ISOBARIC ROPIVACAINE VERSUS ISOBARIC BUPIVACAINE FOR SPINAL ANESTHESIA IN ORTHOPEDIC SURGERY

Abstract

Ropivacaine is the first long acting , injectable local anesthetic to undergo testing in more than 20 years. Although identified as local anesthetic in 1957, ropivacaine testing did not begin until 1988, after Albright 1979 ,observed that accidental intravascular injection of bupivacaine results in serious cardiac toxic effects with poor outcome. Initial studies in animals suggested that ropivacaine is less likely to produce cardiac toxic effects when injected intravenously (Reiz et a/. ,1989 and Feldman eta/., 1989). Intravenous infusion of ropivacaine in

human volunteers results in fewer central nervous system effects or cardiac abnonnalities than did bupivacaine (McClellan and Faulds, 2000)

Ropivacaine has two advantages over bupivacaine. It provides more differential block when given epidurally, allowing for a better separation between sensory and motor block. This feature can be used to its advantage in obstetrics and in postoperative epidural pain relief. Ropivacaine has a lower systemic toxicity than both racemic and Levobupivacaine. Especially its better cardiotoxic profile has been well documented and is an important advantage when using techniques with a potential for high plasma concentrations. Ropivacaine is less potent than bupivacaine and has a shorter duration of action. The magnitude of this potency difference however is not clearly quantified and differs with varying techniques (Stienstra, 2003).