JANUARY 23, 2024
Originally published by our sister publication Anesthesiology News
PHOENIX—Although the past several decades have seen the practice of regional anesthesiology advance by leaps and bounds in terms of safety, ease of use and broad-based applicability, the practice is not without its complications.
In a panel symposium presented at the 2023 annual meeting of the Society for Ambulatory Anesthesia, four seasoned clinicians discussed potential complications of regional
Originally published by our sister publication Anesthesiology News
PHOENIX—Although the past several decades have seen the practice of regional anesthesiology advance by leaps and bounds in terms of safety, ease of use and broad-based applicability, the practice is not without its complications.
In a panel symposium presented at the 2023 annual meeting of the Society for Ambulatory Anesthesia, four seasoned clinicians discussed potential complications of regional anesthesia, and how their peers might identify, address and avoid these pitfalls in their practices.
1. The Importance of Safety Checklists
In the first presentation, Ashley M. Shilling, MD, a professor of anesthesiology and orthopedic surgery at the University of Virginia Health System, in Charlottesville, discussed the importance of safety checklists in regional anesthesia, one that was illustrated by a case where a patient received a wrong-sided continuous nerve block.
“Are there errors when performing regional blocks?” she asked. “There certainly are, and I’m testament to that.” Such errors can come in many and varied forms, and include complications in block technique, anticoagulation concerns and failures, drug errors, local anesthetic maximum dose, and wrong-sided nerve blocks.
And while there are many ways to minimize the risk for such errors, one proven strategy involves the implementation of safety checklists, which Shilling defined as a professional aid used to reduce failure by compensating for potential limits of human memory or attention.
“Checklists help ensure consistency and completeness,” she said.
As Shilling explained, wrong-sided surgery came largely to the public’s attention in 1999 with the release of the “To Err is Human: Building a Safer Health System” report. In 2008, the World Health Organization published a surgical safety checklist of 19 items to help reduce human error.
“This was one of the most notable checklists, and is still in use in the perioperative setting,” Shilling said. By 2014, the American Society of Regional Anesthesia and Pain Medicine (ASRA) had released its regional block pre-procedural checklists, which included nine factors to be considered by clinicians:
“Obviously, the checklist is only successful when the teams using it are committed to the teamwork, discipline and humility that it requires,” Shilling added.
Research has borne out the value of pre-procedural checklists. One study cited by Shilling (Reg Anesth Pain Med 2019 Jan 13. doi:10.1136/rapm-2018-000033) examined the incidence of wrong-sided nerve blocks over an eight-year period before and after the implementation of a pre-procedural checklist, specific to regional anesthesia. It was found that the incidence of wrong-sided blocks fell from 3.95 per 10,000 blocks prior to checklist implementation to none in 35,890 procedures (P=0.0023).
In a systematic review of all anesthesia checklists through 2019 (Anaesth Crit Care Pain Med 2020;39[1]:65-73), researchers found a positive effect from the use of checklists in 23 of 25 included studies (92%).
“What’s even more compelling is that three of the studies actually showed a reduction in mortality when a checklist was used, while another two showed a decrease in significant complications when a checklist was used,” Shilling noted.
As Shilling concluded, the known benefits of pre-procedural checklists are many, and include a decrease in human error, improved communication and improved quality of care for patients in routine and emergency situations.
“But they only work if you comply,” she said.
2. Possible Complications of Continuous Catheters
The symposium’s second presentation was by Marco Lotano, MD, the medical director and chair of anesthesia at MEDRVA Surgery Centers in Richmond, Va., who discussed possible complications with continuous catheter nerve blocks. Unlike his other colleagues, Lotano offered the perspective of a clinician working in private practice, where efficiency is crucial.
As Lotano began, continuous peripheral nerve blocks are desirable because they extend the benefits of single-shot peripheral nerve blocks.
“At our centers, we are providing more of these catheters for extensive orthopedic procedures, usually at the request of our surgeons,” he explained. “However, they require careful planning and patience. It takes extended time to place the catheter using a sterile technique, and they are associated with increased costs and follow-up.” Continuous catheters are also associated with their own set of risks, he added. These include primary and secondary catheter failures; needle-induced injuries; risk for infection; and the possibility of local anesthetic systemic toxicity.
“Continuous catheters can be technically challenging, resulting in improper placement,” Lotano said. “Therefore, they require practice and additional training. They can be easily displaced or migrate; conversely, they can become disconnected, resulting in the leakage of the local anesthetic. In addition, the pump mechanism itself can fail, resulting in complications in the rate of infusion.”
The published failure rate of primary catheters ranges between 0.5% and 26%, suggesting that technique plays a major role in catheter success (Anesth Analg 2017;124[1]:308-335).
