Respiratory inductance plethysmography

Respiratory inductance plethysmography (RIP) is a method of evaluating pulmonary ventilation by measuring the movement of the chest and abdominal wall.

Accurate measurement of pulmonary ventilation or breathing often requires the use of devices such as masks or mouthpieces coupled to the airway opening.

As an alternative RIP devices that sense respiratory excursions at the body surface can be used to measure pulmonary ventilation.

When a known air volume is inhaled and measured with a spirometer, a volume-motion relationship can be established as the sum of the abdominal and rib cage displacements.

RIP is the most frequently used, established and accurate plethysmography method to estimate lung volume from respiratory movements [citation needed].

A respiratory inductance plethysmograph consists of two sinusoid wire coils insulated and placed within two 2.5 cm (about 1 inch) wide, lightweight elastic and adhesive bands.

Konno and Mead [3] extensively evaluated a two-degrees-of-freedom model of chest wall motion, whereby ventilation could be derived from measurements of rib cage and abdomen displacements.

However, accuracy issues arise when trying to assess accurate respiratory volumes from a single respiration band placed either at the thorax, abdomen or midline.

Minute ventilation is equivalent to tidal volume multiplied by respiratory rate and is used to assess metabolic activity.

Apnea & hypopnea classification - Phase relation between thorax and abdomen classifies apnea/hypopnea events into central, mixed, and obstructive types.

Dual band respiratory inductance plethysmography was validated in determining tidal volume during exercise and shown to be accurate.