Introduction:
The majority of patients resuscitated from cardiac arrest (CA) present in coma or with an altered level of consciousness. Although most CA survivors are sedated during targeted temperature management, the effects of sedation on post-arrest outcomes remain to be determined.
Hypothesis:
Sedation after CA improves neurological outcomes by modulating cerebral electrical activity and metabolism.
Methods:
Ten to 14 days after implantation of EEG transmitters, adult male C57BL/6J mice were subjected to CA and cardiopulmonary resuscitation (CPR). After return of spontaneous circulation (ROSC), mice received intravenous infusion of propofol, dexmedetomidine (DEX), or normal saline (vehicle) for 2 hours. Body temperature was maintained at 37°C, and was subsequently lowered to 33°C. Cerebral blood flow (CBF) was measured for 4 hours following ROSC. To quantify time-dependent EEG changes, we calculated the sum of the Delta, Theta, and Alpha band power in consecutive 12-hour intervals after ROSC (D
0-12
and D
12-24
, T
0-12
and T
12-24
, and A
0-12
and A
12-24
, respectively). Because the increase in fast EEG activity over time may reflect neurological recovery after CA, we compared the ratios of D
12-24
to D
0-12
, of T
12-24
to T
0-12
, and of A
12-24
to A
0-12
among groups.
Results:
As compared with vehicle-treated mice, propofol- or DEX-treated mice exhibited improved survival rate and neurological function after CA, though no difference was found between propofol- and DEX-treated mice. In the vehicle group, CBF was higher than the baseline after ROSC, while the increase in CBF was attenuated in the propofol and DEX group. The values of A
12-24
/A
0-12
and T
12-24
/T
0-12
were significantly higher in propofol- and DEX-treated mice than in vehicle-treated mice (
P
= 0.017 and
P
= 0.004, respectively, propofol vs vehicle;
P
= 0.038 and
P
= 0.002, respectively, DEX vs vehicle), but there was no significant difference in D
12-24
/D
0-12
among groups. In all post-arrest mice, both A
12-24
/A
0-12
and T
12-24
/T
0-12
were positively correlated with better neurological function at 24 and 48 hours after CA.
Conclusions:
Post-arrest sedation was associated with a reduction in CBF and a greater recovery of fast EEG activity after CA, and improved neurological outcomes and survival in mice.
Sodium nitroprusside enhanced cardiopulmonary resuscitation improves survival with good neurological function in a porcine model of prolonged cardiac arrest*