BIS Monitor

athomas91 · Nov 18, 2005

sister ... and you are quite welcome.

pasgasser · Nov 20, 2005

We don't use it because there's no proof it does what it purports to do. It's basically voodoo at the moment. Hey, you knew someone would say it.

I agree completely. Multiple studies have shown that EEG is not a reliable method of determining sedation level. BIS only measures frontal lobe in some way that the company will not divulge then puts in a machine, generates a random number that has no units and claims that sedation level is being measured. About two months ago in "Anasthesia and Analgesia" a case report indicated that a patient had recall because the BIS suggested appropriate sedation and the provider decreased th level of anesthesia.

AlexCCRN · Nov 21, 2005

roustan jp, valette s, aubas p, rondouin g, capdevila x.

department of anesthesiology and intensive care medicine, neurological explorations laboratory, lapeyronie university hospital, 295 avenue du doyen g giraud, 34000 montpellier, france.

prolonged use of sedative drugs frequently leads to oversedation of intensive care patients. clinical assessment scales are not reliable in deeply sedated patients. parameters obtained from spectral and bispectral analysis of electroencephalogram (eeg) records have been combined to create an index (bis) to monitor anesthesia depth. the role of such parameters in monitoring the depth of the sedation in intensive care unit (icu) patients has yet to be determined. we designed the present prospective study to redefine and calculate available spectral and bispectral parameters from raw eeg records and estimate their clinical relevance for the diagnosis of under- or oversedation levels in icu patients. forty adult patients receiving continuous midazolam and morphine sedation were included. we obtained 167 clinical evaluations of sedation level using ramsay and comfort scales along with an eeg record of 300 s. six spectral parameters-relative power of 4 frequency bands (beta, alpha, theta, and delta), 95th percentile of the power spectrum (sef95), and 50th percentile of the power spectrum (sef50) and four bispectral parameters, real triple product, bispectrum (bispectrum), bicoherence, and ratio 10-were calculated. the relevance of each of these parameters and combinations in predicting too light (ramsay 1 and 2) or deep (ramsay 5 and 6) sedation levels was assessed. these calculations were performed before and after exclusion of the agitated patients, whose comfort 4 score was above 2. the most relevant parameters for predicting levels of deep sedation (ramsay 5 and 6) were ratio 10 (area under the curve = 0.763; 95% confidence interval, 0.679-0.833) and sef95 (area under the curve = 0.687; 95% confidence interval, 0.597-0.767). the most relevant parameters for predicting light levels of sedation (ramsay 1 and 2) were also ratio 10 (area under the curve = 0.829; 95% confidence interval, 0.695-0.917) and sef95 (area under the curve = 0.798; 95% confidence interval, 0.650-0.898). there is a modest improvement in relevance of their linear combination in predicting sedation level. results were similar after exclusion of agitated patients. we conclude that various calculated eeg descriptive parameters exhibited large interindividual variability. there was a strong correlation between eeg spectral and bispectral parameters. bispectral analysis slightly improves the predictive power of simple spectral analysis in distinguishing too light or deep sedation levels in icu patients. implications: spectral edge frequency 95 and ratio 10 are the most relevant electroencephalogram (eeg) indexes for monitoring the level of sedation in intensive care unit patients but calculated eeg values exhibited large interindividual variability. bispectral analysis of eeg provides a slight improvement over simple spectral analysis.

Gump · Nov 21, 2005

fyi...

american society of anesthesiologists adopts practice advisory on intraoperative awareness and brain function monitoring

tuesday october 25, 12:56 pm et

newton, mass.--(business wire)--oct. 25, 2005--aspect medical systems (nasdaq: aspm - news) today announced that the american society of anesthesiologists (asa) house of delegates has approved a practice advisory for clinicians that addresses intraoperative awareness and the role of brain function monitoring, including aspect's bis technology. intraoperative awareness occurs when patients do not receive enough anesthesia to remain unconscious, leaving them at risk of becoming aware of what is happening and remembering this experience after the surgery is over. the practice advisory is designed to provide guidance to anesthesiologists regarding this important safety concern and was approved at the asa annual meeting in atlanta, georgia today.

