The passage of a diffusible indicator through a microvascular system.

The Aim: (1) To develop a mathematical model of the passage of a diffusible indicator through microcirculation based on a stochastic description of diffusion and flow; (2) To use Goresky transform of the dilution curves of the diffusible indicators for the estimation of the permeability of a tissue-capillary barrier.

The Method: We assume that there are two causes for flow to be stochastic: (a) All microvessels are divided between open and closed microvessels. There exists random exchange between the two groups.

Hemodynamic recovery after hypovolemic shock with lactated Ringer's and keratin resuscitation fluid (KRF), a novel colloid.

Death after severe hemorrhage remains an important cause of mortality in people under 50 years of age. Keratin resuscitation fluid (KRF) is a novel resuscitation solution made from keratin protein that may restore cardiovascular stability. This postulate was tested in rats that were exsanguinated to 40% of their blood volume.

Stochasticity of flow through microcirculation as a regulator of oxygen delivery.

Objective: Observations of microcirculation reveal that the blood flow is subject to interruptions and resumptions. Accepting that blood randomly stops and resumes, one can show that the randomness could be a powerful means to match oxygen delivery with oxygen demand.

Method: The ability of the randomness to regulate oxygen delivery is based on two suppositions: (a) the probability for flow to stop does not depend on the time of uninterrupted flow, thus the number of interruptions of flow follows a Poisson distribution; (b) the probability to resume the flow does not depend on the time for flow being interrupted; meaning that time spent by erythrocytes at rest follows an exponential distribution.

Theory and in vitro validation of a new extracorporeal arteriovenous loop approach for hemodynamic assessment in pediatric and neonatal intensive care unit patients.

Objectives: No simple method exists for repeatedly measuring cardiac output in intensive care pediatric and neonatal patients. The purpose of this study is to present the theory and examine the in vitro accuracy of a new ultrasound dilution cardiac output measurement technology in which an extracorporeal arteriovenous tubing loop is inserted between existing arterial and venous catheters.

Design: Laboratory experiments.

Determining lung water volume in stable hemodialysis patients.

Lung water (LW) reflects the water content of the lung interstitium. Because hemodialysis patients have expanded total body water (TBW) they may also have increased LW. Hypertonic saline promotes a flux of water from lung to blood, which is measured by ultrasound flow probes on hemodialysis tubing.