Forecast for perineural analgesia procedures for ambulatory surgery of the knee, foot, and ankle: applying patient-centered paradigm shifts

Abstract

Although much of the current clinical research is directed toward practitioner-centered refinement of RA techniques and technology, it is important to consider pharmacologic advances in perineural analgesia as the next major patient-centered advancement of our specialty. With all due respect to excellent bench science work with novel drugs and toxins that may not gain approval of the Food and Drug Administration for many years, it is useful to know that four Food and Drug Administration-approved drugs are commercially available for potentially ground-breaking off-label use, pending ongoing research. The extent to which estimated clinical concentrations of clonidine, buprenorphine, and dexamethasone, seem to not influence A-fiber conduction holds significant progress for lower extremity perineural analgesia when weight bearing may be desired, if not at least reducing the risk of falls after these surgeries using typical local anesthetic nerve blocks. Research is also needed to determine the extent to which these four drugs may reduce the needed local anesthetic concentration to achieve a surgical nerve block (on bolus injection). Ongoing research in this direction seems to represent the next major advancement in the subspecialty, being distinguished from refinement research involving strictly techniques and technology.

Figures

Figure 1

Heat anesthesia-analgesia followed by shorter heat withdrawal latencies after sciatic nerve block with ropivacaine. This is an illustration of nociceptive responses of the treated (left) hindlimb to thermal stimuli as a function of treatment and time (P

Figure 2

Preliminary data regarding C-fiber compound action potentials (C-CAPs) after superfusion with increasing concentrations of ropivacaine or perineural analgesic single-drugs clonidine, buprenorphine, dexamethasone, and midazolam. Each vertical arrow indicates a semilog increase in molarity concentration from the previous drug-concentration.. These data are preliminary, are not intended to be interpreted as peer-reviewed, and are submitted as a 2011 poster presentation at the Annual Meeting for the Society for Ambulatory Anesthesia. When alternative analgesic adjuvants were applied to isolated nerve, we observed the following.: * Midazolam at 33 mcg/mL showed small but significant (P=0.03) reductions in C-wave conduction. †Clonidine 8 mcg/mL, a supra-clinical concentration, attenuates C-CAP by 15% (P