"the asa approval of this document represents a significant step forward in addressing intraoperative awareness and the role of brain function monitoring and reinforces the society's leadership in advancing patient safety," said nassib chamoun, president and ceo of aspect. "we believe that the guidance provided by the asa, combined with the sentinel event alert issued to healthcare facilities by the joint commission on accreditation of healthcare organizations, supports the need for healthcare facilities to make brain monitoring available in every operating room that serves patients at risk for awareness."

practice advisory guidance to clinicians

the practice advisory acknowledges the reported incidence of intraoperative awareness of one to two cases per thousand patients receiving general anesthesia. the document also recognizes the significant psychological harm that some patients may experience following an episode of awareness. to address this safety concern, the advisory document states that:

patients should be evaluated for awareness risk factors.
those patients identified as at risk should be informed and anesthetic depth should be monitored using multiple modalities.
although brain function monitoring is not indicated for use on all patients undergoing general anesthesia, the decision to use brain function monitoring for selected patients should be made by individual practitioners on a case-by-case basis. the advisory reports that the majority of asa members (69%) surveyed believe that brain function monitoring is valuable and should be used to help reduce the incidence of awareness in patients at risk.
appropriate patient follow up should be conducted in patients who report awareness, including assessment, reporting and counseling.

according to the practice advisory, clinicians should conduct a preoperative evaluation to identify patients at risk for intraoperative awareness. the report cites studies and case reports that suggest that certain patient characteristics, surgical procedures and anesthesia techniques may be associated with an increased risk of awareness. potential risk factors for awareness listed in the report include:

substance use or abuse;
patient history of awareness;
difficult intubation;
cardiac surgery, cesarean section, trauma and emergency

surgery;

reduced anesthetic doses in the presence of paralysis;
use of muscle relaxants; and
total intravenous anesthesia (tiva) and other anesthesia techniques.

clinical evidence supporting bis monitoring

the asa practice advisory 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. specifically, research cited in the asa practice advisory (and published in the lancet in may 2004) documented that use of bis monitoring to help guide anesthetic dosing reduced the risk of awareness with recall in high-risk patients by 82 percent. the food and drug administration (fda) granted clearance for bis monitoring being associated with the reduction of the incidence of awareness with recall in adults during general anesthesia and sedation. this is the only technology to receive this type of clearance from fda.

"this asa document provides a pathway for caring for patients who may experience awareness and elevates the role of brain function monitoring to a new position of importance within anesthesia practice," said scott kelley, md, aspect's medical director and a practicing anesthesiologist. "when clinicians evaluate the strength of the data supporting bis technology and consider the lack of evidence for other practice interventions and monitoring modalities, we believe that they will recognize the patient safety benefits of bis technology and move toward broader utilization of bis monitoring as an adjunct to conventional monitoring."

aspect will post a commentary providing additional details about the advisory on the company web site (http://www.aspectmedical.com) following public disclosure of the advisory by the asa.

aspect conference call

as announced last week, aspect medical systems will host a conference call and live webcast tomorrow, october 26, 2005 at 12:00 p.m. et to discuss the advisory. to participate in the call, please dial 1-800-289-0494 (domestic), 1-913-981-5520 (international), or access the webcast at www.aspectmedical.com on the investor page or at www.earnings.com. telephone replays will be available by dialing 1-888-203-1112 (domestic), or 1-719-457-0820 (international), access code 9419112. the webcast replay will be available from october 26, 2005, 3:00pm et until november 2, 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 - news) is a global market leader in brain monitoring technology. to date, the company's bispectral index (bis) technology has been used to assess more than 12.2 million patients and has been the subject of approximately 2,000 published articles and abstracts. bis technology is installed in approximately 68 percent of hospitals listed in the july 2005 u.s. news and world report ranking of america's best hospitals and in approximately 40 percent of all domestic operating rooms. in the last twelve months, bis technology was used in approximately 12% of all u.s. surgical procedures requiring general anesthesia or deep sedation. bis technology is available in more than 160 countries. aspect medical systems has oem agreements with seven leading manufacturers of patient monitoring systems. the company is also investigating how other methods of analyzing brain waves may aid in the diagnosis and management of neurological diseases, including depression and alzheimer's disease. 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 guidance concerning intraoperative awareness and the role of brain function monitoring should 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 anesthesiologists, including members of the asa who review the 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 july 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.

