title: Relationship between Hyperventilation-Induced Electroencephalographic Changes and PCO2 Level.
abstract: OBJECTIVE
  We conducted this study to define the relationship between the hyperventilation-induced EEG changes (HV-EEG changes) and PCO2.
  
  
  METHODS
  In consecutive EEG recordings of 190 patients, we gathered data on PCO2 during the hyperventilation procedure. The data included baseline PCO2 (B-PCO2), PCO2 after 5 min of hyperventilation (5 min-PCO2), the mean value of the PCO2 (M-PCO2), and the difference between B-PCO2 and 5 min-PCO2 (ΔPCO2). We divided the enrolled patients into two groups by hyperventilation response (response group and no-response group), presence of epilepsy (epileptic group and non-epileptic group) and age (child-adolescent group and adult group) repeatedly. We compared the four variables between the two groups in each pair.
  
  
  RESULTS
  ΔPCO2 was 14.2±5.0 mmHg (mean±SD) in response group (n=48) and 12.4±5.0 in no-response group (n=142; p=0.033) for all the patients. For adult patients only, 5 min-PCO2 was 24.3±3.4 in response group (n=30) and 26.2±4.6 in no-response group (n=115; p=0.048), and ΔPCO2 was 15.8±4.0 and 12.9±5.0, respectively (p=0.004). In non-epileptic patients, 5min-PCO2 was 23.4±2.2 in response group (n=7) and 26.3±3.8 in no-response group (n=44; p=0.026), and ΔPCO2 was 15.9±4.3 and 12.7±3.9, respectively (p=0.053).
  
  
  CONCLUSIONS
  In adults and non-epileptic patients, ΔPCO2 and 5 min-PCO2 may be crucial to the induction of EEG changes by hyperventilation. PCO2 could be a crucial factor for provoking HV-EEG changes in a limited group of patients.
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Seungnam
authors.initials: S
authors.lastname: Son
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea ; Gyeongsang Institute of Health Science, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Oh-Young
authors.initials: OY
authors.lastname: Kwon
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Seokwon
authors.initials: S
authors.lastname: Jung
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Young-Soo
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea ; Gyeongsang Institute of Health Science, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Soo-Kyoung
authors.initials: SK
authors.lastname: Kim
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea ; Gyeongsang Institute of Health Science, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Heeyoung
authors.initials: H
authors.lastname: Kang
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea ; Gyeongsang Institute of Health Science, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Ki-Jong
authors.initials: KJ
authors.lastname: Park
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea ; Gyeongsang Institute of Health Science, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Nack-Cheon
authors.initials: NC
authors.lastname: Choi
authors.affiliation: Department of Neurology, Gyeongsang National University School of Medicine, Jinju, Korea ; Gyeongsang Institute of Health Science, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Byeong Hoon
authors.initials: BH
authors.lastname: Lim
keywords: Carbon dioxide; Electroencephalography; Hyperventilation