American Society of Anesthesiologists Releases Documents to Members Regarding Intraoperative Awareness and the Role of Brain Function Monitoring.

NEWTON, Mass. -- The American Society of Anesthesiologists (ASA) has released documents concerning intraoperative awareness and the role of brain function monitoring, including Aspect Medical Systems' BIS technology. The documents include a draft practice advisory statement that was developed by an ASA practice parameter task force and an update to ASA members written by ASA President, Eugene P. Sinclair, MD. Both documents are available on the ASA Web site (http://www.asahq.org/). ASA members and the public now have the opportunity to review the draft advisory and provide feedback to the practice parameter task force. Based on this feedback, a final report will be submitted for approval to the house of delegates at the ASA annual meeting in October.

According to an interim statement issued by the ASA to summarize the draft practice advisory, the task force report indicated that brain function monitoring may be useful to help reduce the risk of awareness, particularly in high risk cases. Furthermore, the decision to use brain monitoring should be made by individual practitioners on a case-by-case basis.

"We are pleased with the ASA's guidance concerning intraoperative awareness and the role of brain function monitoring. This marks an important patient safety milestone as the ASA prepares to celebrate its centennial at the annual meeting in October," said Nassib Chamoun, president and CEO of Aspect Medical Systems. "Further, these documents, as well as the Sentinel Event Alert issued to healthcare facilities by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) last October, reflect a growing recognition that awareness is an important clinical problem and a patient safety concern. We believe that the guidance provided by the ASA supports the need for healthcare facilities to make brain monitoring technology available to clinicians and patients and will further accelerate the adoption of BIS monitoring as a routine part of modern anesthesia care."

Dr. Sinclair's update to ASA members presents a number of issues for clinicians to consider when evaluating the use of brain monitoring in clinical practice. Specifically, his update addresses the importance of patient concerns about awareness as well as the significant harm that awareness victims may suffer. Dr. Sinclair also notes the rapidly expanding body of literature about brain function monitoring and draws attention to the current medico-legal environment that anesthesia providers face.

The draft practice advisory provides a summary of the available scientific data and a survey of the opinions of ASA members and expert consultants. The draft cites data showing that BIS-guided anesthesia enables a five-fold reduction in the risk of awareness in high risk patients and provides documentation that BIS is the only brain monitoring technology or clinical intervention that has been shown in large scale, prospective clinical research to reduce the incidence of awareness. Furthermore, the survey data note that 63 percent of consultants and 69 percent of ASA members agree that brain function monitors are valuable and should be used in patients with conditions that may place them at risk for intraoperative awareness.

"The draft advisory takes a step forward in providing information to ASA members regarding strategies to mitigate the occurrence of intraoperative awareness and how to care for patients at increased risk," said Scott Kelley, MD, Aspect's medical director and a practicing anesthesiologist. "Specifically, the draft states that patients should be evaluated for awareness risk factors and those identified as at risk should be informed. Further, intraoperative monitoring of depth of anesthesia should consist of multiple modalities, which may include consciousness monitoring. The draft also states that appropriate patient follow up should be conducted in patients who report awareness, including treatment, reporting and counseling. We believe that BIS monitoring is a useful adjunct to clinical signs and conventional monitoring systems in assessing depth of anesthesia and that this guidance will support efforts to improve the safety and quality of anesthesia care."

The advisory also cites a recent study that showed that deep anesthesia time, as measured by BIS monitoring, was an independent predictor of mortality within one year following surgery. "Anesthesia professionals will need to consider this new patient safety issue while attempting to prevent awareness. BIS monitoring helps clinicians address this concern by allowing them to directly quantify and better target the amount of anesthesia for each patient and avoid the risks of underdosing or overdosing," stated Dr. Kelley.

Aspect will provide the practice parameter task force with additional comments on the draft advisory and will post this information on the company Web site (http://www.aspectmedical.com) on July 27, 2005.

Aspect Conference Call

As announced a few weeks ago, Aspect Medical Systems will host a conference call on July 27, 2005 at 10:00 a.m. ET to report earnings results for the second quarter. At this time, Aspect management will discuss the ASA communications in greater detail. To participate in the call, please dial 1-800-289-0743 (domestic), 1-913-981-5546 (international), or access the Webcast at www.aspectmedical.com on the Investor page. Telephone replays will be available by dialing 1-888-203-1112 (domestic), or 1-719-457-0820 (international), access code 6634477. The Webcast replay will be available from July 27, 2005 until August 4, 2005.

About BIS Monitoring

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

About Aspect Medical Systems, Inc.

Aspect Medical Systems, Inc. (NASDAQ: ASPM) is a global market leader in brain monitoring technology. To date, the Company's BIS technology has been used to assess more than 11.3 million patients and has been the subject of approximately 2,000 published articles and abstracts. BIS technology is installed in approximately 38 percent of all domestic operating rooms and is available in more than 160 countries. Aspect Medical Systems has OEM agreements with seven leading manufacturers of patient monitoring systems. For more information, visit Aspect's Web site at http://www.aspectmedical.com.

Safe Harbor Statement

Certain statements in this release are forward-looking and may involve risks and uncertainties, including statements regarding the Company's expectation that the ASA's draft guidance concerning intraoperative awareness and the role of brain function monitoring will have the effect of accelerating the adoption of BIS monitoring and will support efforts to improve the safety and quality of anesthesia care. There are a number of important factors that could cause actual results to differ materially from those indicated by these forward-looking statements. For example, the Company may not achieve widespread market acceptance of its BIS monitoring technology among members of the ASA who review the final practice advisory statement. The Company also faces other barriers to market penetration and acceptance. The Company may not be able to compete with new products or alternative techniques that may be developed by others, including third-party anesthesia monitoring products approved by the FDA, and also faces competitive and regulatory risks relating to its ability to successfully develop and introduce enhancements and new products. Cases of awareness with recall during monitoring with the BIS system and significant product liability claims are among the factors that could limit market acceptance. There are additional factors that could cause the Company's actual results to vary from its forward-looking statements, including without limitation those set forth under the heading "Factors Affecting Future Operating Results" in the Company's Quarterly Report on Form 10-Q for the Fiscal Quarter ended April 2, 2005, as filed with the Securities and Exchange Commission. In addition, any forward-looking statements represent the Company's views only as of the date of this press release and should not be relied upon as representing the Company's views as of any subsequent date. While the Company may elect to update forward-looking statements in the future, it specifically disclaims any obligation to do so, even if its expectations change. Therefore, you should not rely on these forward-looking statements as representing the Company's views as of any date subsequent to the date of this press release.

Aspect, Bispectral Index and BIS are registered trademarks of Aspect Medical Systems, Inc. All other trademarks, service marks and company names are the property of their respective owners.