title: Subcutaneous interstitial pressure and volume characteristics in renal impairment associated with edema.
abstract: The kidneys and the interstitial compartment play a vital role in body fluid regulation. The latter may be significantly altered in renal dysfunction, but experimental studies are lacking. To help define this we measured the subcutaneous interstitial pressure, bioimpedance volumes, and edema characteristics in 10 healthy subjects and 21 patients with obvious edema and chronic kidney disease (CKD). Interstitial edema was quantified by the time taken for a medial malleolar thumb pit to refill and termed the edema refill time. Interstitial pressure was significantly raised in CKD compared to healthy subjects. Total body water (TBW), extracellular fluid volume (ECFV), interstitial fluid volume, the ratio of the ECFV to the TBW, and segmental extracellular fluid volume were raised in CKD. The ratio of the ECFV to the TBW and the interstitial fluid volume were the best predictors of interstitial pressure. Significantly higher interstitial pressures were noted in edema of 2 weeks or less duration. A significant nonlinear relationship defined interstitial pressure and interstitial fluid volume. Edema refill time was significantly inversely related to interstitial pressure, interstitial compartment volumes, and edema vintage. Elevated interstitial pressure in CKD with obvious edema is a combined function of accumulated interstitial compartment fluid volumes, edema vintage, and tissue mechanical properties. The edema refill time may represent an important parameter in the clinical assessment of edema, providing additional information about interstitial pathophysiology in patients with CKD and fluid retention.
authors.affiliation: 1] Department of Renal Medicine and Research, Manchester Institute of Nephrology and Transplantation, Manchester, UK [2] School of Biomedicine, University of Manchester, Manchester, UK.
authors.forename: Leonard M
authors.initials: LM
authors.lastname: Ebah
authors.forename: Helge
authors.initials: H
authors.lastname: Wiig
authors.forename: Idalia
authors.initials: I
authors.lastname: Dawidowska
authors.forename: Charlotte
authors.initials: C
authors.lastname: O'Toole
authors.forename: Angela
authors.initials: A
authors.lastname: Summers
authors.forename: Milind
authors.initials: M
authors.lastname: Nikam
authors.forename: Anuradha
authors.initials: A
authors.lastname: Jayanti
authors.forename: Beatrice
authors.initials: B
authors.lastname: Coupes
authors.forename: Paul
authors.initials: P
authors.lastname: Brenchley
authors.forename: Sandip
authors.initials: S
authors.lastname: Mitra
mesh_terms: D000328:Adult; D001834:Body Water / Q000378:metabolism*; D016022:Case-Control Studies; D004487:Edema / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D017097:Electric Impedance; D045604:Extracellular Fluid / Q000378:metabolism*; D005260:Female; D018495:Fluid Shifts; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D017711:Nonlinear Dynamics; D011312:Pressure; D051436:Renal Insufficiency, Chronic / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D040521:Subcutaneous Tissue / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors; D014882:Water-Electrolyte Balance; D055815:Young Adult