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Thermometry of red blood cell concentrate: magnetic resonance decoding warm up process.

Reiter G, Reiter U, Wagner T, Kozma N, Roland J, Schöllnast H, Ebner F, Lanzer G - PLoS ONE (2013)

Bottom Line: Mean time constants were τmean = 55.3±3.7 min, τsurface = 41.4±2.9 min and τcore = 76.8±7.1 min, mean relative time shifts were Δsurface = 0.07±0.02 and Δcore = 0.04±0.01.None of the constants correlated significantly with temperature differences between ambient and storage temperature.Independence of constants on differences between ambient and storage temperature suggests validity of models for arbitrary storage and ambient temperatures.

View Article: PubMed Central - PubMed

Affiliation: Healthcare Sector, Siemens AG, Graz, Austria. gert.reiter@siemens.com

ABSTRACT

Purpose: Temperature is a key measure in human red blood cell concentrate (RBC) quality control. A precise description of transient temperature distributions in RBC units removed from steady storage exposed to ambient temperature is at present unknown. Magnetic resonance thermometry was employed to visualize and analyse RBC warm up processes, to describe time courses of RBC mean, surface and core temperatures by an analytical model, and to determine and investigate corresponding model parameters.

Methods: Warm-up processes of 47 RBC units stored at 1-6°C and exposed to 21.25°C ambient temperature were investigated by proton resonance frequency thermometry. Temperature distributions were visualized and analysed with dedicated software allowing derivation of RBC mean, surface and core temperature-time courses during warm up. Time-dependence of mean temperature was assumed to fulfil a lumped capacitive model of heat transfer. Time courses of relative surface and core temperature changes to ambient temperature were similarly assumed to follow shifted exponential decays characterized by a time constant and a relative time shift, respectively.

Results: The lumped capacitive model of heat transfer and shifted exponential decays described time-dependence of mean, surface and core temperatures close to perfect (mean R(2) were 0.999±0.001, 0.996±0.004 and 0.998±0.002, respectively). Mean time constants were τmean = 55.3±3.7 min, τsurface = 41.4±2.9 min and τcore = 76.8±7.1 min, mean relative time shifts were Δsurface = 0.07±0.02 and Δcore = 0.04±0.01. None of the constants correlated significantly with temperature differences between ambient and storage temperature.

Conclusion: Lumped capacitive model of heat transfer and shifted exponential decays represent simple analytical formulas to describe transient mean, surface and core temperatures of RBC during warm up, which might be a helpful tool in RBC temperature monitoring and quality control. Independence of constants on differences between ambient and storage temperature suggests validity of models for arbitrary storage and ambient temperatures.

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Related in: MedlinePlus

Time constants and time of maximum temperature spread versus width-length-ratio.Scatterplots and linear regression lines of time constants (a) τmean, (b) τsurface, (c) τcore and of (d) time tspread of maximal temperature spread versus the width-height-ratio w/h of RBC pouches. Regression equations are to be understood in minutes, RMSE denotes root mean square error, r Pearson’s correlation coefficient.
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pone-0057931-g006: Time constants and time of maximum temperature spread versus width-length-ratio.Scatterplots and linear regression lines of time constants (a) τmean, (b) τsurface, (c) τcore and of (d) time tspread of maximal temperature spread versus the width-height-ratio w/h of RBC pouches. Regression equations are to be understood in minutes, RMSE denotes root mean square error, r Pearson’s correlation coefficient.

Mentions: Neither time constants and shifts nor (time of) maximal relative temperature spread depended on storage temperature or Tambient–Tstorage. Variations in geometric parameters RBC volume (255±17 ml), pouch volume (287±26 ml), pouch height h (13.1±0.5 cm) and width w (3.4±0.2 cm) were small and shifts as well as maximal relative temperature spread did not depend on these parameters (except a weak but significant correlation of r = −0.47 between Δsurface and pouch volume). Correlations between time constants and time of maximal temperature spread with geometric parameters are summarized in Table 1. Linear regression results of τmean, τsurface, τcore and tspread versus the width-height-ratio w/h are shown in Fig. 6.


