262 MEASUREHSNT OF BRONCHIAL OBSTRUCTION BY RESPIRATORY INDUCTANCE PLETHYSMOGRAPHY (RIP) IN SCHOOL CHILDREN

Abstract

Previously reported studies documented that the ratio of time taken to reach peak expiratory flow to total expiratory time (Tme/TE) measured by pneumotachograph (PTG) agreed with those measured by RIP [1].

We used RIP to measure Tme/TE before and after bronchial challenge with cold air (CACH) in a group of 22 school-aged children with history of asthma.

Noncalibrated rib cage (T), abdominal (A) and summed T+A (S) signals were differentiated to flow from which TTme/TE, ATme/ TE and STme/TE were calculated. Surface measured values were compared to pre- (a) and postchallenge (b) values of FEV1% predicted as well as PTG measured Tme/TE. The differences of prae- and postchallenge values (d) of these variables were also compared.

All, pre- and postchallenge values of Tme/TE, STme/TE, TTme/TE and ATme/TE significantly correlated with corresponding values of FEV1. Good correlation was also found between dFEV1 and dTme/TE (p<0.01) and dSTme/TE (p<0.01). dATme/TE better correlated with dFEV1 (p<0.01) when compared to dTTme/TE (p<0.05). Similarly, the close agreement was found between values for aTme/TE (range 0.22 - 0.39) and aSTme/TE (range 0.18 - 0.38) with mean (95% CI) within-pair difference of 0.04 (-0.03,+0.11; max. diff. 0.14) and aATme/TE (range 0.21- 0.33) with a mean difference of 0.02 (-0.01,+0.06; max.diff. 0.12).

Conclusion: Tme/TE, STme/TE and ATme/TE correlated with FEV1 and could be used as a good measure for bronchial obstruction even in non-cooperative subjects.

Ref. [l] Stick S et all. Aroer Rev Respir Pis 1992: 145:A252

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