Chapter 13: Distribution and Diffusion of Arterial Solution

Left off on slide 21

Capillary embalming

Arterial solution is delivered via the arterial system to the capillaries. The goal is to have arterial solution diffuse from the capillaries (intravascular) to the interstitial (extravascular) spaces inside and between body cells. Just as the vascular system and blood brought oxygen and nutrients to the cells during life

The four processes that take place at the same time once flow is established during embalming.

• Injection (Delivery)
• Distribution
• Diffusion
• Drainage

Injection (Delivery)

The delivery of solution from the embalming machine into the artery

Distribution

Movement of arterial solution from the point of injection throughout the arterial system

Diffusion

The movement of arterial solution from inside the vascular system (intravascular) through the walls of the capillaries to the tissues (extravascular)

Drainage

The displacement and discharge of blood, blood clots, embalming solution, interstitial and lymphatic fluids from the body.

Arterial Solution at the Micro-Circulation Level

1. Some solution flows to the capillaries and passes through the capillary walls.

2. Some solution flows through the capillaries and into the venous system.

3. Some solution flows directly from the arteries to the venules

Causes of Intravascular Resistance

• Arteriosclerotic or atherosclerotic narrowing of the lumen of the vessel
• Blockage of the vessel by thrombosis or embolism
• Blockage by postmortem coagula
• Vasoconstriction
• Inflammation of vessels

Overcoming Intravascular Resistance

• Sufficient pressure and rate of flow
• Sectional embalming
• Avoid sclerotic arteries if possible
• Use the largest artery available
• Use the proper size arterial tube

Causes of Extravascular Resistance

• Rigor mortis
• Gas in the cavities
• Expansion of Hollow Viscera
• Tumors and swollen lymph nodes
• Ascites and hydrothorax
• Contact pressure
• Visceral weight
• Bandages
• Skeletal edema
• Inflammation

embalming solution would pass directly through the capillaries into the venous system

Why is vascular pressure necessary for diffusion?

Opening and closing drainage

How can embalmers control arterial pressure?

Yes

Does delayed aspiration help diffusion?

least resistance

arterial solution takes the path of…

no, the solution will not diffuse

Can tissues be preserved without vascular pressure?

Signs that solution is being distributed through the vascular system

• The volume in the tank of your embalming machine is decreasing.
• Pressure reading decreases when flow is opened
• You should be getting drainage

Injection Pressure

The amount of pressure produced by an injection device to overcome initial resistance within the vascular system

Ideal Pressure

The pressure needed to overcome the vascular resistances of the body to distribute the embalming solution to all areas of the body

Ideal Rate of Flow

Flow needed to achieve uniform distribution without distention of the tissues

Pressure

force exerted on an area

Potential Pressure

Pressure indicated by the injector gauge needle when the injector motor is running and the arterial tubing is clamped off.

Potential Pressure Example

When machine valve or stopcock is closed, there is no rate of flow. Pressure builds in the hose until it reaches the pressure set by the valve in the embalming machine (pressure is displayed on the gauge). Any excess empties back into the tank.

Actual Pressure

The pressure indicated by the injector gauge needle when the arterial tube is open and the arterial solution is flowing into the body. The vascular pressure of fluid moving through the body and out of a drainage site.

Actual Pressure Example

If the valve is fully opened the pressure becomes the Force applied to not only the hose and the valve, but to the entire circulatory system of the body, which is the new area. The body has its own pressure (vascular occlusion and blood volume). The pressure of the system becomes equal to the body’s vascular pressure. Flow in excess of this pressure feeds back into the tank of the machine.

Rate of Flow

The amount per unit of time flowing through the body

Rate of Flow Example

If a drainage point is created, pressure decreases until it reaches the open vascular resistance. The liquid moving from the area of higher pressure to the area of lower pressure per unit of time.

