Lecture 5 Oxygen Flashcards
Oxygen that diffuses from the lung or oxygenator into blood is carried in two forms
(PaO2)
SO2
Oxygen dissolved in plasma ?
Percentage?
PaO2
2%
Oxygen bound to hemoglobin ?
Percentage?
SO2
98%
Hb consist of____ heme groups, each heme molecule can carry 1 oxygen molecule
4
measurement of of the amount of oxygen bound to Hb measured in percent)
Oxygen Saturation
Hb + O2 =
HbO2
One gram of Hb can carry ?
1.36 mL O2
_____ _____ reflects optimal conditions that exist to facilitate oxygen loading ion the lung and unloading in the tissue
Sigmoid Shape
oxyhemoglobin dissociation curve
oxyhemoglobin dissociation curve reflects a relationship between ____ ____ ?
Y= SO2 (Oxygen Saturation)
X = PO2 (Partial Pressure)
What does “Hemoglobin-oxygen affinity” mean ?
strength of bond between Hb and O2
P50
PO2 value where 50% of the hemoglobin is saturated
What is a normal P50 value under standard conditions ?
27 mmHg
(pH=7.40, PCO2=40mmHg,
37C, normal 2,3 DPG)
Picture the oxyhemoglobin dissociation curve, In arterial blood,
Large ∆s in PO2 result in
Small ∆s in SO2
Picture the oxyhemoglobin dissociation curve, In venous blood,
small ∆s in PO2 result in ?
large ∆s in SO2
4 things that can affect oxygen affinity ?
- pH
- Temperature
- PCO2
- 2,3 DPG (a byproduct
of RBC metabolism)
Colder temp effects affinity shifts by ?
Increasing Affinity
Warmer temp effects affinity shifts by ?
Decreasing Affinity
What are the results of a LEFT shift in Hemoglobin-oxygen affinity ?
↑ affinity between O2 & hgb.
↑ pH
↓ PCO2
↓Temp
↓2,3-DPG
What are the results of a RIGHT shift in Hemoglobin-oxygen affinity ?
↓ affinity between O2 & hgb.
↓ pH
↑ PCO2
↑Temp
↑2,3-DPG
2,3 DPG
(a byproduct of RBC metabolism)
Oxygen Saturation
ratio of oxygenated Hb: total Hb in 100 ml blood (%)
Arterial Blood Oxygen Supply-Loading.
96 - 98%
Venous Blood Oxygen Supply-Loading
65 - 75% (mixed), SvO2
(CaO2)
(Oxygen Content)
The amount of oxygen in 100 ml of whole blood
Normal Range for Oxygen Content (CaO2) ?
Normal Range = 17 - 20 %
CaO2 equation ?
(1.36 x Hb x SO2) + (.0031 x PO2)
Dissolved O2 is insignificant at normalCaO2 is highly dependent on what ?
[Hb] & Sats
O2 bound to Hb
(1.36 x Hb x SO2)
O2 dissolved
(.0031 x PO2)
Oxygen (Delivery)
DO2
The amount of oxygen being delivered to the tissues. Units (mlO2/min)
(DO2) equation ?
C.O. X CaO2 X 10
Oxygen Consumption (extraction)
The total amount of oxygen consumed by the body per minute
Oxygen Consumption (VO2) Used in conjunction with oxygen transport (DO2) to assess what?
the balance between oxygen supply & demand
Oxygen Consumption (extraction) VO2 normal range ?
200 - 290 mlO2
Primary Oxygen Consumption /extraction(VO2) equation ?
C.O. X 10 X Hgb X 1.36 X (SaO2 - SvO2)
VO2 =
Oxygen Consumption /extraction
Normal range = 200 -290
DO2 =
Oxygen Transport/Delivery
Normal Range =
900 - 1000 ml/min
CaO2 =
Oxygen Content
Normal Range = 17 - 20 %
Oxygen consumption is a good index of
oxygen requirements
Dynamics of O2 Supply/Demand. If you ↑ C.O. you, ?
↓ O2 Supply
↑ O2 Demand
Dynamics of O2 Supply/Demand. ↑ O2 Extraction is reflected by ?
Larger Arterial / Venous saturation difference.
Dynamics of O2 Supply/Demand. What are the 3 compensatory mechanisms ?
- ) ↑ C.O.
- ) ↑ Extraction
- ) Selective Redistribution
4 Specific Threats to O2 Balance ?
- ) ↑ O2 consumption
- ) ↓ in Hb
- ) ↓ in SaO2
- ) ↓ in C.O.
Mixed Venous Oxygen Saturations (SvO2) equation ?
O2 delivered - O2 consumed
A decrease in SvO2 indicates what ?
that the body has called upon its last line of defense to preserve O2 balance and intervention may be appropriate.
Continuous In-Line Blood Monitoring of blood gas parameters improves and simplifies perfusion management. It also improves what ?
Patient Safety
Mixed Venous Oxygen Saturations from a PA catheter ?
good mixing of IVC,SVC, and coronary sinus blood
What do you do when on CPB:
SvO2 Drops from 80% to 60% over 5 minutes ?
↑ Flow