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Discussion in 'Anesthesiology' started by BLADEMDA, Jun 8, 2007.
I got the data on Etomidate. Here are the studies. I also stated my conclusion DAYS AGO.
these were the highlights of my post...
I really was blown away at the complete patient management by an MDA in the OR...
I genuinely had no idea...working in the ER, I am far removed from the OR...
I was ignorant to your broad scope of knowledge...
plankton and SSS, you read me wrong...
i have read the bullsh!t bantering back and forth, here and at allnurses...
it's all a waste of time...
my only beef would be when either side starts mudslinging...
please protect your profession...
I personally have never met a CRNA
I did see the video clips from the CRNA who was stammering (and lying) during his testimony, somewhere else on this site, and laughed when he implied that CRNAs could essentially do without the MDAs...
So please back off lumping me in as a troll...
My goal is teamwork between nurses and docs, period...
Chimichanga, I dont think it is a question of trolling or you choosing sides. I dont think, in my opinion, you said anything offensive. Just bringing it up the issue can cause a huge argument and kill a thread.
When the threads stay clinical, I am finding everyone to be respectful. If they open up a politically-based forum/thread post this there. Debate is the gift of freedom just do it within the appropriate threads (you will know which ones they are).
These cases are nicely presented and create good discussions in which everyone (whatever your status may be) can offer insight and learn (thus helping all be better prepared to care for patients).
You bring up a good point.....long term endpoint of adrenal suppression vs the short term risk/benefit of using a drug which might fit the situation clinically the best at the time. There is some data to suggest adrenal effects last as long as 28 days & perhaps longer after single dose etomidate. However, there are times when one needs to trade future costs for immediate stabilization...
Blade - you were very complete in citing the most recent journal articles, which are few. However, in the interest of completeness, in the same Chest Journal (2005), Murray & Marik have an article in which they state they support the continued use of etomidate cautiously, acknowledging all the problems associated with its use, but also recognizing sepsis is a high mortality illness with mortality related to many factors & successful outcomes of interventions are often time dependent. From their point of view, "...a better anesthetic induction agent is simply not available". Obviously, not all agree.
Someone asked....is there a good prospective randomized study - not the retrospective survey stuff - I don't think so. Its hard to design, select & control all the variables in pts like these, particularly when looking at long term endpoints of 28-90 days post immediate stabilization & at the same time get a high enough n to be significant. There are just too many reasons a septic pt might develop side effects of adrenal suppression (poor glycemic control, etc..) than just one drug dose used for intubation at the start of hospitalization.
I offer no answers & don't mean to beat a dead horse, since I believe the etomidate discussion ended a page or so ago. Forgive me, I've been gone a week & missed this discussion, however I found it interesting to read when I returned
Blade - I do ask a favor however.....would it be possible to separate your cases into separate threads as JPP, Plankton & others have done? I ask for selfish reasons only - its just easier to get back to read those cases which I find interesting to me (drugs), so I understand completely if my request is unreasonable. Thanks for considering.....
I read the other comment in CHEST 2005 about Etomidate being used clinically. However, the issue remains whether a patient should receive 48 or 72 hours of steroid coverage after a single dose of etomidate. I believe the literature supports this treatment and some would argue based on clinical studies that patients who DON'T get this coverage have a SIGNIFICANTLY
I for one will make sure my patients get this coverage after etomidate.
In addition, I am going to significantly curtail my Etomidate use based on the
I for one, don't mind you adding a comment at any time. That is how a discussion board works. Someone can find this discussion a year from now and want to comment (as I have done on other posts)
I also agree with you...in fact, I wanted to say the same thing that I was hoping blade could put each case in a different post.
I completely agree - if you NEED a working neuraxial technique, intrathecal catheter is the answer. I have done this a few times. I don't know how falling platelets would change this. Maybe I would avoid such a large needle in low platelet lady. We are routinely threading the catheter for our wet taps. Our headache rate is very low in these situations.
Just use your regular epidural kit. Yes - a 17g tuoy will make a big hole, but if you leave the catheter in 24hrs, your chance of a PDPH is greatly reduced (65% reduction comes to mind, but I am not exactly sure of the data)
Agreed on steroid tx & the uncertainty about time frame! Perhaps it will become clearer before we retire??
Nice to see someone is leaving the catheter in after puncturing the dura with a 17g toughy. I have read on the internet that this is the best option to minimize the possibility of a PDPH after accidental dural puncture. However, I have also read that significant damage to the dura is possible when the catheter is removed. It is not as likely as a PDPH...but still possible. Have you heard of this? I am thinking now they (whoever they are) are full of it.
HHHHmmm? Sounds like you need a more reliable source of info.
rmh talking to pt: "Don't worry sweety. I read on the internet it's best to leave the catheter in"
Pt's mind: "I'm so f-ed"
Why are you trying to start sh it again? THE INTERNET.....I guess you never read any articles on the net? I said I read about it before....I dont practice it based on one article I have read. I am surprised to see that others do...thats why I brought it up....maybe I will look into it again.
