title: Overinflation of the cuff and pressure on the neck reduce the preventive effect of supraglottic airways on pulmonary aspiration: an experimental study in human cadavers.
abstract: BACKGROUND
  The oesophageal leak pressure is defined as the pressure which breaks the seal between the cuff of a supraglottic airway and the peri-cuff mucosa, allowing penetration of fluid into the pharynx and the oral cavity. As a consequence, a decrease in this variable increases the risk of reflux and can lead to pulmonary aspiration. The aim of this study was to analyse the effects of cuff overinflation and pressure on the neck on the oesophageal leak pressure of seven supraglottic airways.
  
  
  METHODS
  Three laryngeal masks, two laryngeal tubes, and two oesophageal-tracheal tubes were tested in an experimental setting. In five human cadavers, we simulated a sudden increase in oesophageal pressure. To measure baseline values (control), we used an intracuff pressure as recommended by the manufacturer. The first intervention included overinflation of the cuff by applying twice the amount of pressure recommended. A second intervention was defined as external pressure on the neck.
  
  
  RESULTS
  The oesophageal leak pressure was decreased for laryngeal masks (control, 28 cm H2O; overinflation, 9 cm H2O; pressure on the neck, 8 cm H2O; P<0.01) and for laryngeal tubes (control, 68 cm H2O; overinflation, 37 cm H2O; pressure on the neck, 39 cm H2O; P<0.01) and was unaffected for oesophageal-tracheal tubes (control, 126 cm H2O; overinflation/pressure on the neck, 130 cm H2O; n.s.).
  
  
  CONCLUSIONS
  Cuff overinflation and pressure on the neck can enhance the risk of gastro-oesophageal reflux when using supraglottic airways. Therefore, both manoeuvres should be avoided in clinical practice.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, Chefarzt der Abteilung Anästhesiologie und Intensivmedizin, Park-Klinik-Weissensee, Schönstrasse 80, Berlin 13086, Germany hensel@park-klinik.com.
authors.forename: M
authors.initials: M
authors.lastname: Hensel
authors.affiliation: Department of Anaesthesiology, Intensive Care Medicine, Emergency Medicine, Combat Search and Rescue Bundeswehrkrankenhaus, Berlin 10115, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Schmidbauer
authors.affiliation: Department of Anaesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Therapy, Asklepios Klinik Nord Heidberg, Hamburg 22417, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Geppert
authors.affiliation: Department of Medical Biometry and Epidemiology, University Medical Center, Hamburg-Eppendorf, Hamburg 20246, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Sehner
authors.affiliation: Center for Anatomy, Charité-Universitätsmedizin, Berlin 10117, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Bogusch
authors.affiliation: Department of Anaesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Therapy, Asklepios Klinikum Harburg, Hamburg 21075, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kerner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D017214:Laryngeal Masks / Q000009:adverse effects*; D008297:Male; D009333:Neck; D011312:Pressure; D053120:Respiratory Aspiration / Q000517:prevention & control*
keywords: laryngeal masks; models, anatomical; respiratory aspiration