Dr. Robert Raw, M.D., is Director of the Regional Anesthesia Study Center of Iowa (RASCI) at the University of Iowa Hospitals and Clinics, and has practiced using both conventional and ultrasound guided regional anesthesia. Dr. Rajnish Gupta, M.D., Assistant Professor of Anesthesiology at Vanderbilt University School of Medicine, was introduced to ultrasound guidance as a resident. Both are leaders in the field today.

A New Technique Emerges

Robert Raw, MD

Raw pursued USGRA as soon as it became truly feasible in a clinical environment. He saw basic questions surrounding the early practice of USGRA – most notably, how did ultrasound guidance equate with the utility, advisability and advantages of nerve-stimulation? “As an academic regional anesthesia teacher, it was clear I needed to be a debater rather than a listener,” Raw said. “Since the department would not buy an ultrasound for regional anesthesia, at that time, I bought my own system and regarded the machine costs simply as the cost of a learning course. The answers to those early questions are now largely answered, but many new questions have been raised since then.” Raw’s department has subsequently purchased 6 ultrasound systems dedicated to regional anesthesia, and Raw sold his early machine.

Gupta began learning ultrasound guided regional anesthesia during his residency at the University of Michigan. “At the beginning of my residency, about four years ago, students became frustrated pretty quickly with regional anesthesia delivery, partly because it’s difficult to gain a comfort level using nerve stimulators and landmarks to deliver anesthesia,” Gupta said. “During my last year, the hospital acquired a SonoSite MicroMaxx^™, and a few of us had our interest piqued by the machine. We got as much out of that ultrasound system as possible.” Much like Raw, Gupta has seen interest among existing faculty members and residents at Vanderbilt increase over the last few years.

Rajnish Gupta, MD

“When I arrived at Vanderbilt, they had already purchased an ultrasound system for regional anesthesia,” Gupta said. “However, not very many people were comfortable with it. I pushed to learn more, and the value was evident – you could see structures, visualize the variability in people, see the needle and the anesthetic surround the nerves, it was amazing.” Significant advancements in ultrasound technology have continued to increase the level of detail and clarity available to anesthesiologists.

Both Raw and Gupta actively participate in research to advance the field of ultrasound guided regional anesthesia. Raw focuses primarily on clinical delivery of USGRA. “My specific interest will always be primarily in the clinical delivery of regional anesthesia to the benefit of patients and in persuading other anesthesiologists and also surgeons of those benefits,” explained Raw. “Therefore, I seek to design better blocks, better room setups, and better techniques that are more time efficient.” Additionally, Raw explores ultrasound as an investigational tool in studying nerve block injury, and he considers the information derived from the use of ultrasound in regional anesthesia research to be revolutionary.

Gupta agrees, particularly with regard to the study of anatomy related to nerve blocks. “We’re finding out that the structure model we were taught for a long time isn’t always right,” Gupta said. “You can mark the landmarks, and the nerve should be right underneath that, but when you use ultrasound, you discover the rule is actually variation.” Physicians are consistently finding variations of multiple kinds, from the nerve location itself to the relationship with surrounding tissue, and ultrasound facilities the visualization of the nerve location and the surrounding vascular, bony, muscular and visceral structures. Other modalities, including CT and MRI, could also provide guidance in this regard, but ultrasound is by far the most practical modality available.

Gupta’s research focuses on the training of doctors and resident in ultrasound guided regional anesthesia technique, a step key to the further adoption of USGRA. “There’s a huge variation in physical skill sets, the caliber of those skills and in levels of previous training,” Gupta said. “This means we need to find the best ways to get doctors up to speed accurately and effectively.”

Regional Anesthesia and Needle Guidance

Needle guide and sterile cover as used during nerve block

Needle guidance companies, including CIVCO, have developed new needle guidance technology for the regional anesthesia market. CIVCO has multiple regional anesthesia solutions, including the Infiniti Needle Guidance system and the SonoSite L25 Series Needle Guide.  As with many ultrasound guided procedures, some clinicians prefer needle guidance for USGRA, while others choose to freehand during procedures.

