title: Hyperventilation during electroencephalography: safety and efficacy.
abstract: OBJECTIVE
  To determine safety and efficacy of hyperventilation (HV) during electroencephalography (EEG).
  
  
  METHODS
  We report the findings of a prospective multicentre National Service Evaluation of the occurrence of adverse events, seizures and interictal epileptiform discharges seen in association with HV during EEG, in a relatively unselected, largely out patient population of 3475 being investigated predominantly for possible epileptic seizures.
  
  
  RESULTS
  Adverse events occurred rarely, and there were no reported significant cerebrovascular, cardiovascular or respiratory events. Of the 3170 patients suspected of 'epilepsy or possible epilepsy' 69 patients (2.2%) had seizures provoked by HV, but only one (0.03%) had a generalised tonic clonic seizure. The elicitation or increase of interictal epileptiform discharges (IEDs) was seen in 387 (12.2%) of the total 3170 patients with suspected epilepsy who hyperventilated. Furthermore 31 patients (0.9%) had psychogenic non-epileptic seizures.
  
  
  CONCLUSIONS
  HV is rarely associated with adverse events, but contributes to the diagnosis and classification of seizure disorders in an appreciable proportion of patients with epilepsy and non-epileptic attacks. These findings confirm that HV in selected patients is a valid activation technique in diagnostic EEG, where the potential benefits out weigh the risks, and also provide information that may assist the informed consent process.
authors.affiliation: The Grey Walter Department of Clinical Neurophysiology, Frenchay Hospital, Bristol BS16 1LE, United Kingdom. Electronic address: Nick.Kane@nbt.nhs.uk.
authors.forename: Nick
authors.initials: N
authors.lastname: Kane
authors.affiliation: The Clinical Neurophysiology Department, University Hospital of North Staffordshire, ST4 6QG, United Kingdom.
authors.forename: Lesley
authors.initials: L
authors.lastname: Grocott
authors.affiliation: The Department of Clinical Neurophysiology, Royal Hallamshire Hospital, Sheffield S10 2JF, United Kingdom.
authors.forename: Ros
authors.initials: R
authors.lastname: Kandler
authors.affiliation: The Department of Clinical Neurophysiology, Royal Hallamshire Hospital, Sheffield S10 2JF, United Kingdom.
authors.forename: Sarah
authors.initials: S
authors.lastname: Lawrence
authors.affiliation: The Department of Clinical Neurophysiology, University Hospital of Coventry and Warwickshire, CV2 2DX, United Kingdom.
authors.forename: Catherine
authors.initials: C
authors.lastname: Pang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004827:Epilepsy / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000150:complications*; D007223:Infant; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012640:Seizures / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D055815:Young Adult
keywords: Adverse events; Hyperventilation; Interictal epileptiform discharges; Seizures