REGIONAL ANESTHESIA: HISTORICAL ASPECTS


As recently as the early 1940s mortality attributable to the effects of general anesthesia could be as high as 0.1% - even in the US, and few rational physicians would expose patients to such risk unless the perceived gains were large enough to balance the equation. As a consequence, in part because of the insecurities surrounding general anesthesia, throughout the first half of this century there was considerable emphasis placed on, and expertise developed in, alternative strategies for painless elective surgery; in particular techniques for selectively anesthetizing specific, isolated anatomic regions; i.e. regional anesthesia. The risk of mortality and major morbidity associated with these approaches was considered to be vastly lower than that associated with general anesthesia, and there was a great deal of enthusiasm among surgeons for the development of specific sensory nerve blocks of every conceivable anatomic structure.

The term "regional anesthesia" was formally introduced by Harvey Cushing in 1901 when describing pain relief by the use of nerve block. Modern techniques of local anesthesia derive from the use of cocaine for nerve blocks. Cocaine, having been introduced into medical practice in 1884 2, was used for infiltration analgesia of the upper extremity by Halstead and Hall in New York in the 1880s and later by other pioneers in Europe such as Schleich (Berlin) and Reclus (Paris).
Regional anesthesia performed by surgeons at that time obviated the need for an individual dedicated to administering inhalational anesthesia and eliminated the consequences of toxic effects of agents such as ether, ethyl chloride, cyclopropane and chloroform. In early practice the skin was anesthetized with cocaine, the trunks of the brachial plexus were dissected out and then each individually anesthetized. By 1899, Barker had introduced infiltration analgesia using needle injection (the hypodermic needle having been described by Rynd in 1845 and popularized by Alexander Wood of Edinburgh - who also devised an effective syringe).

Substitutes for cocaine were sought actively because of the addictive potential and toxicity of cocaine (Halstead became addicted, presumably as a result of acting as his own guinea-pig during his evaluations of the new drug). Several synthetic agents were developed around the turn of the (19th) century including procaine, which was synthesized by Einhorn in 1904. Tetracaine was synthesized in 1931 and lidocaine in 1943 - although it was not put to clinical use until 1948. Robert Macintosh, in the forward to Winnie's text on plexus anesthesia9 notes that much of the subsequent development of regional anesthetic technique was carried out on the mainland of Europe where the "art and science of general anesthesia had been strangely disregarded". In the USA, as the clinical risks and subjective unpleasantness of general anesthesia declined over the latter half of the twentieth century, general anesthesia increasingly became the bench-standard technique.

The current situation is that general anesthesia is safe for all but the most debilitated patients (with mortality attributable to anesthesia alone now approaching 1:250,000) and has a very high degree of patient acceptance (with the widespread incorporation of agents such as propofol and sevoflurane which have dramatically reduced such anesthetic co-morbidities as nausea and dysphoria). In many reputable and well-managed North American anesthetic practices, it has become common for regional techniques hardly to be used at all. Indeed, it might seem as though there is little indication for isolated nerve blocks when general anesthesia is so safe and pleasant - why bother with anything else? In fact, there are still lively debates in the anesthesiology literature regarding the relative merits of regional versus general anesthetic techniques for a wide variety of surgical interventions, and although it sometimes seems as though there is less than compelling scientific or clinical evidence favoring one over the other, the lines of discussion are quite sharply drawn. It is very clear that for certain categories of surgical practice, and this includes a variety of minor cosmetic procedures, the use of regional anesthesia offers profound advantages both to the practitioner and to the patient.