If alveolar ventilation is 4200 mL/min respiratory frequency is 12 breaths per minute, and tidal volume is 500 mL. what is the anatomical dead space ventilation ?

Options

A. 1800 mL/min
B. 6000 mL/min
C. 350 mL/min
D. 1200 mL/min

Answer

To find the anatomical dead space ventilation (DSV), we can follow these steps:

### Step 1: Identify the given values
- Alveolar ventilation (AV) = 4200 mL/min
- Respiratory frequency (f) = 12 breaths/min
- Tidal volume (TV) = 500 mL

### Step 2: Calculate the minute ventilation (MV)
Minute ventilation (MV) is calculated using the formula:
\[ \text{MV} = \text{TV} \times \text{f} \]
Substituting the values:
\[ \text{MV} = 500 \, \text{mL/breath} \times 12 \, \text{breaths/min} = 6000 \, \text{mL/min} \]

### Step 3: Use the relationship between minute ventilation, alveolar ventilation, and dead space ventilation
The relationship can be expressed as:
\[ \text{MV} = \text{AV} + \text{DSV} \]
We have already calculated MV and we know AV:
\[ 6000 \, \text{mL/min} = 4200 \, \text{mL/min} + \text{DSV} \]

### Step 4: Solve for dead space ventilation (DSV)
Rearranging the equation to find DSV:
\[ \text{DSV} = \text{MV} - \text{AV} \]
Substituting the values:
\[ \text{DSV} = 6000 \, \text{mL/min} - 4200 \, \text{mL/min} = 1800 \, \text{mL/min} \]

### Final Answer
The anatomical dead space ventilation (DSV) is **1800 mL/min**.

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