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.