Your post was worthless.
OK, this brings up another question:
I know that we are witnessing a return of intrathecal catheters after they almost disappeared in the nineties when the micro catheters were taken off the market by the FDA.
Are the residents being taught to insert intrathecal catheters electively or only when an inadverent dural puncture happens?
Since I'm a resident I can comment: More electively than anything. And we use the epidural kit and just go for it. Our pedi epidural kit has an 18 ga Touhy so at least it's a tiny bit smaller than the 17. The only times I've used them are in elderly folks and they have a smaller risk of PDPH as I understand it. I haven't placed one in OB yet (but have had wet taps). There are multiple reasons for this though, for one I have never seen one in OB so I don't know what the reaction would be from nurses and other providers. Also I don't know the degree of caution needed to prevent disaster, be it tape on the door, a malfunctioning pump, etc. We have just enough hand offs that I would worry someone would forget in the middle of the night, bolus 5 cc's and then we're in trouble.
I have left a cath in once when the cath migrated into the SA space...No wet tap, but got a positive test dose. I decided to leave it in and dose it as a spinal cath. After delivery I DC'd the cath....only about 6 hours. She did not develop PDPH...followed her for 5 days. I wonder how much leaving the cath in place had to do with decreasing her chances of PDPH.
It should help but a big hole is a big hole. Been around a long time and seen it all from blood through the catheter (level higher than the tap) to NS to Hextend and now the continuous spinal.
I still do PLENTY of patches after the continuous OB Spinal. Does it help? Probably but the studies always have a SMALL "N" so be careful about making BIG statements. Call me old school but I prefer a working Epidural to a continuos spinal catheter for OB. Also, I think the patients and Nurses like it better as well.
For some providers the continuous spinal technique makes sense:
NO risk for a second wet tap, decreased incidence of PDPH and the procedure is completed without spending more time doing ANOTHER Epidural.
Those who like to do it this way more power to you.
I like "old school". Don't get a wet tap and if you do assess the risk of a second wet tap. You should know whether that second tap is going to occur. THere is something to be said for good motor function during delivery as well. In addition, I want the next provider in OB to easily deal with the situation. So, I usually go up one level and do a working Epidural.
Of Course, the discussion about BLOOD PATCH the next day is brought up.
This conversation which occured before the procedure is now discussed in more detail.
I do things your way too, and since our OB department is covered by CRNA's at night and we take call from home, I tell the CRNA's not to do intrathecal catheters when I am on call, I just get nervous thinking about a CRNA managing an intrathecal catheter, no disrespect to anyone intended.
The times I have done an elective intrathecal cath in the MOR is because the staff DID NOT want to put the patient to sleep, they were HUGE patients for HIP or KNEE, and they really wanted neuraxial to work. As mentioned, none of the OB caths I have seen have been elective.
So are we to believe that you never got a wet tap but that you had a catheter migrate intrathecally, once.
Now that is one of your funniest posts. Give me a break.
I don't believe that there is anyone on this forum that has done a substantial number of epidurals that hasn't had a wet tap.
And in my residency, we got a sh*tload of intrathecal catheter practice because we had crna's doing epidurals, but when they tapped the poor pt we had to take over. Those crna's fat out sucked, beyond bad.
Since we satarted having CRNA night coverage for OB We do 5-6 blood patches per month. We used to do 1 or 2 a year!
I said no wet tap (with the epidural needle) on this patient...meaning I didnt have CSF shooting out of the epidural needle. But when I threaded the cath, taped, and tested...it was positive.
Of course I have had wet taps....anyone who has done a significant number of epidurals will have them. This one case was unusual as it presented. It is the ONLY case where I left the catheter in the space and dosed it as a continuous spinal. Normally, I would remove the epidural needle and approach a different segment.
Is that the break you needed?
That is way too much. Are these CRNA's that do OB exclusively, or just once every 18 to 30 days or so? What I find is the CRNA's (cant speak for the docs) that do OB out of obligation hate it...and they may be out of practice since they dont routinely do epidural blocks...increasing the risk of dural puncture....or any other complication for that matter.
Your group should require the CRNA to have done at least a 100 epidural/SAB procedures before covering OB.
Where did you pull that number from?
Does it rhyme with mass?
Meant to say 100. the rate of Unintentional dural puncture with those with less than 10 blocks, 6%. 2.% for those with 60 blocks, and 1.2% with those with 100 blocks or more.
I hope our CRNA friends realize we are here to discuss Anesthesiology in all its aspects including Clinical cases.
You are bumping a year old thread? for what?
Have you read every case here? Do you have any comments on these cases? I was planning on adding to the cases since this is a good thread.
Do you have a problem with that?
Okay, I have a very interesting private practice case to discuss with you.
The case happened about six months ago so I will attempt to get all my facts straight but please feel free to ask questions.
