Which instrument measures peak inspiratory pressure and plateau pressure?

• A. Ventilator display
• B. Flowmeter
• C. Oxygen analyzer
• D. Circuit pressure gauge

Answer: (D)

Measuring airway pressures relies on monitoring the pressures at the patient’s airway. Peak inspiratory pressure is the highest pressure reached during inspiration and reflects both resistance in the airways and the lung’s compliance. Plateau pressure is read during an inspiratory pause when there is no flow and represents the pressure in the alveoli, giving a measure of lung compliance independent of airway resistance.

The ventilator display is the instrument that provides both values because it is connected to the airway pressure transducer and continuously monitors pressure at the patient end. During normal inspiration it shows the peak, and when you pause the breath, it reveals the plateau. A circuit pressure gauge mainly reflects pressure in the breathing tube and can be influenced by circuit conditions, but it does not reliably show alveolar (plateau) pressure. Flowmeters measure flow, and oxygen analyzers measure O2 concentration. So the ventilator display best provides both peak inspiratory pressure and plateau pressure.