title: Airway mechanosensor behavior during application of positive end-expiratory pressure.
abstract: BACKGROUND
  Positive end-expiratory pressure (PEEP) is commonly used in clinical settings. It is expected to affect the input from slowly adapting pulmonary stretch receptors (SARs), leading to altered cardiopulmonary functions. However, we know little about how SARs behave during PEEP application.
  
  
  OBJECTIVE
  Our study aimed to characterize the behavior of SARs during PEEP application.
  
  
  METHODS
  We recorded single-unit activities from 18 SARs in the cervical vagus nerve and examined their response to an increase of PEEP from 3 to 10 cm H2O for 20 min in anesthetized, open-chest and mechanically ventilated rabbits.
  
  
  RESULTS
  The mean activity of the units increased immediately from 35.7 to 80.5 impulses per second at the fifth breath after increasing PEEP (n = 14, p < 0.001) and then gradually returned to 56.5 impulses per second at the end of 20 min of PEEP application (p < 0.001). In the meantime, peak airway pressure increased from 9.3 to 32.7 cm H2O, and then gradually returned to 29.4 cm H2O (n = 18; p < 0.05) after 20 min. The remaining four units ceased firing at 34.7 s (range 10-56 s) after their initial increased activity upon 10 cm H2O PEEP application. The unit activity resumed as the PEEP was returned to 3 cm H2O.
  
  
  CONCLUSIONS
  High PEEP stimulates SARs and SAR activity gradually returns towards the baseline via multiple mechanisms including receptor deactivation, neural habituation and mechanical adaptation. Understanding of the sensory inputs during PEEP application will assist in developing better strategies of mechanical ventilation.
authors.affiliation: Robley Rex VA Medical Center, University of Louisville, Louisville, Ky., USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Guardiola
authors.forename: Bryan
authors.initials: B
authors.lastname: Moffett
authors.forename: Huafeng
authors.initials: H
authors.lastname: Li
authors.forename: Rajeesh
authors.initials: R
authors.lastname: Punnakkattu
authors.forename: Bogden
authors.initials: B
authors.lastname: Moldoveanu
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Du
authors.forename: Jerry
authors.initials: J
authors.lastname: Yu
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001696:Biomechanical Phenomena; D023421:Models, Animal; D011175:Positive-Pressure Respiration / Q000379:methods*; D011661:Pulmonary Stretch Receptors / Q000502:physiology*; D011817:Rabbits; D012137:Respiratory System / Q000294:innervation*