Evaluation of hydration status calculated from differences in venous and capillary plasma dilution during stepwise crystalloid infusions: A randomized crossover study in healthy volunteers

Abstract

Veno-capillary dilution difference during mVLT depends on the hydration status. The mVLT method could possibly discriminate between the different states of hydration.

Revised Evaluation of Hemodilution Response in the Semi-Closed Loop Infusion System

“…The phenomenon of negative acPED is explained by the level of tissue hydration in which interstitium releases excessive fluid into capillaries during the 5 min period with no fluids after a bolus. Our model, which is described in detail within previous reports [1], [2], is similar to the recently proposed 'physiological model' outlined within the 'Discussion' of the retrospective analysis of data from previous volume kinetic studies in healthy volunteers and patients [14]. The feasibility of the models needs evidence from the direct measurments of changes in pertinent tissues as they expand during the goal directed fluid infusion.…”

“…6) implies that fluid loading is not indicated when hemodilution in capillaries is higher than in arteries as suggested by cPDE > 0.028 p.d.u., according to the results of the present study. The background concept of the mVLT is depicted on physiological basis in the transcapillary reflux model [1], [2]. It explains the changes in acPED during the incremental hemodilution in the the context of changes in viscoelastic properties of the tissues that surround capillaries and the rate of systemic fluid elimination from circulation.…”

“…A mini volume loading test (mVLT) is used for decision making in a semi-closed loop infusion system (SCLIS) [1]- [5]. The mVLT fluid protocol implies hemodilution guided mini fluid challenges.…”

“…The assessment of hemodilution response requires hemoglobin measures before and after each mini fluid challenge (MFC). Hemoglobin in arteries (invasive, aHb) and capillaries (non-invasive, SpHb) are used to calculate the arterial and capillary plasma dilution efficacies (aPDE and cPDE, respectively) and arteriocapillary plasmadilution efficacy difference (acPED) [1], [3]. Based on observations in healthy volunteers [1] and patients [2], a transcapillary reflux model suggests that acPED ≤ 0 p.d.u.…”

In Silico Testing of the Semi-Closed Loop Infusion System with a New Simulator

“…However, conventional clinical methods are not sufficiently sensitive and specific for the detection of when the necessary fluid accumulation in tissues turns into edema during hemodynamic optimization by fluids. Thus, a mini Volume Loading Test (mVLT) for detection of imminent edema during stepwise infusion was proposed [9]- [11]. It requires measurement of haemoglobin concentration (Hb) before and after each fluid challenge.…”