What device is essential for measuring a patient’s airway resistance?

• A. Turbine pneumotachometer
• B. Wheatstone bridge helium analyzer
• C. Geissler tube nitrogen analyzer
• D. Body box

Answer: (D)

The body box is essential for measuring a patient's airway resistance because it allows for the assessment of lung volumes and pressures in a controlled environment. This device operates using the principle of plethysmography, which measures changes in pressure within a closed chamber as the patient breathes. Specifically, it can capture the changes in thoracic volume and pressure when the patient attempts to exhale against a closed outlet, providing data that can be calculated into airway resistance.

In the context of pulmonary function testing, understanding airway resistance is vital as it reflects how easily air can flow through the airways, which can be affected by conditions such as asthma or chronic obstructive pulmonary disease (COPD). The body box's ability to quantify these changes makes it a critical tool in respiratory diagnostics.

While other devices mentioned have their specific uses in respiratory testing or gas analysis, they do not provide the comprehensive capability to specifically measure airway resistance as the body box does. For example, a turbine pneumotachometer primarily measures airflow rates rather than resistance, and the other devices focus on different aspects of gas composition rather than direct airway dynamic measurements.