title: Does a hypertonic saline load predict fluid retention in pacing induced heart failure?
abstract: OBJECTIVE
  We examined the response to hypertonic saline challenge (SC) as a potential predictor of fluid retention during heart failure induced by rapid ventricular pacing.
  
  
  METHODS
  Twelve dogs (22 +/- 4 kg) were given an intra-arterial bolus of 30 ml of 20% saline after establishing baseline fluid intake and urine output (24 h). Dogs were classified according to whether they drank more (Group A) or less (Group B) than the amount required to dilute the s.c. to isotonicity. Fluid retention was then assessed during heart failure after rapid ventricular pacing according to a graded ordinal scale and correlated with the responses to s.c..
  
  
  RESULTS
  No difference was noted in baseline fluid intake (1112 +/- 236 ml in Group A vs. 809 +/- 129 ml in Group B). Five hours after s.c. cumulative water intake was significantly greater in Group A than in Group B (1018 +/- 136 vs. 591 +/- 17 ml) (P < 0.01). Urine sodium concentration was 113 +/- 11 and 124 +/- 28 mmol/l at baseline in Group A and B, respectively; increased to 190 +/- 21 and 295 +/- 59 mmol/l at 5 h and remained elevated 24 h after s.c., 177 +/- 60 and 274 +/- 55 mmol/l (both P < 0.01 for within-group comparisons vs. baseline). Urine sodium concentration was less in Group A than in Group B at 5 and 24 h (P < 0.05). The fluid retention score was greater in Group A (3.6 +/- 0.5) than in Group B (0.8 +/- 0.4) (P < 0.01). Fluid retention in heart failure correlated with water intake after the pre-pacing s.c. (r = 0.68, P < 0.025) and inversely with urine concentrating ability (r = -0.58, P < 0.05). Furthermore, water intake and urine concentrating ability following the s.c. were inversely related (r = -0.67, P < 0.02).
  
  
  CONCLUSIONS
  We conclude that normal dogs may be classified according to their fluid intake after s.c.. Those dogs that drank excessively and produced a dilute urine were more likely to retain fluid during pacing-induced heart failure. Hence, fluid intake and the ability to excrete a concentrated urine after a saline challenge may be useful variables to predict fluid retention in pacing-induced heart failure.
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Fu
authors.forename: D W
authors.initials: DW
authors.lastname: O'Brien
authors.forename: S Y
authors.initials: SY
authors.lastname: Chan
authors.forename: S
authors.initials: S
authors.lastname: Kaufman
authors.forename: G W
authors.initials: GW
authors.lastname: Moe
authors.forename: P W
authors.initials: PW
authors.lastname: Armstrong
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D004285:Dogs; D004326:Drinking; D004487:Edema / Q000175:diagnosis* / Q000209:etiology; D006333:Heart Failure / Q000209:etiology / Q000378:metabolism*; D007671:Kidney Concentrating Ability; D008297:Male; D011379:Prognosis; D012462:Saline Solution, Hypertonic; D012964:Sodium / Q000097:blood / Q000652:urine; D013997:Time Factors
chemical_list: D012462:Saline Solution, Hypertonic; D009320:Atrial Natriuretic Factor; D012964:Sodium