Episode #290 From Blind Needles To Ultrasound: The Safety Revolution In Regional Anesthesia

Hello and welcome back to the Anesthesia Patient Safety Podcast. My name is Alli Bechtel, and I am your host. Thank you for joining us for another show. Have you done a nerve block or neuraxial procedure recently? We have come along way when it comes to regional anesthesia, from an early safety focus on avoidance of high spinal anesthesia, nerve injury, and local anesthetic systemic toxicity to routine use of ultrasound guidance, safer local anesthetics, lipid emulsion therapy, and standardized protocols for LAST. The future directions for regional anesthesia include optimized training, expanding use in high-risk patients, and integrating safety with multimodal perioperative care. Our work has helped to prevent catastrophic complications and move on to refining best practices, minimizing toxicities, and improving patient outcomes.

Before we dive further into the episode today, we’d like to recognize Blink, a major corporate supporter of APSF. Blink has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Blink – we wouldn’t be able to do all that we do without you!”

So, fire up your ultrasound and grab your block needle because our featured article today is from the October 2025 APSF Newsletter. It is “The Evolution of Patient Safety in Regional Anesthesia: A Journey of Progress”

by Shams and colleagues. To follow along with us, head over to APSF.org and click on the Newsletter heading. First one down is the current issue. From there, scroll down to our featured article today. I will include a link in the show notes as well.

Let’s take a trip to the past and explore the early days of regional anesthesia. The year is 1884 and Carl Koller discovered that cocaine could be used as a local anesthetic for the eye which kick started the modern era of local anesthetics and the field of regional anesthesia. Local anesthetics allowed localized pain control right from the beginning during surgery. The early days of regional anesthesia included serious complications such as spinal headache, nerve injury, and local anesthetic toxicity. Let’s meet one of the founding fathers of regional anesthesia, Gaston Labet, a French surgeon. Surgeons were often involved in regional anesthesia at first performing blocks and surgeries at the same time. There was no ultrasound back then so blocks were performed with a blind technique using surface anatomy landmarks to guide needle placement. Early blocks were operator dependent, had varying outcomes, and a high risk for inadvertent intravascular injections and local anesthetic toxicity.

Now we’re going to fast forward a bit. Wrong-sided regional blocks are a “never” event. Did you know that this never event occurs at a rate of 0.5-5.7 per 10,000 blocks performed. One way to prevent wrong sided blocks is with procedural timeouts and in 2014, the American society of Regional Anesthesia and Pain Medicine instituted a procedural timeout with these seven components:

• Patient identification
• Procedure and site verification
• Imaging and equipment preparation
• Local anesthetic verification
• Emergency preparedness
• Team communication and alignment
• And documentation.

Do you use this simple and effective intervention to help prevent wrong-sided blocks in your practice? This is a time to use communication skills and team work to improve patient safety and prevent this never event.

The last time you performed a regional block you also probably reached for a newer piece of equipment, an ultrasound machine. This may be the most significant advancement in regional anesthesia. First introduced in the late 20^th century with widespread use in the 21^st century, this machine provides real-time images of nerves, blood vessels, and surrounding tissues with precise needle placement.  Ultrasound-guided nerve blocks have made regional anesthesia safer and more effective with confirmation of spread of the local anesthetic in the appropriate location, decreased block failure rates, faster time to block onset, and decreased time required to perform the blocks. The ultrasound ushered in another patient safety advancement by allowing less local anesthetic to be used in nerve blocks which helped to decrease the risk for local anesthetic systemic toxicity.

Speaking of LAST, this is a rare and serious complication due to inadvertent intravascular injection of local anesthetic. The incidence of this complication has decreased from 7.5-20 per 10,000 blocks to 0.8-8.7 per 10, 0000 blocks with the incidence of serious cardiac toxicity falling to nearly 0 in the past 30-40 years. These improvements were due to improved local anesthetic dosing protocols, decreased local anesthetics required for ultrasound guided blocks, and, of course, Lipid emulsion therapy and LAST treatment guidelines.

We have some important digital tools in the regional anesthesia toolbox including smartphone applications and online resources. Anesthesia professionals may be reaching for their phones to access information on nerve block techniques, local anesthetic dosages, and anticoagulation guidelines. These are important resources for anesthesia professionals to review ultrasound images, instructional videos, and interactive decision-making algorithms while staying up to date on guidelines and best practices. We hope that you will check out ASRA Coags and Timeout applications. ASRA Coags provides a quick reference for the ASRA Pain Medicine Anticoagulation Guidelines and drug-specific summary information. With so many anticoagulation medications in use today, this app provides essential information for timing of neuraxial and regional procedures for patients on anticoagulation medications. The ASRA Timeout app offers a quick and easy way to perform a pre-procedure timeout before you perform a regional block.

As you can see, we have come a long way with regional anesthesia, but there is still more work to be done until no patient is harmed by regional anesthesia procedures. We are going to discuss some of these remaining threats to patient safety now starting with wrong-sided blocks and failed blocks. Procedural timeouts have greatly reduced the risk for wrong-sided blocks, but these “never” events may still occur. Contributing factors include the following:

Production pressure

Poor communication

Distractions

Rushed or absent timeouts

Absent site markings

And patient repositioning.

