Laparoscopy and pneumoperitoneum
Stem
A 68-year-old man, 94 kg, is scheduled for laparoscopic cholecystectomy. He has ischemic cardiomyopathy with an ejection fraction of 35%, takes metoprolol, lisinopril and furosemide, and has no angina. Room-air SpO2 is 95%, blood pressure 118/72 and heart rate 64. The surgeon plans reverse Trendelenburg with standard insufflation.
Question
How does the pneumoperitoneum affect him, and how will you manage his anesthetic?
Ideal answer
HeadlineThe pneumoperitoneum is the main physiologic insult, and his weak ventricle makes it matter: lowest workable pressure, arterial line before induction, more ventilation.
- Ask for the lowest workable pressure, at the bottom of 12–15 mmHg or below: it raises systemic vascular resistance and can drop cardiac output; reverse Trendelenburg lowers venous return further.
- General with a cuffed tube, PEEP 5–10 cmH2O, volume or pressure control, because the diaphragm rises and compliance and FRC fall.
- Minute ventilation up 15–30%, ETCO2 near 35–40 mmHg,1 because absorbed CO2 must be ventilated off.
- Tilt slowly, small vasopressor doses for hypotension, as position swings preload and afterload; TEE if his function were severely reduced.
- Multimodal analgesia and PONV prophylaxis, because shoulder pain and nausea drive unplanned admissions.
Watch for: capnogram, airway pressure and rhythm at insufflation (embolism, vagal bradycardia, tube malposition); breath sounds rechecked afterward.
Breaking down the answer
- Why low pressure — higher pressure compresses the vena cava and reduces preload, which matters most with heart failure or limited reserve. Assuming laparoscopy is a minimal insult is the judgment error examiners look for.
- Vagal response — peritoneal stretch at insufflation can cause reflex bradycardia or even asystole;1 I tell the surgeon to release the pressure and give atropine 0.5–1 mg or glycopyrrolate.
- Rising ETCO2 — expected for 15–30 minutes, then plateaus; a continuing rise suggests subcutaneous emphysema or extraperitoneal insufflation. Subcutaneous crepitus over the chest, neck or face raises concern for capnothorax.
- Capnothorax — CO2 through diaphragmatic defects or near the hiatus: rising airway pressure, falling SpO2, unilateral breath sounds. I stop insufflation and, if a ruptured bulla is unlikely, increase PEEP; it often resolves on decompression without a drain.2 Tension physiology needs needle decompression.
- Endobronchial intubation — the diaphragm pushes the lungs and carina cephalad by 2–3 cm, so position changes need the same recheck. Trendelenburg also raises intracranial and intraocular pressure.
- Pregnancy — SAGES: safe in any trimester, left lateral positioning after the first trimester, insufflation pressure of 10–15 mmHg, capnography, fetal heart monitoring of a viable fetus before and after; tocolytics are not given prophylactically.3
Follow-up question
At insufflation, the ETCO2 falls from 34 to 12 mmHg, the blood pressure falls to 60/30, and the precordial sound changes.
What is happening, and what do you do?
Follow-up answer
HeadlineCO2 embolism, from a Veress needle placed into a vessel or the liver. I tell the surgeon to stop insufflation and release the pneumoperitoneum.
A sudden fall in ETCO2 is the usual sign. I give 100% oxygen, place him steep head-down and left side down (Durant) to keep gas out of the pulmonary artery, and aspirate through a central catheter if one is present.4 Epinephrine and fluids support the circulation; chest compressions if pulseless, because they break up the gas lock. CO2 is far more soluble than air, so its effects are less marked and the patient usually recovers quickly.4 I reassess ETCO2 and pressure before agreeing to re-insufflate.
Pitfalls that cost points
- Missing CO2 embolism by assuming the drop is a sampling error.
- Using nitrous oxide in a long laparoscopic bowel case, where it distends bowel.
Rapid-fire
Q: Why does ETCO2 rise during laparoscopy? A: CO2 is absorbed across the peritoneum and must be eliminated by the lungs; extraperitoneal insufflation increases absorption.
Q: Why does urine output fall? A: Raised abdominal pressure compresses renal veins and parenchyma and increases ADH and renin; oliguria usually resolves after desufflation.
Q: Why does the patient have shoulder pain? A: Residual CO2 irritates the diaphragm, referring pain to C3–C5; low insufflation pressure and pulmonary recruitment at the end of the case help.
Q: Why is CO2 embolism less lethal than air? A: CO2 is far more soluble in blood (often quoted as about 20 times), so it dissolves quickly.
Numbers to know
| Item | Value |
|---|---|
| Insufflation pressure | 12–15 mmHg |
| Minute ventilation increase | 15–30%1 |
| Carina shift with insufflation | 2–3 cm cephalad |
| Pregnancy insufflation pressure | 10–15 mmHg3 |
| CO2 solubility vs. air | ~20× greater |
Links
- Robotic surgery and steep Trendelenburg, Capnography: waveforms and sudden loss of ETCO2, Venous air embolism and the sitting position, Pneumothorax and tension pneumothorax, Non-obstetric surgery during pregnancy
- SAGES guidelines for the use of laparoscopy during pregnancy
Sources
- 1.Laparoscopic Surgery in Children - Anaesthetic Considerations · J Pak Med Assoc (Ahmed), 2006 · archive.jpma.org.pk
- 2.Capnothorax During Laparoscopy in Trendelenburg Position: A Rare Case Study · Acta Med Port, 2020 · actamedicaportuguesa.com
- 3.Guidelines for the Diagnosis, Treatment, and Use of Laparoscopy for Surgical Problems during Pregnancy · SAGES · sages.org
- 4.Carbon Dioxide Embolism during Laparoscopic Surgery · Yonsei Med J (Park, Kwon, Kim), 2012 · synapse.koreamed.org
Facts on this page were checked against these sources on Oct 14, 2026. Guidelines change; confirm doses against current institutional protocols.