“It’s imperative to confirm your catheter placement,” Lotano said. “We recommend using saline rather than air bubbles because they can distort your image.”
In a 2016 study of more than 1,400 patients receiving interscalene catheters, researchers found that as much as 12% of patients sought medical attention for problems such as catheter obstruction, pump or catheter dislocation resulting in leakage, and persistent alarming from the electronic pump (Anaesthesia 2016;71[4]:373-379).
One simple way to address secondary catheter failure rates is with the use of 2-octyl cyanoacrylate glue (Dermabond, Ethicon), which has been shown to decrease catheter leakage, catheter dislodgement and catheter displacement.
“Taking that extra time and the extra steps required to properly secure the dressing will result in increased success,” Lotano explained. “However, the jury’s still out on whether or not that may actually improve catheter outcomes.” One intervention that has been shown to improve outcomes in continuous catheterization, on the other hand, is patient education regarding postoperative care, particularly with respect to activities.
Another potential complication from these types of catheters comes in the form of bleeding and/or hematoma, which are difficult to diagnose once patients leave the facility. Here, patient education and communication will also help if complications arise, although the risk for an adverse event can be minimized with preoperative and/or postoperative anticoagulation. Clinicians should also understand that deeper blocks pose a greater risk for bleeding/hematoma.
One of the most significant potential complications of continuous peripheral nerve catheters is peripheral nerve injury and postoperative neurologic complications. Indeed, a 2016 study found that 1.8% of such patients reported tingling, weakness or pain lasting longer than six months (Anaesthesia 2016;71[4]:373-379).
Infection is another potential risk with continuous catheters, an adverse event whose incidence is affected by the insertion site, duration of catheterization and patient risk factors. Risk factors associated with catheter-related infections include older age, male sex and multiple comorbidities, such as diabetes and obesity.
“There are also additional risk factors such as length of stay in the ICU, catheter duration longer than 48 hours and also the absence of antibiotics,” Lotano added.
“So how can we avoid all these complications?” Lotano asked. “Provider education is key, and includes ultrasound guidance training, knowledge of proper nerve block selection, and which technique, local anesthetic and type of monitoring to use. And finally, patient selection is a very important factor in successful performance.”
3. Local Anesthetic Systemic Toxicity
Hanae K. Tokita, MD, the director of anesthesia at the Josie Robertson Surgery Center and an associate attending in the Department of Anesthesiology and Critical Care at Memorial Sloan Kettering Cancer Center, in New York City, focused her presentation on local anesthetic systemic toxicity (LAST). In doing so, she noted that LAST is commonly defined as a potentially life-threatening cardiovascular collapse from unintentional intravascular injection or slow absorption of high doses of local anesthetic.
And while potentially devastating, the complication is a rare one, Tokita said.
“Much of the knowledge we have about LAST is derived from case reports, clinical registries and large data sets,” she noted. “So it’s likely that there’s some amount of underreporting, but I think it’s largely agreed upon that the contemporary rate of LAST is around 1.8 per 1,000 nerve blocks with ultrasound guidance.”
One of the key considerations with respect to LAST is the clinical setting where the adverse effect occurs, which has changed markedly in recent years. Indeed, while LAST was once the sole preserve of anesthesiologists working in hospital ORs, a recent review found that of 36 LAST case reports published between 2017 and 2020, 17% occurred in outpatient surgery centers and 14% occurred in outpatient clinics (Anaesthesia 2021;76[suppl 1]:27-39). The individuals performing these procedures have also changed, as 39% cases of LAST came at the hands of surgeons and proceduralists, 5.5% from dentists, with another 5.5% self-administered.
“So there’s been a shift away from anesthesia providers in an OR setting to non-anesthesia providers performing more often in remote locations,” Tokita noted. “That’s something that we should all be aware of, so we can try to raise awareness and educate our non-anesthesiologist colleagues about.”
The clinical manifestations of LAST are several, she continued, and begin with early signs such as dizziness, drowsiness and tinnitus. Unfortunately, these signals may be masked by sedation or general anesthesia, which means that the first indication of the adverse event may be cardiovascular collapse. As a result, patients may also suffer neurologic effects such as seizure, loss of consciousness, coma and myocardial depression.
LAST is further complicated by its variable presentation and speed of onset. Research has shown that only half of all LAST cases occur during or within 10 minutes of the block, with another 19% occurring between 11 and 60 minutes after the block has been placed. Perhaps most alarming is the fact that 8% of cases occur between one and 12 hours of block placement, and another 8% occur more than 12 hours later.
“So if you do these blocks preoperatively and leave the patient, it’s really important to have monitoring protocols in place,” Tokita explained.
