An instrument for at least estimating physiologic pressure such as
central venous pressure (CVP) non-invasively includes an
ultrasound probe coupled to a display that shows the deformation of a
vein as pressure is applied outside the body through the
skin and soft tissues. A pressure
transducer is applied to the
skin to compress a
vein, and an indicator coupled to the
transducer shows the amount of pressure being applied when the
ultrasound probe shows that the
vein has collapsed. In the preferred embodiment, the
transducer is an inelastic
balloon filled with a liquid such as water, and the indicator is in fluid communication with the
balloon. The indicator may be a mechanical gauge or meter, or may include a material that converts applied pressure to an electrical
signal, in which case the electrical
signal may be interfaced to a numerical readout. At least the probe and the transducer are preferably disposed in a hand-held housing.