0
Clinical Investigations: THE PLEURA |

Modification of Pleural Fluid pH by Local Anesthesia*

David Jiménez Castro, MD; Gema Díaz, MD; Esteban Pérez-Rodríguez, MD, PhD; Edgardo Prieto, RN; Roger D. Yusen, MD
Author and Funding Information

*From the Respiratory Disease Service (Drs. Castro, Díaz, Pérez-Rodríguez, and Mr. Prieto), Hospital Universitario Ramón y Cajal, Madrid, Spain; and the Division of Pulmonary and Critical Care Medicine (Dr. Yusen), Washington University School of Medicine, St. Louis, MO.

Correspondence to: David Jiménez Castro, MD, Servicio de Neumologia, Hospital Ramón y Cajal, Apartado 31057, E-28080 Madrid, Spain



Chest. 1999;116(2):399-402. doi:10.1378/chest.116.2.399
Text Size: A A A
Published online

Background: It is a common practice to anesthetize patients before performing a thoracentesis. We postulated that this technique may cause a clinically significant difference in the pH of the pleural fluid.

Methods: We compared two methods of determining pleural fluid pH. Fifty patients undergoing diagnostic or therapeutic thoracentesis were enrolled. Two 4-mL aliquots of pleural fluid were anaerobically collected into blood gas syringes containing heparin, one before (group A) and the other after (group B) anesthetizing the patient with 5 mL of 2% mepivacaine. pH was then determined on both samples using an arterial blood gas machine. Agreement analysis was performed overall and in subcategories of pH used to define complicated (< 7.1), borderline (7.1 to 7.3), or uncomplicated (> 7.3) parapneumonic effusions. We analyzed these same data stratified by the volume of pleural fluid in relationship to the size of the hemithorax (< 15% and > 15%).

Results: There was a statistical difference between the mean pH in both groups (group A, 7.32; group B, 7.28; p < 0.0001). There was a significant correlation between the two measures (r = 0.97; p < 0.0001). Using the pH subcategories, there was 45% discordance in classification for patients with parapneumonic effusions. The pH values obtained in group B wrongly predicted whether the patient required a chest tube in two of four cases (50%). In patients with effusions that occupied < 15% of the affected hemithorax, there was an 80% discordance in classification for patients with parapneumonic effusions, and the pH values obtained in group B wrongly predicted whether the patient required a chest tube in two of two cases (100%).

Conclusions: Local anesthesia is typically used before thoracentesis is performed. However, in cases of suspected parapneumonic effusions that occupy< 15% of the affected hemithorax, pH results may be significantly altered by use of local mepivacaine anesthesia.

Figures in this Article

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Figures

Tables

References

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Sign In to Access Full Content

MEMBER & INDIVIDUAL SUBSCRIBER

Want Access?

NEW TO CHEST?

Become a CHEST member and receive a FREE subscription as a benefit of membership.

Individuals can purchase this article on ScienceDirect.

Individuals can purchase a subscription to the journal.

Individuals can purchase a subscription to the journal or buy individual articles.

Learn more about membership or Purchase a Full Subscription.

INSTITUTIONAL ACCESS

Institutional access is now available through ScienceDirect and can be purchased at myelsevier.com.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Find Similar Articles
CHEST Journal Articles
PubMed Articles
Guidelines
  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543