Abnormal Indicator Dilution Patterns in Dogs Produced by Flowmeter Probes on the Pulmonary Artery
In acute experiments on open chested dogs, indicator dilution curves were recorded before and after placing electromagnetic flow probes on the pulmonary artery. The flow probes caused severe abnormalities in the dilution curves. The abnormalities resembled those seen in cases with left-to-right shunts.
The following facts suggest that the abnormalities are caused by turbulence and eddy formation near the flowmeter probe: (a) Direct measurements with a fiberoptic densitometer showed that clearance of dye just proximal to the probe was delayed. (b) The abnormalities disappeared immediately after removal of the probe or when the dye was injected just downstream to the probe. (c) The areas under curves recorded from the pulmonary artery upstream from the probe were greater than the areas under curves recorded at this same site without the probe.
Cardiac output and systemic arterial pressure were lower in animals with abnormal dilution curves than in those with normal femoral curves.
- Received March 4, 1964.
- © 1964 American Heart Association, Inc.