O2 Content and Delivery
What is normal oxygen delivery rate?
1000 mls O2/min
Oxygen Content of Venous Blood=
15 mls O2/100 mls of blood
Calculating Oxygen Content of Venous Blood: What is the O2 content of venous blood?
15 mls O2/dL of blood
Oxygen Content of Arterial Blood=
20 mls O2/100 mls blood
Oxygen Content of Arterial Blood:
= HbO2 + dissolved = ([Hb]) x (carrying capacity of Hb) x (% sat) + (0.0031 x PaO2 in mm Hg) = (15x1.34x.98) + (0.0031 x 100 mm Hg) = 19.69 + 0.31 = 20 mls O2/100 mls blood
What is the total O2 content when PaO2= 100 mm Hg?
= HbO2 + dissolved O2 = 19.7 mls O2/100 mls blood + 0.3 mls O2/100 mls blood = 20 mls O2/100 mls blood
Delivery= Cardiac Output x Oxygen Content
= [HR x SV] x [(Hb capacity x Hb conc x % Hb Saturation) + 0.0031 x PaO2 mm Hg)] = 5000 mls/min x 20 mls O2 per 100 mls blood = 1000 mls O2/min delivered to the tissues
HR=
Heart Rate (about 72 beats/minute)
Oxygen Delivery to Tissues: Delivery=
Cardiac Output x Oxygen Content
For a 'normal' person, increased heart rate, stroke volume, and Hb concentration will all significantly increase...
O2 delivery
SV=
Stroke Volume (about 70 mls per beat)
On average, we consumer about 250 mls O2/min, but this can increase significantly during...
exercise
In disease, increasing PaO2 and hence HbO2 saturation, (blank) O2 content.
increase
During CO Poisoning, other than increasing dissolved O2 content via increased atmospheric pressure, what can we do?
increase the delivery rate of O2
Typically people with chronic anemia have an....
increased heart rate (because trying to maintain delivery in the face of a lower content)
In polycythemia Hb concentration...
increases
How can we increase the delivery rate of O2 during CO poisoning?
increasing cardiac output (from 5000 mls/min to 6000 mls/min)
Hb concentration can be altered and will change the...
oxygen content
Anything that increases any of the variables in the delivery equation will increase the amount of...
oxygen that is delivered to the tissues
Calculating Oxygen Content of Venous Blood: What is HbO2 saturation?
75%
How does Oxyen Content change in Disease? Anemia
Decreased oxygen content (13.44 mls O2/100 mls of blood)
Cardiac Output During Anemia:
It increases (by increasing our heart rate)
How does Oxygen Content Change in CO Poisoning? % sat...
decreases to 50%
For venous blood, the PvO2=
40 mm Hg
How much O2 is extracted from 100 mls of blood?
5 mls O2 per 100 mls of blood
How do we treat CO poisoning?
Increase dissolved O2 content via increased atmospheric pressure (3 atm)
How Does Oxygen Content Change in Disease? Polycythemia- disease originates in bone marrow
Increased oxygen content (26.57 mls O2/100 mls of blood)
How does Oxygen Content Change in CO Poisoning? oxygen content...
decreases to 10.36 mls O2/100 mls of blood
In anemia Hb concentration...
decreases
