Validation of respiratory inductive plethysmography (LifeShirt) in obesity hypoventilation syndrome

Validation of respiratory inductive plethysmography (LifeShirt system) (RIPLS) for tidal volume (VT), minute ventilation ( V ˙ E ) , and respiratory frequency (fB) was performed among people with untreated obesity hypoventilation syndrome (OHS) and controls. Measures were obtained simultaneously from RIPLS and a spirometer during two tests, and compared using Bland Altman analysis. Among 13 OHS participants (162 paired measures), RIPLS-spirometer agreement was unacceptable for VT: mean difference (MD) 3 mL (1%); limits of agreement (LOA) −216 to 220 mL (±36%); V ˙ E MD 0.1 L min−1 (2%); LOA −4.1 to 4.3 L min−1 (±36%); and fB: MD 0.2 br min−1 (2%); LOA −4.6 to 5.0 br min−1 (±27%). Among 13 controls (197 paired measures), RIPLS-spirometer agreement was acceptable for fB: MD −0.1 br min−1 (−1%); LOA −1.2 to 1.1 br min−1 (±12%), but unacceptable for VT: MD 5 mL (1%); LOA −160 to 169 mL (±20%) and V ˙ E : MD 0.1 L min−1 (1%); LOA −1.4 to 1.5 L min−1 (±20%). RIPLS produces valid measures of fB among controls but not OHS patients, and is not valid for quantifying respiratory volumes among either group.