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Evaluation of a local microsphere injection method for measurement of blood flow in the rabbit lower extremity
Y Maki1, W C Breidenbach, J C Firrell
1Christine M. Kleinert Institute for Hand and Microsurgery, Louisville, Kentucky 40202.
Abstract:
The precision of a modified microsphere technique to measure blood flow in the hind limb of the rabbit was determined. Regional (local) injections made via a catheter in the aorta and blood withdrawn through a catheter in the hind limb enabled deposition of a high concentration of microspheres in the tissues while minimizing the number of microspheres needed for accurate measurement. 95Niobium and 141cerium-labeled 16 microns diameter microspheres were used. Blood flow was measured in 15 locations of muscle and skin for simultaneous injections into the aorta and left ventricle (group A), simultaneous injections of a mixture into the left ventricle (group B), and ventricular injections given 1 h apart (group C). No significant differences in mean blood flow measurements were found. Correlation coefficients between local and ventricular injections ranged from 0.89-0.99 and between 0.994 and 0.999 for two simultaneous ventricular injections. The variability over time was greater, with correlations between the first and second injections ranging from 0.13-0.939. Precision of the local technique compared with the ventricular technique can be kept within 30% with five or six animals. The advantage of this technique over ventricular injections is in the measurement of blood flow in small tissue samples when the number of microspheres deposited from ventricular injections is insufficient.
Insights
This study validates a modified microsphere technique for precise hind limb blood flow measurement in rabbits. The regional injection method offers accurate results, especially for small tissue samples, minimizing microsphere usage.
Area of Science:
- Physiology
- Cardiovascular Research
- Biomedical Engineering
Background:
- Accurate measurement of regional blood flow is crucial in physiological and pharmacological studies.
- Traditional microsphere techniques can be limited by the number of microspheres required for sufficient tissue deposition, particularly in small tissue samples.
Purpose of the Study:
- To determine the precision of a modified regional (local) microsphere technique for measuring blood flow in the rabbit hind limb.
- To compare the accuracy and efficiency of this local injection method against standard ventricular injection techniques.
Main Methods:
- A modified technique involving regional injections via an aortic catheter and blood withdrawal from a hind limb catheter was developed.
- 95Niobium and 141cerium-labeled 16-micron microspheres were used to measure blood flow in 15 muscle and skin locations.
- Comparisons were made between simultaneous aortic and left ventricular injections, single left ventricular injections, and sequential left ventricular injections.
Main Results:
- No significant differences were observed in mean blood flow measurements between the regional and ventricular techniques.
- High correlation coefficients (0.89-0.99) were found between local and ventricular injections.
- The regional technique demonstrated precision within 30% with 5-6 animals, proving advantageous for small tissue samples.
Conclusions:
- The modified regional microsphere technique provides a precise and efficient method for measuring hind limb blood flow in rabbits.
- This technique is particularly valuable for analyzing blood flow in small tissue volumes where ventricular injections may yield insufficient microsphere deposition.
- The method enhances accuracy and reduces the number of microspheres needed, offering a practical alternative for specific research applications.