Gupta has not relied upon needle guidance during the past, but is open to the possibility in the future, particularly while training residents. “Personally, I haven’t normally used one,” explained Gupta. “In the past, I’ve tried older systems, but they were designed for biopsy and vascular procedures, not regional anesthesia. They were made to be used out of plane. Recently, I’ve been investigating concepts similar to CIVCO’s Infiniti guide, which is constrained in the appropriate dimensions and flexible in others.” Infiniti provides accurate in-plane guidance, and offers multiple angle capabilities for both shallow and deep access.

Gupta admits that watching residents learn two-handed technique in potentially dangerous anatomical areas can be nerve-wracking. “As trainers, we need to improve their success rates and skills quickly,” he said. One of the most common problems is drift. “Your eyes are looking at the ultrasound screen, but you may not maintain alignment with your hands – the probe drifts away from the needle,” explained Gupta. “There are a variety of ways to maintain alignment, so we teach these and investigate the best solutions. CIVCO’s Infiniti^™ needle guide is one of these solutions.” The key to making needle guidance a useful training tool for regional anesthesia is specializing the technology to this intended use.

Raw, on the other hand, does not use a needle guidance system for regional anesthesia. “I certainly can see some merit in it for aspiration of large fluids collection and for biopsy of large tissue lesions,” Raw said.

Both Raw and Gupta use sterile covers in more complex regional anesthesia procedures. “We use a full sleeve sterile over when performing large, complex procedures, such as placing perineural catheters,” Raw explained. “This is when we use full wide field sterility, gowns, mask and gloves as well.”

Procedures are similar in Gupta’s facility. “We use sterile probe covers when placing nerve catheters since they are going to stay in for several days,” Gupta said. CIVCO offers a wide variety of probe covers to meet numerous clinical infection control needs.

With prominent clinicians on both sides of the issue, it remains to be seen whether needle guidance becomes a standard of care in regional anesthesia. Constant innovation on the part of ultrasound OEMs and needle guidance developers may well provide clinicians with further solutions, making needle guidance advantageous. Further, as noted by Gupta, needle guidance has huge potential as a training tool for physicians. As young doctors are trained using needle guidance for USGRA, they may continue to do utilize it beyond their training programs.

The Future of Ultrasound Guided Regional Anesthesia

Gupta and Raw agree that ultrasound’s role in regional anesthesia is permanent. “The last decade has been spent defining ultrasound’s role, and it’s pretty well established at this point,”

CIVCO's Infiniti needle guidance system

explained Gupta. “Ultrasound guidance isn’t a necessity, and many people do well without it, but it’s an integral part of current available tools. For many people, it’s an essential tool.” Over time, Gupta feels ultrasound guidance will lead to higher success rates and fewer complications in regional anesthesia.

Raw looks at the future of this field in two facets: clinical applications and technology advances. “Future clinical applications will be a steady process of evolution as doctors simply try things out,” Raw said. “Some ideas will be silly and some will be brilliant. Each new USGRA idea will be brilliant to its own inventor, but broad clinical process will slowly clarify the basic questions: is it safer, is it more effective, and is it easier?” This process of physician innovation will continue to improve and increase the clinical application of USGRA.

Expansion in transducer technology will be a key advancement over the next decade. “A greater variety of transducers being made available gives us more selection flexibility,” Raw said. “I see regional anesthesia dedicated transducers being designed with better hand holding ergonomics. I see multi-scan transducers that are actually complex multiple transducers in one, exploiting better and faster computing capacity of machines. The challenge is to see deeper, better, with faster frame refresh rates.” Raw also envisions enhanced fusion and high frequency transducers and faster refresh rates for portable ultrasound.

Raw emphasizes the importance of increased computing capacity and cart design in future ultrasound systems. “There will be a move towards fixed mini-cart mounted systems with very high computing capabilities,” he explained. “Cart mounted systems also need to have un-interruptible power systems built in. Foot print size is everything and slim, vertical carts are starting to get more common. We need slim standing high capacity systems, something between the mega top-end TEE grade machines, and the low-end hand portable machines.”