contact:

aspect medical systems emily anderson office: 617-559-7032 cell: 617-515-2000 [email protected]

source: aspect medical systems

yoga crna · Nov 22, 2005

First, I must say that I don't use a BIS monitor in my practice and have seen it used once and was not impressed. I do believe that some sort of consciousness monitoring may be useful in trauma cases and open heart surgery.

I would like to state emphatically, that I am very opposed to the marketing campaign of the company that manufactures the BIS monitor. They are taking their marketing ploy to the public by scare tactics and are trying to say that it is standard of care to use it. Standard of care is not determined by an equipment manufacturer, but by the profession.

OK, I know I am old, but I will continue to use my observation skills to administer anesthesia. You can learn a lot about depth of anesthesia by constant vigiliance and watching for trends in vital signs.

One last observation-- I don't need a monitor to tell me when a patient is light, everyone in the OR points out to me if the patient is moving. I recently threatened an OR tech with her job if she told me one more time that the patient was moving and that I was well aware of the depth of anesthesia.

Yoga CRNA

piper77 · Nov 27, 2005

As always, an interesting discussion. Most of the experienced clinicians I work with do not use the BIS monitor, even though it may be available to them. I believe they operate on the same principles that Yoga just talked about. I also know one with over 30 years of experience that uses a BIS monitor on almost every case he has (and he has no relationship with Aspect!). I would not dismiss the BIS monitor as being "voodoo" and completely unreliable. While I also question the marketing tactics, and to a lesser extent,the Aspect-backed studies, it certainly seems reasonable to include it in the armamentum, especially for a high-risk patient. The caveat, is of course, is that the patient's needs drives the anesthetic delivery, and not the monitor. I may not use it much myself, but I have no problem with those who do.

PJMommy · Nov 27, 2005

Can't speak from the anesthesia perspective but can weigh in from the critical care perspective....

Sometimes, particularly with head trauma, we use NMB gtt to paralyze patients. Since paralysis doesn't equal sedation, we'll often use BIS to give us at least a guideline as to whether or not pt is deeply sedated enough. I'd hate to have a pt only lightly sedated and aware of the fact that they can't move. Of course, good ol' fashioned experience is also a guideline as to dosing my diprivan.

gaspassah · Nov 27, 2005

While I also question the marketing tactics, and to a lesser extent,the Aspect-backed studies, it certainly seems reasonable to include it in the armamentum, especially for a high-risk patient. The caveat, is of course, is that the patient's needs drives the anesthetic delivery, and not the monitor

herein lies the problem with the bis and those who rely on its information as to the adequacy of the depth of anesthesia.

if you are using a monitor, you should trust it's validity or accuracy of data output. if you use the bis but dont trust the number and treat the patient according to "feel", why incur the 12 dollar charge for each monitor stip(it may cost more i dont really remember, but thats not the whole point)?

i believe you either "trust" the bis or not. if you aren't willing to treat using the bis number, dont use the bis. i compare it to the pulse ox, you trust the pulse ox and make treatment options based on its number, it's proven to work.

bis not completely proven to work, should you trust the monitor to treat the patient, not me. i have used the bis and found it to be very unreliable.

i have also worked with mda's and was forced to use the bis as a student (he is an investor in aspect medical i believe or was told he was) and treated the patient according to the number and i have never had to give so much beta blocker for a case.

knowledge of anesthesia both the art and science should be adequate to provide safe anesthesia practice.

a majority of the "awareness" "epidemic" is fueled by the woman who wrote silent screams. she had awareness because her anesthesiologist let the vaporizer run dry.

i do not discount the terror felt by people with awareness. i do however do not by into the majic bullet of bis and awareness. proper vigilance would have prevented her awareness. this was user error, not an issue of drug resistance or abnormal pharmicological metabolism.

this is just my 2 cents.

piper77 · Nov 27, 2005

gaspassah...just a couple of things....I have never heard that the author of "Silenced Screams", Jeanette Liska, experienced her awareness because the ologist let the vaporizer run dry.....she does not say that in her book...is there another source?

