Objective. To investigate clinically useful markers for determining the seventy of hemorrhagic shock and adequacy of resuscitation Methods. Prospective study was undertaken in 12 dogs

using an established model for hemorrhagic shock. The anesthetized dogs were bled to a mean arterial pressure of 40 mmHg which was maintained for 3 hours. Then each animal was resuscitated with heperinized whole blood followed by intravenous infusion of dobutamine at a rate of 5 ug. kg-1. min-1 for 10 minutes. Arterial and mixed venous blood gases

arterial lactate concentrations and hemodynamic Parameters were measured throughout the study. Results. A difference in the PCO2 and pH values between arterial and mixed venous blood was observed. Arterial-venous PCO2 and pH difference increased significantly after sustained shock. The arteriovenous carbon dioxide and pH gradients recovered more rapidly than arterial lactate levels after successful resuscitation with blood and dobutamine. Conclusion. Arterial blood gases fail to reflect the acid-base status of tissues during hemorrhagic shock. The differences in PCO2 and pH values between arterial and mixed venous blood could be used as clinical in- dicators for assessing the seventy of shock and efficacy of resuscitation.