From his perspective, Gupta focuses on techniques for improvement in clinical delivery. “I’m not sure which techniques will win out over the next decade, but reducing hand-eye difficulties and maintaining the stability of the probe at the same time will be important,” he said. “Imaging techniques are constantly evolving, with higher resolution and then 3D visualization.” Gupta does see development in the application of 3D imaging to USGRA, which can be more difficult than application to tumor imaging or biopsy. “At a recent ASRA meeting, Ultrasonix displayed a pseudo-3D tracking system – you can see the tip tracking, but the image actually looks like the 2D image that you are used to,” Gupta said. “This kind of tip tracking increases accuracy, precision and speed, acquiring the image like it’s needed for medication delivery.” The SonixGPS technology mentioned by Gupta incorporates CIVCO’s eTRAX™ needle tip tracking system.

Ultrasound guidance for regional anesthesia traces its roots back to 1978, when the first procedure was performed and described for publication. Since then, a dedicated group of clinicians have researched and practiced the technique, and ultrasound OEMs have continually delivered advanced technology. “The level of detail we’re seeing now that we couldn’t see even five years ago is unbelievable,” commented Gupta. The past five years have marked a paradigm shift within regional anesthesia.[ii] Given the ability of USGRA to minimize patient discomfort, procedure length and nerve injuries while increasing success rates, ultrasound guidance for regional anesthesia will continue to expand and mature over the next decade.

[ii] “Center for Ultrasound-Guided Regional Anesthesia.” Dartmouth-Hitchcock Medical Center. . N.p., n.d. Web. 17 Jun 2010. <http://www.dhmc.org/dhmc-internet-upload/file_collection/reg_anes_for_web.pdf>.

eTRAX: CIVCO’s Breakthrough Needle Guidance System

CIVCO Medical Solutions has introduced eTRAX, a breakthrough needle guidance system, expanding real-time image-guided navigation into a new dimension. Featuring an electromagnetic sensor embedded into the needle tip, eTRAX is an image-guidance tool kit which supports image fusion for ultrasound and enables real-time 3D instrument guidance in a variety of clinical settings. eTRAX acts as a real-time, 3D anatomical roadmap for the body, aiding in minimally invasive procedures.

Paired with a sterile sheath, eTRAX’s electromagnetic (EM) tracking needle guidance enables accurate placement of a broad spectrum of standard instruments using co-axial technique. Given the ability to fuse other imaging modalities with ultrasound, eTRAX provides physicians with a greater range of choices for targeting and supremely accurate tool for tracking of the tip of a needle under real-time, image-guided navigation.  “The eTRAX tool kit is unique in both its design and clinical versatility,” said Dr. Bill Whitmore, MD, Chief Medical Officer at CIVCO. “The system is also designed to allow indefinite re-use of the relatively expensive active EM tracking sensors.”

EM tracking with eTRAX provides significant clinical advantages, including increased clinical confidence in targeting difficult to access lesions. “Ultrasound alone cannot always provide clinical confidence, often due to multiple tissue interfaces, bone or air blockages,” explained Jack Scully, Vice President of Ascension Technology Corporation. Ascension developed and manufactures the EM tracking sensors used in eTRAX.  “Importantly, EM tracking allows both in and out-of-plane navigation to optimize the needle’s trajectory to a lesion,” continued Scully. “With 3D guidance, the physician can independently position both the biopsy needle and an ultrasound transducer for the safest and fastest target access.”

With eTRAX, ultrasound brackets enable attachment of a sensor for real-time image fusion and also support an in-plane mechanical guide for ease of instrument orientation during ultrasound assisted targeting. Coupled with an OEM ultrasound system, eTRAX can improve the safety, speed and accuracy of instrument placement and save costs by reducing both procedure time and complications.

eTRAX in Action

eTRAX Guidance User Interface

Dr. Thierry de Baere, head of Interventional Radiology at the Institut Gustave Roussy in Villejuif, France, worked with CIVCO to validate the eTRAX system. “The system components are easy to work with, fast to setup before a biopsy, and very intuitive,” said de Baere.  CIVCO’s guidance system may be used with devices for numerous applications; de Baere and his group initially used the system for tissue biopsy, but plan to utilize eTRAX during ablation procedures as well.  “We biopsied six patients using the eTRAX guidance system, and all patients were successfully biopsied with rapid placement of the needle within the target,” said de Baere. “eTRAX allows you to follow the progression of your needle tip more easily, due to the excellent accuracy of the system.”

de Baere also took advantage of eTRAX’s flexibility during the validation testing. “It allows different access routes for the needle and the imaging, which is really useful when an intercostal access is chosen for a liver biopsy,” he said. “We could appreciate that in two of our six biopsies. It is much more flexible than any guiding kit linked to the probe.”

