Organ blood flow and distribution of cardiac output in hypocapnic ketamine-anesthetized swine.

Organ blood flow and distribution of cardiac output (CO) were determined in 9 awake (control) and ketamine-anesthesized swine (4 mg/kg bolus followed by continuous infusion of 0.3 mg/kg/min, IV), using 15 micron diameter radionuclide-labeled microspheres. Absolute values of blood flow (per 100 g basis) were determined for various organs and peripheral tissues. Internal organs of the swine, which constituted 8.25 +/- 0.79% of the total body mass, received 55.83 +/- 5.13% of the CO. The fraction of CO received by brain, heart, kidneys, liver (via hepatic artery), and gastrointestinal tract was 1.10%, 2.67%, 19.84%, 11.81%, and 16.84%, respectively. During ketamine anesthesia, the fraction of CO perfusing the kidneys and liver (hepatic artery) increased from control and values for brain, heart, and splanchnic organs remained unchanged. Blood flow (per unit weight) of brain, cardiac, and splanchnic organs decreased; kidney and skeletal muscle blood flow was unaltered; and hepatic arterial blood flow increased from the awake (control) values. The hyperdynamic state often associated with ketamine anesthesia was not evident in these pigs during intermittent positive-pressure ventilation resulting in hypocapnia.