Intrathoracic blood volume (ITBV)-guided volume therapy maintains intestinal perfusion and oxygenation despite positive end expiratory pressure (PEEP) ventilation

Introduction

Reduced intestinal perfusion is one major cause in the development of multiple organ failure. Furthermore, the harmful effects of PEEP on intestinal perfusion and oxygenation are well described and it has been demonstrated that volume therapy reduces these effects. But there is no evidence on how to guide volume therapy, or whether volume therapy alone restitutes intestinal perfusion and oxygenation at PEEP levels above 10 cmH₂O. Therefore we explored the effects of PEEP in an animal model of ITBV-guided volume loading.

Methods

Twenty anesthetized and ventilated pigs were studied. An ultrasonic flow probe was placed around the superior mesenteric artery, catheters were inserted into the femoral artery and mesenteric vein. Animals were randomly assigned to: group 1 = controls (n = 9), received crystalloids; and group 2 = ITBV (n = 11), received crystalloids and continuous colloid substitution to maintain ITBV at the baseline level. Measurements were made at ZEEP and PEEP of 5, 10, 15 and 20 cmH₂O. ITBV was measured by the COLD^® System. Oxygen metabolism was calculated according to Fick's Law. Intestinal CO₂ was determined by tonometry.

Results

See Table 1. All data are presented as the median.

Table 1

Conclusion

ITBV-guided volume loading maintains intestinal blood flow and O₂ delivery up to a PEEP level of 20 cmH₂O. The intestinal–arterial CO₂ gap remained unchanged. In conclusion, ITBV-guided volume therapy is a helpful concept to reduce the harmful intestinal effects of PEEP.