A 60 kg female patient is in ICU on mechanical ventilation. Her static compliance is calculated as: plateau pressure = 28 text cmH _2text O , PEEP = 8 text cmH _2text O , tidal volume = 360 text mL . What is the static compliance and is it normal?

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Nursing QUESTION #9245

Question 1

A 60 kg female patient is in ICU on mechanical ventilation. Her static compliance is calculated as: plateau pressure \(= 28 \text{ cmH}_2\text{O}\), PEEP \(= 8 \text{ cmH}_2\text{O}\), tidal volume \(= 360 \text{ mL}\). What is the static compliance and is it normal?

\(C_{\text{stat}} = 18 \text{ mL/cmH}_2\text{O}\) — severely reduced, consistent with ARDS✔️
\(C_{\text{stat}} = 45 \text{ mL/cmH}_2\text{O}\) — normal compliance
\(C_{\text{stat}} = 25 \text{ mL/cmH}_2\text{O}\) — reduced but borderline
\(C_{\text{stat}} = 36 \text{ mL/cmH}_2\text{O}\) — mildly reduced

Correct Answer Explanation

Correct Answer: A — \(C_{\text{stat}} = 18 \text{ mL/cmH}_2\text{O}\), severely reduced

Formula for Static (Lung) Compliance:
\[C_{\text{stat}} = \frac{V_T}{P_{\text{plateau}} - \text{PEEP}}\]
\[C_{\text{stat}} = \frac{360}{28 - 8} = \frac{360}{20} = 18 \text{ mL/cmH}_2\text{O}\]

Normal static compliance: \(50 - 100 \text{ mL/cmH}_2\text{O}\)

Interpretation:

\(> 50\): Normal
\(30 - 50\): Mildly reduced
\(< 30\): Severely reduced — consistent with ARDS, pulmonary fibrosis, pulmonary edema

Compliance of \(18 \text{ mL/cmH}_2\text{O}\) indicates severely stiff lungs. The nurse should document this, inform the intensivist, and ensure lung-protective ventilation parameters are maintained.

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