Analytical Capillary Viscometry: A Measurement-Science Framework
Structured Abstract:
Background. Whole-blood rheology is physiologically important, yet routine clinical translation has remained limited despite extensive experimental and theoretical development. The manuscript argues that this gap arises principally from measurement-science challenges: rheological quantities are inseparable from specimen definition, measurement conditions, analytical assumptions, and computational interpretation, preventing reliable comparison and cumulative interpretation when these conditions differ.
Objective. To establish a technology-neutral measurement-science framework for analytical capillary viscometry that defines the conditions under which capillary-derived whole-blood rheological quantities may be considered scientifically identifiable, analytically valid, and biologically interpretable.
Methods. This review synthesizes the historical development of analytical capillary viscometry, classical correction architecture, measurement-science principles, hemorheological evidence, and published guidance for whole-blood rheology. The analysis is organized around the complete measurement chain—from physical law and analytical corrections through biological specimen standardization, traceability, uncertainty, and interpretation—rather than around any individual instrument.
Results. The review demonstrates that capillary viscometry represents a mature analytical methodology whose successful application to whole blood requires explicit definition of the measurand, validated correction architecture, standardized specimen handling, appropriate calibration and traceability, computational transparency, and clear separation of analytical validity from physiological and clinical interpretation. It further identifies the absence of a commutable whole-blood reference material and an unbroken traceability chain as major remaining metrological barriers to harmonized whole-blood rheology.
Conclusions. Analytical capillary viscometry should be regarded primarily as a measurement-science problem rather than solely as an instrumentation problem. A defensible whole-blood rheological measurement requires concurrent specification of the specimen, analytical method, computational model, calibration hierarchy, measurement uncertainty, and intended biological interpretation. This framework provides a technology-neutral scientific foundation for future analytical validation, standardization, interlaboratory harmonization, and subsequent clinical translation of whole-blood rheology.