title: Hyperventilation during orthostatic challenge in spinal cord-injured humans.
abstract: OBJECTIVE
  To determine whether arterial hypotension is related to hyperventilation during standing in individuals with complete spinal cord injury (SCI).
  
  
  METHODS
  Sixteen individuals with SCI (thoracic 1 to thoracic level 12, ASIA grade: A) and 18 able-bodied individuals participated in this study. Individuals with SCI were divided into a group with injury level at or above thoracic (T) 7 [higher SCI (HSCI), n = 9] and a group with injury level at or below T10 (lower SCI, n = 7). Subjects carried out 6-min quiet sitting and then 6-min quiet standing using a standing frame.
  
  
  RESULTS
  Significant decrease in mean arterial blood pressure (MAP) and significant increase in minute ventilation (V(E)) by postural change from sitting to standing were observed only in HSCI. In HSCI, MAP decreased from 81 +/- 11 to 75 +/- 16 mmHg (P < 0.05), while V(E) increased from 8.4 +/- 1.1 to 9.9 +/- 1.0 l min(-1) (P < 0.01). There was a significant negative correlation between changes in MAP and V(E) in subjects in the HSCI group (r = -0.72, P < 0.05).
  
  
  CONCLUSIONS
  We concluded that the magnitude of hyperventilation during standing is associated with individual difference in the magnitude of hypotension in individuals with SCI. The mechanism(s) for this relationship remains unresolved, but afferent signals from baroreceptors to the brainstem respiratory center and/or action of pressor substances on the central nervous system might have caused hyperventilation.
authors: Department of Rehabilitation for Movement Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Saitama, Japan. hisaoga@rehab.go.jp
authors: Hisayoshi
authors: H
authors: Ogata
authors: Miwa
authors: M
authors: Nakahara
authors: Takeshi
authors: T
authors: Sato
authors: Shinya
authors: S
authors: Hoshikawa
authors: Toru
authors: T
authors: Ogata
authors: Kimitaka
authors: K
authors: Nakazawa
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D006801:Humans; D006985:Hyperventilation / Q000209:etiology* / Q000503:physiopathology; D007024:Hypotension, Orthostatic / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D013116:Spinal Cord / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology*; D055815:Young Adult