Which instrument is used in body plethysmography for calculating lung volumes?

Body plethysmography is a technique used to measure lung volumes and airway resistance by assessing changes in pressure and volume within a closed system. The instrument used in this technique is essentially a sealed chamber, or box, that the patient enters. By measuring the changes in pressure inside this box as the patient breathes, it allows for precise calculations of different lung volumes, including total lung capacity and functional residual capacity.

The box creates a controlled environment where the patient’s respiratory movements can be accurately measured, enabling healthcare professionals to evaluate lung function effectively. This method is particularly useful because it accounts for air that may not be expelled during regular spirometry, providing a comprehensive assessment of lung health.

Other instruments listed, such as the spirometer, are primarily used for measuring airflow and volumes during respiratory maneuvers but do not capture the complete range of lung volume dimensions the box does during body plethysmography.