Assessing perfusion failure during circulatory shock.

In patients with circulatory shock, monitoring of tissue perfusion requires assessment of systemic oxygen metabolism. The presence of lactic acidosis helps identify critical hypoperfusion as marked by anaerobic metabolism. Mixed venous oxygen tension and saturation help determine the use of compensatory mechanisms to maintain oxidative metabolism. Measurements of systemic oxygen consumption and oxygen delivery help define underlying pathophysiology and the direction for therapeutic intervention. Tonometrically measured gastric intramucosal pH appears to be a useful method for monitoring splanchnic hypoperfusion and may have implications for assessing global perfusion failure.