Laparoscopic Surgery Basics
On this page
Direct answer
Pneumoperitoneum begins changing the patient's physiology the moment the insufflator starts: carbon dioxide at 12-15 mmHg raises intra-abdominal pressure, reduces venous return and cardiac output, splints the diaphragm, and is absorbed into the blood as hypercarbia. CO2 is chosen because it is cheap, non-flammable, highly soluble and rapidly excreted by the lungs — which also makes any gas embolism smaller and more survivable than air. Entry is by Veress needle with blind first trocar, or by open Hasson cut-down, the safer route after previous surgery. The complications that matter are major vessel injury at entry, bowel injury, gas embolism and the late port-site hernia — which is why every port of 10 mm or more gets its fascia closed.
What you must remember
- Physiological chain: raised intra-abdominal pressure increases systemic vascular resistance, reduces venous return and cardiac output, and can drop blood pressure at insufflation; bradycardia may follow peritoneal stretch (atropine if sustained); functional residual capacity falls with atelectasis; hypercarbia invites arrhythmia; renal perfusion and urine output dip — most changes resolve with desufflation.
- Why CO2: non-combustible (safe with diathermy), highly blood-soluble, rapidly excreted through the lungs and inexpensive; the trade-off is systemic absorption producing hypercarbia and acidosis in long procedures, hardest for patients with chronic lung disease.
- Entry techniques: Veress needle insertion with saline-drop and aspiration checks, Palmer's point in the left hypochondrium for previously operated abdomens; Hasson open cut-down is preferred after previous surgery and in children.
- Gas embolism response: sudden fall in end-tidal CO2 with cardiovascular collapse and the classical mill-wheel murmur — deflate the pneumoperitoneum, left lateral head-down position, aspirate through a central line, 100% oxygen.
- Entry injuries: aortic or iliac puncture is the lethal one — immediate laparotomy with vascular repair; bowel injuries are frequently recognised late; bladder injury follows low insertion, so catheterise before pelvic surgery.
- Port-site rules: close fascia at every site of 10 mm or more to prevent Richter-type hernia; use retrieval bags for specimens in cancer surgery to limit port-site metastasis.
- Balance sheet: less pain, earlier gut recovery, shorter stay and better cosmesis against loss of tactile feedback, two-dimensional vision, a learning curve, and monopolar capacitance-coupling burns from insulated instruments.
What pneumoperitoneum does to the patient
Watch the anaesthetist's monitors during a routine cholecystectomy and the physiology writes itself. At insufflation the airway pressures rise and the arterial pressure may wobble as the compressed vena cava returns less blood; over the next twenty minutes the end-tidal CO2 climbs as peritoneum absorbs the gas, and the anaesthetist raises minute ventilation to defend the pH. Oliguria appears on the chart — renal venous compression and hormonal changes, not a dry patient — and Trendelenburg positioning compounds the diaphragmatic splinting. The patient with cardiac disease tolerates the raised afterload poorly and the patient with COPD cannot blow off the CO2 load — both facts change operative planning more than any instrument does.
The emergencies are monitored, not anticipated. A sudden fall in end-tidal CO2 with a collapsing pressure curve is gas embolism until proven otherwise — the response is drilled: deflate, left lateral head-down, aspirate, oxygen. A falling saturation with rising airway pressure in a long procedure may be capnothorax. And the quiet complication is the day-three bowel injury presenting as unexplained pain with low-grade fever after a "keyhole" operation — any laparoscopic patient who looks worse than expected earns a CT rather than reassurance.
Where students slip
The standard slips are answering "nitrous oxide" for the insufflation gas (it supports combustion with diathermy) and forgetting that air is never used (embolism risk). The examinable decision pair is Hasson after previous surgery versus Veress in the virgin abdomen, with Palmer's point named as the alternative entry site. The gas embolism stem tests sequence — deflate and position first. NBE also likes the physiology as a pharmacology-style question — hypercarbia in the COPD patient — and the port-site question, where the keyed answer is fascial closure of 10 mm ports.
Frequently asked questions
Why is carbon dioxide the standard insufflation gas?
It is non-flammable with diathermy, highly soluble so small emboli are absorbed, rapidly excreted by the lungs, and cheap — unlike air or nitrous oxide.
What are the signs of gas embolism and the first response?
Sudden fall in end-tidal CO2 with cardiovascular collapse, sometimes a mill-wheel murmur — immediately deflate, tip the patient left lateral and head-down, give 100% oxygen, and aspirate a central line.
Which entry technique is preferred after previous abdominal surgery?
The open Hasson cut-down, because adhesions under the old scar make blind Veress-trocar entry hazardous; Palmer's point is the alternative Veress site.
Which port sites require fascial closure?
All sites of 10 mm or more in adults (5 mm ports in children by many units' policy), to prevent port-site hernia.
What physiological effects limit laparoscopy in cardiac and lung disease?
Raised afterload and reduced venous return stress the heart, and absorbed CO2 burdens the lungs of COPD patients who cannot compensate — both groups need lower pressures and shorter procedures.