54 terms

# Oxygen Transport

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What is the equation for oxygen delivery to tissues?
Cardiac Output x Oxygen Content
DO2 = CO x CaO2
What are the two main compartments that get oxygen out to tissues?
Hemoglobin and Plasma
Hemoglobin Equation
1.34 x Hb x SaO2
Plasma Equation
.003 x PaO2
Plasma or Dissolved Compartment
O2 physically dissolved into blood, in capillary area.
Henry's Law
PO2
Hemoglobin or Combined Compartment
O2 chemically attaches to hemoglobin, can load up in lungs and unload. 98% of O2 carried this way.
Each gram of Hb can carry 1.34 ml of O2
Normal = 15 grams% per 100 ml of blood.
HCT / 3 =Hb.
As PO2 goes up your PaO2 goes up T or F
True, there is a direct relationship
For every 100 ml of blood 5 vol% are extracted
T or F
True, this is the A-V difference
What is normal CvO2?
15 vol%
Right Heart
What is normal CaO2?
20 vol%
Left Heart
Normal O2 Consumption
250 ml/min
Normal CO2 production
200 ml/min
What is normal Cardiac Output? CO
5 LPM
Venous Blood SvO2? PvO2?
75%
40 Torr
Arterial Blood SaO2? PaO2?
97%
90 Torr
What % of Cardiac Output doesn't participate in gas exchange?
2-5%
Oxygenated and NonOxygenated blood mixed
Shunt
Perfusion without Ventilation
What is the Transit time?
Less than 1 second
It is how long the RBC is in contact with the area where gas exchange takes place.
How many Hb molecules are in each RBC?
280 Million
How many molecules can the Hb hold? Atoms?
4 molecules or 8 atoms
Hb isn't fully saturated until what PO2?
150
Carbon Monoxide has what affinity ?
250x more than oxygen
Define Reduced Hb
Uncombined or deoxygenated Hb
Hb not bound with O2
Oxyhemoglobin Dissociation Curve
Relationship between PO2 and SO2
PO2 of 60
Is SaO2 of 90
if curve is normal
P50
What PO2 does it take to saturate hemoglobin to 50%
pH has a big effect on P50
When normal P50 is 27 Torr
Explain the steep part of the curve
How a small change in PO2 can cause a big change in the SaO2
Pulse Oximeter
Tells how much your hemoglobin is saturated
Shift to Right
P50 goes up. Makes it easier to give up O2, at tissue level
Shift to Left
P50 goes down. Holds onto O2 tighter. Loads up easier at capillary level.
Left Shift Causes
High- pH Low-PCO2, Low-Temp, Low-DPG,
HbF-(Fetal)
COHb
Right Shift Causes
Low-pH High-PCO2, High Temp, High-DPG
DPG
Contained inside RBC
Hb affinity for O2 decreases as DPG increases
Factor affecting CaO2-Anemia
Only 1/2 as much ability to do O2 transport by reducing amount of Hb to carry O2
Factor affecting CaO2-Polycythemia
Opposite of anemia, Increases Hb unless a result of Chronic Lung Disease
Factor affecting CaO2-Cyanide
Blocks ability of cells to uptake O2 at mitochondrial level
A-V difference becomes zero
Factor affecting CaO2-Altitude
Increases Hb over time, but SaO2 and PaO2 stay low.
Increase altitude =decrease PIO2
Short term= SaO2 and PaO2 decreases
Factor affecting CaO2-Hyperbarics
Only slightly affects SaO2 but affects plasma significantly
Factor affecting CaO2- Carbon Monoxide
Hb affect cant do O2 transport because its bound up with Carbon Monoxide PO2 not reliable anymore
If you keep the numbers the same and you reduce Co what happens?
Only half as much O2 is delivered, but the content is the same. When CO decreases your DO2 changes.
Factors that decrease the SvO2
Decreased CO, Periods of increased O2 consumption
Exercise, Seizures, Shivers, Hyperthermia
4 Types of Hypoxia
Hypoxic Hypoxia
Anemic
Circulatory
Histotoxic
Hypoxic Hypoxia
Low Alveolar PO2, Diffusion Impairment, V/Q Mismatch
Fix=Increase FIO2
Define Hypoxia
Low O2 at the cellular level
Define Hypoxemia
Low O2 in the blood
What is the greatest cause of Hypoxia in the hospital
V/Q Mismatch
Anemic Hypoxia
Low O2 at cellular level because of anemia
Blood carrier problem, Low Hb, Inability of Hb to carry O2
Ex. Carbon monoxide poisoning
How to treat Carbon Monoxide Poisoning
1st-get out of area to fresh air
2nd-Use non-rebreather to give highest FIO2 possible
3rd-Evaluate need for Hyperbaric chamber
Circulatory Hypoxia (Stagnet)
Arterial Venous Shunting-instead of going to tissues arterial blood goes back to venous blood circulation
Blood doesnt circulate well
No adequate perfusion to the core during CPR
Histotoxic Hypoxia
Classic Example-Cyanide poisoning
Tissues cant uptake O2
Cyanide doesnt allow the cells to utilize the oxygen delivered
Define what makes you Cyanotic
5 grams% reduced Hb in 100 ml of blood
Define OxyHb
Combined or Oxygenated Hb
Hb bound with O2
CarboxyHb
Carbon Monoxide bound to Hb