title: Hyperventilation during routine electroencephalography: are three minutes really necessary?
abstract: OBJECTIVE
  Hyperventilation induces absence seizures in children with absence epilepsy, and routine electroencephalography studies include three minutes of hyperventilation. We studied the duration of hyperventilation required to provoke a first absence seizure to determine whether three minutes of the procedure are indeed necessary.
  
  
  METHODS
  Electroencephalography records of children who experienced absence seizures during hyperventilation were reviewed. The time from hyperventilation onset to a first and further seizure(s) was measured, and the occurrence of absences during the posthyperventilation phase was also noted.
  
  
  RESULTS
  Sixty-two studies were evaluated. Mean time from hyperventilation onset to a first absence was 52 seconds (median 32 seconds). The vast majority (85.5%) had an absence within 90 seconds. Most (68%) children sustained a single event. All eight children with posthyperventilation seizures had experienced at least one event during hyperventilation.
  
  
  CONCLUSIONS
  Our findings suggest that current guidelines for routine pediatric electroencephalography recording requiring three minutes of hyperventilation may not be clinically necessary. We found that the vast majority of children referred for suspected absence seizures experience a seizure less than 90 seconds after hyperventilation onset, and even more so by 120 seconds. Hence, a larger prospective study is warranted to establish more accurate hyperventilation duration parameters. We also suggest that once an absence seizure has been recorded at any time during hyperventilation, this procedure could be stopped, thus reducing the amount of discomfort for the child.
authors: Meir Medical Center, Tel Aviv University, Israel. Electronic address: nathan.watemberg@clalit.org.il.
authors: Nathan
authors: N
authors: Watemberg
authors: Meir Medical Center, Tel Aviv University, Israel.
authors: Michael
authors: M
authors: Farkash
authors: Meir Medical Center, Tel Aviv University, Israel.
authors: Miki
authors: M
authors: Har-Gil
authors: Baskent University, Ankara, Turkey.
authors: Taner
authors: T
authors: Sezer
authors: Schneider Medical Center, Tel Aviv University, Israel.
authors: Hadassah
authors: H
authors: Goldberg-Stern
authors: Baskent University, Ankara, Turkey.
authors: Füsun
authors: F
authors: Alehan
mesh_terms: D000293:Adolescent; D001921:Brain / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000150:complications / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000150:complications / Q000503:physiopathology*; D008297:Male; D012640:Seizures / Q000209:etiology / Q000503:physiopathology*; D013997:Time Factors
keywords: EEG; absence seizures; child; electroencephalography; hyperventilation; time-to-event