Safety During Regional Anesthesia: What Do We Know and How Can We Improve Our Practice?

A lthough not all experts accept this thesis, 1 most support the idea that mortality after general anesthesia (GA) has significantly decreased within the last 20 years. Although the intuitive response suggests that the safety of regional anesthesia (RA) has improved similarly, our knowledge is much weaker. What is well established is that mortality associated with RA is less than with GA, especially in certain populations such as obstetric patients, but it is less apparent if mortality associated with RA has decreased over the years. Despite safety recommendations and the widespread availability of capnography and pulse oximetry in the 1990s, outcome for neuraxial cardiac arrest was not significantly different between the 1980s and 1990s claims in the US Closed Claims database. It is also unclear if the rate of severe morbidity after RA has diminished in recent years. Some investigators have noted that the incidence of serious complications of obstetric epidural analgesia has not changed over a 17-year study period. In addition, it has been shown that the rate of pregnancy-related neurological complications after epidural used for labor analgesia has not changed substantially over the years. By contrast, the review by Ruppen et al of nearly 1.4 million epidurals for obstetric anesthesia/analgesia suggests that adverse events were 4 times more frequent in studies published before 1990 when compared with the more recent ones. We also have limited information to suggest that the rate of peripheral nerve blockYrelated complications is decreasing over the years. The article by Barrington et al in the NovemberYDecember 2009 issue of Regional Anesthesia and Pain Medicine shows disappointingly that the incidence of neurological complications associated with peripheral nerve blocks seems very similar to what has been obtained in previous studies. This is surprising and disappointing because one might have expected that RA-associated neurological complications should have decreased for several reasons. First, improved safety advances for both GA and RA (eg, high-quality monitoring, postoperative surveillance, less toxic drugs, technical advances, etc) have emerged over the last 20 years and were expected to have positive effects on RA-induced morbidity and mortality. There has also been an increased use of peripheral nerve blocks everywhere in the world, and given the usual relation between volume and better outcomes, improved practice patterns and greater safety were expected. Data from large studies, however, do not support these expectations. The Auroy et al study described cases collected in 1998Y1999, whereas the Capdevila et al study performed in the early 2000 period reported complication rates that are similar to those described by Barrington et al. In other words, no major change in RA-associated mortality and morbidity can be seen over a 10-year time frame. Why does the rate of complications remain unchanged? Is it only a Btechnical[ issue related to the statistical difficulty to detect subtle changes, or is this a real plateau as suggested by the very wide confidence interval obtained in the study of Barrington et al (95% confidence interval, 0.08Y1.1:1000)? Why do technical advances produce such profound changes in the GA area and yet are apparently ineffective for improving safety in the field of RA? In the Barrington et al study, two thirds of blocks were performed using ultrasound guidance, but the incidence of neurological complications was overall unchanged, and 2 of 3 neurological complications occurred with ultrasound use. This has also been observed in another recent Australian study in which the incidence of neurological complications occurring after 1000 ultrasound-guided blocks was in the range of the usual frequency obtained with nonYultrasound-guided blocks. As noted above, even with the already large numbers of patients included in these 2 studies, their power is likely insufficient given the baseline low frequency of events. This might be of paramount importance because most experts expect that the use of ultrasound will lead to a decrease in these complications. EDITORIAL