Episode #74 The Luer of Anesthesia Patient Safety

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. This week we are going to explore the Rapid Response section of the October 2021 Newsletter to “Luer” you further into the APSF Newsletter. We are going to review a simple and common component of many medical devices that anesthesia professionals use every day.

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

To follow along with us, head over to APSF.org. Click on the Newsletter heading. First one down is the current issue. Then, scroll down until you see our featured article today, “Air Entrainment by Extension Connectors to Central Venous Cather” by Michael Kuntz and Alfonso Casta. This article highlights an important patient safety concern discovered by the authors when an intravenous line extension was connected to a central line, but the connection did not seal completely. When the clinician aspirated through the extension, air was noted to be in the extension line and syringe despite an appropriately secured connection. The anesthesia team replaced the extension set successfully and their vigilance helped to keep the patient safe.

At this point, you might be thinking, I need more details about the case. Alright, well here we go! A 6.3kg, 7 month old male infant was brought to the OR for repair of complex congenital heart disease including pulmonary atresia, intact ventricular septum, and atrial septal defect. After induction of general anesthesia, a 3Fr, 8cm single lumen central venous catheter was placed in the left internal jugular vein. Then, a Baxter catheter extension was attached to the catheter. For pictures of the central line and extension set, check out the article and I will include a link in the show notes as well. Once the extension set was connected to the central line, slow aspiration on the extension set was performed. This is when air was seen entering into the aspirate at the site of the catheter-extension connection site. The luer locking connection was checked to make sure that it was secure and the syringe on the extension site was checked as well. Air continued to be entrained during aspiration. The next step included removing the first extension set and placing a smith medical three-way stopcock extension. However, the problem of entraining air during aspiration persisted. At this point the team connected a different Baxter extension set to the central line. This time, the connection between the central line and extension set completely sealed and no air entered the line during slow aspiration.

Has a similar situation ever happened in your operating room? Have you ever seen air entrainment during catheter aspiration?

This may occur due to an inadequate seal between the catheter and extension set. This is a threat to patient safety since results of this failed seal may be air entrainment while administering an IV infusion or leaking of IV fluids around the connection site and incomplete medication and fluid delivery to the patient. Air entrainment through a central venous catheter puts patients at risk for cardiovascular and neurologic complications and even death could result from a large air embolism. Prevention of this complication involves carefully securing the extension to the catheter, ensuring that the catheter is secure, and aspirating blood prior to using the catheter.

The authors discuss some of the details of this case. All of the connectors were standard Luer connectors. Was the problem in this case related to the manufacturing of the device or was the insecure connection due to using interconnecting devices from different manufacturers? Following this case, at the authors institution, when using the 3 Fr, 8cm single lumen central venous catheter, the first 2 extension sets were not used due to concern for insecure connections and only the 3^rd extension set which demonstrated a complete seal was used. Education was provided about the importance of routine careful aspiration through the extension set to confirm a complete seal between the catheter and the extension. The authors leave us with the following call to action: “Anesthesia professionals and other health care providers should be aware of the potential for a poor connection, which should prompt the selection of an alternative extension that does not entrain air.”

Thank you so much to the authors for sharing this case with us. An important feature of the rapid response is the response from members of the APSF Committee on Technology and industry partners as well as further education. We have so much more to talk about when it comes to the Luer connector, so let’s check out the article by Jeffrey Feldman, “The “Luer” of a Simple Device.” You can find this article in the October 2021 APSF Newsletter in the section, Rapid Response to questions from our readers.

The article starts off with an overview of Luer connectors. This medical technology allows connections to be made between catheters and extensions with a complete seal to maintain a continuous lumen. These devices are used every day during anesthesia care. Have you used a Luer connector today?

The risks associated with using a Luer connecter include the following: leaks, disconnections, and inappropriate connection such as connecting an IV infusion to an epidural catheter. In order to prevent inappropriate connections or misconnections, there are new devices available. There is also a 7-part standard, ISO 80369, which does the following:

“provides the methodology to assess non-interconnectable characteristics of small-bore connectors based on their inherent design and dimensions in order to reduce the risk of misconnections between medical devices or between accessories for different applications.”

This was published in 2018 and I will include the reference in the show notes as well. This standard is related to luer connections in part 7 which involves the use of a tapered fitting connection for a leak-free seal.

Next, Feldman addresses the case that we just reviewed and highlights the concern that even though standard Luer connectors were used, two of the connections were not leak-free which may have been due to manufacturing consistency. Was the faulty connection a result of variations in manufacturing the actual device, a weakness in the basic standard, or extreme conditions of negative pressure outside of the specification for testing for air leaks? Another consideration is that the two extensions that failed to seal had fixed-skirt luer connectors. The successful connection was made with a swivel-skirt luer connector. The fixed-skirt connectors may involve a twisting force or torque on the tubing and connection. On the other hand, swivel-skirt connectors can be engaged without this additional torque. You will have to tune in next week because we are going to further Luer you in to talk all about the Luer technology. Mark your calendars now!

Let’s get back into the article. Feldman highlight two additional manufacturing standards. The original standard for the Luer connection is ISO-594 which included general requirements and lock fittings. The general requirements for luer connections includes the range of dimensions of basic Luer connectors and the procedures for sizing the components, testing for air and fluid leaks, separation force, and stress cracking. It is required that manufacturers have their components tested to make sure that they adhere to the standard requirements and this facilitates interconnection between devices.

The new standard for intravascular connectors that we talked about earlier has been updated with new liminitations on material properties and more precise dimesions to ensure secure connections. Connectors that are compliant with the new standard should be backwards compliant with ISO 594. Next week, we are going to review the article by Bruce Hansel who is the Principal and Cief Scientist at the Accident and Forensic Investitation for ECRI institute and learn all about vascular connectors. Feldman tells us that since the Luer connector is so simple to use, healthcare professionals may be “lured” into thinking that we don’t have to be vigilent when making this connection. The new standard should help to prevent misconnections between incompatible devices such as IV tubing and an epidural catheter, but we will also continue to use the simple tapered connector for vascular access and infusions so we need to make sure that the connectors are secured without leaks or disconnections in order to keep patients safe.

Before we go, are there any researchers in the audience?! Don’t be shy! We hope that you will consider applying for the Joint APSF and Foundation of Anesthesia Education and Research Mentored Research Training Grant. This is an exciting opportunity for the next generation of perioperative patient safety scientists. This is a two-year, $300,000 award with a goal for anesthesiologists within 10 years of their first faculty appointment to develop skills and collect preliminary data to go on an become independent investigators in the field of anesthesia patient safety. Mark your calendars for December 1, 2021 which is right around the corner. Be ready to submit your letter of intent. The submission period will close on January 1, 2022. For more information, head over to APSF.org and click on Grants and Awards Heading. I will include the link in the show notes as well.

If you have any questions or comments from today’s show, please email us at [email protected].

Visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.  Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. Thanks for tuning in and if you liked this show, please share it with your friends and colleagues, and leaders at your institution. Plus, if you get a chance, can you leave us a 5 star review. This helps our show to stay visible so that every interested in perioperative patient safety is able to tune in.

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

© 2021, The Anesthesia Patient Safety Foundation