A Medical Device Daily

This week's American Society of Anesthesiologists (ASA; Park Ridge, Illinois) meeting in San Francisco will feature nearly 100 scientific studies related to Bispectral Index (BIS) monitoring technology from Aspect Medical Systems' (Norwood, Massachusetts).

The company said the research covers a broad spectrum of topics, including the short- and long-term benefits of BIS monitoring and the role of fluctuations in trends of BIS values in assessing patient response during surgery.

The technology has a somewhat controversial dimension since the company has pitched the technology as helping to avoid surgical awareness, in which the patient becomes aware during surgery but is paralyzed by anesthetic.

Using a sensor placed on the patient's forehead, BIS monitoring translates information from the EEG into a single number that represents each patient's level of consciousness. That number, known as the BIS value, ranges from 100 (indicating an awake patient) to zero (indicating the absence of brain activity).

The company said that using the BIS value to guide administration of anesthetic medication, in conjunction with other vital signs, "allows clinicians to make better-informed decisions to achieve optimal anesthesia."

Research being presented at ASA that was sponsored by Aspect includes two studies that evaluated how rapid changes in BIS values may be useful in assessing patient response to pain during surgery.

The first study explored how the brain responds to different forms of surgical stimulation using bilateral BIS monitoring. Study results showed that when stimulation was localized to one side of the body, the opposite brain hemisphere showed a relatively greater response, thereby demonstrating how painful stimulus can lead to specific brain responses.

The second study, conducted on pediatric patients, demonstrated that highly variable BIS measurements during surgery were associated with patients reporting greater pain during recovery. That result is consistent with findings from a similar study conducted in adults that were presented at the ASA meeting last year.

"Collectively, these studies further suggest that assessing intraoperative BIS variability may be clinically useful in improving pain management and comfort for patients during and after their surgery," said Scott Greenwald, PhD, VP of research at Aspect and co-author of the studies.

A third study provided a prospective, randomized evaluation of 118 patients to explore the relationship between depth of consciousness as measured by BIS and changes in inflammatory biomarkers after major orthopedic surgery. BIS-guided anesthesia was compared with standard clinical practice to determine the effects of exposure to inhalational anesthetics on post-operative inflammatory response.

Patients in the BIS-monitored group showed a reduced C-reactive protein response (a marker of inflammatory response and a strong predictor of future cardiovascular events) compared to standard practice not using BIS.

"These findings confirm results from our pilot study conducted last year and suggest that BIS-guided anesthetic titration may help moderate the inflammatory response to the trauma of surgery," said Peter Sebel, a professor of anesthesiology at Emory University School of Medicine (Atlanta) and investigator in the study.

Nassib Chamoun, president/CEO of Aspect, said, "The volume and diversity of BIS-related research presented at the ASA meeting reflect the growing global interest in use of BIS to help clinicians improve the safety and quality of care."

He added, "This interest reinforces the need to provide our customers with more product choices that are best suited to their practice requirements, and to provide standardized, scaleable education programs that support their adoption of BIS in clinical practice. The BIS family of monitoring solutions and educational programs are designed to address these needs."

Aspect is presenting a complete family of BIS products in its booth on the Moscone Convention Center exhibit floor, accompanied by a new BIS Education program. The products being presented at the meeting include the BIS VistaI and BIS Vie monitors, and BISx or modular integration solutions for Datascope, Dixtal, Draeger, GE Healthcare, Mindray, Nihon Kohden, Philips and Spacelabs.

Aspect said it has developed a variety of online and peer-based BIS Education resources to help customers implement use of BIS technologies.

"We've designed the BIS Education program to allow an ever-increasing number of anesthesia professionals using our monitoring systems to access thorough and consistent training," said Scott Kelley, MD, VP of medical affairs for Aspect. "The need for formal training regarding proper usage of medical devices in the operating room is a prominent topic at the ASA annual meeting. With more than 40,000 BIS monitors in use, we are committed to providing our customers with a diversity of education resources to enhance the integration of BIS monitoring into their patient care."

The education program also provides customers with resources to facilitate training at the bedside, including a team of clinician educators who are available to provide hands-on training in the operating room or to provide educational lectures.

In other news from the ASA meeting: B. Braun (Bethlehem, Pennsylvania), a leader in regional anesthesia, launched its Contiplex Stim Stimulating Catheter Nerve Block System.

Stuart Grant, professor of anesthesiology at Duke University (Durham, North Carolina), who recently used the prototype system, said, "We used the catheter system successfully in a variety of upper and lower limb nerve blocks and were impressed with its ease of use. The needle and catheter are easily visible under ultrasound, which is a bonus for our practice."

The company said the Contiplex Stim system removes procedural steps that used to divert attention away from the patient. The new Stimuplex Switch allows anesthesia providers to switch current from needle to catheter without the need to unplug and reconnect wiring. "The switch works well and allows transition from needle to catheter to occur without any reconnections. This allows anesthesiologists to keep their hands steady and focus on the nerve block," Grant said.

Tim Richards, senior VP of U.S. marketing for B. Braun, said, "[We] recognized the need to raise the standard for stimulating catheter nerve block products. The Contiplex Stim system is designed to make catheter placement as easy as possible. We are pleased to hear the positive feedback from clinicians using the catheter with nerve stimulation, ultrasound guidance or a combination of both techniques."

B. Braun said that the Contiplex Stim will be available nationwide in the U.S. and Canada beginning in January.

More than 10,000 anesthesiologists and related clinicians are attending the ASA meeting, which continues through tomorrow.