title: Acute fluid ingestion in the treatment of orthostatic intolerance - important implications for daily practice.
abstract: BACKGROUND
  Rapid water ingestion improves orthostatic intolerance (OI) in multiple system atrophy (MSA) and postural tachycardia syndrome (PoTS). We compared haemodynamic changes after water and clear soup intake, the latter being a common treatment strategy for OI in daily practice.
  
  
  METHODS
  Seven MSA and seven PoTS patients underwent head-up tilt (HUT) without fluid intake and 30 min after drinking 450 ml of water and clear soup, respectively. All patients suffered from moderate to severe OI because of neurogenic orthostatic hypotension (OH) and excessive orthostatic heart rate (HR) increase, respectively. Beat-to-beat cardiovascular indices were measured non-invasively.
  
  
  RESULTS
  In MSA, HUT had to be terminated prematurely in 2/7 patients after water, but in 6/7 after clear soup. At 3 min of HUT, there was an increase in blood pressure of 15.7(8.2)/8.3(2.3) mmHg after water, but a decrease of 11.6(18.9)/8.1(9.2) mmHg after clear soup (P < 0.05). In PoTS, HUT could always be completed for 10 min, but OI subjectively improved after both water and clear soup. The attenuation of excessive orthostatic HR increase did not differ significantly after water and clear soup drinking.
  
  
  CONCLUSIONS
  In MSA, clear soup cannot substitute water for eliciting a pressor effect, but even worsens OI after rapid ingestion. In PoTS, acute water and clear soup intake both result in improvement of OI. These findings cannot solely be explained by difference in osmolarity but may reflect some degree of superimposed postprandial hypotension in widespread autonomic failure in MSA compared to the mild and limited autonomic dysfunction in PoTS.
authors.affiliation: Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland.
authors.forename: W J
authors.initials: WJ
authors.lastname: Z'Graggen
authors.forename: C W
authors.initials: CW
authors.lastname: Hess
authors.forename: A M
authors.initials: AM
authors.lastname: Humm
mesh_terms: D000328:Adult; D001794:Blood Pressure; D004435:Eating / Q000502:physiology; D005260:Female; D005440:Fluid Therapy; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000150:complications; D054971:Orthostatic Intolerance / Q000209:etiology / Q000628:therapy*; D054972:Postural Orthostatic Tachycardia Syndrome / Q000150:complications; D018667:Tilt-Table Test; D013997:Time Factors