BACKGROUND: The purpose of this study is to evaluate the effects of spinal anesthesia with or without epinephrine on pulse oximeter readings, recorded from sympathetically affected(foot) and unaffected (hand) areas. METHODS: 20 Adult male patients, scheduled for arthroscopic surgery, received 3 ml of 0.5% hyperbaric bupivacaine with(group 1) or without(group 2) 0.1 mg of epinephrine into the subarachnoid space. Two pulse oximeter probes were applied to the index finger and toe of the patients, and the SpO2 values at 10min, 20min and 30min were recorded. RESULTS: After the onset of spinal anesthesia, a progressive decrease of SpO2 value recorded from the hand was observed at 20 min and 30 min (group 1), 10 min, 20 min, 30 min(group 2) compared with values from the foot. There is no significant difference in SpO2 value between group 1 and group 2 except for the SpO2 values of foot at 10 min after block. CONCLUSIONS: Because of compensatory vasoconstriction, which can occur more slowly when epinephrine is added to local anesthetics, pulse oximetry during spinal anesthesia gives a falsely low readings when oximetric sensor is placed at the upper limb.
Adult ; Anesthesia ; Anesthesia, Spinal* ; Anesthetics, Local ; Arthroscopy* ; Bupivacaine ; Epinephrine* ; Fingers ; Foot ; Hand ; Humans ; Male ; Oximetry ; Reading ; Subarachnoid Space ; Toes ; Upper Extremity ; Vasoconstriction