Perfusion Pressure Manipulation in Porcine Sepsis: Effects on Intestinal Hemodynamics

A. KROUŽECKÝ, M. MATĚJOVIČ, J. RADĚJ, R. ROKYTA JR., I. NOVÁK

Intensive Care Unit, First Medical Department, Faculty of Medicine and Teaching Hospital, Charles University, Plzeň, Czech Republic

Received date June 22, 2005
Accepted date November 9, 2005
On-line available December 12, 2005


Summary
Limited information is available about selection of the threshold for arterial blood pressure in critically ill patients, particularly in sepsis when normal organ blood flow autoregulation may be altered. The present experimental study investigated whether increasing perfusion pressure using norepinephrine in normotensive hyperdynamic porcine bacteremia affects intestinal macro- and microcirculation. Nine pigs received continuous i.v. administration of Pseudomonas aeruginosa (PSAE) to develop hyperdynamic, normotensive (mean arterial pressure [MAP]  65 mm Hg) sepsis. Norepinephrine was used to achieve 10-15 % increase in MAP. Mesenteric arterial blood flow (Qgut), ileal mucosal microvascular perfusion (LDFgut) and ileal-end-tidal PCO2 gap (PCO2 gap) were measured before norepinephrine, after 60 min of norepinephrine infusion and 60 min after norepinephrine infusion had been discontinued. During a 12 h period of PSAE infusion all pigs developed hyperdynamic circulation with significantly decreased MAP. Although the mesenteric blood flow remained unchanged, infusion of PSAE resulted in a gradual fall of ileal microvascular perfusion, which was associated with progressively rising PCO2 gap. Norepinephrine which induced a 10-15 % increase in perfusion pressure (i.e. titrated to attain near baseline values of MAP) affected neither Qgut nor the intestinal blood flow distribution (Qgut/CO). Similarly, norepinephrine did not change either LDFgut or PCO2 gap. In this hyperdynamic, normotensive porcine bacteremia, norepinephrine-induced increase in perfusion pressure exhibited neither beneficial nor deleterious effects on intestinal macrocirculatory blood flow and ileal mucosal microcirculation. The lack of changes suggests that the gut perfusion was within its autoregulatory range.


Key words
Sepsis • Shock • Perfusion pressure • Microcirculation • Norepinephrine