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Oxygen Transport

Terms in this set (29)

Normal blood gas range Arterial
pH 7.35-7.45
Pco2 35-45 mm Hg PaCO2
HCO2 22-28 mEq/L
Po2 80-100 mm Hg Pa02
Normal blood gas range Venous
ph 7.30-7.40
Pco2 42-48 mmHg PVc02
HCO2 24-30 mEq/L
Po2 35-45 mm Hg PbO2
As Oxygen diffuses from the alveoli into the pulmonary capillary blood, it dissolves in the plasma of the blood.
...
Dissolve
when a gas like oxygen enters the plasma, it maintains its precise molecular structure (in this case, O2) and moves freely throughout the plasma in its normal gaseous state.
Henry's Law
states that the amount of gas that dissolves in a liquid at a given temperature is proportional to the partial pressure of the gas.
How much oxygen will dissolve at normal body temperature, in blood.
about 0.003 mL of oxygen will dissovel in 100mL of blood every 1 mm HG or Po2.
How much hemolobin molecules does RBC contain
280 million
What is the normal about of hemoglobin in the body
12 to 15%
Reasons for normal physiologic shunts
Thebesian venous drainage into the left atrium
Bronchial venous drainage into the pulmonary veins
Alveoli that are under ventilated relative to pulmonary blood flow
The total oxygen content of the arterial blood (Ca02), mixed venous blood (Cvo2), and pulmonary capillary blood (Cco2) is calculated as follows...
Ca02 : (Hb x 1.34 x Sao2) + (Pa02 x 0.003)
Cvo2 : (Hb x 1.34 x Sv02) + (Pv02 x 0.003)
Cc02 : (Hb x 1.34 ) + (PA02 x 0.003)
PA02 : ([PB - 47].21) - ( PaC02 x 1.25)
PAO2
Normal over 100 on R/A but never over 120 or assume the pt. has had O2.
47= PH2O
Normal PB 760
P(A-a)
PAO2-PaO2
Should be 5-10 mmHg on R/A and 65mmHg on 100%
Dissociation Curve
Plots the relationship between Hgb and plasma PO2
S Shaped curve with steep slope where O2 combines rapidly as PO2 increases
Flat portion sees little change in SaO2 for increases or PO2
Oxygen dissociation curve
Normally P50 is about 27mm Hg. when the curve shifts to the left or right it causes the P50 to change.
What causes a shift to the left
Affinity of hemoglobin for oxygen increases, causing the hemoglobin to be more saturated at a given P02. The P50 decreases when this happens. When hemoglobin reaches the tissues the oxygen is not released.
Decreased Body temp, PH increase and 2,3 DPG concentration increased, Decreased levels of CO2, T, [H}
What causes a shift to the right
Affinity of hemoglobin for oxygen decreases, causing hemoglobin to be less saturated at a given P02. the P50 increases.
Increased body temp, PH is offset somewhat by the increased 2,3 DPG level which shifts the curve to the right.conversely as the PH decreases, the 2,3 DPG concentration decreases, Raised levels of CO2, T, [H]
2,3 Diphosphoglycerate
Stabilizes Hgb and reduces affinity for oxygen so it is released easier
Stored blood has low levels
Total oxygen delivery DO2
D02 : QT x (Ca02 x 10)
Arterial venous oxygen content difference C(a-v)O2
CaO2-CVO2
Oxygen consumption or Oxygen uptake VO2
QT[C(a-V)O2 x 10]
Factors to increase the C(a-v)02
Exercise
Seizures
Shivering
Hyperthermia
Factors that decrease the C(a-v)O2
Increased cardiac output
Skeletal muscle relaxation
Peripheral shunting
Certain poisons
Hypothermia
Classic shunt equation Qs/Qt %
CcO2- CaO2
-----------
Cc02-Cvo2
Pulmonary Shunting
Defined as a portion or C.O. that enters the left side of the heard without exchanging gases.
Anatomic shunt due to bronchial and thevesian veins or anomalies.
Capillary shunt due to alveolar collapse, consolidation or fluid accumulation
There can also be a "Shunt-like effect"
Normal Shunt
less the 10%
10-20% indicates intrapulmonary abn
20-30% significant diseases
Each g% of Hb is capable of carrying approximately how many mL os oxygen
1.34 mL of oxygen
Which is attached to Hgb
What is Bohr effect
the affect of CO2 on the loading of O2
Cyanosis
exists when more than 5 grams of Hgb are reduced in 100 ml of blood
SaO2 x Hgb then subtract from total amt of Hgb
Types of Hypoxia
Hypoxemic Hypoxia
Anemic Hypoxia
Circulatory Hypoxia
Histotoxic Hypoxia
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