EEG and spectral edge frequency: analysis in posthypoxic newborn piglets.
OBJECTIVE
To evaluate the frequency content of the electroencephalogram (EEG) during recovery after a severe hypoxic insult in newborn piglets.


METHODS
EEG was continuously monitored in nine newborn piglets exposed to a severe hypoxic period. Power spectra in five frequency bands were calculated using Fourier transformation. Spectral edge frequency 90 (SEF90) was defined as the frequency below which 90% of the power in the EEG was located. The piglets were divided into two groups; Group 1 represented piglets with some EEG recovery and Group 2 represented piglets without any EEG recovery.


RESULTS
The recovery of the EEG in Group 1 had the same time course in all frequency bands. SEF90 indicates recovery earlier than the value of total power. But SEF90 also signals activity in the EEGs that were almost completely suppressed. When SEF90 was calculated during periods of periodic EEG activity during the very early phase of recovery, the values fell within the same range as during the control period.


CONCLUSIONS
Spectral analysis of continuous EEG in newborn piglets exposed to very severe hypoxia showed that no specific frequency band of the EEG preceded the other ones during recovery. The results of the SEF90 measure, demonstrates the need for critical analysis of the raw EEG before any reliable estimation of cerebral function can be made.
Flisberg
Anders
A
Department of Pediatrics, Division of Neonatology, The Queen Silvia Children's Hospital, Sahlgrenska University Hospital - Ostra, Göteborg, Sweden. anders.flisberg@vgregion.se
Kjellmer
Ingemar
I
Bågenholm
Ralph
R
Lindecrantz
Kaj
K
Löfgren
Nils
N
Thordstein
Magnus
M
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000503:physiopathology*; D004195:Disease Models, Animal; D004569:Electroencephalography; D000860:Hypoxia / Q000503:physiopathology*; D002534:Hypoxia, Brain / Q000503:physiopathology*; D020127:Recovery of Function; D012720:Severity of Illness Index; D013552:Swine; D013997:Time Factors