Evaluating the clinical value of oscillatory cardiopulmonary coupling in patients with obstructive sleep apnea hypopnea syndrome by impedance cardiogram

A New Method of Identifying Characteristic Points in the Impedance Cardiography Signal Based on Empirical Mode Decomposition

The accurate detection of fiducial points in the impedance cardiography signal (ICG) has a decisive impact on the proper estimation of diagnostic parameters such as stroke volume or cardiac output. It is, therefore, necessary to find an algorithm that is able to assess their positions with great precision. The solution to this problem is, however, quite challenging with regard to the high sensitivity of the ICG technique to the noise and varying morphology of the acquired signals. The aim of this study is to propose a novel method that allows us to overcome these limitations. The developed algorithm is based on Empirical Mode Decomposition (EMD)-an effective technique for processing and analyzing various types of non-stationary signals. We find high correlations between the results obtained from the algorithm and annotated by an expert. This, in turn, implies that the difference in estimation of the diagnostic-relevant parameters is small, which suggests that the method can automatically provide precise clinical information.

Evaluation of forced oscilometry technique's parameters in severe obstructive sleep apnea patients without breathing disorder

Background:

Forced oscillometry technique (FOT) is a noninvasive technique that measures reactance and resistance capacity of the lung and is a practical and less time-consuming technique for respiratory effort assessment. Recently, FOT has provided beneficial data regarding the screening of the patients with obstructive sleep apnea (OSA) and assessing the disease progression. The current study aimed to evaluate the correlation of FOT parameters with severity of the apnea-hypnea index (AHI).

Methods:

In the current case series, all patients who had a body mass index ranging between 30 and 35, suffering severe OSA with AHI of more than 30 times per hour, were enrolled. Patients underwent FOT before treatment to measure the following FOT parameters: Respiratory resistance at 5 and 20 Hz (R5 and R20, respectively), resistance difference between R5 and R20, reactance at 5 Hz (X5), and resonant frequency (Fres).

Results:

In the current study, 22 patients were enrolled; whereas 12 (54.5%) were male and 10 (45.5%) were female with a mean age of 5.27 ± 4.34. A statistically significant, strong negative correlation was observed between Fres and AHI, during Pearson correlation analysis (r (20) =0.59, P < 0.0001). However, the relationship between the AHI and R5, R20, R5-R20 and X5 was not statistically significant. Similarly, the multiple regression model showed that, only Fres variable added statistically significantly to the prediction, P = 0.01.

Conclusion:

FOT is a useful tool in evaluation of AHI severity in patients suffering OSA and can be used as a diagnostic material in monitoring and management of these patients.