Succinylcholine-induced increases in CSF pressure are not affected by PaCO2 or mean arterial pressure in dogs.
The effects of PaCO2 and mean arterial pressure (MAP) on succinylcholine-induced changes in cerebrospinal fluid (CSF) pressure were examined in 31 dogs anesthetized with halothane (0.7% end-expired) and nitrous oxide (66% inspired) in oxygen. Group 1 (n = 9) received succinylcholine (1.5 mg/kg i.v.) without control of PaCO2 or MAP. Group 2 (n = 12) received succinylcholine with CO2 maintained at control, and no regulation of MAP. Group 3 (n = 10) received succinylcholine without regulation of PaCO2 and maintenance of MAP at control values with trimethaphan. Succinylcholine produced an increase in CSF pressure of 1.7 +/- 1.7-3.9 +/- 3.6 cm H2O (mean +/- SD). There were no differences in CSF pressure increase between groups. The increase in CSF pressure was compared to the variation in the uncontrolled physiological parameter (i.e., CSF pressure was compared to PaCO2 and MAP in group 1, MAP in group 2, and PaCO2 in group 3). The CSF pressure increase over time did not strictly parallel changes in PaCO2 and/or MAP, and the magnitude of increase of CSF pressure did not correlate significantly with PaCO2 and/or MAP. It is concluded that, in anesthetized dogs, succinylcholine produces relatively small increases in CSF pressure whether or not PaCO2 or MAP is controlled. These results do not support the hypothesis that a succinylcholine-induced increase in CSF pressure is due chiefly to an increase in PaCO2 and/or MAP and can be abolished by preventing those changes.
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Department of Anesthesiology, School of Medicine, University of Washington, Seattle, Washington, USA.