CAE Healthcare Fidelis Lucina, User Manual

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Using Lucina
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Hematology Model
The physiological model calculates hematocrit values (i.e. percentage of total blood hemoglobin)
dynamically and continuously, taking into account blood and fluid losses, as well as the intravenous
infusion of fluids such as whole blood, packed red blood cells, colloids and crystalloids.
Instructors can create patients with both normal and pathophysiological hematocrit levels. In addition,
learners discover how administering various fluids affects hematocrit, the oxygen-carrying capacity of
blood, and the resulting patient response.
The following important assumptions have been made in the design of the Hematology Model:
• Blood is comprised of two components: red blood cells and plasma.
• Plasma is comprised of two components: colloid and crystalloid. The term
colloid is used to describe substances that generate a clinically significant
colloid osmotic pressure - for example, fresh frozen plasma, albumin and
hetastarch. The term “crystalloid” is used to describe salt solutions for
infusion - for example, normal saline, dextrose in water and Ringer’s
Lactate.
• The mixing of blood and its various constituents is instantaneous and
homogeneous. In other words, one liter of crystalloid administered
intravenously equilibrates immediately and homogeneously throughout
the entire circulation.
• This Hematology Model does not distinguish between the differing clinical
effects of colloids and crystalloids. For example, osmotic pressures and
capillary leakage rates are not taken into account. Likewise, fluid kinetics
and fluid distribution within the circulation and interstitial and intracellular
spaces are also not modeled.
In the Hematology Model, the following model variables, definitions and relationships have been
established:
• Red Blood Cell Volume : The volume of red blood cells within the circulation.
• Plasma Volume : The volume of plasma within the circulation.
• Total Blood Volume: The volume of blood (i.e. Red Blood Cell Plasma
Volume) within the circulation.
• Blood Volume Loss: The amount or rate of decrease in the total blood volume. A given
amount or rate of blood loss proportionally decreases both the Red Blood Cell Volume
and the Plasma Volume according to the current hematocrit.
• Plasma Volume Loss: The amount or rate of decrease in the plasma volume. A given
amount or rate of plasma loss decreases the plasma volume without changing the
red blood cell volume. Plasma Volume Loss refers collectively and generically to all
plasma fluid losses, including evaporative, transcellular (e.g. ascites, pleural effusion),
bowel and third space losses.
• Hematocrit: The ratio of Red Blood Cell Volume to Total Blood Volume,
expressed as a percentage.