Laparoscopy:

Capnoperitoneum at 15mmHg

Airway	· Insufflation -> ↑abdo pressure -> regurgitation -> aspiration · Head down -> airway oedema (if prolonged)
Breathing	· Insufflation -> diaphragmatic embarrassment -> o ↓Ventilation: restrictive impairment o ↓Oxygenation: small airway collapse -> shunt · Insufflation -> pneumothorax, pneumomediastinum, VAE · CO2 -> respiratory acidosis, accumulation in body compartments · Head down -> worse embarrassment
Circulation	· Insufflation -> complex effects o Immediate: ejection -> ↑VR, ↑SVR -> ↑↑mAP o Subsequent: compression -> ↓VR -> normalise mAP o Idiosyncratic: vagal (stretch), Bezold-Jarisch (empty LV contracts) · CO2 -> o Systemic vasodilatation -> heat loss o Pulmonary vasoconstriction -> ↑PVR o ↑HR, ↑BP, arrhythmias, ischaemia o If pH <7.2: ↓contractility · Head up -> ↓VR to RV -> ↓mAP (especially if hypovolaemic) · Not sure where this goes: ↓Renal blood flow -> ↓GFR
Disability	· CO2 -> CNS vasodilatation -> ↑arterial volume -> ↑ICP · Insufflation -> ↑intrathoracic pressure -> ↓venous drainage -> ↑ICP · Head down -> ↓venous drainage -> oedema (esp if prolonged) · Effects partly offset by spinal displacement of CSF · Essential to maintain normocapnoea