Wednesday January 14, 2009
IABP in severe septic shock - Bench to bedside?

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. 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 109 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 109 colony-forming units/kg), control animals challenged with the highest dose (8 x 109 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.
• In animals receiving the highest bacterial dose, intra-aortic balloon counterpulsation improved survival time (23.4 +/- 10 hrs longer) and lowered norepinephrine requirements (0.43 +/- 0.17 [mu]g/kg/min) and systemic vascular resistance index (1.44 +/- 0.57 dynes/s/cm5/kg) compared with controls.
• Despite these beneficial effects, intra-aortic balloon counterpulsation was associated with an increase in blood urea nitrogen and creatinine
• 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.


Reference: Click to get abstract

Effects of intra-aortic balloon counterpulsation in a model of septic shock - Critical Care Medicine. 37(1):7-18, January 2009.