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Anesth Analg 2006;103:1213-1218
© 2006 International Anesthesia Research Society
doi: 10.1213/01.ane.0000237400.29668.e6

CRITICAL CARE AND TRAUMA

The Effect of Tracheal Gas Insufflation on Gas Exchange Efficiency

Michael R. Pinsky, MD*{dagger}, Edgar Delgado, RRT{ddagger}, and Bernard Hete, PhD§

From the *Cardiopulmonary Research Laboratory, {dagger}Department of Critical Care Medicine, {ddagger}Respiratory Care, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and §Respironics Inc, Murrysville, Pennsylvania.

Address correspondence and reprint requests to Michael R. Pinsky, MD, Department of Critical Care Medicine, University of Pittsburgh, 606 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261. Address e-mail to pinskymr{at}upmc.edu.

Transtracheal gas insufflation (TGI) improves gas exchange efficiency, but is associated with hyperinflation, and usually requires ventilator adjustment to compensate for the increased gas flow. Although bidirectional TGI (Bi-TGI) minimizes hyperinflation, it does not preclude the need to reduce tidal volumes to prevent hyperinflation. A flow-compensation system was developed by Respironics (Murrysville, PA) to match TGI flows; however, neither that nor the efficacy of Bi-TGI have been tested in vivo. We tested the hypotheses that flow compensation allows for a constant minute ventilation; Bi-TGI produces less hyperinflation than does unidirectional TGI (Uni-TGI), and endotracheal tube size influences the degree of hyperinflation during TGI. Seven anesthetized intact dogs were studied during positive-pressure ventilation using the Respironics flow compensation system. Measurements were made during steady-state conditions at constant and measured levels of CO2 production. Gas exchange efficiency (assessed by expired gas analysis for dead space) and hyperinflation (measured as an increase in pleural pressure) were compared during Bi- and Uni-TGI and for endotracheal tube sizes varying from 7 to 10F. Bi- and Uni-TGI could be delivered at constant minute ventilation without adjusting ventilatory setting when the flow compensation circuit was present. Uni-TGI produced more hyperinflation than did Bi-TGI with all sizes of endotracheal tube, and hyperinflation was universally present as tube size decreased to 7.5F. We conclude that this new flow compensation system allows for the delivery of TGI without the need for adjustments to the ventilator settings, and that Bi-TGI produces less hyperinflation than does Uni-TGI, even with small diameter endotracheal tubes.






Lippincott, Williams & Wilkins Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999 HighWire Press
Copyright © 2006 by the International Anesthesia Research Society.