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In what forms is carbon dioxide transported in the blood and how much of it is usually transported?
- 3 forms:
- 1. dissolved in physical solution
- 2. chemically combined with protein
- 3. ionized as bicarbonate
Approximately 45 to 55 ml/dl
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Hamburger phenomenon is the same as what?
Chloride shift
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What is the Chloride shift?
the shifting of chloride ions (Cl-) from the plasma into the erythrocyte
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Which form of carbon dioxide transport accounts for the highest amount of CO2 transported?
ionized as bicarbonate, 80%
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How much carbon dioxide is transported as Carbaminohemoglobin?
12%
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How much does dissolved carbon dioxide account for total carbon dioxide expelled from the lungs?
8%
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What is significant of the Carbon Dioxide curve as opposed to the HbO2 Curve?
there is more direct relationship between partial pressure of CO2 and the amount of CO2 content in the blood
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What is the Haldane effect?
the influence of oxyhemoglobin saturation on CO2 dissociation curve
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The CO2 dissociation curve occurs along a linear or curved line?
linear
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High SaO2 ________ the blood�s capacity to hold CO2, helping it unload at the lungs.
decreases
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Lower SvO2 ________ the bloods capacity for CO2 aiding uptake at the tissues
increases
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Hypoxia occurs when DO2 falls short of cellular needs due to what?
- (1) decreased of arterial blood content (hypoxemia),
- (2) decreased cardiac output or perfusion (shock or ischemia),
- (3) Abnormal cellular function prevents proper uptake of O2 (dysoxia)
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What is the equation for Impaired Oxygen Delivery?
DO2 = CaO2 x Qt
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What is hypoxia?
When oxygen delivery falls short of cellular needs
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When does hypoxia occur?
- occurs when DO2 falls short of cellular needs. This is
- due to:
- (1) decreased of arterial blood content (hypoxemia),
- (2) decreased cardiac output or perfusion (shock or ischemia),
- (3) Abnormal cellular function prevents proper uptake of O2 (dysoxia)
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What is hypoxemia?
when the partial pressure of oxygen in the arterial blood (PaO2)is decreased to lower than the predicted normal based on the age of the patient. It can also occur when there is an Impaired oxygen delivery also occurs in the presence of abnor-malities that prevent saturation of the Hb with oxygen.
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What things cause hypoxemia?
- Low PIO2
- Hypoventilation
- V/Q imbalance (Low V/Q)
- Anatomic shunt
- Physiologic shunt
- Diffusion defect
- Normal aging
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What is the most common cause of hypoxemia in patients with lung disease?
Low V/Q�s
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What is Refractory hypoxemia?
an abnormal deficiency of oxygen in the arterial blood that is resistant to treatment; usually indicates the presence of right-to-left shunting
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What is Responsive hypoxemia?
Hypoxemia that shows a significant increase in PaO2 from an increase in FIO2.
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One may estimate the expected PaO2 in older adults by using the following formula: Expected PaO2 =
100.1 - (0.323 X Age in years)
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Decreased of arterial blood content (hypoxemia).
factor that impairs oxygen delivery to the tissues
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Decreased cardiac output or perfusion (shock or ischemia).
factor that impairs oxygen delivery to the tissues
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Abnormal cellular function prevents proper uptake of O2 (dysoxia).
factor that impairs oxygen delivery to the tissues
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What is diffusion defect?
thickening of the alveolar-capillary membrane, gas exchange is impeded
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What causes diffusion defect?
Disorders of the alveolar-capillary membrane such as; pulmonary fibrosis, interstitial edema, and interstitial lung disease
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What indicates diffusion defect and how can it be fixed?
- Low PaO2
- High P(A-a)O2 on air; resolves with O2
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For low PiO2 (hypoxia), what is the lab assessment for it?
- PaO2 is low
- P(A-a)O2 gradient on room air and supplemental O2 are normal
- CaO2 is low
- CvO2 is normal (if cardiac output increases to compensate)
- Example: is travel to high altitudes; low barometric pressure, creating mountain sickness.
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For hypoventilation (hypoxia), what is the lab assessment for it?
- PaO2 decreased
- Normal P(A-a)O2 on room air and supplemental O2
- CaO2 decreased
- CvO2 normal (if cardiac output increases to compensate)
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What is VENTILATION/PERFUSION IMBALANCES (Low V/Q) caused by?
Perfusion in excess of ventilation; such as with bronchospasm, secretions in airway, and low volumes
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What are the primary indicators for VENTILATION/PERFUSION IMBALANCES (Low V/Q)?
- Low PaO2
- High P(A-a)O2 on air; decreases with O2 :)
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For VENTILATION/PERFUSION IMBALANCES (Low V/Q [hypoxia]), what is the lab assessment for it?
