In patients with chronic airflow limitation (CAL), the detection of upper airway obstruction (UAO) by analysis of forced flows can be difficult due to the masking of conventional UAO indices. We analyzed five indices: maximum inspiratory flow at 50% of forced vital capacity (FIF50), the ratio of maximum expiratory to inspiratory flow at 50% of forced vital capacity (FEF50/FIF50), the ratio FEV1/PEFR, the ratio FEV1 to forced expiratory volume in 0.5 s (FEV1/FEV0.5), and the ratio maximum voluntary ventilation (MVV)/FEV1, to determine their usefulness in evaluating patients with simultaneous UAO and CAL. One hundred and thirty-seven patients participated: 54 had UAO alone, 23 presented simultaneous UAO and CAL and 60 suffered from CAL with no evidence of UAO. The patients with UAO and CAL on the average presented fewer abnormal indices and these were less severely altered. Twenty-seven of the 60 with CAL alone presented at least one abnormal index, but in no case were more than two present. FEF50/FIF50 and FEV1/PEFR were significantly less sensitive in patients with both UAO and CAL than in those with UAO alone (35 vs. 85% and 52 vs. 72%, respectively). In all patients the most specific indices (100%) were FEF50/FIF50 and MVV/FEV1. The index MVV/FEV1 was the most accurate in patients with UAO and CAL. We conclude that when patients with CAL present 3 or more abnormal UAO indices, or have FEF50/FIF50 ≧l or MVV/FEV1 < 25, the possibility of simultaneous UAO must be strongly considered.

Keywords:
Upper airway obstruction, Chronic airflow limitation, Tracheal stenosis, Laryngeal disease
This content is only available via PDF.
© 1994 S. Karger AG, Basel
1994
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.