Density Spectral Array Patterns During Total Intravenous Anesthesia with Intravenous Lidocaine for Craniotomy: An...

Intravenous lidocaine is used as an adjuvant to total intravenous anesthesia (TIVA). To our knowledge, density spectral array (DSA) patterns during intravenous lidocaine administration in propofol-remifentanil TIVA for craniotomy have rarely been described. We present two illustrative cases for educational and hypothesis-generating purposes.

Two adults underwent craniotomy for tumor resection (left cerebellopontine angle, Case 1; suprasellar, Case 2) with effect-site target-controlled infusion of propofol (Schnider model) and remifentanil (Minto model) and a bilateral scalp block. After a 1.5 mg/kg bolus, lidocaine was infused at 1.5 mg/kg/hour (Case 1) or 2 mg/kg/hour (Case 2) and stopped 30 minutes before the end of surgery. Frontal bispectral index (BIS) and DSA were recorded throughout and interpreted qualitatively at the bedside and offline.

In Case 1, an alpha-delta pattern persisted during maintenance, including at the lowest targets used (propofol 1.8 mcg/mL, remifentanil 2.5 ng/mL; BIS 39-45). In Case 2, the DSA showed more pronounced delta dominance, attenuated alpha and beta activity, and intermittent burst suppression, which persisted when propofol was reduced to 1.5 mcg/mL. In both patients, transient beta-power increases were temporally associated with surgical stimulation; electromyographic contribution could not be excluded. No hemodynamic instability or adverse effect attributable to lidocaine was observed.

This two-patient illustrative case series demonstrates differing DSA patterns during propofol-remifentanil TIVA with two intravenous lidocaine infusion regimens. Because the observations come from different patients with multiple clinical and anesthetic confounders, no dose-response relationship or causal effect of lidocaine can be established. These hypothesis-generating observations require evaluation in controlled studies.