Welcome to the new Outpatient Surgery website! Check out our login FAQs.
Thinking of Buying...Consciousness Monitoring Devices
Case mix, concerns and convenient information drive your decision.
Michael Schneider
Publish Date: February 9, 2008   |  Tags:   Anesthesia

Will the consciousness monitor ever become a must-have machine? While approxi-mately 60 percent of hospital ORs nationwide are equipped for consciousness monitoring, the technology is used for only about 17 percent of procedures requiring general anesthesia or deep sedation, according to a leading manufacturer of the devices. This seeming disconnect is likely related to the American Society of Anesthesiologists' decision not to consider the technology a standard of care at present. But given the process's ability to offer anesthesia providers an important additional view on their patients' conditions, every facility should at least open a discussion on the devices. Here's some background information on what's currently available.

Relatively speaking
More than anything else, what we call "consciousness monitoring devices" are designed to provide feedback about a patient's level of sedation. Their main function is to measure and report a global sense of patient alertness or awareness, letting anesthesia providers deliver their medications more precisely.

Brain activity is usually measured by electroencephalography (EEG), but few physicians have access to multi-channel EEG monitoring in real-time OR situations. The advent of fast microprocessors allowed the development of consciousness monitoring devices that provide a processed approximation of EEG, reducing a complex diagnostic signal down to an intuitively understood clinical statistic. Each manufacturer has chosen a different part of the EEG signal to process for their devices, but they all create a numerical score to account for the overall level of sedation.

This technology and its response is not by any means a diagnostic test, but rather a relative scale. Still, it's a research-tested, valuable assessment that can complement EKG, pulse oximetry, end tidal CO2 and the other signals monitored during a case. Put another way: It's one more tool at your anesthesia provider's command.

Case demands
If you've been considering bringing consciousness monitoring to your facility, the first thing you need to do is examine the type of cases you're doing. The technology might not be a necessity for some single-specialty surgery centers. If you're mainly doing cataract surgeries, your patients may be unconscious for such a short period of time that there's no need to monitor consciousness electronically. The same rule of thumb applies to any facilities that primarily use minimal IV sedation.

For multispecialty facilities that host a more extensive range of surgeries, however, and for any facility employing moderate to deep sedation or general anesthesia, the devices become more useful. Keep this factor in mind if your facility's case mix changes and as you perform more or fewer general anesthesia procedures.

Provider needs
Before making a decision to purchase the equipment, even before making a decision to trial it, you'll want to talk to your anesthesia providers about their perceptions of consciousness monitoring.

Ask them how anesthesia awareness has been discussed among surgical personnel. Ask how patients have expressed their concerns about awareness and how surgical personnel have responded to those concerns. Assess your facility's policy on awareness. Does the policy meet current guidelines? An active, back-and-forth discussion between managers and anesthesia providers can help identify the critical issues that direct monitoring decisions. Once it's agreed that consciousness monitoring is a technology that may be useful in your ORs, then you can review the state of the art.

Currently available devices are fairly similar in purpose and in the raw information provided to the clinician. Each technology involves adhesive electrode sensors applied to a patient's head and a processing monitor for output of waveforms and case data. Trialing is, of course, essential: manufacturers will need to give you a chance to see how the machine operates in your work environment. Additionally, training needs to be provided on each device to allow providers to use the monitors correctly.

Chiefly, you want the monitor to tell you what you need to know quickly. The different forms of data it provides should be clearly segregated, storable and transferable to electronic patient record systems. It's also helpful if the information is obvious to someone who doesn't have extensive experience with the monitor.

Weigh your options
It's true that there are only a handful of players in the consciousness monitoring field, but there is a choice in the marketplace. While one manufacturer clearly holds significant U.S. market share, others are racking up solid reviews out of the European market. It behooves administrators and anesthesia providers to look at all their options in order to determine which works best for them and their facilities.

Price is, of course, an important component of any monitoring decision. The cost of consciousness monitors includes not only the output devices but also the single-use sensors applied to patients. Pricing may be dependent on contract obligations or discounts through GPOs, and the cost of the disposables could quickly outstrip the cost of the monitors at a busy surgical facility.

Finally, maintain a clear-eyed view of what this technology is expected to do. It's often stated that consciousness monitoring can — by allowing the precise delivery of sedation — help you reduce your facility's anesthesia costs. If you use fewer amounts of anesthesia drugs, that's great (and make sure you congratulate your anesthesia team). But the real goal of consciousness monitoring is taking better care of your patients, which is, as you know, an entirely different, and ultimately more satisfying, case result.

Aspect Medical Systems
BIS Vista Monitoring System
List price: $8,500 (volume discounts available)
FYI: Aspect's Bispectral Index, or BIS, technology lets you reliably measure the dynamic and patient-specific effects of drugs on the brain, says the company. You place a proprietary, single-use sensor on a patient's forehead to capture the brain's electrical activity. A monitor then translates this information into the BIS value, a number that represents each patient's level of consciousness — from 100 (an awake patient) to zero (the absence of brain activity). The lower the number, the deeper the patient's level of sleep or hypnosis.

Cerebral State Monitor
(800) 899-1367
List price: $3,800 to $5,600, depending on accessories
FYI: Danmeter's Cerebral State Monitor, distributed by Tri-anim Health Services (www.Tri-anim.com, (800) TRI-ANIM), is a portable brain function monitor that uses an EEG-based Cerebral State Index to measure a patient's level of consciousness, says the company, letting providers tailor the amount of anesthesia they administer to the patient. Low-profile sensors that offer several placement options are provided with the unit. Other available options include a remote screen display and documentation capability.

GE Healthcare
Entropy Module
(800) 345-2700 x3357
List price: $7,900 for module only
FYI: GE Healthcare's Entropy Module, available with the Datex-Ohmeda Anesthesia Monitor and Compact Anesthesia Monitor, is designed to provide information on the state of the central nervous system during general anesthesia. According to the company, Entropy's monitoring is based on the acquisition and processing of raw EEG and FEMG signals by using the Entropy algorithm, an application of two spectral entropies, State Entropy and Response Entropy, to aid in monitoring the effects of certain anesthetic agents administered to the patient.

Stryker Instruments
Snap II Level of Consciousness EEG Monitor
(800) 253-3210
List price: not disclosed
FYI: Stryker's portable Snap II is a level-of-consciousness EEG monitor that analyzes the electrical activity of the brain and offers increased sensitivity in measuring patients' levels of consciousness while under anesthesia, says the company. High- and low-frequency EEG combine to create one index that measures the state of the brain and responds to changes in consciousness level rapidly, adds Stryker.