Scully emphasizes the safety aspect of EM tracking for interventional procedures, such as those performed by de Baere. “Faster, more accurate and safer procedures reduce costs and patient trauma,” he said. “For deep-seated lesions, the data is showing EM tracking facilitates 100% success with a single needle stick. The technology is especially helpful in enabling biopsy procedures to be performed successfully by less experienced physicians while significantly shortening an otherwise steep learning curve.” de Baere, a highly experienced physician, also appreciates eTRAX’s short learning curve, as well as the easy to understand display provided by OEM software.

As eTRAX continues to develop and is used by more clinicians, de Baere sees continued benefits to both patient and clinician. “In the future, it will probably contribute to shortening the overall biopsy time, namely the duration of the needle placement itself,” he said. “Consequently, the procedure will be better tolerated by the patient. In a few cases, it might reduce the number of punctures.”

Whitmore agrees and underscores the increase in clinical confidence gained through eTRAX usage. “Any physician using images for guiding a medical procedure wishes to ‘see’ and to feel comfortable knowing exactly where they are going, in real-time, as accurately as possible,” he said. “Electromagnetic instrument tracking and multi-modality image fusion with accurate registration is the current state of the art for satisfying this need.”

Evolution and Future of Tracking Technology

eTRAX During Procedure

The EM tracking technology at the core of eTRAX has a significant history, developing from a military technology to a commercially viable medical accessory over the course of the last 30 years.  Vermont-based Ascension Technology Corporation supplies eTRAX’s EM tracking sensors. “Sensor-driven ultrasound is the ultimate hand-eye coordinator,” said Scully. “It lets the physician see the needle tip, the internal target, and the anatomy in real-time – without radiating the patient or the clinician.”

eTRAX enhances the value of image fusion, which in itself has been a major technological advancement in the image-guidance industry recently. GE Healthcare’s LOGIQ E9^©, Ultrasonix’s SonixTOUCH^™ and Esaote’s Virtual Navigator^™ all offer image fusion and assisted navigation for interventional and ultrasound procedures.  Philips Healthcare recently acquired Toronto-based Traxtal, Inc. Traxtal has been a pioneer in EM tracking and guidance with their PercuNav computer assisted image-guidance system. PercuNav, like eTRAX, utilizes both multi-modality image fusion and EM tracking needle guidance.

eTRAX and PercuNav are today’s cutting-edge technology – developed to better patient care and enhance clinicians’ capabilities. Whitmore and Scully see EM tracking becoming the stand of care for image-guided procedures. As that happens, the technology involved will continue to develop rapidly. Whitmore sees software, hardware and robotics advancing congruently. “Hardware will advance in parallel to the point where precise 4D instrument navigation using active tracking will be paired with robotics,” said Whitmore. “This will enable a qualified clinician to precisely and safely target a lesion with a single pass of the instrument anywhere in the body from a remote console using something similar to a joystick in a video game. This will be dramatically safer for both the patient and the physician.”

Scully believes eventually there will be a progressive reduction in the cost of EM tracking sensors. “The next frontier will be truly disposable, low-cost sensors,” said Scully. “It will happen once sensor-driven ultrasound becomes standard practice. We also will see steady advances in signal processing and metal immunity that will widen applications and acceptability in numerous new image-guidance procedures. Long-term, first embedded, and then wireless sensors will make tracking less obtrusive and permit tighter integration into medical instruments become standard issue.”

eTRAX Sensor and Cord

The evolution of EM tracking for image-guided medical interventions will continue to benefit both patient and clinician. “Electromagnetic tracking alone and possibly in combination with other tracking methods will increasingly be applied for image-guided medical interventions,” said Whitmore. “As imaging technology advances and image management and workflow software improves, more accurate diagnoses, treatment planning and faster, safer targeting will be further supported by increasingly accurate and continuously updated image fusion.”

eTRAX, and its counterparts, are a significant step in this direction. For more information on eTRAX, please visit www.CIVCO-etrax.com.