Exam 3 Flashcards
Before getting an ABG on a pt what steps should one take
Review chart for physician’s orders
Check on pt’s condition
What does the Modified Allen’s test show
Clotting ability and collateral circulation
Define Arteriotomy
Sample obtained by insertion of needle into a major artery
Name some sites where one can obtain an ABG
Radial
Dorsalis pedis
Bronchial
Femoral
What is the difference between arterial and venous
Arterial - provides more info regarding oxygenation and acid-base balance
Provides info on lung function and the adequacy of CO2 removal
How long should you apply pressure for after ABG
Until it stops bleeding
Define thrombosis
Formation of an abnormal clot within the vessel which can lead to cessation of blood flow
Define Hemorrhage
Pt’s on anticoagulation medications or low platelet count
Define hematoma
Leakage of blood into the tissues
Which population are at a higher risk of getting hematoma’s and why
Elderly
due to lack of sufficient elastic tissues to seal the puncture sites
Described as secondary reflex to pain
Arteriospasm
Reflects the lung’s ability to transfer O2 from the inspired gas into the circulating blood
PaO2
PaO2 depends on
O2 concentration
Barometric P
Lung function
Age
Prescence of disease
Normal range for PaO2 on RA
80-100 mmHg
What is the formula used to calculate PAO2(alveolar air equation)
PAO2= FiO2(pB-pH2O)-(PaCO2* 1.25) or
paCO2 / 0.8
Defined as below normal regardless of FiO2, less than 80 mmHg
Hypoxemia
Define hypoxia
inadequate oxygenation of the tissues
Classification of hypoxemia:(less than 60 years of age)
40-59 mmHg
Moderate
Classification of hypoxemia:(less than 60 years of age)
< 40 mmHg
Severe
Classification of hypoxemia:(less than 60 years of age)
60-79 mmHg
Mild
if PaO2 is <60 mmHg at any age it is defined as
hypoxemia
If paO2 is < 40 mmHg at any age it is defined as
Severe
Name some causes of hypoxemia
V/Q mismatch
Hypoventilation
Pulmonary shunting
Diffusion defect
Breathing in gas with a low FiO2
Described as abnormalities in the lung structure that slow diffusion of O2 thru ACM, resulting in hypoxemia
Diffusion defect
Diffusion defect respond well to O2 therapy(true or false)
True
What is the normal alveolar-arterial O2 difference (PA-aO2 /A -aDO2)
10-15 mmHg on RA
How can you estimate the patient’s A.a
0.3 * pt. age in years
When does V/Q mismatch happen
occurs when inhaled gas does not match with lung perfusion
It is the most common cause of hypoxemia in cases of respiratory disease
V/Q mismatch
Define deadspace ventilation
Ventilation in excess of perfusion
Define shunt
Perfusion without ventilation or in excess of ventilation
Whats the normal for V/Q
0.8
If V/Q is greater than 0.8 it is considered
Deadspace
If V/Q is less than 0.8 it is considered to be
Shunting
Perfusion in excess of ventilation is caused from
Atelectasis
Ventilation in excess of perfusion is caused from
Pulmonary emboli
Define venous admixture
Deoxygenated venous mixing with oxygenated arterial in turn reducing paO2
Define O2 saturation
Amount of O2 Hb carries in a given volume of blood
What does O2 saturation depend on
Hb concentration
If a patient was in a fire accident which device would obtain a true saO2
Co-oximeter
True or false
PaO2 is a calculated value
False
SaO2 is a calculated value
What is the normal anatomic shunt (in %)
3%
What is the normal Hb with O2
97%
Relationship between the paO2 and saO2 can be demonstrated by the
Oxyhemoglobin curve
Where is 2,3 DPG found in
Erythrocytes
What’s the purpose of 2,3 DPG
Aids in reducing the affinity of O2 and releasing it to the cells
What causes an increase in 2,3 DPG level(right shift)
Strenuous exercises(enhances unloading of O2)
Anemia
Hypoxemia associated with COPD
What causes a left shift(decrease) in 2,3 DPG level
Septic shock(bacterial infection in lung)
Stored blood( eg. for transfusion)
Fetal blood
True or false
The oxyhemoglobin curve has a linear relationship
False
It has no linear relationship
Are there minimal or significant changes in saO2 when the paO2 changes above 80mmHg
Minimal changes in saO2
Are there minimal or significant changes in saO2 when the paO2 changes below 80mmHg
Significant changes in saO2
When the curve shifts to the left what happens
There is easier binding of O2 to hgb.
Higher SaO2 for a given PaO2
When the curve shifts to the right. What happens
Decreased O2 affinity for Hgb.
Lower saO2 for a given PaO2
Whats the affinity for CO to bind to Hgb
240 X
When CO binds to Hgb, shift curve to which side
To the left
True or false
A pt can be hypoxic even with a normal PO2
True
Fetal curve shifted to the ——facilitates uptake of O2 by placenta at very low pO2(27 mmHg)
Fetal curve to the Left
It is the measurement of PO2 at 50% Hb saturation
P-50
What is the normal value for P-50
27 mmHg
What is the most sensitive indicator of a curve
P-50
What other factors can lead the P-50 to shift
PH,
Temp
PCO2
When there is low P-50 and the graph shifts to the ——-there is a ———-affinity
Left shift
High affinity
When there is high P-50 and the graph shifts to the ——-there is a ———-affinity
Right shift
Low affinity
What is the normal CaO2 value
16-20 Ml/dl
Consists of ——and ——–dissolved in the plasma
O2 bound Hgb
O2 physically
True or False; CaO2 significantly influence tissue oxygenation
True
What is the greatest factor effect content in CaO2
hgb
Formula for CaO2
1.34 * Hb * SaO2 ( ml/ dl)
If hgb is not normal is the pt still considered
Hypoxic
Normal PVO2 value
35 - 45 mmHg
What is considered a good representation of tissue oxygenation
PVO2
A true sample of the tissue oxygenation is obtained from
Pulmonary artery
O2 delivery is a function of
Cardiac output and CaO2
Why is PVO2 a good indicator for hypoxia
Because it is a reflection of the interaction of the pulmonary and CV system
What does venous provides information on
The balance of O2 supply and demand
If CO is low with constant O2 extraction
Low PVO2 below normal
If CO is high with constant O2 extarction
High PVO2
What is the normal (C(a-v)O2)
3.5 -5.0 vol%
What is (C(a-v)O2) used as an indicator for
Cardiac output
What (C(a-v)O2) provide an estimation of
Tissue perfusion (CO) and Oxygenation
Formula for QT
HINT: QT is CO
VO2( Consumption of O2 ) / C(a-v) O2
Increased C(a-v) O2 (8 vol%) =
Reduced QT, ( constant VO2)
Decreased C(a-v) O2(3 vol%)
Increase QT (Constant VO2)
What is the formula for CaO2
1.34 *Hb *saO2 + 0.003 * paO2
What is the formula for svO2
1.34 * Hb * svO2 + 0.003 * pvO2
What are the units for both SaO2 & SVO2
Vol %
Normal Carboxyhemoglobin(
< 3%
What device gets an accurate reading of the hgb(O2) in the blood if a pt. has been in a fire incident ( HbCO)
Co-oximeter
If CO is inhaled it shifts the curve to which side of the graph and why
Left
causing tissue hypoxia due to the decreased unloading of O2 to tissues
What are the 2 problems with HbCO
Inhibits the carrying capacity of O2 &
Prevents unloading of O2 at the tissues
