Changes in visceral blood flow with elevated intraabdominal pressure

Area of Science:

• Physiology
• Surgical Research

Background:

• Elevated intraabdominal pressure (IAP) is common in critical care settings, including intraabdominal bleeding, ascites, and trauma.
• Previous research documented renal perfusion changes with elevated IAP, but visceral blood flow data were lacking.

Purpose of the Study:

• To investigate the impact of graded increases in IAP on organ blood flow (OBF) in various abdominal viscera.
• To determine if changes in OBF are solely due to altered cardiac output or involve local mechanisms.

Main Methods:

• Nine mongrel dogs were anesthetized, and IAP was incrementally increased using an intraabdominal inflatable bag.
• Hemodynamic parameters and OBF were measured using radioactive microspheres at baseline and elevated IAP levels (20 and 40 mm Hg).
• Organ blood flow index (OBFI) was calculated for stomach, intestines, pancreas, liver, spleen, kidneys, and adrenal glands.

Main Results:

• Elevated IAP decreased OBF in all measured organs except the adrenal glands, which showed increased OBF.
• The OBFI significantly decreased for most intraabdominal viscera, excluding the renal cortex and adrenal glands.
• Observed OBF changes were more pronounced than predicted by cardiac output alterations alone, suggesting local regulatory involvement.

Conclusions:

• Elevated IAP can lead to significant reductions in blood flow to intraabdominal organs, potentially causing visceral ischemia.
• Local control mechanisms likely play a role in modulating visceral blood flow during elevated IAP.
• These findings highlight the risk of organ dysfunction associated with increased intraabdominal pressure.