The patterns in urine excretion and transvascular fluid exchange in human subjects during intravenous fluid infusion: A quantitative analysis

• Published in: Clinical physiology and functional imaging Vol. 44; no. 5; pp. 396 - 406
• Main Authors: Curry, FitzRoy E., Michel, C. Charles
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.09.2024
• Subjects: acetated ringer infusion; Adult; Dilution; Excretion; Female; Fluid flow; Fluid Therapy - methods; Functions (mathematics); Hemoglobin; Hemoglobins - metabolism; Humans; Indicator Dilution Techniques; individualized fluid therapy; Infusions, Intravenous; Intravenous administration; Isotonic Solutions - administration & dosage; Linear Models; Logarithms; Mathematical functions; models of whole body fluid distribution; Models, Biological; Pattern analysis; plasma volume regulation; Predictive control; Quantitative analysis; Renal Elimination; Ringer's Solution; Time Factors; Time lag; Time measurement; transvascular fluid exchange; Urination; Urine; Variation; Water-Electrolyte Balance; individualized fluid therapy; models of whole body fluid distribution; transvascular fluid exchange; plasma volume regulation; acetated ringer infusion
• ISSN: 1475-0961; 1475-097X; 1475-097X
• DOI: 10.1111/cpf.12887

Introduction Investigations of responses of animals and humans to changes of plasma volume are usually reported as average responses of groups of individuals. This ignores considerable quantitative variation between individuals. We examined the hypothesis that individual responses follow a common temporal pattern with variations reflecting different parameters describing that pattern. Methods We illustrate this approach using data of Hahn, Lindahl and Drobin (Acta Anaesthesiol Scand.2011, 55:987‐94) who measured urine volume and haemoglobin dilution of 10 female subjects during intravenous Ringer infusions for 30 min and subsequent 3.5 h. The published time courses were digitised and analysed to determine if a family of mathematical functions accounted for the variation in individual responses. Results Urine excretion was characterised by a time delay (Td) before urine flow increased and a time course of cumulative urine excretion described by a logarithmic function. This logarithmic relation forms the theoretical basis of a family of linear relations describing urine excretion as a function of Td. Measurement of Td enables estimation of subsequent values of urine excretion and thereby the fraction of infused fluid retained in the body. Conclusion The approach might be useful for physiologists and clinical investigators to compare the response to infusion protocols when both test and control responses can be described by linear relations between cumulative urine volume at specific times and Td. The approach may also be useful for clinicians by complementing strategies to guide fluid therapy by enabling the later responses of an individual to be predicted from their earlier response.