Correlation of carotid blood flow and corrected carotid flow time with invasive cardiac output measurements
Date
2017-04-20
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Abstract
Background
Non-invasive measures that can accurately estimate cardiac output may help identify volume-responsive patients. This study seeks to compare two non-invasive measures (corrected carotid flow time and carotid blood flow) and their correlations with invasive reference measurements of cardiac output. Consenting adult patients (n = 51) at Massachusetts General Hospital cardiac catheterization laboratory undergoing right heart catheterization between February and April 2016 were included. Carotid ultrasound images were obtained concurrently with cardiac output measurements, obtained by the thermodilution method in the absence of severe tricuspid regurgitation and by the Fick oxygen method otherwise. Corrected carotid flow time was calculated as systole time/√cycle time. Carotid blood flow was calculated as π × (carotid diameter)2/4 × velocity time integral × heart rate. Measurements were obtained using a single carotid waveform and an average of three carotid waveforms for both measures.
Results
Single waveform measurements of corrected flow time did not correlate with cardiac output (ρ = 0.25, 95% CI −0.03 to 0.49, p = 0.08), but an average of three waveforms correlated significantly, although weakly (ρ = 0.29, 95% CI 0.02–0.53, p = 0.046). Carotid blood flow measurements correlated moderately with cardiac output regardless of if single waveform or an average of three waveforms were used: ρ = 0.44, 95% CI 0.18–0.63, p = 0.004, and ρ = 0.41, 95% CI 0.16–0.62, p = 0.004, respectively.
Conclusions
Carotid blood flow may be a better marker of cardiac output and less subject to measurements issues than corrected carotid flow time.
Description
Keywords
Citation
Critical Ultrasound Journal. 2017 Apr 20;9(1):10