Diffusion/O2 transport/Co2 transport

Venous admixture

Mixing of shunted blood and oxygenated blood

Two Ways Oxygen can be transported

In plasma and bound to hemoglobin

Normal transit time of blood flow through the capillaries

0.3-1 seconds

Under normal conditions, how long does it take oxygen and carbon dioxide to diffuse across the alveolar-capillary membrane

0.75 seconds

At a normal body temp, alveolar gas contains humidity in the form of water vapor that exerts a force of what

47mmHg

Hypoxia Hypoxia

Inadequate oxygen at the tissue level due to a low PaO2

At a normal body temperature each hemoglobin has the ability to bind to how many mLs of Oxygen

1.34mL

What is the normal hemoglobin range for a male? Female?

14-16mL, 12-15mL

What can cause a right shift in the oxyhemoglobin dissociation curve

Decreased in pH, increase in temp, increase in 2-3 BPG

What can cause a left shift in the oxyhemoglobin dissociation curve?

Increase in pH, decrease in temp and decrease in 2-3 BPG

Oxyhemoglobin

Hemoglobin bound to Oxygen

In a normal adult hemoglobin, how many heme groups are there?

4

Polycythemia

Increased production of RBCs in response to chronically low oxygen levels

CO2 diffuses across the alveolar-capillary membrane how many times faster than O2

20 times

What is the test that determines the diffusing rate across the alveolar-capillary membrane

DLCO (diffusion capacity of carbon monoxide)

CO2 has an affinity for hemoglobin how many times greater than O2

210x greater

Is absolute shunting responsive to O2 therapy

No

Abnormal Anatomic shunts

Congenital heart disease, intrapulmonary fistula, vascular lung tumors

P50

Point of oxyhemoglobin dissociation curve where the hemoglobin is 50% saturated

760mmHg

Barometric pressure at sea level

Dalton’s Law

Law of partial pressure tells us the total pressure exerted by a mixture of gases is the sum off the pressure extorted individually by each gas

Diffusion

Movement of gas particles from an area of high concentration to an area of low concentration

Fick’s Law

The diffusion of gas is directly proportional to the surface area the diffusion constant and the partial pressure difference and inversely proportional to the thickness of the tissue that gas is diffusing through

Henry’s Law

Amount of gas dissolved in a liquid at a given temp is proportional to the partial pressure of the gas, carbon dioxide is 24 times more soluble in a liquid medium than oxygen

Graham’s Law

The rate of diffusion of a gas through a liquid is directly proportional to the solubility coefficient of the gas, indirectly proportional to the square root of the gram molecular weight of the gas

Gram molecular weight of Oxygen

5.6

Gram molecular weight of carbon dioxide

6.6

A-a gradient

Difference of alveolar and arterial (as you get older, the gradient increases)

PAO2

Alveolar partial pressure of oxygen

Henry’s Law

The amount of a gas dissolved in a liquid is proportional to its partial pressure

Left Shift

Hang onto Oxygen (LOVE)

Right shift

Give up oxygen (RELEASE)

Absolute shunt

Shunts where you have flow going through but because of ventilation issues you can’t get alveolar oxygen to the blood

Relative shunt

Something that induces a shunt like effect

Hypoxemia

Low oxygen in blood

Normal PaO2 levels

80-100 torr

Mild hypoxemia

60-80 torr

Moderate hypoxemia

40-60 torr

Severe hypoxemia

<40 torr

Anemic hypoxia

Doesn’t have enough hemoglobin or the hemoglobin that we do have is not functioning properly

Circulatory hypoxia

Decrease cardiac output or clots

Histotoxic Hypoxia (Dysoxia)

Tissue calls have an impaired ability to use (cyanide)

CO2 transport

6 ways (3 in plasma, 3 in RBC)

Plasma transport

Carbamino compound, hydrolysis, dissolved in CO2

RBC transport

Intracellular fluid, carbamino - Hb, hydrolysis with carbonic anhydrase

Haldane effect

In the presence of deoxygenated blood the loading of CO2 is enhanced