Effects of vasopressors on renal tissue gas tensions during hemorrhagic shock in dogs.

Effects of dopamine, epinephrine, and norepinephrine on renal tissue gas tension changes during hemorrhagic shock in dogs were investigated. The changes in the renal tissue gas tension were determined by the use of a Teflon membrane mass spectrometer. The animals were bled to a mean arterial pressure (MAP) of 50 mm Hg and maintained for one hour. Then, vasopressors were administered to maintain the MAP above 100 mm Hg. After the infusion of dopamine, the renal tissue oxygen tension (PrO2) was elevated for 20 min and tissue CO2 tension (PrCO2) decreased for 70 min. Neither PrO2 nor PrCO2 returned to the control levels. When epinephrine was infused, there was an initial slight transient rise in PrO2, which decreased gradually while PrCO2 decreased for 30 min and then gradually rose. When norepinephrine was infused, there was also an initial slight transient elevation in PrO2 which then decreased, while PrCO2 decreased transiently and then rose rapidly. These results suggest that although dopamine was the most useful vasopressor for improving renal tissue gas exchange during hemorrhagic shock, it did not restore completely oxygen delivery.