A Longitudinal Study of Respiratory Mechanics in Pregnant Women with Obesity and Overweight

PURPOSE

Respiratory mechanics and the role of sex hormones in pregnancy are not well elucidated. We examined longitudinal and positional changes in lung mechanics in pregnancy and investigated the role of sex hormones.

METHODS

A longitudinal study enrolled 135 women with obesity in early pregnancy. Fifty-nine percent of women identified as White; median body mass index at enrollment was 34.4 kg/m2. Women with respiratory disease were excluded. We obtained measurements of airway resistance and respiratory system reactance in various positions using impedance oscillometry and sex hormones in early and late pregnancy.

RESULTS

With pregnancy progression, there was a significant increase in resonant frequency (Fres) (p = 0.012), integrated area of low frequency reactance (AX) (p = 0.0012) and R5-R20Hz (p = 0.038) in the seated position, and a significant increase in R5Hz (p = 0.000), Fres (p = 0.001), AX (p < 0.001 = 0.000), and R5-R20Hz (p = 0.014) in the supine position. Compared to the seated position, the supine position was associated with a significant increase in R5Hz, R20Hz, X5Hz, Fres, and AX in early (p-values < 0.026) and late pregnancy (p-values ≤ 0.001). Changes in progesterone levels between early and late pregnancy predicted the change in R5, Fres, and AX (p-values ≤ 0.043).

CONCLUSION

Resistive and elastic loads increase with pregnancy progression and a change in body position from seated to supine increases resistive and elastic loads in both early and late pregnancies. The increase in airway resistance is primarily related to an increase in peripheral rather than central airways resistance. There was an association between the change in progesterone levels and airway resistance.

The relationship between respiratory system impedance and lung function in asthmatics: A prospective observational study

INTRODUCTION

The aim was to elucidate the relationship between the annual changes in respiratory system impedance, measured by FOT, and lung function tests in patients with asthma.

METHODS

Between March 2011 and March 2012, asthma outpatients who attended Kobe City Medical Center West Hospital were recruited. Lung function tests, FOT were conducted every 6 months until March 2016. The relationships between annual parameter changes were evaluated.

RESULTS AND CONCLUSION

Sixty-four patients were completed this study. The median follow-up period was 55 months. At enrollment, although resistance showed no relationship with forced expiratory volume in one second (%FEV₁), the reactance was moderately correlated with X5 (r=0.524, r²=0.275, <0.001), Fres (r=-0.498, r²=0.248, <0.001) and ALX (r=-0.416, r²=0.173, p=<0.001). By contrast, the annual resistance change at 5Hz (R5) was highly and significantly associated with%FEV₁ change (r=-0.564, r²=0.318, p<0.001). Longitudinal changes in airway resistance and reactance measured by FOT might be useful for the assessment of lung function in patients with asthma.

Three-dimensional imaging forced oscillation technique to assess position-dependent airway obstruction in relapsing polychondritis: A case report

Relapsing polychondritis (RP) is characterized by recurrent systemic inflammation of the cartilages and is accompanied by central airway collapse. We report a case wherein three-dimensional imaging of respiratory system resistance (Rrs) and respiratory system reactance (Xrs) by using MostGraph (CHEST M.I., Tokyo, Japan), a forced oscillation system, revealed that Rrs and Xrs in the inspiratory and expiratory phases correlated with proximal airway collapse. The degree of difference in Rrs and Xrs between the supine and sitting positions reflected airway collapse more closely than did the pulmonary function test. MostGraph could be a useful tool for assessing airway collapse in RP.