Nonlinear model for estimating respiratory volume based on thoracoabdominal breathing movements.
OBJECTIVE
Respiratory inductive plethysmography is a non-invasive technique for measuring respiratory function. However, there are challenges associated with using linear methods for calibration of respiratory inductive plethysmography. In this study, we developed two nonlinear models, artificial neural network and adaptive neuro-fuzzy inference system, to estimate respiratory volume based on thoracoabdominal movements, and compared these models with routine linear approaches, including qualitative diagnostic calibration and multiple linear regression.


METHODS
Recordings of spirometry volume and respiratory inductive plethysmography were obtained for 10 normal subjects and 10 asthmatic patients, during asynchronous breathing for 7 min. The first 5 min of recording were used to develop the models; the remaining data were used for subsequent validation of the results.


RESULTS
The results from the nonlinear models fitted the spirometry volume curve significantly better than those obtained by linear methods, particularly during asynchrony (P < 0.05). On a breath-by-breath analysis, estimates of tidal volume, total cycle time and sigh values using the artificial neural network model were accurate by comparison with qualitative diagnostic calibration. In contrast to the artificial neural network model, there was a significant correlation between values for thoracoabdominal asynchrony and increased error of qualitative diagnostic calibration (P < 0.05).


CONCLUSIONS
These results indicate that the nonlinear methods can be adapted to closely simulate variable conditions and used to study the patterns of volume changes during normal and asynchronous breathing.
Department of Physiology, School of Medical Sciences, Tarbiat Modares University, London, UK.
Mohammad Reza
MR
Raoufy
Sohrab
S
Hajizadeh
Shahriar
S
Gharibzadeh
Ali R
AR
Mani
Parivash
P
Eftekhari
Mohammad Reza
MR
Masjedi
D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D017711:Nonlinear Dynamics; D010991:Plethysmography / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*; D013147:Spirometry; D055815:Young Adult