What are the regional circulatory changes that occur during laparoscopy?

What are the regional circulatory changes that occur during laparoscopy?

Cerebral

Laparoscopy causes an increase in intracranial pressure (ICP). Firstly, the absorption of CO₂ and the resultant hypercarbia cause an increase in cerebral blood flow and consequently ICP. Secondly, the pneumoperitoneum increases ICP, with or without an increase in PaCO₂. The increase in IAP determines the extent of increase in ICP. High IAP compresses the inferior vena cava causing an increase in lumbar spinal pressure, which decreases drainage of cerebrospinal fluid from the lumbar plexus. In turn, there is decreased cerebrospinal fluid drainage and increased ICP. This increase is unresponsive to hyper-ventilation, yet ICP is higher when ventilation is inadequate. High IAP also causes a cephalad shift of the diaphragm, increasing intrathoracic pressure, also increasing ICP.

Hepatoportal

There is controversy in the literature regarding the effects of increased IAP on splanchnic perfusion. Some believe that the CO₂ pneumoperitoneum causes vasodilat-ing effects that counteract the effects of increased IAP on perfusion. Others believe that there is a decrease in splanchnic flow that results both from mechanical com-pression of the mesenteric vasculature and from humoral factors, i.e., antidiuretic hormone causing superior mesen-teric artery constriction.

Renal

There is a decrease in renal blood flow when IAP >15 mmHg. There is a decline in glomerular filtration rate (GFR), urine output, creatinine clearance, sodium excretion, and the potential for volume overload in the face of excessive fluid administration. Patients with pre-existing renal dys-function should have optimization of their hemodynamics during pneumoperitoneum and the use of nephrotoxic drugs should be avoided.

Lower limb

The development of pneumoperitoneum causes a decrease in femoral venous flow increasing the risk of deep vein thrombosis. This is especially problematic if the patient is placed in the reverse Trendelenburg position because of blood pooling in the lower extremities. Intermittent sequential compression stockings should be used.