title: Intra-abdominal pressure may be decreased non-invasively by continuous negative extra-abdominal pressure (NEXAP).
abstract: OBJECTIVE
  To investigate the possibility of artificially decreasing intra-abdominal pressure (IAP) by applying continuous negative pressure around the abdomen.
  
  
  METHODS
  We investigated the effects of negative extra-abdominal pressure (NEXAP) on IAP and central venous pressure (CVP) in 30 patients admitted to our intensive care unit (age 57+/-17 years, BMI 26.1+/-4.0 kg/m2, SAPS II 41.8+/-17.0). Patients with severe hemodynamic instability and/or those admitted following a laparotomy were not studied. Measurements included bladder pressure as an estimate of IAP, CVP, invasive mean arterial pressure (MAP) and heart rate (HR). In five patients extensive hemodynamic measurements were also taken using a Swan-Ganz catheter. Following measurements at baseline (Basal), NEXAP (Life Care - Nev 100, Respironics) was applied on the abdomen, in random order, at a pressure equal to IAP (NEXAP0), 5 cmH(2)O (NEXAP-5) or 10 cmH(2)O (NEXAP-10) more negative than NEXAP0.
  
  
  RESULTS
  Basal IAP ranged from 4 to 22 mmHg. NEXAP decreased IAP from 8.7+/-4.3 mmHg to 6+/-4.2 (Basal vs NEXAP0 p<0.001). There was a further decrease of IAP when more negative pressure was applied: 4.3+/-3.2 mmHg, 3.8+/-3.7 mmHg (NEXAP-5 and NEXAP-10 vs NEXAP0, respectively, p<0.001). Similarly, CVP decreased from 9.3+/-3.4 mmHg to 7.5+/-3.8 (Basal vs NEXAP-10, p<0.001). The lower the IAP when NEXAP was applied, the lower the CVP (r2=0.778, p<0.001, multiple linear regression). When measured, cardiac output did not significantly change with NEXAP.
  
  
  CONCLUSIONS
  Negative extra-abdominal pressure may be applied in critically ill patients to decrease intra-abdominal pressure non-invasively.
authors.affiliation: Istituto di Anestesia e Rianimazione, Ospedale Maggiore di Milano-Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Università degli Studi di Milano, Via F. Sforza 35, 20122, Milan, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Valenza
authors.forename: Nicola
authors.initials: N
authors.lastname: Bottino
authors.forename: Katia
authors.initials: K
authors.lastname: Canavesi
authors.forename: Alfredo
authors.initials: A
authors.lastname: Lissoni
authors.forename: Salvatore
authors.initials: S
authors.lastname: Alongi
authors.forename: Sabina
authors.initials: S
authors.lastname: Losappio
authors.forename: Eleonora
authors.initials: E
authors.lastname: Carlesso
authors.forename: Luciano
authors.initials: L
authors.lastname: Gattinoni
mesh_terms: D000005:Abdomen; D000368:Aged; D000403:Airway Resistance; D000704:Analysis of Variance; D001794:Blood Pressure; D002407:Catheterization, Swan-Ganz; D002496:Central Venous Pressure; D003422:Critical Care / Q000379:methods; D016638:Critical Illness / Q000628:therapy; D005260:Female; D006339:Heart Rate; D006801:Humans; D008150:Lower Body Negative Pressure / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D008170:Lung Compliance; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D012044:Regression Analysis; D012121:Respiration, Artificial / Q000379:methods; D015656:Respiratory Mechanics; D013990:Tidal Volume; D014546:Urinary Catheterization