title: Effects of perfusion pressure on tissue perfusion in septic shock.
abstract: OBJECTIVE
  To measure the effects of increasing mean arterial pressure (MAP) on systemic oxygen metabolism and regional tissue perfusion in septic shock.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Medical and surgical intensive care units of a tertiary care teaching hospital.
  
  
  METHODS
  Ten patients with the diagnosis of septic shock who required pressor agents to maintain a MAP > or = 60 mm Hg after fluid resuscitation to a pulmonary artery occlusion pressure (PAOP) > or = 12 mm Hg.
  
  
  METHODS
  Norepinephrine was titrated to MAPs of 65, 75, and 85 mm Hg in 10 patients with septic shock.
  
  
  RESULTS
  At each level of MAP, hemodynamic parameters (heart rate, PAOP, cardiac index, left ventricular stroke work index, and systemic vascular resistance index), metabolic parameters (oxygen delivery, oxygen consumption, arterial lactate), and regional perfusion parameters (gastric mucosal Pco2, skin capillary blood flow and red blood cell velocity, urine output) were measured. Increasing the MAP from 65 to 85 mm Hg with norepinephrine resulted in increases in cardiac index from 4.7+/-0.5 L/min/m2 to 5.5+/-0.6 L/min/m2 (p < 0.03). Arterial lactate was 3.1+/-0.9 mEq/L at a MAP of 65 mm Hg and 3.0+/-0.9 mEq/L at 85 mm Hg (NS). The gradient between arterial P(CO2) and gastric intramucosal Pco2 was 13+/-3 mm Hg (1.7+/-0.4 kPa) at a MAP of 65 mm Hg and 16+/-3 at 85 mm Hg (2.1+/-0.4 kPa) (NS). Urine output at 65 mm Hg was 49+/-18 mL/hr and was 43+/-13 mL/hr at 85 mm Hg (NS). As the MAP was raised, there were no significant changes in skin capillary blood flow or red blood cell velocity.
  
  
  CONCLUSIONS
  Increasing the MAP from 65 mm Hg to 85 mm Hg with norepinephrine does not significantly affect systemic oxygen metabolism, skin microcirculatory blood flow, urine output, or splanchnic perfusion.
authors.affiliation: Saint Vincents Hospital and Medical Center, New York Medical College, New York, USA.
authors.forename: D
authors.initials: D
authors.lastname: LeDoux
authors.forename: M E
authors.initials: ME
authors.lastname: Astiz
authors.forename: C M
authors.initials: CM
authors.lastname: Carpati
authors.forename: E C
authors.initials: EC
authors.lastname: Rackow
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage*; D010101:Oxygen Consumption / Q000187:drug effects*; D011312:Pressure; D011446:Prospective Studies; D012039:Regional Blood Flow; D012772:Shock, Septic / Q000378:metabolism* / Q000503:physiopathology*
chemical_list: D009638:Norepinephrine