Intravenous lidocaine does not cause shivering-like tremor or alter thermoregulation

We tested the hypotheses that systemic absorption of epidural lidocaine: (1) contributes to the shivering-like tremor seen during epidural anesthesia by causing central nervous system disinhibition of spinal reflexes, or (2) activates or alters thermoregulatory mechanisms. In a double-blind, placebo, cross-over study, nine healthy volunteers were given intravenous lidocaine (or saline) to approximate the plasma levels of lidocaine achieved during epidural anesthesia for major abdominal surgery. Five volunteers were studied in a warm room (to test for nonthermoregulatory tremor), and four volunteers were studied in a cold room (to test the effects of lidocaine on normal thermoregulation). Central temperatures, peripheral vasoconstriction, tremor and clonus were unaffected by intravenous lidocaine. We conclude that the systemic absorption of epidural lidocaine does not contribute to tremor or shivering by these mechanisms.