Podcast
Questions and Answers
How does an increased temperature affect the oxyhemoglobin dissociation curve?
How does an increased temperature affect the oxyhemoglobin dissociation curve?
- It stabilizes hemoglobin, preventing oxygen binding.
- It has no effect on the oxyhemoglobin dissociation curve.
- It causes a shift to the left, increasing hemoglobin's affinity for oxygen.
- It causes a shift to the right, decreasing hemoglobin's affinity for oxygen. (correct)
Which of the following represents the correct calculation for alveolar pressure of oxygen (PAO2), assuming FiO2, barometric pressure (PB), and PH2O are known?
Which of the following represents the correct calculation for alveolar pressure of oxygen (PAO2), assuming FiO2, barometric pressure (PB), and PH2O are known?
- PAO2 = FiO2 + (PB - PH2O)
- PAO2 = FiO2 - (PB - PH2O)
- PAO2 = FiO2 x (PB - PH2O) - RQ (correct)
- PAO2 = FiO2 x (PB + PH2O)
What is the expected effect on the oxyhemoglobin dissociation curve in a patient with acute alkalosis?
What is the expected effect on the oxyhemoglobin dissociation curve in a patient with acute alkalosis?
- No change in the position of the curve.
- A shift to the left, increasing oxygen saturation at a given PaO2. (correct)
- A shift to the right, decreasing oxygen saturation at a given PaO2.
- An unpredictable change dependent on other blood parameters.
What is the primary implication of a ventilation-perfusion (V/Q) ratio that approaches infinity?
What is the primary implication of a ventilation-perfusion (V/Q) ratio that approaches infinity?
What is the impact of decreased 2,3-DPG levels on the oxyhemoglobin dissociation curve and oxygen delivery to tissues?
What is the impact of decreased 2,3-DPG levels on the oxyhemoglobin dissociation curve and oxygen delivery to tissues?
In the context of pulmonary function, what does the term 'tidal volume' (TV) specifically refer to?
In the context of pulmonary function, what does the term 'tidal volume' (TV) specifically refer to?
How does carbon dioxide ($CO_2$) transport from the systemic capillaries to the alveoli for exhalation?
How does carbon dioxide ($CO_2$) transport from the systemic capillaries to the alveoli for exhalation?
What is the primary reason for measuring a patient's alveolar-arterial (A-a) oxygen gradient?
What is the primary reason for measuring a patient's alveolar-arterial (A-a) oxygen gradient?
Which factor is most likely to cause a 'shift to the right' in the oxyhemoglobin dissociation curve?
Which factor is most likely to cause a 'shift to the right' in the oxyhemoglobin dissociation curve?
What is the expected normal range for the difference in oxygen between the alveolar gas and arterial blood (A-a gradient)?
What is the expected normal range for the difference in oxygen between the alveolar gas and arterial blood (A-a gradient)?
How does the alveolar-capillary membrane facilitate gas exchange in the lungs?
How does the alveolar-capillary membrane facilitate gas exchange in the lungs?
What is the typical ventilation-perfusion (V/Q) ratio in a healthy lung?
What is the typical ventilation-perfusion (V/Q) ratio in a healthy lung?
Which of the following explains why hypoxemia can cause a shift to the right in the oxyhemoglobin dissociation curve?
Which of the following explains why hypoxemia can cause a shift to the right in the oxyhemoglobin dissociation curve?
Which condition would most likely lead to a V/Q mismatch characterized by a shunt?
Which condition would most likely lead to a V/Q mismatch characterized by a shunt?
What is the significance of the alveolar-arterial (A-a) oxygen gradient in pulmonary diagnostics?
What is the significance of the alveolar-arterial (A-a) oxygen gradient in pulmonary diagnostics?
How does 'cold' cause a shift to the left in the oxygen dissociation curve?
How does 'cold' cause a shift to the left in the oxygen dissociation curve?
In a patient with a pulmonary embolism, which type of V/Q mismatch is most likely to occur?
In a patient with a pulmonary embolism, which type of V/Q mismatch is most likely to occur?
Which statement accurately describes the relationship between alveolar ventilation (V), perfusion (Q), and the resulting V/Q ratio?
Which statement accurately describes the relationship between alveolar ventilation (V), perfusion (Q), and the resulting V/Q ratio?
