Effects of intra-aortic balloon counterpulsation in a model of septic shock.
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.
Solomon
Steven B
SB
Department of Critical Care Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA. ssolomon@cc.nih.gov
Minneci
Peter C
PC
Deans
Katherine J
KJ
Feng
Jing
J
Eichacker
Peter Q
PQ
Banks
Steven M
SM
Danner
Robert L
RL
Natanson
Charles
C
Solomon
Michael A
MA
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