Abstract
Decreased arterial carbon dioxide tension (PaCO2) results in decreased cerebral
blood flow, which is associated with diminished cerebral electrical activity. In
such a situation, cerebral fractional oxygen extraction (CFOE) would be expected
to increase to preserve cerebral oxygen delivery. This study aimed to determine
whether changes in blood gases in infants less than 30 wk' gestation were
associated with changes in background electroencephalograms (EEG) and CFOE.
Thirty-two very low birth weight infants were studied daily for the first three
days after birth. Digital EEG recordings were performed for 75 min each day.
CFOE, mean blood pressure and arterial blood gases were measured midway through
each recording. EEG was analysed by (a) spectral analysis and (b) manual
calculation of interburst interval. Blood pressure, pH and PaCO2 did not have any
effect on the EEG. On day one, only PaCO2 showed a relationship with the relative
power of the delta frequency band (0.5-3.5 Hz) and the interburst interval. The
relative power of the delta band remained within normal limits when PaCO2 was
between 24 and 55 mmHg on day one. There was a negative association between PaCO2
and CFOE. The associations between PaCO2 and EEG measurements were strongest on
day one, weaker on day two, and absent on day three. The slowing of EEG and
increased CFOE at lower levels of PaCO2 are likely to be due to decreased
cerebral oxygen delivery induced by hypocarbia. When PaCO2 was higher, there was
suppression of the EEG.
blood flow, which is associated with diminished cerebral electrical activity. In
such a situation, cerebral fractional oxygen extraction (CFOE) would be expected
to increase to preserve cerebral oxygen delivery. This study aimed to determine
whether changes in blood gases in infants less than 30 wk' gestation were
associated with changes in background electroencephalograms (EEG) and CFOE.
Thirty-two very low birth weight infants were studied daily for the first three
days after birth. Digital EEG recordings were performed for 75 min each day.
CFOE, mean blood pressure and arterial blood gases were measured midway through
each recording. EEG was analysed by (a) spectral analysis and (b) manual
calculation of interburst interval. Blood pressure, pH and PaCO2 did not have any
effect on the EEG. On day one, only PaCO2 showed a relationship with the relative
power of the delta frequency band (0.5-3.5 Hz) and the interburst interval. The
relative power of the delta band remained within normal limits when PaCO2 was
between 24 and 55 mmHg on day one. There was a negative association between PaCO2
and CFOE. The associations between PaCO2 and EEG measurements were strongest on
day one, weaker on day two, and absent on day three. The slowing of EEG and
increased CFOE at lower levels of PaCO2 are likely to be due to decreased
cerebral oxygen delivery induced by hypocarbia. When PaCO2 was higher, there was
suppression of the EEG.
| Original language | English |
|---|---|
| Journal | Pediatric Research |
| Volume | 58 |
| Issue number | 3 |
| Publication status | Published - 2005 |