How to improve the yield of the Routine EEG by Hyperventilation ?

 Hyperventilation technique to improve the yield of the Routine EEG

1. Deep breathing room air.
2. Rate 18 to 24 breaths/ min3 to 5 minutes.
3. Warn about dizziness / lightheadedness.
4. Use of assistive tools in children.
5. Post HV 3-5 minutes.
6. Watch the patient-Clinical symptoms/testing.

Contraindications to HV

1. Recent stroke (intracranial or subarachnoid hemorrhage) or myocardial infarction (Ml).
2. Significant cardiac disease
3. Pulmonary disease(i.e.COPD patient breathless at rest)
4. Sickle cell disease or trait.
5. Known moyamoya disease.
6. Advanced pregnancy.

Yield

1. Dependent of the patient cohort
2. Generalized Epilepsies in children » adults
   Trigger clinical absences in CAE or JAE 60-70%, less in JME33%
   EEG : 12.3% had GSW only, in adult cohort.
3. Focal Epilepsies.
   Accentuate focal slowing.
   Yield for epileptiform discharges is low.

Post HV : bi frontal slowing contd normal for 5 minutes 

CAE after hyperventilation Occipital intermittent rhythmic delta activity (OIRDA) can occur

* CAE -  Childhood absence epilepsy