- PaO2 decreased
- P(A-a)O2 widened on room air but decreased widening with supplemental oxygen
- CaO2 is decreased
- CvO2 is normal (if cardiac output increases to compensate)
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How can a Low V/Q be fixed?
supplemental O2
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What is an Anatomical shunt?
- This is considered to be a true shunt
- Caused by:
- Blood flow between right and left sides of circulation; congenital heart disease
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What are the primary indicators of Anatomical shunt?
- Low PaO2
- High P(A-a)O2 on room air; does not resolve with O2 :(
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For Anatomical shunt (hypoxia), what is the lab assessment for it?
- PaO2 will be very low (if over 25-30% shunt)
- P(A-a)O2 is very wide and widens even further with supplemental oxygen (if over 25-30% shunt)
- CaO2 is decreased
- CvO2 is normal (if cardiac output increases to compensate)
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As the shunted blood increases to 30%; it becomes ___________ to make up the oxygen of blood going by totally unventilated alveoli
impossible
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What is a Physiologic shunt, what are the indicators, and can it be fixed with O2?
- Perfusion without ventilation; atelectasis, pneumonia, and pulmonary edema
- Low PaO2 High P(A-a)O2 on air; does not resolve with O2 :(
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For Physiologic shunt (hypoxia), what is the lab assessment for it?
- Extremely low PaO2 (as % shunt increases)
- P(A-a)O2 widened with increased widening with supplemental O2 (as % shunt increases)
- CaO2 is low
- CvO2 is normal (if cardiac output increases to compensate)
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What is the 50/50 rule of thumb?
If the oxygen concentration is more than 50% and the PaO2 is less than 50 mmHg, significant shunting is present; otherwise the hypoxemia is mainly due to a simple V/Q imbalance
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What is HEMOGLOBIN DEFICIENCIES ABSOLUTE, and what are the primary indicators for it?
- Loss of hemoglobin (Hb) anemia; due to hemorrhage or inadequate erythropoiesis
- Low Hb content, Reduced CaO2
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For HEMOGLOBIN DEFICIENCIES ABSOLUTE (hypoxia), what is the lab assessment for it?
- PaO2 may be normal or low
- P(A-a)O2 is normal both on and off oxygen
- CaO2 is low
- CvO2 is low
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Progressive decreases in Hb causes large or small drops in CaO2?
large
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What is HEMOGLOBIN DEFICIENCIES RELATIVE, and what are the primary indicators for it?
Abnormal hemoglobin; carboxyhemoglobin, methemoglobin, and abnormal hemoglobin (those causing left shift of oxyhemoglobin dissociation curve)
Abnormal SaO2 (done by co-oximeter), Reduced CaO2
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For HEMOGLOBIN DEFICIENCIES ABSOLUTE (hypoxia), what is the lab assessment for it?
- PaO2 may be normal or decreased
- P(A-a)O2 gradient is normal on room air and oxygen
- CaO2 is reduced (co-oximeter)
- CvO2 is reduced (co-oximeter)
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What is the difference between HEMOGLOBIN DEFICIENCIES ABSOLUTE, and RELATIVE?
absolute refers to a loss of Hb (anemia), relative refers to abnormal hemoglobins that cause a left shift of HbO2 curve
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What is REDUCED BLOOD FLOW, and what are the primary indicators for it?
Decreased perfusion; (1) circulatory failure (shock) and (2) local reduction in perfusion such as MI, CVA (ischemia)
Increased (widened) C(a-v)O2, Decreased CvO2
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For REDUCED BLOOD FLOW (hypoxia), what is the lab assessment for it?
- PaO2 is normal
- P(A-a)O2 is normal on room air and on oxygen
- CaO2 is normal
- CvO2 is decreased
- C(a-v)O2 is widened (increased)
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What is DYSOXIA, and what are the primary indicators for it?
Dysoxia is a form of hypoxia in which the cellular uptake of oxygen is abnormally decreased. Cyanide poisoning (disruption of cellular enzymes) and tissue oxygen consumption dependent on oxygen delivery
Normal CaO2, Increased CvO2
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For DYSOXIA (hypoxia), what is the lab assessment for it?
- PaO2 is normal
- P(A-a)O2 on room air and supplemental oxygen is normal
- CaO2 is normal
- CvO2 is increased
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What is the primary goal of treating hypoxia?
to give sufficient oxygen to ensure that the patient is safe and his or her condition does not deteriorate
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What is the treatment for various types of hypoxia?
- most can be solved with oxygen the only kind that can't are:
- Physiologic shunt
- Anatomical shunt
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What causes for hypoxia have an extremely low PaO2 value attained from assessment?
Anatomical shunt (if over 25-30% shunt), and Physiologic shunt (as % shunt increases)
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What causes for hypoxia have a normal OR low PaO2 value attained from assessment?
HEMOGLOBIN DEFICIENCIES ABSOLUTE and RELATIVE
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What causes for hypoxia have a normal PaO2 value attained from assessment?
REDUCED BLOOD FLOW and DYSOXIA
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