Thermometry of red blood cell concentrate: magnetic resonance decoding warm up process.

Reiter G, Reiter U, Wagner T, Kozma N, Roland J, Schöllnast H, Ebner F, Lanzer G - PLoS ONE (2013)

Time constants and time of maximum temperature spread versus width-length-ratio.Scatterplots and linear regression lines of time constants (a) τmean, (b) τsurface, (c) τcore and of (d) time tspread of maximal temperature spread versus the width-height-ratio w/h of RBC pouches. Regression equations are to be understood in minutes, RMSE denotes root mean square error, r Pearson’s correlation coefficient.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585280&req=5

pone-0057931-g006: Time constants and time of maximum temperature spread versus width-length-ratio.Scatterplots and linear regression lines of time constants (a) τmean, (b) τsurface, (c) τcore and of (d) time tspread of maximal temperature spread versus the width-height-ratio w/h of RBC pouches. Regression equations are to be understood in minutes, RMSE denotes root mean square error, r Pearson’s correlation coefficient.
Mentions: Neither time constants and shifts nor (time of) maximal relative temperature spread depended on storage temperature or Tambient–Tstorage. Variations in geometric parameters RBC volume (255±17 ml), pouch volume (287±26 ml), pouch height h (13.1±0.5 cm) and width w (3.4±0.2 cm) were small and shifts as well as maximal relative temperature spread did not depend on these parameters (except a weak but significant correlation of r = −0.47 between Δsurface and pouch volume). Correlations between time constants and time of maximal temperature spread with geometric parameters are summarized in Table 1. Linear regression results of τmean, τsurface, τcore and tspread versus the width-height-ratio w/h are shown in Fig. 6.

Bottom Line: Mean time constants were τmean = 55.3±3.7 min, τsurface = 41.4±2.9 min and τcore = 76.8±7.1 min, mean relative time shifts were Δsurface = 0.07±0.02 and Δcore = 0.04±0.01.None of the constants correlated significantly with temperature differences between ambient and storage temperature.Independence of constants on differences between ambient and storage temperature suggests validity of models for arbitrary storage and ambient temperatures.

View Article: PubMed Central - PubMed

Affiliation: Healthcare Sector, Siemens AG, Graz, Austria. gert.reiter@siemens.com

ABSTRACT

Purpose: Temperature is a key measure in human red blood cell concentrate (RBC) quality control. A precise description of transient temperature distributions in RBC units removed from steady storage exposed to ambient temperature is at present unknown. Magnetic resonance thermometry was employed to visualize and analyse RBC warm up processes, to describe time courses of RBC mean, surface and core temperatures by an analytical model, and to determine and investigate corresponding model parameters.

Methods: Warm-up processes of 47 RBC units stored at 1-6°C and exposed to 21.25°C ambient temperature were investigated by proton resonance frequency thermometry. Temperature distributions were visualized and analysed with dedicated software allowing derivation of RBC mean, surface and core temperature-time courses during warm up. Time-dependence of mean temperature was assumed to fulfil a lumped capacitive model of heat transfer. Time courses of relative surface and core temperature changes to ambient temperature were similarly assumed to follow shifted exponential decays characterized by a time constant and a relative time shift, respectively.

Results: The lumped capacitive model of heat transfer and shifted exponential decays described time-dependence of mean, surface and core temperatures close to perfect (mean R(2) were 0.999±0.001, 0.996±0.004 and 0.998±0.002, respectively). Mean time constants were τmean = 55.3±3.7 min, τsurface = 41.4±2.9 min and τcore = 76.8±7.1 min, mean relative time shifts were Δsurface = 0.07±0.02 and Δcore = 0.04±0.01. None of the constants correlated significantly with temperature differences between ambient and storage temperature.

Conclusion: Lumped capacitive model of heat transfer and shifted exponential decays represent simple analytical formulas to describe transient mean, surface and core temperatures of RBC during warm up, which might be a helpful tool in RBC temperature monitoring and quality control. Independence of constants on differences between ambient and storage temperature suggests validity of models for arbitrary storage and ambient temperatures.

Show MeSH
Related in: MedlinePlus