ASSESSMENT OF GASTRIC-MUCOSAL PERFUSION DURING SIMULATED HYPOVOLEMIA IN HEALTHY-VOLUNTEERS

We described here an original device for laser Doppler (LD) flowmetry measurements of gastric mucosal perfusion, which was used here in heal thy volunteers. A modified nasogastric tube containing the LD probe wa s inserted. Aspiration via a catheter, fixed in parallel to the probe, held the probe against the gastric wall. This new device was used to assess gastric mucosal perfusion in seven volunteers during simulated hypovolemia induced by lower body negative pressure (LBNP) application . The LBNP consisted of th ree successive levels of depression (-10, - 20, and -30 mm Hg). Although mean arterial pressure remained unchanged during negative pressure application, there was a significant decreas e in cardiac output (transthoracic electrical impedance) at each stage of LBNP. In contrast, gastric mucosal perfusion decreased significant ly only at higher level of sympathetic stimulation corresponding to un loading of both cardiopulmonary and arterial baroreflexes (-30 mm Hg). It may be hypothetized that local vascular mechanisms exist to mainta in gastric mucosal perfusion during moderate sympathetic stimulation i nduced by selective unloading of cardiopulmonary receptors. In the hea lthy volunteers studied, we found that LD flowmetry is a valuable tool to evaluate gastric mucosal perfusion when the probe is maintained in a constant position by the technique described here.