Effects of increasing MAP on tissue perfusion (original) (raw)

Comments Hypotension and impaired tissue perfusion are major problems in septic shock. Different hemodynamic endpoints have been suggested as goals for resuscitation, often without critical evaluation. One such goal is a target mean arterial pressure (MAP) of > 60 mmHg. Below this value, autoregulation in the renal, cardiac and cerebral vasculature fails, resulting in organ ischemia. The authors sought to determine if titrating MAP to levels above 60 mmHg (up to 85 mmHg) improved indices of tissue perfusion or oxygenation.In this small study it did not. In particular tissue perfusion, as measured by urine output, gastric mucosal pCO 2 , and skin red blood cell (RBC) flow were unchanged, as was total oxygen consumption. The study was limited by its small size, only 10 patients. In particular, only three patients had chronic hypertension, and it was these patients who were thought to have potentially altered autoregulation requiring higher than expected MAP for adequate organ perfusion. An additional limitation was that not all the patients received identical vasoactive agents. While all required norepinephrine (NE), others received dopamine and/or dobutamine. This may have resulted in direct drug effects which altered the results. The authors recognize these issues. Nonetheless this limited study does suggest that the current practice of titrating MAP to > 60 mmHg is reasonable and that more rigorous study is needed.