Source: Annual Congress 2002 - Bridging the gap - lung function from infancy through childhood
Disease area: Airway diseases, Paediatric lung diseases

Abstract

Partial (RTC) and full (RVRTC) forced expiratory manoeuvres are both frequently used to assess airway function in infants, but little is known about the relationship between the two in this age group. The aim of this study was to assess whether prior lung inflations influence V'_maxFRC in infants. Methods: Paired measurements (pre- and post RVRTC) of V'_maxFRC were obtained in 10 healthy infants (aged 7-40 weeks, weight 3.6-10.5 kg). Within each infant, an identical jacket pressure was used during both sets of measurements. The lung inflation was set to 3 kPa for the RVRTC.
Results: Mean(SD) V'_maxFRCwas significantly lower (p=0.01) following RVRTC than beforehand (95%CI: -56,-8 mL.s^-1, average decrease: 20%). There were minimal changes in breathing pattern between the two sets of measurements.
Conclusion: RVRTC manoeuvres appear to influence small airway function, but the mechanisms underlying these observations remain uncertain. Possible explanations may include changes in: a) airway smooth muscle properties, b) airway-parenchymal relationships, c) stretch receptor activity, d) lung volumes or e) PV characteristics of the lungs and airways. Until clarified, partial forced expiratory manoeuvres should be performed prior to those from raised lung volume.
This study is funded by the Foundation for the Study of Infant Deaths, Portex plc and Innovative Medizinische Forschung, Munster, Germany.

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Citations should be made in the following way:
S. Lum, G. Hulskamp, A. F. Hoo, A. Cantarella, J. Stocks (London, United Kingdom). Effect of raised lung volume (RVRTC) technique on V'_maxFRC in infants. Eur Respir J 2002; 20: Suppl. 38, 251

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