Continuous measurements of microcirculatory blood flow in gastrointestinalorgans during acute haemorrhage

Hypoperfusion of splanchnic organs is an important contributor to the devel opment of multiple organ failure after major surgery and trauma. During gen eral anaesthesia and surgery we compared changes in systemic haemodynamics and regional blood flow with changes in the distribution of microcirculator y flow (MBF) in multiple splanchnic organs in pigs exposed to acute haemorr hage. Seven pigs (25 kg) were bled to a mean arterial pressure of 40 mm Hg; 180 min later the shed blood was retransfused. MBF was measured in the int estinal mucosa (stomach, jejunum, colon), pancreas, liver and kidney using a six-channel laser Doppler flowmeter. Cardiac output was measured by therm odilution and superior mesenteric artery flow by ultrasonic flowmetry. Duri ng haemorrhage, MBF in the gastric and colon mucosa and flow in the liver a nd kidney decreased to a similar extent to regional and systemic flows (30- 50%). In contrast, MBF in the jejunal mucosa remained virtually unchanged a nd flow in the pancreas decreased significantly more than systemic and regi onal flows (60%, P<0.05). We conclude that: (1) changes in the distribution of MBF in the gastrointestinal tract during acute haemorrhage are heteroge neous and cannot be predicted from changes in systemic or regional haemodyn amics; (2) MBF in the jejunal mucosa did not decrease during haemorrhage, i ndicating that autoregulation of blood flow in the mucosa remained intact d uring shock; and (3) MBF in the pancreas decreased significantly more than systemic and regional flows during shock, suggesting that the pancreas is p articularly vulnerable to haemorrhage.