Limits...
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.

Show MeSH

Related in: MedlinePlus

Time dependence of relative temperatur differences.Average time courses (solid lines) and corresponding uncertainties (dotted lines) of relative temperature differences of mean, surface and core temperature to ambient temperature of RBC during warm up. Recalculation of relative temperature difference scale to temperature scale at the right hand side was done (for convinience) for Tstorage = 3.6°C and Tambient = 21.25°C.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585280&req=5

pone-0057931-g005: Time dependence of relative temperatur differences.Average time courses (solid lines) and corresponding uncertainties (dotted lines) of relative temperature differences of mean, surface and core temperature to ambient temperature of RBC during warm up. Recalculation of relative temperature difference scale to temperature scale at the right hand side was done (for convinience) for Tstorage = 3.6°C and Tambient = 21.25°C.

Mentions: Measured relative temperature differences θmean, θsurface and θcore fulfilled lumped capacitance model of heat transfer [Eq. (1)] and “shifted” exponential decays [Eqs (2) and (3)] close to perfect. Mean R2 were 0.999±0.001, 0.996±0.004 and 0.998±0.002, respectively. The resulting mean time constants were τmean = 55.3±3.7 min, τsurface = 41.4±2.9 min and τcore = 76.8±7.1 min, resulting mean time shifts Δsurface = 0.07±0.02 and Δcore = 0.04±0.01. Average time courses of θmean, θsurface and θcore together with corresponding uncertainties are shown in Fig. 5. Mean time when relative temperature spread is maximal [Eq. (4)] was tspread = 45.5±4.1 min, the corresponding mean maximal relative temperature spread was θspread(tspread) = 0.26±0.04.


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 dependence of relative temperatur differences.Average time courses (solid lines) and corresponding uncertainties (dotted lines) of relative temperature differences of mean, surface and core temperature to ambient temperature of RBC during warm up. Recalculation of relative temperature difference scale to temperature scale at the right hand side was done (for convinience) for Tstorage = 3.6°C and Tambient = 21.25°C.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0057931-g005: Time dependence of relative temperatur differences.Average time courses (solid lines) and corresponding uncertainties (dotted lines) of relative temperature differences of mean, surface and core temperature to ambient temperature of RBC during warm up. Recalculation of relative temperature difference scale to temperature scale at the right hand side was done (for convinience) for Tstorage = 3.6°C and Tambient = 21.25°C.
Mentions: Measured relative temperature differences θmean, θsurface and θcore fulfilled lumped capacitance model of heat transfer [Eq. (1)] and “shifted” exponential decays [Eqs (2) and (3)] close to perfect. Mean R2 were 0.999±0.001, 0.996±0.004 and 0.998±0.002, respectively. The resulting mean time constants were τmean = 55.3±3.7 min, τsurface = 41.4±2.9 min and τcore = 76.8±7.1 min, resulting mean time shifts Δsurface = 0.07±0.02 and Δcore = 0.04±0.01. Average time courses of θmean, θsurface and θcore together with corresponding uncertainties are shown in Fig. 5. Mean time when relative temperature spread is maximal [Eq. (4)] was tspread = 45.5±4.1 min, the corresponding mean maximal relative temperature spread was θspread(tspread) = 0.26±0.04.

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