title: Double-lumen tubes and auto-PEEP during one-lung ventilation.
abstract: BACKGROUND
  Double-lumen tubes (DLT) are routinely used to enable one-lung-ventilation (OLV) during thoracic anaesthesia. The flow-dependent resistance of the DLT's bronchial limb may be high as a result of its narrow inner diameter and length, and thus potentially contribute to an unintended increase in positive end-expiratory pressure (auto-PEEP). We therefore studied the impact of adult sized DLTs on the dynamic auto-PEEP during OLV.
  
  
  METHODS
  In this prospective clinical study, dynamic auto-PEEP was determined in 72 patients undergoing thoracic surgery, with right- and left-sided DLTs of various sizes. During OLV, air trapping was provoked by increasing inspiration to expiration ratio from 1:2 to 2:1 (five steps). Based on measured flow rate, airway pressure (Paw) and bronchial pressure (Pbronch), the pressure gradient across the DLT (ΔPDLT) and the total auto-PEEP in the respiratory system (i.e. the lungs, the DLT and the ventilator circuit) were determined. Subsequently the DLT's share in total auto-PEEP was calculated.
  
  
  RESULTS
  ΔPDLT was 2.3 (0.7) cm H2O over the entire breathing cycle. At the shortest expiratory time the mean total auto-PEEP was 2.9 (1.5) cm H2O (range 0-5.9 cm H2O). The DLT caused 27 to 31% of the total auto-PEEP. Size and side of the DLT's bronchial limb did not impact auto-PEEP significantly.
  
  
  CONCLUSIONS
  Although the DLT contributes to the overall auto-PEEP, its contribution is small and independent of size and side of the DLT's bronchial limb. The choice of DLT does not influence the risk of auto-PEEP during OLV to a clinically relevant extent.
  
  
  BACKGROUND
  DRKS00005648.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Str. 55, Freiburg 79106, Germany johannes.spaeth@uniklinik-freiburg.de.
authors.forename: J
authors.initials: J
authors.lastname: Spaeth
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Str. 55, Freiburg 79106, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Ott
authors.affiliation: Department of Anaesthesia, Intensive Care and Emergency Medicine, Zentralklinik Bad Berka, Robert-Koch-Allee 9, Bad Berka 99437, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Karzai
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Str. 55, Freiburg 79106, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Grimm
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Str. 55, Freiburg 79106, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Wirth
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Str. 55, Freiburg 79106, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schumann
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Str. 55, Freiburg 79106, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Loop
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061810:One-Lung Ventilation / Q000295:instrumentation*; D011175:Positive-Pressure Respiration / Q000706:statistics & numerical data*; D011446:Prospective Studies
keywords: airway management; airway resistance; intrinsic peep; one-lung ventilation