Measurement of thoraco-abdominal synchrony using respiratory inductance plethysmography: technical aspects and a proposal to overcome its limitations.

BACKGROUND

Thoraco-abdominal asynchrony (TAA) is usually assessed by respiratory inductance plethysmography. The main parameter used for its assessment is the calculation of the phase angle based on Lissajous plots. However, there are some mathematical limitations to its use.

RESEARCH DESIGN AND METHODS

Sequences of five breaths were selected from a) normal subjects, b) COPD patients, both at rest and during exercise, and c) patients with obstructive apnea syndrome. Automated analysis was performed calculating phase angle, loop rotation (clockwise or counterclockwise), global phase delay and loop area. TAA severity was estimated quantitatively and in subgroups.

RESULTS

2290 cycles were analyzed (55% clockwise rotation). Phase angle ranged from -86.90 to + 88.4 degrees, while global phase delay ranged from -179.75 to + 178.54. Despite a good correlation with global phase delay (

CONCLUSIONS

Global phase delay covers the whole spectrum of TAA situations in a single value. It may be a relevant parameter for diagnosis and follow-up of clinical conditions leading to TAA.

CLINICAL TRIAL REGISTRATION

The trial from which the traces were obtained was registered at ClinicalTrials.gov ;(identifier: NCT04597606).