Infectious complications related to regional anesthesia are rare.
Since the only information is available in case reports and retrospective
surveys, it is likely that these complications are underreported. The
objective of this chapter is to summarize information from the literature on
infections associated with regional anesthesia, as well as to discuss the
mechanism and to suggest strategies to prevent these complications.
Microorganisms from exogenous or endogenous sources may gain access to
the subarachnoid, epidural, or tissue space surrounding peripheral nerves in
several ways. Microorganisms from the patient's or anesthesia practitioner's
flora can be inoculated directly when a catheter or needle is inserted into
those spaces. Several reports in the literature suggest that infections are
on occasion caused by the anesthesia practitioner's flora.1–3 For example, Trautmann and colleagues reported a case of
meningitis caused by a Staphylococcus aureus strain that was identical by pulsed-field gel
electrophoresis to the S. aureus isolate from the anesthesiologist's
nose.2 Microorganisms can also enter the epidural space by
hematogenous spread from other body sites, such as infected
skin,2,4 or by migrating along the catheter
tract.5,6 Several case reports suggested that infection
was caused by spread of bacteria from infected sites through the bloodstream
to the epidural space.7–9 Others maintain that
infections at distal sites are not contraindications to epidural anesthesia.
For example, Newman concluded that distal infections did not increase the
risk of epidural infection because traumatic injuries are often infected and
no epidural catheter-related infections were identified among over 3000
patients who had epidural neural blockades for postoperative or
posttraumatic analgesia.10 The anesthetic agents injected
into the patient's subarachnoid or epidural space are another possible
source of infection. Infections from contaminated multidose vials are likely
to be rare because most anesthetic drugs are weak bases dissolved in acidic
solutions that inhibit growth of bacteria and fungi11–13; besides most multidose local anesthetic solutions contain a
bacteriostatic agent. Nevertheless, the case report by North and Brophy
suggests that contaminated multidose vials still can be a source of
infection. These authors reported an infection in which S. aureus isolates with
matching phage types were recovered from an abscess and a multidose
Streptococcal species, S. aureus, and Pseudomonas aeruginosa are the most common causative agents.
Microorganisms from the patient's or anesthesia practitioner's flora can be
inoculated directly when a catheter or needle is inserted into the epidural
or subarachnoid space.
Because it is easy to contaminate the needle or the catheters,
anesthesiologists must strictly adhere to hygienic measures.
To assess whether contamination of the anesthetic agent or the
equipment (needles, syringes, tubing) is related to subsequent infections,
investigators have cultured these items after they have been used with
patients or during simulations. In four studies, 0–29% of used catheters
were contaminated,14–17 and James and coworkers found
that 5 of 101 syringes used to inject ...