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October 16-20, 2010 San Diego, CA Home Abstract Archive Search Abstracts 2010 Session Grid 2010 Meeting Website Policy Statements ASA Website Feedback 
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A1052
October 20, 2009 8:00 AM - 9:30 AM Room Room 356 |
| The Modelling of Urinary Data Improves a Volume Kinetic Model in Female Volunteers |
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Christer H. Svensen, M.D., Ph.D., Husong Li, M.D., Ph.D., Dan Drobin, M.D., Ph.D., Robert G. Hahn, M.D., Ph.D., Peter M. Rodhe, M.Eng. Department of Anesthesiology, Karolinska Institutet/Södersjukhuset, Stockholm, Sweden |
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Background
This project aims to further develop existing volume kinetic models [1] for fluid therapy. There is a clinical interest to better understand the fluid balance of surgical patients. It is apparent that many patients are edematous because they allocate infused fluid peripherally [2]. We have modelled simultaneously both plasma dilution and urinary output to better describe how the fluid is allocated. Methods Ten healthy female volunteers, aged 21-39 year (mean 29), with a bodyweight of 58-67 kg (mean 62.5 kg) were included. They were given lactated Ringer's solution, 25 ml/kg over 30 minutes. Blood samples (4 mLs) were taken every five minutes during the first 120 min, and thereafter the sampling rate was every 10 Min until the end of experiments at 240 min. Hemoglobinsamples were taken (B-Hb) for calculation of plasmadilution. A urinary catheter was inserted to simultaneously measure urinary output. The mathematical approach was done by creating a three compartment model, that aimed at computing the fluid shifts, dehydration state, elimination efficacy, time delay and the overall distribution at a given time point. Input values for the model analyses were gender, body weight, hemoglobin, hematocrits, infusion rate, urinary output and infusion time. The parameters to estimate were ( k t , k r , k b , k c , µ, T u ). Statistics Parameter values are presented as medians and ranges. Results All subjects were possible to fit into the model. Four of them are shown in a figure.(Fig 1). The subjects showed a variying fluid distribution as a response to the fluid challenge. Maximum urinary flow rates varied with a median value of 18.5 ml/min (40-2), during the experiment. The maximum peripheral upload of fluid also varied considerably with a median of 655 ml (293–1059). From the model we computed the elimination efficacy, k b ⋅ k r 19 ml/min (0.7 – 59.2), time delay of urinary output T u 18 min (0–188) and basal elimination k b 0.63 ml/min (0.02-4.83). Figure legend. Boxes = central compartment, Dashed = peripheral compartment Circles = urinary output.[figure1]Discussion By the simultaneous modelling of plasma dilution and urinary output it is possible to analyze and quantify the peripheral accumulation of fluid, and associated flows, at each time point. This is of interest for the clinician because it shows unnecessary fluid accumulation that could potentially be harmful for the patient. The clinician may thus be able to make necessary adjustments to the fluid therapy, by detecting any renal elimination defiency and/or peripheral accumulation of crystalloid fluid. Conclusion By using the above model it was possible to compute the peripheral accumulation of fluid and its corresponding elimination efficacy. From Proceedings of the 2009 Annual Meeting of the American Society Anesthesiologists. |
Figure 1
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