Entry
Veress
- Blind establishment of pneumoperitoneum – confirmation of location by aspiration of no blood or enteric content, and maintenance of low opening pressure
- Complications include vessel injury and bleeding, gas embolism, organ injury (bowel injury)
Hasson open entry
- Visual confirmation of entry to peritoneal cavity and blunt finger dissection to identify adhesions to body wall
Visual optical entry
- 0 degree laparoscope with visualisation of layers during advancement of radially dilating rotating trochar
Pneumoperitoneum
Normal intra-abdominal pressure is 5 – 7 mmHg
CO2 used for insufflation – colourless, non combustible, very soluble in blood, water and tissue, and is cheap.
Because it is rapidly absorbed can lead to problems – hypercarbia.
15 mmHg is common pressure used, although 12 mmHg may be preferable
Physiological issues:
- Venous flow and caval compression – reduction in venous return
- Cardiac arrhythmias due to hypercarbia
- Increased intra-abdominal pressure limits diaphragmatic movement – reduction in functional reserve capacity
- Head down positioning will further reduce functional reserve capacity
- Hypercarbia stimulates sympathetic nervous system -> increased heart rate and peripheral vascular resistance (also reduces cardiac output)
- Oliguria often seen with increased abdominal pressure – renal parenchymal compression and renal vein compression
- Metabolic (and respiratory) acidosis – problem in COPD patients who cannot compensate
- Reduced venous return – peripheral venous stasis can predispose to VTE
- Increased abdominal pressures may exacerbate a hiatus hernia and lead to reflux or aspiration
- Pneumoperitoneum can occasionally trigger vagal responses and bradyarrhythmia
- “Tension pneumoperitoneum” – drop in blood pressure due to rapid widespread increase in peripheral vascular resistance
Complications of insufflation and pneumoperitoneum
Bowel insufflation
Gas embolism – 200 mL of gas into circulation produces complete right ventricular outflow block – drop in end tidal CO2 during insufflation suggestive of gas embolism. Immediately stop, and place patient right side up (aspirate gas bubble with central venous catheter).
Barotrauma – hypotension, reduced cardiac output, secondary to drop in venous return caused by caval compression. Manifests as increased ventilation pressures
Subcutaneous emphysema
Pneumomediastinum, pneumothorax and pneumopericardium
Positioning complications
Neuropraxias
Ischaemic optic neuropathy with increased intraocular pressures from prolonged reverse Trendelenburg
Rhabdomyolysis – muscle ischaemia from prolonged compression, leading to myoglobinuria and tubular obstruction / renal failure
Obesity troubles
- Inadequate length of instruments
- Decreased range of motion of trochars and instruments
- Need for higher pneumoperitoneum pressure to keep working space
- Excessive adipose tissue preventing dissection
- Higher risk of positioning problems and neuropraxias – may need special equipment, beds and stirrups
- Increased pressure with head down -> decreased respiratory compliance and difficulty ventilating