Accuracy of indirect measurement of blood pressure in neonatal foals.

The researchers investigated the accuracy of two automated indirect oscillometric monitors used to measure mean arterial pressure (MAP) in anesthetized neonatal foals. They found that the type of monitor and the location where the cuff was placed significantly influenced the accuracy of the measurements. Further, the study revealed that blood pressure was not a good predictor of cardiac output in anesthetized foals.

Study Design and Procedure

• The study involved 10 neonatal foals that were anesthetized and fitted with a catheter in the metatarsal artery. This setup was done in order to facilitate direct MAP monitoring and assessment of cardiac output using lithium dilution.
• Concurrent MAP measurements were conducted using Cardell and Dinamap oscillometric monitors. These monitors were fitted with cuffs that were positioned at three different body sites (coccygeal, metatarsal, and median arteries).
• Manipulation of blood pressure was achieved by altering the depth of anesthesia in the foals and administrating dobutamine or phenylephrine.

Findings

• The results showed that the accuracy of the indirect MAP measurements greatly depended on the type of machine used and where the cuff was applied. The Cardell monitor yielded significantly lower bias when the cuff was placed over the coccygeal artery compared to placement over the median or dorsal metatarsal artery.
• No considerable difference in bias was found when cuff placement was varied with the Dinamap monitor.
• The correlation between MAP and cardiac output was found to be 0.47, indicating a weak correlation.

Conclusion

• The research found that the use of indirect oscillometry with a cuff positioned over the coccygeal artery or dorsal metatarsal artery is a satisfactory method for the determination of MAP in foals.
• However, they also concluded that blood pressure measurements are not a well-suited indicator of cardiac output in anesthetized foals.