Effects of 0.5 and 1.0 MAC isoflurane, sevoflurane and desflurane on intracranial and cerebral perfusion pressures in children.
BACKGROUND
Isoflurane has been a commonly used agent for neuroanesthesia, but newer agents, sevoflurane and desflurane, have a quicker onset and shorter emergence from anesthesia and are increasingly preferred for general pediatric anesthesia. But their effects on intracranial pressure (ICP) and cerebral perfusion pressure (CPP), especially in pediatric patients with already increased ICP, have not been well documented.


METHODS
We studied 36 children scheduled for elective implantation of an intraparenchymal pressure device for 24 h monitoring for suspected elevated ICP. After a standardized intravenous anesthesia, the patients were moderately hyperventilated with 60% nitrous oxide (N2O) in oxygen. The patients were then randomized to receive 0.5 and 1.0 MAC of isoflurane (Group I, n = 12), sevoflurane (Group S, n = 12) or desflurane (Group D, n = 12) in 60% N2O in oxygen. Respiratory and hemodynamic variables, ICP and CPP were recorded at baseline and after exposure to a target level of test drug for 10 min or until CPP fell below 30 mmHg (recommended lower ICP level is 25 mmHg in neonates, rising to 40 mmHg in toddlers).


RESULTS
When comparing baseline values with values at 1.0 MAC, mean arterial pressure (MAP) decreased (P < 0.001) in all groups, with no differences between the groups. ICP increased (P < 0.001) with all agents, mean +2, +5, and +6 mmHg in Group I, S and D, respectively, with no differences between the groups. Regression analyzes found no relationship between baseline ICP and the increases in ICP from baseline to 1.0 MAC for isoflurane or sevoflurane. However, increased baseline ICP tended to cause a higher ICP increase with 1.0 MAC desflurane; regression coefficient +0.759 (P = 0.077). The difference between regression coefficients for Group I and Group D were not significant (P = 0.055). CPP (MAP-ICP) decreased (P < 0.001) in all groups, mean -18, -14 and -17 mmHg in Group I, S and D, respectively, with no significant difference between the groups.


CONCLUSIONS
0.5 and 1.0 MAC isoflurane, sevoflurane and desflurane in N2O all increased ICP and reduced MAP and CPP in a dose-dependent and clinically similar manner. There were no baseline dependent increases in ICP from 0 to 1.0 MAC with isoflurane or sevoflurane, but ICP increased somewhat more, although statistically insignificant, with higher baseline values in patients given desflurane. The effect of MAP on CPP is 3-4 times higher than the effect of the increases in ICP on CPP and this makes MAP the most important factor in preserving CPP. In children with known increased ICP, intravenous anesthesia may be safer. However, maintaining MAP remains the most important determinant of a safe CPP.
Sponheim
S
S
Department of Anesthesiology, Rikshospitalet University Hospital, Oslo, Norway. sjur.sponheim@rikshospitalet.no
Skraastad
Ø
Ø
Helseth
E
E
Due-Tønnesen
B
B
Aamodt
G
G
Breivik
H
H
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D002675:Child, Preschool; D000077335:Desflurane; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007427:Intracranial Pressure / Q000187:drug effects*; D007530:Isoflurane / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008738:Methyl Ethers / Q000494:pharmacology*; D011446:Prospective Studies; D000077149:Sevoflurane
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D000077335:Desflurane; D007530:Isoflurane