Session 1 Principles Flashcards
Vein used in CABG procedure?
Saphenous Vein
What is the formula for “Oxygen Delivery”?
DO2 = arterial O2 x cardiac output
What is the formula for “Oxygen Consumption”?
VO2 = (arterial O2 - venous O2) x cardiac output
What is the formula for “Oxygen Extraction Ratio”?
OER = consumption/delivery or VO2/DO2
Oxygen transport (DO2) is based on what normally?
Demand of tissues.
Balance between intravascular and extravascular fluid volume is important for which compounds in the body primarily?
Electrolytes. Hyponatremia and Hypokalemia
What 3 main variables can affect delivery of oxygen from outside air to tissues?
Atmospheric air, air quality and humidity.
Upper respiratory tract is compromised of what structures?
Nasal cavity, pharynx and larynx.
Lower respiratory tract is composed of the following..?
Trachea, Primary bronchi, and lungs.
Smoking does what to cilia? (generally speaking)
Paralyzes the cilia.
Muscles involved with inspiration that lead to increased volume of pleural cavities
External intercostals ( elevate ribs), diaphragm, depress inferior wall of thoracic cacvity. Scalenes/ Sternocleidomastoid as well
Muscles involved with expiration that lead to decreased volume of pleural cavities
internal intercostals (compress ribs), abdominals ( compress abdominal cavity)
What is diffusion for CVP?
Transfer of oxygen from alveolar sacs to pulmonary circulation.
What is diffusion based on?
1) Surface area of alveolar membrane
2) Diffusing capacity of alveolar capillary membrane
3) Pulmonary capillary blood volume
4) Ventilation/perfusion ratio
5) Transit time of blood in alveolar capillary membrane
What is perfusion?
Blood flow.
How to optimize a patient’s ventillation?
Keep them upright (gravity).
How does surface area and thickness affect the diffusion of O2 through a membrane?
Decreased surface area and increased thickness will DECREASE the amount of O2 in the blood
Increased surface area and decreased thickness will INCREASE the amount of O2 in the blood.
Perfusion is greatest at the top or base of the lung due to gravity?
What is the ideal Ventilation/Perfusion ratio?
Base
.8
Myocardial function depends on the coupling of what 2 things?
Electrical conduction and mechanical conduction coupling.
Define Preload
End-Diastolic pressure when the ventricle is filled.
Amount of tension on the muscle when it begins to contract
Define Afterload
Pressure in the artery leading from the ventricle.
Load against which the muscle exerts its contractile force.
If you have a higher preload…
You have higher volume of blood in the heart.
Large vessels have what characteristics of the tissue generally?
elastic connective tissues to withstand larger pressure.
Medium to small vessels have more what?
Smooth muscle
Arterioles regulate what?
Blood flow through regional vascular beds (capillaries).
What is oncotic pressure?
Pressure from proteins to pull water into circulatory system.
What is hydrostatic pressure?
Pressure from fluid on it’s neighboring walls.
How is pressure maintained in the capillary beds through pressure (oncotic vs hydrostatic)?
Hydrostatic pressure pushes water away from capillary beds, while oncotic pressure pulls in water due to the higher concentration of proteins that are too large enough to cross over.
Oncotic pressure pulls in, hydrostatic pushes out.
Average extraction rate for O2?
23%
Rate of O2 extraction regulated by what?
DEMAND of oxygen, not availability.
Factors that alter O2 transport?
Normal factors: activity, stresses, anatomical position.
Disease states, infection, medication, fluid imbalance, fever, bedrest.
Greatest influence on O2 transport?
Gravity.
Restricted activity does what to cardiac output, VO2, and OER?
Decreases.
Loss of gravity will shift fluid where?
Towards head and thorax
