They are result of the cephalic displacement of the diaphragm, which conditions a decrease in pulmonary compliance and an increase in the peak inspiratory pressure. The most frequent respiratory problems caused by pneumoperitoneum are atelectasis, hypercapnia and hypoxemia. These alterations are more frequent and severe in patients with previous lung disease, obesity, during long periods of inflation or with the use of high inflation pressure (> 18 mmHg or 25 cmH2O).
Although CO2 is flame-resistant, it is very soluble in blood, this absorption combined with a decreased tidal volume, causes an increase in the levels of arterial CO2 (up to of 10 mmHg) and alveolar CO2 (up to of 8 mmHg), which coupled with a decrease in pH, could influence respiratory acidosis.
2 Cardiovascular alterations: mainly due to the collapse of most of the abdominal veins (particularly of the inferior vena cava), with consequent decrease in venous return, drop the preload, and therefore decrease in cardiac output and blood pressure. Also hypercapnia can lead us to a stimulation of the sympathetic nervous system, causing hypertension, tachycardia and increased cardiac arrhythmias, the latter also induced hypoxia, respiratory acidosis and vagal stimulation.
3 Renal alterations:
Caused when intra-abdominal pressure is greater than 20 mmHg. Renal blood flow and glomerular filtration diminished by the increase in renal vascular resistance, reduction in glomerular filtration grade and decrease in cardiac output.
4 Alteration in gastric function:
Problems like gastric reflux, are due to the increase in intra-abdominal pressure that predisposes to passive reflux of gastric contents. However they are also due to other factors that influence as initial Trendelemburg, Insufflation pressure and peritoneal gas position in the abdomen by the surgical team.