In unrestrained whole body plethysmography (WBP), the spontaneously breathing subject moves freely within a small, closed plethysmograph chamber. Changes in pressure within the chamber along with the flow in and out of the box are measured using pressure transducers and pneumotachographs. Analyzers within the software (iox by emka TECHNOLOGIES) provide endpoints such as breathing frequency (f) and duration, estimates of tidal volume (TV), minute ventilation (MV) as well as a dimensionless quantity known as enhanced pause (Penh). Additional temperature and humidity sensors may be added to compensate thermodynamic effects in the chamber.
In head-out plethysmography (HOP), the subject is conscious, spontaneously breathing, and situated in a conical restraint. The conical restrainers follows the animal’s head shape and ensures that air, displaced by the chest wall motion, is isolated from the total air moving in and out of the lungs, thus permitting true flow measurements. This approach provides a true tidal volume (TV) along with measurements of breathing frequency (f) and minute ventilation (MV).
In plethysmography applications, IOX can control automated delivery of aerosolized compounds to evaluate the effects of nebulized challenges and treatments on respiratory patterns.
The whole body plethysmography chamber allows for the automated exposure to gas challenges, along with the continuous recording of the subjects ventilatory parameters. During acute exposures, IOX software can control the mixing and delivery of controlled gases with Mass Flow Controllers (MFC). The MFCs can be automated in protocols to vary severity and duration of challenges and returns to normoxia. These challenges can lead to erratic breathing and apneic events, which are recorded and quantified in real time.