Clinicians can take steps to mitigate the risk for LAST from occurring, beginning with a choice of the least cardiotoxic local anesthetic type, technique and dose. In terms of block conduct, ultrasound guidance has been shown to substantially decrease the risk for LAST; other possibilities include incremental injections, aspiration prior to injection, potential use of epinephrine as a marker of intravascular injection and performing blocks in awake patients, which may allow for earlier detection.
Should LAST occur, clinical management is critical. In this regard, Tokita recommended that clinicians follow ASRA’s 2020 checklist (Reg Anesth Pain Med 2021;46[1]:81-82).
“The most important take-home point from the checklist is that if you have a suspected case involving LAST, get the intralipid emulsion going while you’re calling for help and managing the airway,” she said. “However, remember that although lipid emulsion is a crucial antidote in LAST, it’s not a cure-all. Deaths have still occurred in LAST when lipid emulsion has been given.”
As Tokita concluded, while the incidence of LAST is low, even a single episode can lead to serious harm or damage if not treated promptly.
“So being vigilant, having safety protocols in place, raising awareness and educating our non-anesthesiology colleagues is very important,” she said. “Finally, Intralipid [IV fat emulsion, Baxter] is very cheap and has a very long shelf life.”
4. Neurologic Injuries From Peripheral Nerve Blocks
The symposium’s final presentation came from Sakura Kinjo, MD, a clinical professor of anesthesia and perioperative care at the University of California, San Francisco, who discussed potential neurologic injuries from peripheral nerve blocks.
“We are talking about nerve injury because this is a serious complication, and can lead to long-term disability in patients,” Kinjo said. Despite the potential for such consequences, the incidence of neurologic injury following peripheral nerve blockade is rare, occurring in 1.5 to 4.0 of 10,000 blocks, depending on the block type.
Although several mechanisms are typically responsible for nerve injury in peripheral nerve blocks (mechanical, stretch, pressure, chemical and vascular), most injuries are multifactorial and can range from mild to severe in nature. Indeed, injuries characterized by no axon loss only require days to weeks to recover. However, if the axon is damaged, it could take weeks to months to heal, while complete transection (by avulsion or massive trauma) typically results in severe nerve injuries.
Given the multifactorial nature of nerve injury, it should come as little surprise that several patient factors play a role in the occurrence of these adverse events. These include preexisting neuropathies, peripheral vascular disease, smoking, hypertension and obesity.
“Of course, the most important question is how we prevent nerve injury from occurring in the first place,” Kinjo said. One way, she noted, is to use either ultrasound or nerve stimulation to identify the nerve in question. Another possible method, although less well accepted, involves using pressure manometry to gauge injection pressures.
Assessment and diagnosis of nerve injury can take many forms, the first of which are electrophysiologic studies such as electromyography and nerve conduction studies, both of which can help determine the site, severity and chronicity of the injury, and can help monitor for nerve recovery. Magnetic resonance neurography can also indicate the site and severity of the injury, although it has less sensitivity in milder nerve injuries. Finally, ultrasound can be used to assess for nerve swelling, neural interruption and compression.
Should nerve injury occur during peripheral nerve blockade, Kinjo recommended a management approach that begins with an assessment of the injury’s urgency.
“In addition, the patient needs to be assessed as soon as possible by a peripheral nerve expert,” she said.
Although a milder form of nerve injury, neuropathic pain can also prove troubling for patients, a fact that demands vigilance and awareness by anesthesiologists. The first line of therapy in neuropathic pain is conservative treatment with medication, including anticonvulsants, serotonin–norepinephrine reuptake inhibitors or tricyclic antidepressants. Beyond this, recent literature has described the use of ketogenic diets or dietary supplements.
In a recent article, Terkawi et al suggested a clinical approach to the chronic neuropathic pain that may result from nerve injury (Anesthesiol Clin 2023;41[2]:489-502). This approach begins with a steroid nerve block, but depending on pain severity increases to radiofrequency neuromodulation and cryotherapy; temporal peripheral nerve stimulation; and permanent peripheral nerve stimulation. In the most severe cases, the authors recommend spinal cord and dorsal root ganglion stimulators.
“My take-home message here is that you may find yourself in a situation where you’ve caused some type of nerve injury during peripheral nerve blockade, because most of us have,” Kinjo concluded. “In those situations—even though it may be a little bit awkward—I feel it’s important to let your patients know you care, so they don’t feel abandoned. And if they don’t want to talk to you, please have a colleague talk to them, so you can make sure you are always working toward addressing their injury, no matter how mild it may seem.”
By Michael Vlessides
The sources reported no relevant financial disclosures.
