title: Low Transmission of Airway Pressures to the Abdomen in Mechanically Ventilated Patients With or Without Acute Respiratory Failure and Intra-Abdominal Hypertension.
abstract: OBJECTIVE
  Intra-abdominal pressure, measured at end expiration, may depend on ventilator settings and transmission of intrathoracic pressure. We determined the transmission of positive intrathoracic pressure during mechanical ventilation at inspiration and expiration into the abdominal compartment.
  
  
  RESULTS
  We included 9 patients after uncomplicated cardiac surgery and 9 with acute respiratory failure. Intravesical pressures were measured thrice (reproducibility of 1.8%) and averaged, at the end of each inspiratory and expiratory hold maneuvers of 5 seconds. Transmission, the change in intra-abdominal over intrathoracic pressures from end inspiration to end expiration, was about 8%. End-expiratory intra-abdominal pressure was lower than "total" intra-abdominal pressure over the entire respiratory cycle by 0.34 cm H2O. It was 0.73 cm H2O higher than "true" intra-abdominal pressure over the entire respiratory cycle, taking transmission into account. The percentage error was 3% for total and 10% for true pressure. Results did not differ among patients with or without acute respiratory failure and decreased respiratory compliance or between those with (≥12 mm Hg, n = 5) or without intra-abdominal hypertension.
  
  
  CONCLUSIONS
  Transmitted airway pressure only slightly affects intra-abdominal pressure in mechanically ventilated patients, irrespective of respiratory compliance and baseline intra-abdominal pressure values. End-expiratory measurements referenced against atmospheric pressure may suffice for clinical practice.
authors.affiliation: 1 Department of Intensive Care, St Antonius Ziekenhuis, Nieuwegein, the Netherlands.
authors.forename: Bram G A D H
authors.initials: BG
authors.lastname: Heijnen
authors.affiliation: 2 The Vrije Universiteit Medical Centre, Amsterdam, the Netherlands.
authors.forename: Angelique M E
authors.initials: AM
authors.lastname: Spoelstra-de Man
authors.affiliation: 3 The Erasmus Medical Centre, Rotterdam, the Netherlands.
authors.forename: A B Johan
authors.initials: AB
authors.lastname: Groeneveld
mesh_terms: D034841:Abdominal Cavity; D000368:Aged; D005260:Female; D006801:Humans; D059325:Intra-Abdominal Hypertension / Q000503:physiopathology* / Q000628:therapy; D008170:Lung Compliance; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results; D012121:Respiration, Artificial / Q000009:adverse effects / Q000379:methods; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy; D013990:Tidal Volume
keywords: abdominal compliance; acute respiratory distress syndrome; acute respiratory failure; intra-abdominal hypertension; positive end-expiratory pressures; respiratory compliance