title: [RESPIRATORY IMPEDANCE MEASURING BY MostGraph-01 IS AFFECTED BY OBESITY].
abstract: BACKGROUND
  The forced oscillation technique (FOT) is a noninvasive method of measuring respiratory impedance, which includes respiratory system resistance (Rrs) and reactance (Xrs). The MostGraph-01 FOT device recently became clinically available in Japan, but standard impedance values for this device have not been determined in Japan.
  
  
  OBJECTIVE
  To assess the correlation between spirometry parameters and respiratory impedance in obese (body mass index [BMI]>=25) and non-obese (BMI<25) subjects.
  
  
  METHODS
  Clinical data were collected from 63 subjects without respiratory diseases who underwent spirometry and MostGraph-01 from January to October 2014. We investigated the correlation between spirometry parameters and respiratory impedance, and assessed the differing correlations among obese and non-obese subjects.
  
  
  RESULTS
  The Rrs at 5 Hz (R5) was significantly correlated with vital capacity (VC), forced vital capacity (FVC), and forced expiratory volume in 1 second (FEV1). The Xrs at 5 Hz (X5), frequency of resonance (Fres), and low-frequency reactance area (ALX) were significantly correlated with the VC, FVC, and FEV1. Obese subjects showed a significantly lower X5 (median, -0.68 cmH2O/l/s vs. -0.35), higher Fres (median, 9.76 Hz vs. 7.46), and higher ALX (median, 2.65 cmH2O/l vs. 1.24) compared to non-obese subjects. Moreover, the VC, FVC, and FEV1 were more highly correlated with R5, X5, Fres, and ALX in nonobese subjects than in obese subjects. A p value of less than 0.05 was considered statistically significant.
  
  
  CONCLUSIONS
  For MostGraph-01, it is suggested that obesity may influence Xrs rather than Rrs.
authors.affiliation: Isobe Clinic.
authors.forename: Zen
authors.initials: Z
authors.lastname: Isobe
authors.forename: Kenichirou
authors.initials: K
authors.lastname: Hara
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Maeno
mesh_terms: D000368:Aged; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D013147:Spirometry / Q000295:instrumentation* / Q000379:methods; D014797:Vital Capacity