1. Relationship of mouth pressure (Pmo) and box pressure (Pbox) by body plethysmography under closed–loop panting conditions (left) and open-loop panting conditions (right).
Relationship of mouth pressure (Pmo) and box pressure (Pbox) by body plethysmography under closed–loop panting conditions (left) and open-loop panting conditions (right). Under conditions of no-flow (left), mouth pressure would approximate alveolar pressure, so the relationship of alveolar pressure to change in lung volume (as determined by change in box pressure) is measured. When the shutter is opened (right), the relationship between flow and lung volume (change in box pressure) is measured. Airway resistance (Raw) is calculated as the change in alveolar pressure (Palv) divided by flow, which is derived by multiplying the slope of the closed shutter maneuver and the inverse slope of the open shutter maneuver, with the lung volume terms cancelling out. (From Reference 3, with permission.)‏
David A Kaminsky Respir Care 2012;57:85-99
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