Utility of Phase Angle to Identify Responders with Acute Airway Obstruction in the Emergency Room
Published on: 2015-11-15
Background: Few studies combine impulse oscillometry (IOS) and respiratory inductance plethysmography (RIP) for assessing acute obstruction in the pediatric emergency department (ED). We correlated the clinical score, IOS and RIP, and evaluated their ability to differentiate “responders” from “non-responders” at baseline. Methods: A study of 40 patients in mild-to-moderate respiratory distress. Clinical score consisted of: respiratory rate (RR), wheezing, and degree of muscular retraction. Biomarkers included: IOS [Respiratory resistance (Rrs5-20), reactance (Xrs5 ), resonant frequency (fres) and IOS severity score] and RIP [Phase angle, phase relation during total breath (PhRTB) and labored breathing index (LBI)]. Measurements were performed before and after pharmacotherapy. The percent change in Rrs5 (?%Rrs5 ) was used as the gold standard. Results: Twelve of 40 patients (6-18 yrs.) completed all testing. Median IOS score was 2 (moderate obstruction). Baseline Xrs5 , fres, and LBI correlated with RR; Phase angle and PhRTB correlated with the clinical score. Higher baseline Rrs10 and phase angles were associated with larger decreases in ?%Rrs5 . Receiver operating characteristic demonstrated: Rrs10 (AUC 0.86), RR (AUC 0.86) and phase angle (AUC 0.83). Conclusions: Compared to clinical asthma scores, IOS (Rrs10) and RIP parameters (phase angle) may better identify responders from non-responders to pharmacotherapy in pediatric ED settings.