Peripheral nerve blocks (PNBs) are commonly utilized in surgical anesthesia and for providing postoperative and nonsurgical pain relief. They present clear advantages over general or neuraxial anesthesia in specific clinical scenarios. Moreover, PNBs can offer superior analgesia compared to other approaches for certain patients. Nerve blocks can be either a single injection or continuous, with the use of a catheter. Infection is always a risk with procedures that breach the protective barrier of the skin. Infection risk varies greatly for nerve block with and without a catheter.

The indications for using PNBs are diverse and vary widely. These blocks are often chosen to mitigate the potential side effects and complications associated with alternative anesthetics or analgesics. In particular, the anesthesiologist and surgeon may wish to circumvent the adverse effects and complications associated with general anesthesia (GA), particularly those related to respiration, and to ensure adequate pain relief while minimizing the use of opioids.

A single-injection nerve block, sometimes referred to as a “single-shot” block, involves administering a single dose of local anesthetic (LA) near the nerve or plexus to achieve surgical anesthesia and/or analgesia. The duration and potency of the block depend on factors such as the dose, concentration, and pharmacological properties of the chosen LA. Clinically effective duration may range from less than an hour to 24 hours or more. Because this type of nerve block is administered over a very short, discrete amount of time, a needle is used and a catheter is not needed, greatly decreasing infection risk.

Continuous infusion of LA through a catheter placed percutaneously near the peripheral nerve or plexus delivers prolonged anesthesia/analgesia within the nerve or plexus distribution. This approach can be managed on an inpatient or outpatient basis and is especially beneficial for patients anticipated to require extended analgesic support. Continuous blocks contribute to enhanced patient satisfaction by reducing pain, opioid consumption, side effects, and sleep disturbances. Inserting a catheter adjacent to a nerve or plexus allows for the extension of the nerve block through intermittent injections or continuous infusion. After locating the nerve using nerve stimulation or ultrasound guidance, a flexible catheter is positioned alongside the nerve or plexus.

Continuous blockade can be administered in either a hospital or ambulatory setting. Managing outpatient continuous nerve catheters necessitates a comprehensive protocol, including thorough preoperative instructions, regular postoperative follow-up, 24-hour accessibility to an anesthesiologist for managing queries or complications, and an examination by a clinician, often the operating surgeon, within the first week following discharge. Under these conditions, most patients can self-manage and remove their catheters at home. The catheters are inserted with sterility and are typically left in place for up to seven days, with the duration limited by the volume of LA remaining in the pump after hospital discharge.

Various kits are available for catheter placement, typically containing a needle and catheter, along with equipment to secure the catheter in position. Most kits utilize a catheter-through-needle technique, although catheter-over-needle products are also an option. When longer needles are required and nerve stimulation is unnecessary, a standard epidural tray can be employed for continuous catheter techniques. Continuous catheters can be placed using nerve stimulation and/or ultrasound techniques. Utilizing ultrasound guidance, as opposed to nerve stimulation, may decrease the time from needle insertion to catheter placement, as well as pain during the placement procedure and the risk of accidental vascular puncture.

A meticulous sterile technique and proper draping are imperative during the placement of a catheter for continuous nerve block to minimize infection risk. A sterile ultrasound probe cover is utilized to prevent direct contact between the probe and the sterile block area, and a sterile drape or towels are employed to create a sterile field around the procedural area. While antibiotics may be used during a surgical procedure to reduce catheter infection risk, they are not typically warranted when placing continuous nerve block catheters for nonsurgical pain control.

The risk of infection for single-shot PNBs is exceedingly low. Bacterial colonization of peripheral nerve catheters ranges from 7.5 to 57 percent, but the risk of infection is minimal (0 to 3.2 percent). The likelihood of infection is higher in patients with critical care unit admission, trauma, compromised immunity, male gender, and the absence of antibiotics. This risk can be minimized by removing the catheter within 48 to 72 hours of placement.

References

1. Lin E, Choi J, Hadzic A. Peripheral nerve blocks for outpatient surgery: evidence-based indications. Curr Opin Anaesthesiol 2013; 26:467.
2. Bingham AE, Fu R, Horn JL, Abrahams MS. Continuous peripheral nerve block compared with single-injection peripheral nerve block: a systematic review and meta-analysis of randomized controlled trials. Reg Anesth Pain Med 2012; 37:583.
3. Swenson JD, Bay N, Loose E, et al. Outpatient management of continuous peripheral nerve catheters placed using ultrasound guidance: an experience in 620 patients. Anesth Analg 2006; 103:1436.
4. Ludot H, Berger J, Pichenot V, et al. Continuous peripheral nerve block for postoperative pain control at home: a prospective feasibility study in children. Reg Anesth Pain Med 2008; 33:52.
5. Cuvillon P, Ripart J, Lalourcey L, et al. The continuous femoral nerve block catheter for postoperative analgesia: bacterial colonization, infectious rate and adverse effects. Anesth Analg 2001; 93:1045.
6. Capdevila X, Bringuier S, Borgeat A. Infectious risk of continuous peripheral nerve blocks. Anesthesiology 2009; 110:182.

nerve block infection