title: Interaction between intra-abdominal pressure and positive-end expiratory pressure.
abstract: OBJECTIVE
  The aim of this study was to quantify the interaction between increased intra-abdominal pressure and Positive-End Expiratory Pressure.
  
  
  METHODS
  In 30 mechanically ventilated ICU patients with a fixed tidal volume, respiratory system plateau and abdominal pressure were measured at a Positive-End Expiratory Pressure level of zero and 10 cm H2O. The measurements were repeated after placing a 5 kg weight on the patients' belly.
  
  
  RESULTS
  After the addition of 5 kg to the patients' belly at zero Positive-End Expiratory Pressure, both intra-abdominal pressure (p<0.001) and plateau pressures (p=0.005) increased significantly. Increasing the Positive-End Expiratory Pressure levels from zero to 10 cm H2O without weight on the belly did not result in any increase in intra-abdominal pressure (p=0.165). However, plateau pressures increased significantly (p< 0.001). Increasing Positive-End Expiratory Pressure from zero to 10 cm H2O and adding 5 kg to the belly increased intra-abdominal pressure from 8.7 to 16.8 (p<0.001) and plateau pressure from 18.26 to 27.2 (p<0.001). Maintaining Positive-End Expiratory Pressure at 10 cm H2O and placing 5 kg on the belly increased intra-abdominal pressure from 12.3 +/- 1.7 to 16.8 +/- 1.7 (p<0.001) but did not increase plateau pressure (26.6+/-1.2 to 27.2 +/-1.1 -p=0.83).
  
  
  CONCLUSIONS
  The addition of a 5 kg weight onto the abdomen significantly increased both IAP and the airway plateau pressure, confirming that intra-abdominal hypertension elevates the plateau pressure. However, plateau pressure alone cannot be considered a good indicator for the detection of elevated intra-abdominal pressure in patients under mechanical ventilation using PEEP. In these patients, the intra-abdominal pressure must also be measured.
authors.affiliation: Departamento de Patologia, Faculdade de Medicina e Instituto Central, Central do Hospital das Clinicas, Universidade Cruzeiro do Sul, São Paulo/SP, Brasil. jamilianbar@yahoo.com
authors.forename: Jamili Anbar
authors.initials: JA
authors.lastname: Torquato
authors.forename: Jeanette Janaina Jaber
authors.initials: JJ
authors.lastname: Lucato
authors.forename: Telma
authors.initials: T
authors.lastname: Antunes
authors.forename: Carmen Valente
authors.initials: CV
authors.lastname: Barbas
mesh_terms: D000005:Abdomen / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D018467:Positive-Pressure Respiration, Intrinsic; D011312:Pressure; D012121:Respiration, Artificial / Q000379:methods*; D013990:Tidal Volume / Q000502:physiology; D055815:Young Adult