Calculation of corrected flow time: Wodey's formula vs. Bazett's formula

Mohammadinejad, Payam; Hossein‐Nejad, Hooman

doi:10.1016/j.jcrc.2017.10.046

Cited by 21 publications

(13 citation statements)

References 5 publications

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“…These cut-offs identified a 10% difference in SV with a sensitivity and specificity of 96% and 93% for Wodey and 91% and 93% for Bazett (AUC 0.97 and 0.96, respectively). That Ftc Wodey and Ftc Bazett do not differ as surrogates for SV change is compatible with the findings of Mohammadinejad and Nossein-Nejad [ 35 ] who studied Ftc in 93 patients undergoing dialysis and 142 healthy volunteers during a passive leg raise (PLR).…”

Section: Discussionsupporting

confidence: 86%

Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

Kenny

MacKenzie

Eibl

et al. 2020

ICMx

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Background Change of the corrected flow time (Ftc) is a surrogate for tracking stroke volume (SV) in the intensive care unit. Multiple Ftc equations have been proposed; many have not had their diagnostic characteristics for detecting SV change reported. Further, little is known about the inherent Ftc variability induced by the respiratory cycle. Materials and methods Using a wearable Doppler ultrasound patch, we studied the clinical performance of 11 Ftc equations to detect a 10% change in SV measured by non-invasive pulse contour analysis; 26 healthy volunteers performed a standardized cardiac preload modifying maneuver. Results One hundred changes in cardiac preload and 3890 carotid beats were analyzed. Most of the 11 Ftc equations studied had similar diagnostic attributes. Wodeys’ and Chambers’ formulae had identical results; a 2% change in Ftc detected a 10% change in SV with a sensitivity and specificity of 96% and 93%, respectively. Similarly, a 3% change in Ftc calculated by Bazett’s formula displayed a sensitivity and specificity of 91% and 93%. FtcWodey had 100% concordance and an R2 of 0.75 with change in SV; these values were 99%, 0.76 and 98%, 0.71 for FtcChambers and FtcBazetts, respectively. As an exploratory analysis, we studied 3335 carotid beats for the dispersion of Ftc during quiet breathing using the equations of Wodey and Bazett. The coefficient of variation of Ftc during quiet breathing for these formulae were 0.06 and 0.07, respectively. Conclusions Most of the 11 different equations used to calculate carotid artery Ftc from a wearable Doppler ultrasound patch had similar thresholds and abilities to detect SV change in healthy volunteers. Variation in Ftc induced by the respiratory cycle is important; measuring a clinically significant change in Ftc with statistical confidence requires a large sample of beats.

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Section: Discussionsupporting

confidence: 86%

Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

Kenny

MacKenzie

Eibl

et al. 2020

ICMx

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“…Bazett’s formula is calculated by dividing the flow time by the square root of the cycle time. Wodey’s formula is calculated according to the following: flow time measured + [1.29 × (heart rate − 60)] [ 17 ]. All three FTc measurements were performed in real time by a single pre-trained examiner, while another independent investigator noted the other haemodynamic and respiratory parameters.…”

Section: Methodsmentioning

confidence: 99%

Ability of Carotid Corrected Flow Time to Predict Fluid Responsiveness in Patients Mechanically Ventilated Using Low Tidal Volume after Surgery

Jung

Kim

et al. 2021

JCM

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Predicting fluid responsiveness in patients under mechanical ventilation with low tidal volume (VT) is challenging. This study evaluated the ability of carotid corrected flow time (FTc) assessed by ultrasound for predicting the fluid responsiveness during low VT ventilation. Patients under postoperative mechanical ventilation and clinically diagnosed with hypovolemia were enrolled. Carotid FTc and pulse pressure variation (PPV) were measured at VT of 6 and 10 mL/kg predicted body weight (PBW). FTc was calculated using both Bazett’s (FTcB) and Wodey’s (FTcW) formulas. Fluid responsiveness was defined as a ≥15% increase in the stroke volume index assessed by FloTrac/Vigileo monitor after administration of 8 mL/kg of balanced crystalloid. Among 36 patients, 16 (44.4%) were fluid responders. The areas under the receiver operating characteristic curves (AUROCs) for the FTcB at VT of 6 and 10 mL/kg PBW were 0.897 (95% confidence interval [95% CI]: 0.750–0.973) and 0.895 (95% CI: 0.748–0.972), respectively. The AUROCs for the FTcW at VT of 6 and 10 mL/kg PBW were 0.875 (95% CI: 0.722–0.961) and 0.891 (95% CI: 0.744–0.970), respectively. However, PPV at VT of 6 mL/kg PBW (AUROC: 0.714, 95% CI: 0.539–0.852) showed significantly lower accuracy than that of PPV at VT of 10 mL/kg PBW (AUROC: 0.867, 95% CI: 0.712–0.957; p = 0.034). Carotid FTc can predict fluid responsiveness better than PPV during low VT ventilation. However, further studies using automated continuous monitoring system are needed before its clinical use.

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“…Fluid-responsive status was defined as ≥10% increase in SV via NICOM™ [15]. Systolic and cycle times were analyzed by the bedside operator’s interpretation of ultrasound-captured images and ccFT values were calculated using Wodey’s formula, FTcorrected= FTmeasured+1.29(HR−60), which has been shown to better correct for fast heart rates in comparison to widely used Bazett’s formula (FTcorrected= FTmeasruredRR interval) [16, 17]. A second, blinded investigator reevaluated unprocessed bedside images to avoid treatment bias and assessinter-user variability.…”

Section: Methodsmentioning

confidence: 99%

Ultrasound Assessment of the Change in Carotid Corrected Flow Time in Fluid Responsiveness in Undifferentiated Shock

Barjaktarević

Toppen

et al. 2018

Critical Care Medicine

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Calculation of corrected flow time: Wodey's formula vs. Bazett's formula

Cited by 21 publications

References 5 publications

Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

Ability of Carotid Corrected Flow Time to Predict Fluid Responsiveness in Patients Mechanically Ventilated Using Low Tidal Volume after Surgery

Ultrasound Assessment of the Change in Carotid Corrected Flow Time in Fluid Responsiveness in Undifferentiated Shock

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