In an individual with an increased A-a gradient, which of the following conditions is most likely to be present?
In an individual with an increased A-a gradient, which of the following conditions is most likely to be present?
What is the primary clinical significance of understanding pulmonary gas exchange?
What is the primary clinical significance of understanding pulmonary gas exchange?
Flashcards
What is Tidal Volume (TV)?
What is Tidal Volume (TV)?
The volume of air inhaled or exhaled during normal breathing.
What is Inspiratory Reserve Volume (IRV)?
What is Inspiratory Reserve Volume (IRV)?
The additional volume of air that can be forcibly inhaled after a normal inspiration.
What is Expiratory Reserve Volume (ERV)?
What is Expiratory Reserve Volume (ERV)?
The additional volume of air that can be forcibly exhaled after a normal exhalation.
What is Residual Volume (RV)?
What is Residual Volume (RV)?
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What is Total Lung Capacity (TLC)?
What is Total Lung Capacity (TLC)?
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What is Vital Capacity (VC)?
What is Vital Capacity (VC)?
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What is the V/Q ratio?
What is the V/Q ratio?
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What is a normal V/Q unit?
What is a normal V/Q unit?
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What is a dead space unit?
What is a dead space unit?
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What is Shunt Unit?
What is Shunt Unit?
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What is PaO2?
What is PaO2?
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What is SaO2?
What is SaO2?
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What is Oxyhemoglobin Dissociation Curve?
What is Oxyhemoglobin Dissociation Curve?
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What does a shift to the right mean?
What does a shift to the right mean?
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What does a shift to the left mean?
What does a shift to the left mean?
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What is PAO2?
What is PAO2?
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What is the A-a gradient?
What is the A-a gradient?
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What are possible causes of a gradient > 20 MMHG?
What are possible causes of a gradient > 20 MMHG?
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Study Notes
- Respiratory concepts part 1: Introduction
Pulmonary Ventilation Volumes and Capacities
- Total Lung Capacity (TLC) ranges from 5700-6200 mL
- Tidal Volume (TV) = 500 mL, which is the volume of exhaled air after normal inspiration
- Inspiratory Reserve Volume (IRV) ranges from 3000-3300 mL
- Expiratory Reserve Volume (ERV) ranges from 1000-1200 mL
- Residual Volume (RV) = 1200 mL.
- Vital Capacity (VC) ranges from 4500-5000 mL, theoretical
Ventilation Perfusion Ratio
- Alveolar Ventilation = 4 L/min (V)
- Perfusion = 5 L/min (Q)
- V ÷ Q Ratio = 4.5 = 0.8
VQ Relationships
- Normal Unit (C)
- Dead Space Unit (E)
- Shunt Unit (A)
Oxyhemoglobin Dissociation Curve
- Oxygen is transported in blood in two ways:
- Dissolved in plasma (~3%), measured as PaO2
- Bound to Hgb (SaO2)
- Curve depicts the relationship between dissolved O2 and Hgb bound 02
- A shift in the curve alters the affinity of Hgb for 02
Shift to the Right
- There is a decrease in the O2 saturation for any given PaO2
- Hgb has less affinity for O2
- Picks up less O2 in lungs, but releases it more readily to the tissues
- Causes include Fever, Hypercapnea, Reduced pH (acidosis), Increase in 2.3 DPG
Shift to the Left
- Increased O2 saturation for any PaO2
- This impairs delivery of O2 to the tissues, Hgb holds the O2 to itself
- Causes include: Cold, Alkalosis, Low CO2, Low 2,3 DPG
Pulmonary Gas Exchange
- Gives the clinician information about tissue oxygenation
Estimating Intrapulmonary Shunting
- Alveolar Pressure of Oxygen: PAOâ‚‚ = FiO2(PB - PHâ‚‚O) -
- PB = Barometric Pressure
- RQ = Respiratory Quotient (0.8)
- Normal < 25-65
- A-a gradient = PAO2 - PaO2
- PAOâ‚‚ = FiO2(713) -
- Normally A-a gradient is <20 MMHG
- If it is greater, there is pathology
- Causes: Intracardiac shunts, pulmonary AV malformations, pulmonary diseases, or complete alveolar collapse
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