• ⬆intra-abdominal pressure ⮕ ⬇VR, ⬆ITP, ⬆Paw
• main overall effects
  • variable effect on BP
    • ⬆BP physiologically = net result of ⬇VR, ⬆AL/⬆SVR, +ENS
    • if hypovolemic / significant ⬇VR = ⬇BP
  • ⬆ITP, ⬆Paw
  • ⬆HR
• Normal insufflation 12-15 mmHg

• insufflation of CO2
  • CO2 is low cost, non-flammable, chemically stable, high diffusion capacity (rapid excretion)
  • but also causes hypercapnia and acidosis
• ⬆abdominal volume
• ⬇abdominal wall compliance
• ⬆IAP (intra-abdominal pressure)

• BP = CO x SVR
• initial ⬆VR (compression of splanchnic BV) ⮕ ⬆BP
• ⬆SVR
  • mechanical compression of Abdominal Aorta
  • production of neurohumoral factors (vasopressin, activation RAAS)
• IAP < 10 mmHg
  • ⬆VR = ⬆CO
• IAP 10-20 mmHg
  • ⬆IAP = ⬇VR = ⬇CO
  • ⬆IAP = ⬆SVR
  • BP = ⬇CO x ⬆SVR = same / high
• IAP > 20 mmHg
  • ⬇⬇VR = ⬇⬇CO = ⬇BP
• ⬇VR ⮕ ⬇CO ⮕ ⬇BP (esp if hypovolaemic)
  • compression of IVC
• cephalad displacement of diaphragm
  • ⬆ITP (intra-thoracic pressure) ⮕ IVC compression ⮕ ⬇VR
  • compression of pulmonary parenchyma ⮕ ⬆PVR ⮕ ⬇CO

• ⬇diaphragmatic excursion
  • ⬆ITP
  • ⬇pulmonary compliance 35-40%
  • ⬇FRC
• ⬆peak airway pressures
• leading to: pulmonary atelectasis, alteredV/Q relationships, and hypoxaemia.
• absorption of insufflated CO2 ⮕ ⬆pCO2 ⮕ further exacerbation of VQMM
• absorption of CO2
  • ETCO2 35 to 40 mmHg = 14%

• ⬇BQ to kidney and liver
• IAP > 20 mmHg ⮕ 40% ⬇mesenteric + GIT mucosal BQ

• ⬆ITP ⮕ ⬇cerebral venous drainage ⮕ ⬆ICP
• CPP = MAP - ICP
  • CPP maintained by ⬆MAP
  • but ⬆ICP leads to cerebral oedema
  • NB. pts with temporary neurological dysfunction after prolonged laparoscopic procedures with steep Trendelenburg

• stretching of parietal peritoneum = ENS++ ⮕ ⬆HR

Laparoscopic abdominal surgery, BJAE 2004

Cardiovascular and Ventilatory Consequences of Laparoscopic Surgery