Much of current media frenzy about awareness might be attributed to Aspect's marketing efforts, and the efforts of another woman who suffered awareness during eye surgery.

Awareness is a real entity, and not something one can pass off on a dry vaporizer. As for the BIS monitor, I do not use it much myself, and agree that our vigilance is most important. On the monitor side of life, tho, I'm not sure I agree with an all or nothing philosophy....either trust it or not...I think patient context is pretty important. I don't always trust the pulse ox, either! :)

thanks for listening.......

Pete495 · Nov 27, 2005

Excuse the ignorance, but is it true the BIS is not accurate in the presence of electric cautery? Someone once told me this, and I always wondered if it was true.

gaspassah · Nov 28, 2005

I have never heard that the author of "Silenced Screams", Jeanette Liska, experienced her awareness because the ologist let the vaporizer run dry

it was on the discovery channel show and it was mentioned quickly in passing.

Much of current media frenzy about awareness might be attributed to Aspect's marketing efforts

i believe this to be true, also when the anesthesia provider does not do a good enough job of explaining the anesthesia to be provided can lead to problems. i have had patients during the interview process claim to have awareness. when probing further and looking at the previous anesthetic record, the patient had a mac. i always tell patients during the preop for a mac that they will be well sedated and may even "sleep" during the procedure, but may remember events or conversations that occur during surgery because they wont be completely anesthetized.

Awareness is a real entity, and not something one can pass off on a dry vaporizer.

again, i am in no way discounting patients that have had awareness or the trauma it caused them. however i would like to know the numbers of patients with true awareness (patients recieving at least surgical mac of agent) that was not caused by some provider negligence like a dry vaporizer or wrong agent in vap etc. i dont think the numbers would bare witness to the amount of awareness we hear about.

I'm not sure I agree with an all or nothing philosophy....either trust it or not...I think patient context is pretty important. I don't always trust the pulse ox, either

i agree that machines are not infalible. what i am saying is that under normal circumstances when you look at a pulse ox, you would readily believe the number, i doubt anyone continously troubleshoots a good pulse ox reading if there are no indications to do otherwise. this is what i call trust in a monitor. if a patient is blue but the pulse ox says 100% i wouldnt believe it either. but that's not a normal cirucumstance.

however bis has not been shown to be that reliable. a former classmate of mine did his masters project on the bis. electorcautery, magnetic interference from other machines, even the pole the bis is on, if it is touching a surface with vibrations will give an inaccurate reading, if the strip is not placed just so, or if it is over an artery etc. too many variables.

also bis does not take into account the mac associated with nitrous.

to me, when people tailor their anesthetic according to a bis number that may not be reliable may cause MORE awareness than may decrease awareness...when i was doing clinical as a student, the mda over my room insisted on the bis, (he was a stockholder i was told), would not let me increase my agent because the bis number read a good reading. but i have never had to give as much beta blocker as i did that day.

i dont feel comfortable, delivering agents based on data that i feel is not accurate. if bis improves to a point to equal the reliability of a pulse ox or ekg or bp cuff, then i would have no problem using it routinely. i just dont see it as that reliable yet.

as an addendum, for those who like the bis i in no way fault you for its use, that is up to you. my feelings are from personal experience and are a reflection as such.

d

Brenna's Dad · Nov 29, 2005

I didn't train with the BIS, but have begun using it in my new practice. I must echo what many have said here. I just don't trust it.

I would estimate that I get erroneous readings more than 10% of the time. By erroneous, I mean the BIS just isn't reflecting what I see clinically.

It seems like too expensive a tool to 1. confirm what I think is going on clinically, or 2. for me to say, hmmm, I guess the BIS isn't working during this case.

I wonder whether BIS would accept any liablity for awareness that occurred when using their product?