Background: Pleural fluid (PF) pH measurement is important for establishing a diagnosis and for guiding clinical management. The current standard practice is to collect PF samples for pH measurement in heparinized syringes at room temperature and to instantaneously process these samples. Objective: The purpose of this study is to investigate the effect of collecting PF in heparinized versus non-heparinized syringes at room temperature on PF pH measurements when processed at various time intervals. Methods: From 50 consecutive thoracenteses, 1 ml of PF was collected anaerobically in each of six 3-ml syringes. Only three syringes were coated with heparin. The samples were processed for PF pH measurements at time 0 (T₀) and 1 h (T1) and 2 h (T2) after collection. All specimens were preserved at room temperature, until the measurements were carried out in duplicates by a calibrated blood gas analyzer. Results: PF pH values were significantly lower with heparinized versus non-heparinized syringes at all time intervals (T₀: pH heparinized = 7.378 ± 0.107 vs. pH non-heparinized = 7.390 ± 0.108; T1: pH heparinized = 7.378 ± 0.115 vs. pH non-heparinized = 7.389 ± 0.111; T2: pH heparinized = 7.367 ± 0.105 vs. pH non-heparinized = 7.389 ± 0.121). In the heparinized syringes, there was a significant decrease in PF pH values at T2 versus T₀ and T1. There were no significant changes in PF pH values over time in the non-heparinized syringes. Conclusions: For serial PF pH measurements, the same type of syringes (either heparinized or non-heparinized) should be consistently used. With heparinized syringes, processing of PF pH measurements should be performed within 1 h after collection.

Keywords:
Pleural fluid pH measurements, Heparinized syringes, Non-heparinized syringes
1.
Good JT Jr, Taryle DA, Maulitz RM, Kaplan RL, Sahn SA: The diagnostic value of pleural fluid pH. Chest 1980;78:55–59.
2.
Aelony Y, Yao JF, King RR: Prognostic value of pleural fluid pH in malignant epithelial mesothelioma after talc poudrage. Respiration 2006;73:334–339.
3.
Heffner JE, Heffner JN, Brown LK: Multilevel and continuous pleural fluid pH likelihood ratios for draining parapneumonic effusions. Respiration 2005;72:351–356.
4.
Chandler TM, McCoskey EH, Byrd RP, Roy TM: Comparison of the use and accuracy of methods for determining pleural fluid pH. South Med J 1999;92:214–217.
5.
Goldstein LS, McCarthy K, Mehta AC, Arroliga AC: Is direct collection of pleural fluid into a heparinized syringe important for determination of pleural pH? A brief report. Chest 1997;112:707–708.
6.
Sarodia BD, Goldstein LS, Laskowski DM, Mehta AC, Arroliga AC: Does pleural fluid pH change significantly at room temperature during the first hour following thoracentesis? Chest 2000;117:1043–1048.
7.
Pieters T, Rodenstein DO: Use of nonheparinized syringes for collecting pleural fluid samples. Chest 1998;114:656–657.
8.
Cheng DS, Rodriguez RM, Rogers J, Wagster M, Starnes DL, Light RW: Comparison of pleural fluid pH values obtained using blood gas machine, pH meter, and pH indicator strip. Chest 1998;114:1368–1372.
© 2007 S. Karger AG, Basel
2007
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.