Preliminary analysis of data from an ongoing multicenter trial suggests that epidural analgesia may be about to take its most radical turn in more than a century. The analysis found that a novel computerized injection pump technology is as successful in identifying the epidural space as are fluoroscopy and loss of resistance, which one of the study’s authors calls a “game changer” for the practice.
“This technology originally comes from the dental arena,” commented Ralf E. Gebhard, MD, professor of anesthesiology, professor of orthopedics and rehabilitation, and chief of the Division of Regional Anesthesia and Acute Perioperative Pain Management at the University of Miami Miller School of Medicine. “One of my colleagues went to the dentist and received an injection without any pain. When he asked about it, the dentist showed him the injection pump technology, which allows clinicians to give slow, controlled injections that don’t cause any pain.”
Pressure measurement at the tip of the epidural needle—combined with real-time graphic, acoustic and numeric display of such pressures via a computerized injection pump (CompuFlo Epidural Computer Controlled Anesthesia System, Milestone Scientific Inc.)—has been demonstrated to successfully identify the epidural space (Reg Anesth Pain Med 2008;33:346-352). In the current study, Dr. Gebhard and his colleagues sought to compare the technology with both loss of resistance and fluoroscopy.
To that end, the investigators presented preliminary data on 204 patients scheduled to receive epidural needle placement as part of their medical management. Participants were randomly assigned to have the epidural space identified by standard-of-care methods (loss of resistance or fluoroscopy; n=98; mean age, 57.3 years) or the computerized device (n=106; mean age, 56.4 years).
As Dr. Gebhard reported at the 2016 annual meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 1210), identification of the epidural space was comparable between the three groups. What’s more, there was first-attempt success with the device in 95.3% of patients compared with 96.9% of those receiving loss of resistance. There was 100% agreement with the radiological findings in each group. No evidence of a clinically significant adverse event was seen in any patient.
This technology, Dr. Gebhard explained, gives anesthesiologists more options for correctly determining the epidural space in all patients. “Unless you use fluoroscopy, the biggest problem with epidural anesthesia is that you don’t have an objective way of identifying the epidural space,” he told Anesthesiology News. “And in many scenarios you cannot use fluoroscopy, so we are relying on the subjective feeling of loss of resistance with our hands. But we know our hands are not the greatest tools, so this technology gives us an objective way of verifying true loss of resistance, and consequently, the true identification of the epidural space.
“And that’s why I think this is a game changer; because over the last hundred years or so, really nothing much has changed with epidural anesthesia.”
Yet despite his excitement of the device’s potential to improve patient safety, Dr. Gebhard noted that the FDA has some concerns about potential adverse events, hence the need for the trial. “Obviously the FDA is concerned when you introduce a computerized injection pump into the epidural space,” he noted. “They’re concerned about technology failure. So far we haven’t seen that, but the final data are still outstanding.”
Should the CompuFlo system ultimately be approved for use in the United States (it is currently limited to use as an investigational device), Dr. Gebhard noted that it would offer more benefits than just identification of the epidural space. “The good thing is that you get constant readings of the pressure in a graphic, numeric and acoustic display,” he said. “You get constant feedback while you advance the needle on your way to the epidural space.
“Afterwards,” he said, “you can print out the data and include it in the patient’s chart. So for the first time we have a way of objectively documenting that we did the right thing, that we identified the epidural space for the patient. So that’s another huge benefit of this technology.”
In the end, the technology may prove a useful alternative to methods that are either very subjective (loss of resistance) or invasive (radiological fluoroscopy). “I’m excited about the technology, because it’s a real shift in epidural anesthesia,” he said. “Subjective identification of the epi[dural] space has been around for a very long time and has not been replaced by anything else. So introducing some innovative technology may be of benefit.”
Jeff Gadsden, MD, told Anesthesiology News that it has been clearly established that “anesthesiologists are notoriously poor at estimating injection pressure with ‘syringe feel’. Any technology that provides an objective end point rather than a subjective feel has tremendous potential advantages, both in terms of patient safety as well as the ability to effectively document and communicate what exactly was done.” Dr. Gadsden is associate professor of anesthesiology at Duke University Medical Center, in Durham, N.C.
“While the success rates using the device were similar to established techniques of locating the epidural space, I wonder if there might be a difference with difficult spines, or in those patients with poor landmarks such as the obese?” Dr. Gadsden asked. “I would be very interested to see the results of a trial in that specific population.
“I fully agree with the investigators that the ability to save a graphical and/or numerical representation of the technique in the patient’s chart will enhance care, especially in those situations where different care providers are managing the epidural infusion and boluses over a period of time.”
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