Renal blood flow distribution in septic hyperdynamic pigs

Acute hyperdynamic sepsis in man is associated with increased renal blood flow (RBF) and polyuria, presumably due to high RBF to the medulla causing washout of interstitial osmoles. This presumption was studied in 14 hyperdynamic piglets with hindlimb sepsis and compared to 11 control piglets. RBF distribution was measured by ⁵¹Cr-labeled microspheres previously injected into the left ventricle and compared to cardiac output measured by rate of isotope disappearance.Both septic and control piglets had comparable vital signs at the time of the study. Cardiac output and RBF were significantly increased in septic piglets; cortical flow was also significantly increased whereas medullary flow was only slightly increased. These data demonstrate that polyuria in hyperdynamic septic piglets is not due to interstitial medullary washout secondary to increased medullary flow. Polyuria probably reflects tubular dysfunction unrelated to renal hemodynamic changes.