We must remain vigilant and continue to improve our system processes to help keep patients safe from wrong-sided blocks going forward.

Ultrasound-guidance has greatly reduced the risk for block failure…by more than 50% and decreased the risk of conversion to general anesthesia, but this is likely a risk that will never be completely eliminated. Factors contributing to failed blocks include the following:

Anatomical variations

Communication barriers

Obesity or other anatomic factors

Surgical factors

And proceduralist experience.

Another important complication from regional anesthesia is the risk of neurologic injury. Once again, there have been improvements in imaging and needle guidance, but keep in mind that long-term neurological injury still occurs at a rate of 2-4 in 10,000 blocks. Even though we can now see the nerves and often fascicles and avoid direct contact with needle visualization, nerve injury can still occur. Let’s review Table 1 in the article for a review of the components of nerve injury. First up, there are a couple of host factors:

• Pre-existing neuropathy including diabetic neuropathy, peripheral vascular disease, chemotherapy-induced neuropathy, and neurologic diseases such as multiple sclerosis and lupus.
• Surgical elements including trauma surgery, prolonged tourniquet time, high levels of neural stretch, and surgical type.

Next, there are the causative agents:

• Needle trauma with considerations for the presence of paresthesia during the procedure and short vs long bevel shape
• Pressure injury since higher injections pressures may indicate intraneural needle location.

Finally, there are environmental factors including.

• Ultrasound versus Nerve Stimulation. Keep in mind that there is no difference in neurologic complications, but improved efficacy and decreased failure rates with ultrasound use
• Injection Pressure Monitoring may help decrease the risk of intrafascicular injection.

The risk for nerve injury may not be eliminated completely. It may be that just injecting local anesthetic, which is a neurotoxic substance near nerves in patients who are susceptible to nerve injury may lead to long-term neurological dysfunction, but there are steps that anesthesia professionals can take to help decrease the risk going forward including:

• Using a short-beveled needle
• Appropriately dosing local anesthetics
• Visualizing nerves directly with ultrasound
• Injection pressure monitoring
• Appropriate patient counseling

The future is exciting for regional anesthesia with important emerging technologies. Right now, we are using 2D ultrasound imaging with a flat, cross-sectional view. 3D imaging reconstructs anatomical structures in 3 dimensions to allow a more comprehensive view of the target area.  4D imaging provides real-time visualization of moving structures such as blood vessels and nerves. These advanced imaging modalities would help to improve the precision and safety of regional anesthesia. Wide-spread use of these advanced imaging technologies would lead to new standards and allow for a reduced learning curve for complex nerve blocks and other challenging regional procedures.

Another exciting development is in needle guidance technology which can be integrated with ultrasound machines to provide real-time feedback on needle positioning. These systems use electromagnetic or optical tracking to determine the path of the needle and help make sure it remains on course. For more information, check out the 2019 article, “Needle tip tracking for ultrasound-guided peripheral nerve block procedures-An observer blinded, randomized, controlled, crossover study on a phantom model.” This study involved 40 anesthesiologists who performed in-plane and out of plane simulated blocks with and without the needle guidance technology. For out of plane procedures, the needle guidance reduced the procedure time and number of hand movements while no significant differences were found for in-plane blocks. I will include the citation in the show notes as well. Needle guidance technology has the potential to make regional anesthesia safer and more accessible going forward.

Pressure injection monitoring is another way to improve patient safety during blocks by monitoring the pressure exerted during the injection of local anesthetic. This provides an early warning if the needle tip is in intraneural or intravascular space. There is an association between high injection pressures and the risk of nerve injury so this can really help to prevent complications.

So, where are we going from here? The authors report that future promising areas currently under development include the following:

• Artificial Intelligence and the development of AI algorithms to help with ultrasound interpretation, needle trajectory planning, and complication prediction. This use of AI has the potential to provide personalized recommendations for each patient to optimize safety and efficacy.
• Wearable Sensors that could be used to monitor patient physiology in real time and provide early warnings of complications such as LAST or nerve injury and support intervening and treatment without delay.
• And high-fidelity simulation training to allow anesthesia professionals to become proficient in complex blocks in a risk-free environment. This is vital to ensure competency while minimizing errors.

The authors leave us with this conclusion that I’m going to read now:

“The evolution of patient safety in regional anaesthesia has been nothing short of remarkable. From the early days of blind techniques and rudimentary safety measures to the modern era of real-time ultrasound-guidance, intralipid therapy, and advanced imaging, the field has made tremendous strides. Each innovation has brought us closer to the ideal of a safe, effective, and patient-centred practice.

As we look to the future, the integration of emerging technologies such as 3D/4D imaging, AI, and needle guidance systems promises to further enhance safety and precision. By continuing to prioritize patient safety and embrace innovation, regional anaesthesia will continue to remain an important subset of the field of anaesthesiology.”

If you have any questions or comments from today’s show, please email us at [email protected]. Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. We hope that you will visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.

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Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

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