Spinal cord blood flow following sub-arachnoid lidocaine

Twelve mongrel dogs were randomized into two equal groups. Cervical, thoracic and lumbosacral spinal cord and spinal dural blood flows were measured using the radioactive microsphere technique. Blood flow determinations were made prior to and 20 and 40 minutes following lumbar subarachnoid injection of: two per cent lidocaine (100 mg) or two per cent lidocaine (100 mg) with 1/25,000 epinephrine (200 micrograms). Dogs receiving subarachnoid lidocaine demonstrated a decrease in mean arterial blood pressure of 23 per cent and 14 per cent (p less than 0.05), while dogs receiving lidocaine with epinephrine had a decrease of 38 and 34 per cent (p less than 0.05) at 20 and 40 minutes respectively. Cardiac index was not significantly changed in either group. Lumbar subarachnoid lidocaine (100 mg) produced a rapid regional dural hyperemia (observed at 20 minutes postinjection) and a delayed regional spinal cord hyperemia (observed at 40 minutes postinjection) which were not observed following the addition of epinephrine (200 micrograms).