JOURNAL HOME CME HOME THIS MONTH PAST ISSUES ETOC COLLECTIONS AUTHORS REVIEWERS EDITORIAL BOARD FEEDBACK RSS HELP
		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kawati, R. Articles by Lichtwarck-Aschoff, M. Search for Related Content PubMed PubMed Citation Articles by Kawati, R. Articles by Lichtwarck-Aschoff, M. Related Collections Critical Care Airway

---

CRITICAL CARE AND TRAUMA

Change in Expiratory Flow Detects Partial Endotracheal Tube Obstruction in Pressure-Controlled Ventilation

Rafael Kawati, MD, PhD^*, Laszlo Vimlati, MD^*, Josef Guttmann, PhD, Göran Hedenstierna, MD, PhD, Ulf Sjöstrand, MD, PhD^*, Stefan Schumann, PhD, and Michael Lichtwarck-Aschoff, MD, PhD^*

From the Departments of *Surgical, and Medical Sciences, University Hospital, Uppsala, Sweden; Department of Anesthesiology and Critical Care Medicine, University Hospital, Freiburg, Germany; Department of Anesthesiology and Critical Care Medicine, Klinikum Augsburg, Augsburg, Germany.

Address correspondence and reprint requests to Rafael Kawati, MD, Department of Surgical Sciences/Anesthesiology & Intensive Care, Uppsala University Hospital, SE-751 85 Uppsala, Sweden. Address e-mail to r.kawati{at}comhem.se.

Only extreme degrees of endotracheal tube (ETT) narrowing can be detected with monitoring of tidal volume (V_T) during pressure-controlled ventilation (PCV). To assess the degree of ETT obstruction in PCV and to compare it to V_T monitoring, we produced 3 levels of partial ETT obstruction in 11 healthy anesthetized piglets using ETTs of 4 different inner diameters (IDs 9.0, 8.0, 7.0, and 6.0 mm). An expiratory flow over volume (_e–V) curve was plotted and the time constant (_e) at 15% of expiration time (T_e) was calculated. We also calculated the fractional volume expired during the first 15% of T_e (V_{ex fract,15}) and compared those variables to full expiratory V_T for each of the 3 obstructions. V_T monitoring failed to detect ETT narrowing. By contrast, V_{ex fract,15} decreased and _e increased significantly with increasing ETT narrowing (for IDs 9.0, 8.0, 7.0, and 6.0, mean V_{ex fract,15} was 195, 180, 146, and 134 mL respectively and mean _e was 380, 491, 635, 794 ms for IDs 9.0, 8.0, 7.0, and 6.0 respectively). We conclude that when the elastic recoil that drives _e is appropriately considered, analysis of _e and V_{ex fract,15} detects partial ETT obstruction during PCV.

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