Carotid Doppler Measurement Variability in Functional Hemodynamic Monitoring: An Analysis of 17,822 Cardiac Cycles

• Published in: Critical care explorations 2021-06, Vol.3 (6), p.e0439-e0439
• Main Authors: Kenny, Jon-Émile S., Barjaktarevic, Igor, Mackenzie, David C., Elfarnawany, Mai, Math, Zhen Yang B., Eibl, Andrew M., Eibl, Joseph K., Kim, Chul Ho, Johnson, Bruce D.
• Format: Article
• Language: English
• Subjects: Brief Report
• ISSN: 2639-8028; 2639-8028
• DOI: 10.1097/CCE.0000000000000439

Carotid Doppler ultrasound is used as a measure of fluid responsiveness, however, assessing change with statistical confidence requires an adequate beat sample size. The coefficient of variation helps quantify the number of cardiac cycles needed to adequately detect change during functional hemodynamic monitoring. DESIGNProspective, observational, human model of hemorrhage and resuscitation. SETTINGHuman physiology laboratory at Mayo Clinic. SUBJECTSHealthy volunteers. INTERVENTIONSLower body negative pressure. MEASUREMENTS AND MAIN RESULTSWe measured the coefficient of variation of the carotid artery velocity time integral and corrected flow time during significant cardiac preload changes. Seventeen-thousand eight-hundred twenty-two cardiac cycles were analyzed. The median coefficient of variation of the carotid velocity time integral was 8.7% at baseline and 11.9% during lowest-tolerated lower body negative pressure stage. These values were 3.6% and 4.6%, respectively, for the corrected flow time. CONCLUSIONSThe median coefficient of variation values measured in this large dataset indicates that at least 6 cardiac cycles should be averaged before and after an intervention when using the carotid artery as a functional hemodynamic measure.