title: Effects of intra-aortic balloon counterpulsation in a model of septic shock.
abstract: BACKGROUND
  Fluid refractory septic shock can develop into a hypodynamic cardiovascular state in both children and adults. Despite management of these patients with empirical inotropic therapy (with or without a vasodilator), mortality remains high.
  
  
  OBJECTIVE
  The effect of cardiovascular support using intra-aortic balloon counterpulsation was investigated in a hypodynamic, mechanically ventilated canine sepsis model in which cardiovascular and pulmonary support were titrated based on treatment protocols.
  
  
  METHODS
  Each week, three animals (n = 33, 10-12 kg) were administered intrabronchial Staphylococcus aureus challenge and then randomized to receive intra-aortic balloon counterpulsation for 68 hrs or no intra-aortic balloon counterpulsation (control). Bacterial doses were increased over the study (4-8 x 10(9) cfu/kg) to assess the effects of intra-aortic balloon counterpulsation during sepsis with increasing risk of death.
  
  
  RESULTS
  Compared with lower bacterial doses (4-7 x 10(9) colony-forming units/kg), control animals challenged with the highest dose (8 x 10(9) colony-forming units/kg) had a greater risk of death (mortality rate 86% vs. 17%), with worse lung injury ([A - a]O2), and renal dysfunction (creatinine). These sicker animals required higher norepinephrine infusion rates to maintain blood pressure (and higher FIO2) and positive end-expiratory pressure levels to maintain oxygenation (p < or = 0.04 for all). In animals receiving the highest bacterial dose, intra-aortic balloon counterpulsation improved survival time (23.4 +/- 10 hrs longer; p = 0.003) and lowered norepinephrine requirements (0.43 +/- 0.17 microg/kg/min; p = 0.002) and systemic vascular resistance index (1.44 +/- 0.57 dynes/s/cm5/kg; p = 0.0001) compared with controls. Despite these beneficial effects, intra-aortic balloon counterpulsation was associated with an increase in blood urea nitrogen (p = 0.002) and creatinine (p = 0.12). In animals receiving lower doses of bacteria, intra-aortic balloon counterpulsation had no significant effects on survival or renal function.
  
  
  CONCLUSIONS
  In a canine model of severe septic shock with a low cardiac index, intra-aortic balloon counterpulsation prolongs survival time and lowers vasopressor requirements.
authors.affiliation: Department of Critical Care Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA. ssolomon@cc.nih.gov
authors.forename: Steven B
authors.initials: SB
authors.lastname: Solomon
authors.forename: Peter C
authors.initials: PC
authors.lastname: Minneci
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Deans
authors.forename: Jing
authors.initials: J
authors.lastname: Feng
authors.forename: Peter Q
authors.initials: PQ
authors.lastname: Eichacker
authors.forename: Steven M
authors.initials: SM
authors.lastname: Banks
authors.forename: Robert L
authors.initials: RL
authors.lastname: Danner
authors.forename: Charles
authors.initials: C
authors.lastname: Natanson
authors.forename: Michael A
authors.initials: MA
authors.lastname: Solomon
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D007423:Intra-Aortic Balloon Pumping; D012720:Severity of Illness Index; D012772:Shock, Septic / Q000209:etiology / Q000601:surgery*; D013203:Staphylococcal Infections / Q000150:complications