++
Over 40% of ambulatory patients experience moderate-to-severe
postoperative pain at home following orthopedic
procedures.1 Single-injection peripheral nerve blocks with
long-acting local anesthetics can provide excellent postoperative analgesia.
However, the analgesic benefit of single-injection blocks is typically
limited to the duration of the blockade and, subsequently, patients must usually rely on
oral opioids to control pain. Unfortunately, opioids are associated with
undesirable side effects, such as pruritus, nausea and vomiting, sedation,
and constipation. To improve postoperative analgesia following ambulatory
surgery, increasing interest has focused on providing perineural local
anesthetic infusions, also called, continuous peripheral nerve blocks, to
outpatients. This technique involves a percutaneous insertion of a catheter
directly adjacent to the peripheral nerve(s) supplying the surgical site.
Local anesthetic is then infused via the catheter, providing prolonged,
site-specific analgesia.
++
In 1946, Ansbro first described continuous regional blockade using a
cork to stabilize a needle placed adjacent to the brachial plexus divisions
to provide a continuous supraclavicular block.2 However,
for decades, patients were required to remain hospitalized because the
available pumps used to infuse local anesthetic were large, heavy, and
technically sophisticated. It was not until 52 years later that outpatient
perineural infusion using a percutaneous catheter and a small, lightweight,
portable infusion pump was described.3
++
The first report of continuous infusion of local anesthetics at home
was reported by Rawal and colleagues.3 Shortly thereafter,
numerous reports or series of ambulatory perineural infusions were
published, which described the use of catheters in various anatomic
locations, including paravertebral,4
interscalene,5–7
intersternocleidomastoid,8
infraclavicular,6 axillary,9 psoas
compartment,9,10 femoral,9,11 fascia
iliaca,5 sciatic,9,10
popliteal,6,12 and tibial nerve.6
Ambulatory continuous peripheral nerve blocks in pediatric patients also
were reported.13
++
Klein and colleagues were first to study and
quantify the benefits of perineural infusion of local anesthetic.14In their randomized, double-blind, placebo-controlled
investigation, patients undergoing open rotator cuff repair who received an
interscalene block and perineural catheter preoperatively, were randomized
to receive either perineural ropivacaine 0.2% or normal saline
postoperatively (10 mL/h). Patients receiving perineural placebo averaged a
3 on a 0–10 visual analog pain scale (VAS), compared with a 1 for subjects
receiving ropivacaine. Although a portable pump was used, patients remained
hospitalized during local anesthetic infusion of less than 24 h, and
catheters were removed by the investigators prior to home
discharge.14 Consequently, while these data suggested that
perineural infusion may improve postoperative analgesia following hospital
discharge, the actual advantages of continuous nerve blocks for patients
at home remained unknown.
++
Data from perineural infusion in outpatients subsequently were provided in
four randomized, double-blind, placebo-controlled studies.15–18 Patients receiving perineural local anesthetic achieved
significantly lower resting and breakthrough pain scores than did those
using exclusively oral opioids for analgesia (Figure 64–1). In
addition, they required significantly fewer oral analgesics to achieve their
improved ...