Pressure - Exam 4 MORS 113 Flashcards
- The force required to destribute an embalming fluid solution throughout the body.
- Action of force against an opposing force (a force applied or acting against resistance).
Pressure
With any mechanical injector, desired pressure should be set ______ it is permitted to flow into the body. This is accomplished by running the machine against a closed rate of flow while setting the pressure control.
Before
- Actual
- Blood
- Differential
- Injection
- Intravascular
- Potential
Types of Pressure
That pressure indicated by the injector gague needle when the arterial tube is open and the arterial solution is flowing into the body.
Actual Pressure
Pressure exerted by the blood on vessel walls measured in millimeters of mercury.
- When this pressure is too high, it can cause capillaries to pop.
Blood Pressure
Difference between potential and actual pressure.
Differential Pressure
Amount of pressure produced by an injection device to overcome initial resistance within (intravascular) or on (extravascular) the vascular system (arterial or venous).
Injection Pressure
Pressure deveoped as the flow of embalming solution is established and the elastic arterial walls expand and then contract, resulting in filling the capillary beds and development of pressure filtration.
Intravascular Pressure
Pressure indicated by the injector gague needle when the injector motor is running and the arterial tubing is clamped off.
Potential Pressure
Passage of embalming solution through the capillary wall to diffuse wtih the interstitial fluids by application of positive intravascular pressure. Embalming solution passes from an intravascular to an extravascular position.
Pressure Filtration
A supplemental piece of equipment attached to the embalming machine which measures the flow of fluids in both galls per hour and ounces per minute (more common is ounces per minute).
Flow Meter
Speed at which fluid is injected; measured in ounces per minute.
Rate of Flow
To force a fluid through (an organ or tissue), especially by way of the blood vessels; Injection during vascular (arterial) embalming.
Perfusion
Indicated by the amount of vascular resistance and the speed of fluid flow.
- No fluid flow without this.
- Calculated by subtracting the potential pressure from the actual pressure.
Note: Differential Pressure
In vascular injection, the arterial fluid solution moves toward tissue saturation by way of the arteries, to the arterioles, into the capillaries pushing the congested blood into the venules. From there into the veins, and then most importantly to:
The Point of Least Resistance or Easy Exit (Open Drain Tube or Forceps)
- The condition of the remains
- Body Temperature
- Solution Temperature
- Solution Characteristics
- Postmortem Interval
- The arterial tube (canula) lumen
- Drainage volume
- The progess of the embalming process
Factors Which Will Alter or Distort Pressure Requirements
The general vascular condition and degree of resistance will be th factors of cheif significance.
- Swelling
Pressure Requirements- The Condition of the Remains
Fluid moving to the areas of least resistance due to excessively rapid injector and may often necessitate multiple points of injection and drainage. The condition of the vascular system is most significant. If you should see this, turn the machine off and abduct the arteries and veins required. (Restricted cervical method may be used).
Swelling- The condition of the Remains
Time, as well as _________ are both unreliable indicators of pressure requirements.
Body Temperature
Warmth stimulates fluid penetration, and _____ ______ indicates the remains to tbe recently deceased. This situation tends to reduce pressure requirements, but it is also possible that a remains in ____ ______ may have severely sclerosed arteries or had a lingering agonal illness causing extensive agonal clot formation. This would raise the pressure requirements.
Postmortem Caloricity
The warmer the temperature, the more rapid the liberation of formaldehyde gas. This causes a decrease in pressure requirements, but only for short distances. Blood drainage will coagulate and harden in the vascular system, thus causing severe swelling when the pressure is increased to overcome drainage blocks.
Solution Temperature
Should only be used in desperation and cases of decomposition. Cold water embalming should be the norm in the vast majority of the cases. The rapid liberation of formaldehyde gas is not as important as the maximum fluid distribution and maximum drainage.
Hot Water Embalming
- Hot water
- High index (30+)
- Waterless embalming
3 Ways to do Instant Tissue Fixation (Head Freeze)
With today’s modern fluids, they play a very minor role. The lone exception is the improper use of humectant based restorative pre- and co-injections. These require an increase in pressure requirements and may lead to swelling and feature distortion. Use of the femoral artery for injection is recommended (only in last gallon).
Solution Characteristics
- Adds moisture in the body
- Maintains moisture loss
- Only used as a coinjection
- More viscous
- May lead to feature distortion and swelling
- Femoral is recommended for injection (as well as for active dyes).
Characteristics of Humectants
Their progress plays a major role in determining pressure requirements. Rigor mortis is the major change that affects pressure requirements because it exerts extravascular pressure, a compression of the vascular system.
Postmortem Interval (Postmortem chemical and physical changes)
One of the most popular of the many misconceptions is the belief that a small arterial tube can be used effectively to reduce injection pressure.
- As the diameter is decreased, pressure increases.
The Arterial Tube (canula) Lumen
Some of the more modern, so-called electronic machines have a built in rate of flow switch that functions on low speed when the rate of flow is constricted by vascular resistance. That is, the rate of flow will automatically decrease or increase depending on the diameter of the arterial tube.
Exception: The Arterial Tube (Canula) Lumen
The diameter of the drain tube and the volume of drainage has a measurable effect on the pressure requirements.
Drainage Volume
____ 1____ will reduce the arterial injection pressure requirements, while ___ __2___ will increase them.
- Copious Drainage
- Poor Drainage
A back pressure can be created to overcome vascular resistance and lossen clots, which will in turn decrease the pressure requirements from the machine.
Restricting Drainage
Vascular resistance rises progressively during injection. As the fluid moves from the larger vessels to the smaller vessels, the saturation of the tissues with arterial solution will decrease the rate of penetration until the arterial solution appears in drainage.
The Progress of the Embalming Process
Many embalmers have rejected this practice because as more and more fluid accumulates in the tissues and vessels, it offers a greater resistance to the entrance of still more solution. It may also cause feature swelling and distortion, known as water logging.
Pre-Injection
As you fill the ____, the pressure needle will not move. Once the ____ is filled, the pressure needle should twitch.
Aorta
That pressure which will overcome vascular resistance and cause a moderate, uniform movement of arterial solution from the injector into the vascular system and ultimately into the tissue cells.
Ideal (recommended) Injection Pressure
- Dislodge congested drainage (blood clots)
- Stimulate capillary filtration
- Minimize fluid loss due to excessive drainage.
- Saturate the capillary bed without causing ruptures.
- Penetrate surface tissue and not cause feature swelling.
Ideal Pressure Must be Sufficient to:
Becomes a variable factor and is often inaccurate. In some bodies, a gague reading of two pounds will cause A.F.S. to enter the body rapidly. In other bodies, ten pounds may be required.
Ideal (recommended) Pressure
Directly related to intravascular and extravascular factors affecting resistances to fluid distribution.
- Intravascular resistances
- Extravascular resistances
- Cause and manner of death
- Postmortem interval
- Types of apparatus used
Factors Affecting Injection Pressure
To fluid distribution, meaning within the vessels.
- Can also hinder diffusion (extravascular)
- Condition of the vascular system
- Local congestion
- Surface Tension
Intravascular Resistances
Diseases such as sclerosis, arteritis, phlebitis and syphillis, in addition to creating a demand for increase in pressure, may reduce the lumen of the vessels and create and abnormally high resistance to fluid distribution.
- Danger
- Fricitional resistance
Condition of the Vascular System