Thread goes silent, I go away for few days, I look back and there's, enough reading for about a week.
Trust the scientists to get picky about, EEGs showing no activity after Cardiac arrest.. Ive skimped a little on some of the links, but there appears to be quite a few links mentioning names and studies that show this might not be so
I will have try and find evidence if this is the case, the only thing that will convince a scientist, is science right.
thought I read earlier forgive me if I am wrong, that electrical activity in the brain ceases after a much shorter period
Than what Hip mentioned from Barb ?
I only say this because it doesn't seem to add up to what others are saying, and mentioning studies,
Of course they haven't cited the studies here. fools. So they must be telling porkys.
I would be surprised if that turned out to be true. I suspect studies may exist. But of course those studies will have to be un arguable, because we know how much they will be scrutinized once presented.
----- here is what our old friends again have said ----
After the heart stops beating due to a significant reduction of blood flow, the pressures across the entire body and within the arteries and the veins reach a point in which they equalise within approximately 50 seconds. Studies have shown that due to a lack of heart beat and blood flow there is a cessation of brain electrical activity within approximately 10 seconds. This simply reflects a lack of brain function that is brought about due to a lack of blood flow into the brain
http://www.horizonresearch.org/main_page.php?cat_id=84
------ And from the other link posted on here---------
NEUROPHYSIOLOGY DURING CARDIAC ARREST
Through many studies in both human and animal models, cerebral function has
been shown to be severely compromised during cardiac arrest, with sudden loss
of consciousness and of all body reflexes, but also with the abolition of brain-stem
activity with the loss of the gag reflex and of the corneal reflex, and fixed and dilated
pupils are clinical findings in those patients (Parnia and Fenwick, 2002). And also
the function of the respiratory center, located close to the brainstem, fails, resulting
in apnoea. Complete cessation of cerebral circulation is found in induced cardiac
arrest due to ventricular fibrillation (VF) during threshold testing at implantation
of internal defibrillators. This complete cerebral ischemic model can be used to
study the result of anoxia of the brain. The middle cerebral artery blood flow, Vmca,
which is a reliable trend monitor of the cerebral blood flow, decreases to 0 cm/sec
immediately after the induction of VF (Gopalan et al., 1999). Electrical activity in
both cerebral cortex and the deeper structures of the brain has been shown to be
absent after a very short period of time. Monitoring of the electrical activity of the
cortex (EEG) has shown that the first ischemic changes in the EEG are detected an
average of 6.5 seconds from the onset of circulatory arrest, and with prolongation
of the cerebral ischemia
always progression to isoelectricity occurs within 10 to
20 (mean 15) seconds (De Vries et al., 1998; Clute and Levy, 1990; Losasso
et al., 1992; Parnia and Fenwick, 2002). After defibrillation the Vmca, measured by
transcranial Doppler technique, returns rapidly within 1–5 seconds after a cardiac
arrest of short duration (Gopalan et al., 1999). However, in the case of a prolonged
cardiac arrest of more than 37 seconds, normal EEG activity may not return for
many minutes to hours after cardiac function has been restored, depending on the
duration of the cardiac arrest, despite maintenance of adequate blood pressure in
the recovery phase (Smith et al., 1990). Additionally, EEG recovery sometimes
underestimates the metabolic recovery of the brain, and cerebral oxygen uptake
may be depressed for a considerable time after restoration of circulation (De Vries
et al., 1998).---------
Its a bit over my head. But I think it seems to suggest, That for the most part
EEGs would show little on no activity after only a short period of Cardiac arrest.
So much to read on here. it will take me a while.
