title: On the minute by minute variations of urine output: a study in a porcine model.
abstract: BACKGROUND
  Urine output (UO) is usually measured hourly in acutely ill patients. Devices capable of more continuous (minute by minute urine output, UOm) measurements have become available recently. This paper aims to (1) analyze the minute by minute variations of UO, (2) analyze the impact of sepsis on those variations and (3) test if UO measured over periods shorter than 60 min provides information not available in hourly measurements.
  
  
  METHODS
  Fifteen male pigs were anesthetized, tracheostomized and mechanically ventilated. Sepsis was induced by the administration of live Escherichia coli. Three groups were studied: nonseptic (n = 7) and septic (n = 4), both receiving sodium chloride (NaCl) 0.9 % at 4 ml kg(-1) h(-1); and septic (n = 4) receiving NaCl 0.9 % at 17 ml kg(-1) h(-1). UOm was measured during 6 h.
  
  
  RESULTS
  There was a significant variation of UOm over time, as assessed by the coefficient of variation of the root-mean-squared error (CV(RMSE)), which was significantly more pronounced under conditions of sepsis than under control conditions. A UO production pattern in sepsis was identified, characterized by low UO production compared to baseline levels for approximately 30 min, followed by high UO production for approximately 30 min after initiation of the septic challenge. This pattern was noticeable if UO was measured every 10 min but not over longer periods of time.
  
  
  CONCLUSIONS
  UOm provides information not conveyed by hourly measurements, especially under the cardiovascular alterations associated to sepsis. This information could enable an early identification of sepsis.
authors.affiliation: Universidad San Pablo CEU, Boadilla del monte, Madrid, Spain, abraham.otero@gmail.com.
authors.forename: Abraham
authors.initials: A
authors.lastname: Otero
authors.forename: Pablo
authors.initials: P
authors.lastname: Cardinal-Fernández
authors.forename: Yeny
authors.initials: Y
authors.lastname: Rojas
authors.forename: Nicolás
authors.initials: N
authors.lastname: Nin
authors.forename: Leticia
authors.initials: L
authors.lastname: Martínez-Caro
authors.forename: Andrés
authors.initials: A
authors.lastname: Esteban
authors.forename: José A
authors.initials: JA
authors.lastname: Lorente
mesh_terms: D000818:Animals; D004927:Escherichia coli Infections / Q000150:complications; D008297:Male; D018805:Sepsis / Q000382:microbiology / Q000503:physiopathology*; D013552:Swine; D013997:Time Factors; D014554:Urination / Q000502:physiology*; D014556:Urine; D059349:Urine Specimen Collection