Differential Pressure

The difference between potential pressure and actual pressure, an indication of the rate of flow, or how fast we are embalming.

low

If the differential pressure is high, then rate of flow is…

Rate of Flow

The amount per unit of time flowing through the body

Gauge: Closed, potential pressure

Gauge: open, actual pressure

Gauge: rate of flow, differential pressure

Arch of the Aorta

the center of distribution

Right Atrium of the Heart

the center of drainage

what vessels come off of the arch of the aorta?

the brachiocephalic artery, left common carotid, and left subclavian

Signs of Distribution

• Observation of active dye

• Distension of superficial blood vessels

• Blood drainage

• Bleaching/drying/filling of tissues

• Loss of skin elasticity/firming of tissues

• Leakage from IV punctures

• Clearing of intravascular blood discolorations

If you take note of these conditions of the tissues before injection, you will see changes in the tissues during arterial injection

• Livor mortis

• Rigor mortis

• Superficial vascular distension

• Skin discolorations, including pallor

• Tissue firmness

Best Practice regarding Distribution

Most embalmers use several signs of distribution to ensure that a sufficient amount of arterial solution has reached a body area

Distribution

why does drainage occur?

50%

How much solution is lost to drainage?

It does not enter the tissues

Why is solution lost to drainage?

Improving Arterial Distribution

• Firm massage

• Injection with pulsation

• Temporarily increase pressure

• Temporarily increase rate of flow

• Inject an adequate amount of solution

• Restricted drainage (intermittent and alternate)

• Relieve extreme abdominal pressure caused by fluid or edema

• Use measures to improve drainage

The process by which diffusion occurs, requires no energy by the cell to operate.

Diffusion of Arterial Solution

• Blood nutrients and oxygen pass through the walls of the capillaries and into the interstitial fluid. The interstitial fluid comes into contact with the tissues.

• The key to successful arterial embalming

• Blood does not come into direct contact with most body tissues

Pressure Filtration

• Caused by intravascular pressure

• The most important passive transport system

• Both the solute and the solvent can pass through the walls of the capillary

• The remainder of the solution that does not enter the interstitial spaces moves through the capillaries and takes with it the blood that was forced out, carrying it away as drainage

Osmosis

A passive transport mechanism. The solvent passes through a semipermeable membrane FROM the side that is more dilute TO the side that has more solute. The solute consists of the chemicals dissolved in the embalming solution. The solvent (water) passes through the capillary walls.

hypotonic solution

more dilute (less dense) and water moves into the interstitial tissues

hypertonic solution

less dilute (more dense) and will draw water from the interstitial tissues

If there are more solutes outside the cell than inside

Fluids tend to try to spread out solutes so that they are evenly distributed. Osmosis will carry the chemicals in the embalming solution through the cell wall into the cell.

Osmotic Pressure

The hydrostatic pressure produced by a difference in concentration (dilution) between the solution on the two sides of a semi permeable membrane.

Osmotic Pressure with an Isotonic Solution

there is no hydrostatic pressure and the solvent will not move through the membrane

Dialysis

The diffusion of crystalloid solutes of a solution through a semi-permeable membrane.

1. Diffusion of the dissolved crystalloid (little) solutes of a solution through a semipermeable membrane.

2. Colloids (big) solutes cannot pass through the cell membrane, but crystalloids can.

Embalming solutions containing crystalloid solutes (small solutes)

• Formaldehyde

• Preservatives

• Germicides

Gravity Filtration

• The extravascular settling of embalming solution, by gravitational force, into the dependent areas of the body

• Not gravitation through the vascular system, the movement of solution through the interstitial fluid.

Areas of the Body that Gravity Filtration Pertains to

• Lower back

• Buttocks

• Backs of arms

• Backs of legs

• Shoulders

Signs of Diffusion

• Loss of skin elasticity

• Firming of the deep tissues

• Drying of the tissues

• Rounding of the fingertips, lips and toes

• Mottling and bleaching of the tis