title: Hemodynamic characteristics of high-altitude headache following acute high altitude exposure at 3700 m in young Chinese men.
abstract: BACKGROUND
  This study aimed to identify the systemic and cerebral hemodynamic characteristics and their roles in high-altitude headache (HAH) among young Chinese men following acute exposure.
  
  
  METHODS
  The subjects (n = 385) were recruited in June and July of 2012. They completed case report form questionnaires, as well as heart rate (HR), blood pressure, echocardiogram and transcranial Doppler examinations at 3700 m following a two-hour plane flight. A subgroup of 129 participants was examined at two altitudes (500 and 3700 m).
  
  
  RESULTS
  HAH was characterized by increased HR and cardiac output (CO) and lower saturation pulse oxygen (SpO(2)) (all p < 0.05). The change in tricuspid regurgitation was also different between the HAH positive (HAH+) and HAH negative (HAH-) subjects. Furthermore, the HAH+ subjects exhibited faster mean (V(m)), systolic (V(s)) and diastolic (V(d)) velocities in the basilar artery (BA; all p < 0.05) and a faster V(d) ( 25.96 ± 4.97 cm/s vs. 24.76 ± 4.76 cm/s, p = 0.045) in the left vertebral artery (VA). The bilateral VA asymmetry was also significantly different between the two groups. The pulsatility index (PI) and resistance index (RI) of left VA were lower in the HAH subjects (p < 0.05) and were negatively correlated with HAH (p < 0.05). Baseline CO and Vm in left VA (or right MCA in different regressions) were independent predictors for HAH, whereas CO/HR and ΔV(d) (V(d) difference between bilateral VAs) were independent risk factors for HAH at 3700 m.
  
  
  CONCLUSIONS
  HAH was characterized, in part, by increased systemic hemodynamics and posterior cerebral circulation, which was reflected by the BA and left VA velocities, and lower arterial resistance and compliance. Furthermore, baseline CO and V(m) in left VA or right MCA at sea level were independent predictors for HAH, whilst bilateral VA asymmetry may contribute to the development of HAH at high altitude.
authors.affiliation: Institute of Cardiovascular Diseases, Xinqiao Hospital, Third Military Medical University, 183 Xinqiao Street, Chongqing, 400037, China, bianshizhu@163.com.
authors.forename: Shi-Zhu
authors.initials: SZ
authors.lastname: Bian
authors.forename: Jun
authors.initials: J
authors.lastname: Jin
authors.forename: Qian-Ning
authors.initials: QN
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.forename: Cai-Fa
authors.initials: CF
authors.lastname: Tang
authors.forename: Rong-Sheng
authors.initials: RS
authors.lastname: Rao
authors.forename: Shi-Yong
authors.initials: SY
authors.lastname: Yu
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Zhao
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
authors.forename: Lan
authors.initials: L
authors.lastname: Huang
mesh_terms: D000293:Adolescent; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000150:complications / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006261:Headache / Q000209:etiology / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D011795:Surveys and Questionnaires; D055815:Young Adult