title: Effect of Lanz pressure regulating valve on self-sealing mechanism and air leakage across the tracheal tube cuffs in a benchtop model.
abstract: BACKGROUND
  The aim of the present study was to investigate the effect of the Lanz system on air sealing by self-inflation in high volume-low pressure (HVLP) tube cuffs.
  
  
  METHODS
  In vitro tracheal air sealing was studied in HVLP tracheal tube cuffs (internal diameter [ID] 8.0 mm) made from polyurethane ([PU] Seal Guard tracheal tube, Covidien, Athlone, Ireland) and from polyvinylchloride ([PVC] HiLo tracheal tube, Covidien) with and without Lanz pressure regulating valve. Tube cuffs were placed in a vertical 22 mm ID artificial trachea and inflated to 5, 10, 15, 20, 25, or 30 cm H2O cuff pressures. Pressure control ventilation with peak inspiratory pressures (PIPs) of 20 or 25 cm H2O was applied and air leakage was assessed spirometrically as the ratio of expiratory to inspiratory tidal volumes. Nonparametric Mann-Whitney test was applied to compare the air leakage with and without Lanz system for both cuff types at each cuff pressure and PIP (P < .05).
  
  
  RESULTS
  The PVC tube cuffs with Lanz system resulted in significant air leakage at both 20 and 25 cm H2O PIP as compared to those without the Lanz system, especially at cuff pressures lower than the preset PIP (P < .05). Although PU tube cuffs with Lanz system showed reduced air sealing when compared with cuffs without Lanz, the difference was not statistically significant.
  
  
  CONCLUSIONS
  Cuff pressure compensation with the Lanz system during cyclic respiratory pressure changes interferes with the self-sealing mechanism in HVLP tube cuffs at cuff pressures lower than PIP level. This results in larger air leak across tube cuffs particularly in tube cuffs made from PVC.
authors: Department of Anaesthesia, University Children's Hospital, Steinwiesstrasse, Zurich, Switzerland. mital.dave@kispi.uzh.ch
authors: Mital H
authors: MH
authors: Dave
authors: Nelly
authors: N
authors: Spielmann
authors: Jacqueline
authors: J
authors: Mauch
authors: Markus
authors: M
authors: Weiss
mesh_terms: D004867:Equipment Design / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects / Q000295:instrumentation*; D008176:Lung Volume Measurements; D011175:Positive-Pressure Respiration / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012121:Respiration, Artificial / Q000379:methods*; D013147:Spirometry; D018709:Statistics, Nonparametric
chemical_list: D011933:Reagent Kits, Diagnostic