Effects of norepinephrine during intra-abdominal hypertension on renal blood flow in bacteremic dogs.

Objective: Intraabdominal hypertension reduces organ blood flow. Restoring abdominal perfusion pressure (APP) may restore renal blood flow, especially when sepsis is present. The effects of intra-abdominal pressure (IAP), followed by restoration of APP with norepinephrine, on renal blood flow were determined.

Design: Longitudinal study with bacteremia after nonbacteremic (control) conditions.

Setting: University animal laboratory.

Subjects: Ten anesthetized mongrel dogs.

Interventions: IAP was raised to 10, 20, and 30 mm Hg, using intra-abdominal bags filled with saline. After each intervention, decompression was achieved by emptying the bag. Bacteremia was induced by injection of Escherichia coli. Cardiac output and renal blood flow were measured using surgically placed flow probes. Norepinephrine infusion was used to restore the mean arterial pressure to baseline at each IAP. A hypervolemic circulation was maintained throughout by infusing saline.

Measurements And Main Results: Induction of bacteremia resulted in significant decreases in blood pressure, cardiac output, and renal blood flow (p < .01). Serial increases in IAP decreased cardiac output and renal blood flow both in control and bacteremic dogs (p < .001). These decreases were substantially corrected by abdominal decompression. In nonbacteremic control conditions, restoring APP back to baseline with norepinephrine did not fully restore cardiac output and renal blood flow (p < .001). However, in bacteremic conditions, norepinephrine was able to substantially restore cardiac output and renal blood flow to bacteremic baseline at all levels of IAP. In bacteremic conditions, the renal perfusion fraction returned to bacteremic baseline levels after correction of APP with norepinephrine and after decompression.

Conclusions: Restoration of APP using norepinephrine improves renal blood flow in bacteremic animals with IAPs up to 30 mm Hg, and maintaining a therapeutic APP may preserve renal blood flow in patients with intra-abdominal hypertension who are at risk of IAP-induced renal injury but who have yet to meet accepted criteria for surgical decompression.