Capillary Filtration of Plasma Is Accelerated During General Anesthesia: A Secondary Population Volume Kinetic Analysis

Figures

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  Figure 1. Kinetic model. (a) Schematic drawing of the kinetic model used in the study. (b) Predictive check based on 1000 simulations. The plot allows visual comparison between the observed confidence intervals and the one predicted by the final model. (c, d) The plasma volume expansion (Vc) predicted by simulating infusion of 800 and 1600 mL of Ringer's over 15, 30, and 60 min in the awake and anesthetized states. The best estimates of the parameters in Table 3 were used.

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  Figure 2. Covariates. (a) The influence of the body weight on estimated size of the central fluid space, Vc. (b, c) Relationships between the infused volume and the rate constant for the return flow of distributed fluid to the plasma (k21) and the elimination rate constant (k10). (d‐f) Boxplots comparing the influence of general anesthesia of the rate constant k12 (distribution rate constant), the volume of Vc, and the elimination rate constant, k10. (f) Same plot but for the urine output.

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  Figure 3. Simulations. Distribution of 1600 mL of Ringer's solution infused intravenously over 30 min as given by the best estimates shown in Table 2 and divided into awake and anesthetized subjects. (a) Vc, (b) Vt1, (c) Vt2, and (b) excreted urine volume.

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  Figure 4. Relationship between Vt1 and Vt2. The remote interstitial fluid space, Vt2, opens for marked accumulation of infused fluid (y‐axis) when a specific amount has accumulated in the fast‐exchange interstitial fluid space (x‐axis, Vt1).

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  Figure 5. Fixed parameters over time. The deviation of each parameter in the base model during each 10‐min period from 0 to 50 min from the estimate representing the period after 50 min. The estimates include both awake and anesthetized subjects and each analysis was performed together with all six parameters in the base model and the three first covariates shown in Table 3.