Monitoring Neurological Injury by qEEG - Quantitative EEG Analysis Methods and Clinical Applications - page 182

not in hypothermic or hyperthermic rats. The 72-hour NDS of the hypothermia
group was significantly higher than that of the normothermia and hyperthermia
groups ( p 0.001) [67].

No significant difference was observed in IQ values during the periods of hypo-
thermia in sham animals (no CA injury). Unnormalized IQ values also did not show
significant differences between baseline halothane anesthesia and the washout peri-
ods. Hence, the eventual differences in IQ were attributed to the injury and tempera-
ture in the three experimental groups. Hypothermia produced greater recovery of
IQ (0.74

<

± 0.03) compared to normothermia (0.60 ± 0.03) ( p < 0.001) or

0.016). This study demonstrates beneficial effects of
hypothermia and harmful effects of hyperthermia post-CA resuscitation.
EEG monitoring may be used early, preferably immediately after resuscitation.
The basis for that suggestion is that early monitoring may provide a prognostic indi-
cation of eventual outcome and serve as a guide for therapeutic interventions. More
specifically, the question is whether recovery assessed using qEEG can be correlated
with the NDS. Figure 7.8(a) shows that there is a significant difference ( p < 0.01) in
the IQ values of the animals in each of the three groups within the first 2 hours after
ROSC. In fact, these differences are seen consistently at 30 minutes, 1 hour, 2 hours,
24 hours, and 72 hours. Importantly, the IQ values obtained as early as 30 minutes
after ROSC correlate well with the NDS evaluation done at the end of the study
duration (72 hours) [Figure 7.8(b)].

hyperthermia (0.56 ± 0.03) ( p =

7.5.2 qEEG-IQ Analysis of Brain Recovery After Immediate Versus
Conventional Hypothermia
The therapeutic benefits of hypothermia are becoming increasingly evident. How-
ever, out of practical consideration or historic reasons, hypothermia is convention-
ally applied quite some time (up to several hours) after CA and resuscitation. One
impediment is access to the subject during out-of-hospital resuscitation, delaying the
application of hypothermia. However, in certain situations, such as when the
patient is in the intensive care unit, it may be possible to deliver hypothermia in a
timely manner. Most clinical studies delay the initiation of hypothermia by 2 or
more hours after resuscitation [21, 42, 43, 68]. It may also be possible to monitor
the efficacy of hypothermia. Previous studies have shown that cooling may be suc-
cessful even if it is delayed by 4 to 6 hours [23]. Our studies show that mild to mod-
erate hypothermia (33ºC to 34°C) mitigates brain injury when induced before [39],
during [39, 40], or after ROSC [40, 41, 69].
Additional results demonstrating the effect of immediate (upon restoration of
spontaneous circulation) therapeutic hypothermia on brain recovery after CA are
further examined. Immediate initiation of 6-hour hypothermia (IH) upon successful
resuscitation was compared to conventional hypothermia (CH) initiated at 1-hour
postresuscitation. The conventional hypothermia group was designed to mimic the
delay of intervention, as noted in most clinical cases in actual practice. The EEG sig-
nals are analyzed with the help of real-time qEEG tracking, and the study is termi-
nated following functional outcome assessment and histological assessment. Two
groups of animals, receiving 7- and 9-minute CA were studied with animals divided
into two groups of CH (1 hour after ROSC) and IH. Hypothermia is induced by