title: Central venous and bladder pressure reflect transdiaphragmatic pressure during pressure support ventilation.
abstract: OBJECTIVE
  To determine whether the change in bladder pressure (Pblad) and central venous pressure (Pcvp) may reflect the changes in esophageal pressure (Pes) and gastric pressure (Pgas) when inspiratory pressure support (IPS) is altered.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  The ICUs of a teaching hospital.
  
  
  METHODS
  Ten patients currently receiving IPS ventilation via a tracheostomy or an endotracheal tube who already had bladder and central venous catheters in situ.
  
  
  RESULTS
  Airway pressure, Pes, Pgas, Pcvp, Pblad, and flow were measured at the original IPS setting. IPS then was reduced by 5-cm H(2)O increments until IPS was zero or was at the minimum pressure that could be tolerated by each patient. At each level of IPS, pressures and flow were measured at steady-state breathing. The maximum pressure difference for each pressure during inspiration was calculated. We found that the Delta Pblad correlated closely with the Delta Pgas (r = 0.904) and that the Delta Pes correlated with the Delta Pcvp (r = 0.951). When the Delta Pcvp - Delta Pblad was compared with the transdiaphragmatic pressure for each patient as the IPS was altered, the correlation coefficients varied from 0.952 to 0.999.
  
  
  CONCLUSIONS
  Although absolute values for the Delta Pcvp during mechanical ventilation do not always reflect the Delta Pes, useful information can be obtained from this route. In individual patients, the two sites of measurement followed each other when IPS was changed, enabling a bedside assessment of the response to reducing respiratory support.
authors.affiliation: Department of Anesthesia, University College London Medical School, London, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Chieveley-Williams
authors.forename: Lila
authors.initials: L
authors.lastname: Dinner
authors.forename: Anna
authors.initials: A
authors.lastname: Puddicombe
authors.forename: Debbie
authors.initials: D
authors.lastname: Field
authors.forename: A T
authors.initials: AT
authors.lastname: Lovell
authors.forename: John C
authors.initials: JC
authors.lastname: Goldstone
mesh_terms: D000328:Adult; D000368:Aged; D002496:Central Venous Pressure; D003964:Diaphragm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D012121:Respiration, Artificial; D001743:Urinary Bladder / Q000502:physiology*