoma matters as pressure climbs with time.2
- Near-zero fluid balance, baseline pressure, arterial line, to limit head and neck edema,1 and no anemia.
- Nonslip pad, arms tucked and padded, face clear; no robot pressing on it, and the team agrees an emergency undocking plan before docking.1
Breaking down the answer
- Rising peak pressure after tilting — the tube may be endobronchial until proven otherwise; the cephalad diaphragm explains every ventilator change, and low tidal volume with PEEP is the recommended strategy.1
- Pressure and tilt are negotiable — keeping intra-abdominal pressure as low as possible, even under 8–10 mmHg with low-flow insufflation, softens the hemodynamic and respiratory effects.1 Asking the surgeon is the communication examiners want to hear.
- Eyes — mean intraocular pressure rose from 10.4 mmHg after induction to 21.7 on tilting and 29.6 before returning flat in one series;2 prolonged head-down positioning raises the risk of blindness in glaucoma.1
- Optic neuropathy — ischemic optic neuropathy is rare but reported after robotic prostatectomy and hysterectomy; consent for visual loss is reasonable in long cases.3
- Brain — pneumoperitoneum plus steep tilt can raise intracranial pressure, occasionally above 20 mmHg, which matters with tumors or neurologic disease.1
- Airway at the end — facial, conjunctival and tongue swelling warn of laryngeal edema; I do a cuff-leak check and extubate fully awake, or wait sitting up.
- Positioning — shoulder braces and sliding stretch the brachial plexus, and tucked arms hide IV and arterial lines, so every line is tested before draping.
Follow-up question
Two hours in, his end-tidal CO2 suddenly drops from 42 to 16 mmHg, his blood pressure falls to 60/30, and you hear a coarse murmur over the precordium.
The robot is docked. What do you do?
Follow-up answer
HeadlineA likely massive CO2 gas embolism with cardiovascular collapse. I say: "Stop insufflation, release the pneumoperitoneum, and prepare to undock now."
100% oxygen, no nitrous oxide, epinephrine in boluses and fluids, and call for help and the code cart. Docked, his position cannot be changed without undocking, so the team carries out the plan we agreed before docking.1 After undocking, if he is still perfusing, he stays head down and is tilted left side down to keep gas in the right heart; if he loses a pulse, we lay him flat and start CPR. I aspirate through a central line if one is in place, reassess with end-tidal CO2, arterial pressure and echocardiography, and plan ICU care.
Pitfalls that cost points
- Treating rising airway pressure with more pressure before checking for a mainstem intubation.
- Extubating a swollen face without assessing the airway.
Rapid-fire
Q: Why does CO2 climb more in robotic than open surgery? A: Absorption from the peritoneum plus less effective ventilation in tilt, so I raise minute ventilation and watch for subcutaneous emphysema.
Q: Who is at greatest ocular risk? A: Patients with moderate or high-pressure glaucoma in prolonged head-down positions.1
Q: What are ischemic optic neuropathy risk factors from spine data? A: Male sex, obesity, the Wilson frame, longer anesthetic and greater blood loss.3
Q: What fluid strategy fits a bloodless robotic case? A: Near-zero balance or goal-directed fluid, to limit head and neck edema.1
Numbers to know
| Item | Value |
|---|---|
| Steep Trendelenburg | ≥30°; 25° raises IOP less1 |
| Compliance during RALP | ~60 → 28 mL/cmH2O1 |
| Intra-abdominal pressure target | As low as feasible, <8–10 mmHg possible1 |
| IOP baseline → end of tilt | 10.4 → 29.6 mmHg2 |
| ICP with tilt plus pneumoperitoneum | Occasionally >20 mmHg1 |
Links
- laparoscopy, Postoperative visual loss and prone positioning, Peripheral nerve injury and positioning, Venous air embolism and the sitting position, Ventilator modes, PEEP and IMV vs. pressure control
- ASA Practice Advisory for Perioperative Visual Loss Associated with Spine Surgery (2019)
Sources
- 1.Challenges for anaesthesia for robotic-assisted surgery in the elderly: A narrative review · Eur J Anaesthesiol Intensive Care (Aceto et al.), 2023 · pmc.ncbi.nlm.nih.govEur J Anaesthesiol Intensive Care 2023;2(2):e0019.
- 2.Ocular parameters before and after steep Trendelenburg positioning for robotic-assisted laparoscopic radical prostatectomy · Clinical Ophthalmology (Mizumoto et al.), 2017 · dovepress.com22 patients at 30° head-down; mean IOP 10.4, 21.7, 29.6 mmHg.
- 3.Postoperative Visual Loss (POVL) · APSF · apsf.org
Facts on this page were checked against these sources on Oct 16, 2026. Guidelines change; confirm doses against current institutional protocols.