title: Use of near-infrared spectroscopy as a physiologic monitor for intra-abdominal hypertension.
abstract: BACKGROUND
  Intra-abdominal hypertension (IAH) is increasingly recognized as an important parameter in critically ill (ICU) patients. IAH affects perfusion to all abdominal components including the abdominal wall (AW). Near infrared spectroscopy (NIRS) measures changes in three chromophores including oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (Hb), and cytochrome aa3 (Cyt), providing information concerning dysoxia. We sought to examine whether NIRS measurement of the AW was safe, and correlated with intra-abdominal pressure (IAP) in ICU patients.
  
  
  METHODS
  A NIU-Pro001 system recorded NIRS data over 24 hours from the AW of 9 ICU patients at risk for IAH. IAP was recorded from the bladder. Changes in chromophore values are interpolated from best-fit polynomial curves.
  
  
  RESULTS
  Sixty-six paired IAP and NIRS readings were taken from 9 ICU (4-12 observations/patient) patients. No measurement related adverse reactions occurred. The mean (range) first values measured in these patients were; IAP 17.2 mm Hg (9-31); HbO2 0.41 micromol/L (-8.4 to 7.6); Hb 2.6 micromol/L (-3.1 to 12.2); and Cyt 0.65 micromol/L (-3.4 to 4.8). A significant, inverse (or negative) association was found between DeltaNIRS HbO2 level and DeltaIAP (coefficient, -0.1588; p = 0.008). No association was found between DeltaNIRS Hb or DeltaCyt and DeltaIAP.
  
  
  CONCLUSIONS
  NIRS of the AW appears safe. NIRS measurement of changes in HbO2 appears to be associated with DeltaIAP, and warrant further study in greater numbers of ICU patients with more frequent IAP readings, over longer periods of critical illness.
authors.affiliation: Regional Trauma Services, Foothills Medical Centre, Calgary, Alberta, Canada.
authors.forename: Sandy
authors.initials: S
authors.lastname: Widder
authors.forename: Michael K
authors.initials: MK
authors.lastname: Ranson
authors.forename: David
authors.initials: D
authors.lastname: Zygun
authors.forename: Linda
authors.initials: L
authors.lastname: Knox
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Laupland
authors.forename: Philip
authors.initials: P
authors.lastname: Laird
authors.forename: Chad G
authors.initials: CG
authors.lastname: Ball
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Kirkpatrick
mesh_terms: D000005:Abdomen; D000368:Aged; D000369:Aged, 80 and over; D003161:Compartment Syndromes / Q000145:classification*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000145:classification*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D011312:Pressure; D019265:Spectroscopy, Near-Infrared; D014947:Wounds and Injuries / Q000145:classification* / Q000401:mortality