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Questions and Answers
What is the formula for Total Oxygen Content - Arterial (CaO2)?
What is the formula for Total Oxygen Content - Arterial (CaO2)?
CaO2 = (1.34 x Hgb x SaO2) + (PaO2 x 0.003)
Calculate CaO2 if Hgb = 15 g/dl, SaO2 = 97%, and PaO2 = 100.
Calculate CaO2 if Hgb = 15 g/dl, SaO2 = 97%, and PaO2 = 100.
19.8 vol%
What is the formula for Total Oxygen Content - Mixed Venous (CvO2)?
What is the formula for Total Oxygen Content - Mixed Venous (CvO2)?
CvO2 = (1.34 x Hgb x Svo2) + (PvO2 x 0.003)
Calculate CvO2 if Hgb = 15 g/dl, SvO2 = 75%, and PvO2 = 40 mmHg.
Calculate CvO2 if Hgb = 15 g/dl, SvO2 = 75%, and PvO2 = 40 mmHg.
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What is C(a-v)O2?
What is C(a-v)O2?
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Calculate C(a-v)O2 if CaO2 = 20 vol% and CvO2 = 15 vol%.
Calculate C(a-v)O2 if CaO2 = 20 vol% and CvO2 = 15 vol%.
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What is the normal Deadspace/Tidal Volume Ratio (Vd/Vt)?
What is the normal Deadspace/Tidal Volume Ratio (Vd/Vt)?
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What is Bohr's Equation?
What is Bohr's Equation?
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Calculate PAO2 with PB = 760 mmHg, PH2O = 47 mmHg, FIO2 = 21%, and PaCO2 = 40 mmHg.
Calculate PAO2 with PB = 760 mmHg, PH2O = 47 mmHg, FIO2 = 21%, and PaCO2 = 40 mmHg.
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What is the formula to calculate Percent Solution?
What is the formula to calculate Percent Solution?
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How much do you need to add to 15 mL of 20% Mucomyst to achieve a 15% solution?
How much do you need to add to 15 mL of 20% Mucomyst to achieve a 15% solution?
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What is the formula for Alveolar Ventilation (VA)?
What is the formula for Alveolar Ventilation (VA)?
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Calculate VA if f = 12, Vt = 500 mL, and Vd = 150 mL.
Calculate VA if f = 12, Vt = 500 mL, and Vd = 150 mL.
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What is the formula for calculating Ideal Body Weight (IBW) for MEN?
What is the formula for calculating Ideal Body Weight (IBW) for MEN?
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What does the Classic Shunt Equation (Qs/Qt) calculate?
What does the Classic Shunt Equation (Qs/Qt) calculate?
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When should you use the Classic Shunt Equation?
When should you use the Classic Shunt Equation?
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What is the equation for the Modified Shunt Equation (Qs/Qt)?
What is the equation for the Modified Shunt Equation (Qs/Qt)?
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When should you use the Modified Shunt Equation?
When should you use the Modified Shunt Equation?
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What is Static Compliance (Cst)?
What is Static Compliance (Cst)?
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What is the formula for Cylinder Duration (gas)?
What is the formula for Cylinder Duration (gas)?
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What is the formula for calculating Percent Body Humidity?
What is the formula for calculating Percent Body Humidity?
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Study Notes
Total Oxygen Content - Arterial (CaO2)
- CaO2 formula: CaO2 = (1.34 x Hgb x SaO2) + (PaO2 x 0.003)
- Normal hemoglobin (Hgb): 12-16 g/dl
- Normal arterial Hgb saturation (SaO2): >92%
- Normal partial pressure of oxygen in arterial blood (PaO2): >80 mmHg (60-100 mmHg)
Total Oxygen Content Calculation Examples
- For Hgb = 15 g/dl, SaO2 = 97%, PaO2 = 100 mmHg, CaO2 = 19.8 vol%
Total Oxygen Content - Mixed Venous (CvO2)
- CvO2 formula: CvO2 = (1.34 x Hgb x SvO2) + (PvO2 x 0.003)
- Normal venous Hgb saturation (SvO2): 70-75%
- Normal partial pressure of oxygen in venous blood (PvO2): 37-43 mmHg
Mixed Venous Oxygen Content Calculation Example
- For Hgb = 15 g/dl, SvO2 = 75%, PvO2 = 40 mmHg, CvO2 = 15.2 vol%
Arterial-Mixed Venous Oxygen Content Difference (C(a-v)O2)
- C(a-v)O2 formula: C(a-v)O2 = CaO2 - CvO2
C(a-v)O2 Calculation Example
- Given CaO2 = 20 vol%, CvO2 = 15 vol%, resulting in C(a-v)O2 = 5 vol%
Deadspace/Tidal Volume Ratio (Vd/Vt)
- Vd/Vt ratio normal value: 33%
- Vd = deadspace; Vt = tidal volume
Bohr's Equation
- Bohr's Equation: Vd/Vt = (PaCO2 - PeCO2) / PaCO2
- Example calculation: Vd/Vt = 0.125 or 13%
Alveolar Air Equation (PAO2)
- PAO2 = (PB - PH2O)FIO2 - (PaCO2/RQ)
- Normal values: PAO2 = 99 mmHg, PB = 760 mmHg, PH2O = 47 mmHg, RQ = 0.8
PAO2 Calculation Example
- Given PB = 760 mmHg, PH2O = 47 mmHg, FIO2 = 21%, PaCO2 = 40 mmHg, PAO2 = 100 mmHg
Active Ingredient Concentration
- Relationship: mL active/mL total = mg active/mL total
Active Ingredient Example
- In a 1% solution, 10 mg is present in 1 cc (mL).
Active Ingredient Calculation Example
- In 0.7 mL of 1:200 Isuprel, there are 3.5 mg of active ingredient.
Concentration Calculation of Solutions
- Use V1C1 = V2C2 to find concentrations or volumes.
Dilution Calculation Example
- To dilute 15 mL of 20% Mucomyst to 15%, add 5 mL of diluent.
Alveolar Ventilation (VA)
- VA formula: VA = f(Vt - Vd)
- VA measures alveolar ventilation per minute using respiratory rate (f), tidal volume (Vt), and deadspace (Vd).
Ideal Body Weight (IBW) Formula
- For men: IBW = 106 + 6 for each inch over 5'
- For women: IBW = 100 + 5 for each inch over 5'
Classic Shunt Equation (Qs/Qt)
- Qs/Qt formula: Qs/Qt = (CcO2 - CaO2) / (CcO2 - CvO2)
When to Use Classic Shunt Equation
- Applicable when FIO2 ≥ 30%.
Modified Shunt Equation (Qs/Qt)
- Modified formula: Qs/Qt = (P(A-a)O2 x 0.003) / [(P(A-a)O2 x 0.003) + C(a-v)O2]
- P(A-a)O2 = alveolar-arterial oxygen tension gradient.
When to Use Modified Shunt Equation
- Relevant when PO2 ≥ 150 mmHg on any FIO2.
Static Compliance (Cst)
- Cst formula: Cst = corrected Vt / (Pplat - PEEP)
Cylinder Duration for Gas
- Calculation: PSI x tank factor / liter flow, with specific tank factors for different gases.
Cylinder Duration for Liquid
- Calculation: 3.44 x liquid weight / liter flow.
Percent Body Humidity Calculation
- Formula: Content / 44 mg/L x 100 = % Body Humidity.
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Description
This quiz focuses on calculating the Total Oxygen Content in arterial blood (CaO2) using hemoglobin content, oxygen saturation, and partial pressure of oxygen. Examine the formula and practice your calculation skills with sample values to enhance your understanding of respiratory physiology.