65 year white male for CABG surgery (SDS admission). He is scheduled for CABG X 5 starting at 0730 and will be an on pump case. His Chief complaint is SOB with exercise or sex.
History of MI X 2 with Coronary Stent (bare Metal) 6 months ago
Obesity (he weighs 280 and is 5'11")
GERD (well Controlled on meds)
Left Total Knee Replacement
Right Inguinal Hernia repair (open)
Meds (he is an HMO/Humana patient so CHEAPO drugs)
Asa (off 5 days)
Viagra (not too often)
NTG (not with the Viagra)
WNL - Renal function WNL, EKG-SR LVH, q's inf. leads CAth report- multivessel disease, EF=35% No significant valvular disease Blood Sugar=140 this morning.
Vitals: 145/85 HR=68 T=98.5 RR=16
He took ALL of his pills this morning except the Viagra.
The surgeon wants a 'fast-track' anesthetic and extubation within the first 2 hours or earlier.
What are your concerns here? What invasive monitors do you want?
What non-invasive monitors do you want/routinely use? What induction drugs will you use? What "drips" do you have prepared in the room if any?
Your Medical Student asks if it is "safe" to proceed with surgery on this patient because he had a bare metal stent 6 months ago and he heard somewhere that it was better to wait longer. How do you answer him. What study is he referencing?
Appendix A - Preoperative MedicationsAs a general rule, for patients scheduled for surgery with anesthesia, we recommend all medications should be continued on the day of surgery to be taken with a sip of water prior to coming to the hospital. Exceptions to this recommendation are summarized below:
CLASS OF MEDICATIONS
Oral Hypoglycemic Agents
Metformin/Glucophage Actos/ Glyburide/ Tolinase/ Avandia/ Amaryl/ all others
Hold at least 8 hours
holding am dose, day of
Hold am day of surgery, unless prescribed for CHF - these patients should take their am dose of diuretics.
Lisinopril/Lotrel/Captopril/Lotensin/ Monopril/ Prinzide/ Atacand/ Benicar/ Diovan/ Avalide
Hold am of surgery, unless prescribed for CHF - these patients should take their am dose of meds.
Hold insulin am day of surgery. Bring insulin with patient to hospital.
All Herbal Supplements
See extensive list in Preoperative Guidelines section
Stop all Herbal Supplements at least 24 hours prior to surgery.
*In particular, it is very important for patients to take their am dosage of the following medications:
Beta blockers and any antiarrythmics such as Digoxin or Calcium Channel blockers.
Asthmatic medications including inhalers, Theophylline, Singulair and/or steroids.
Statins such as Lipitor, Zocor, Crestor, etc.
Aspirin - unless specifically told by their surgeons, patients should continue to take their ASA.
ACE/ARB - consider having patients take these if HTN is difficult to control without them.
Consider starting patients on Beta blockers preoperatively who could be considered at risk for
cardiac ischemia. Please refer to the Beta blocker protocol in our Preoperative guidelines.
Please advise them to take these medications with a sip of water prior to coming to the hospital.
Is the Hopkins guide to preoperative Medications correct? In particular, should this Cardiac Surgery patient have taken his Metformin in the A.M. before his scheduled CABG? The Hopkins guide says "no" but what do you think?
What about other oral hypoglycemic agents like Glyburide? What about anti-HTN agents like Cardizem and Vasotec?
Please post your opinions on this case and preop meds as we have much to discuss. You see it was not too long ago the literature suggested to discontinue the Statins preoperatively. Now, we know the Statins are actually beneficial.
What about Metformin?
Don't buy into the "old" medical jargon. Question everything and demand data.
Anesth Analg 2007;104:42-50
© 2007 International Anesthesia Research Society
Recent Metformin Ingestion Does Not Increase In-Hospital Morbidity or Mortality After Cardiac Surgery
Your Medical Student asks the patient why he wan't on a special class of drugs called B-Blockers after his first MI. The patient stated he took Toprol XL for a while but had a nasty side-effect to deal with so "there was no way in hell" he was going back on that medicine.
This was a very interesting case. Anybody want to play along here?
What about that landmark study on Bare Metal and Coated Stents in Anesthesiology? Anybody want to answer the Medical Student's question? What about this same patient for an elective total knee replacement (assuming asymptomatic and decent exercise tolerance) Comments?
October 2008 - Volume 109 - Issue 4 - pp 573-575
Noncardiac Surgery for Patients with Coronary Artery Stents: Timing Is Everything
Rade, Jeffrey J. M.D.; Hogue, Charles W. M.D.
Home > October 2008 > This Month in Anesthesiology
October 2008 - Volume 109 - Issue 4 - p 9A
This Month In Anesthesiology
Back to Top | Article Outline
Cardiac Risk of Noncardiac Surgery after Percutaneous Coronary Intervention with Drug-eluting Stents 596
This single-center retrospective study examined the risk for complications of noncardiac surgery (NCS) performed within 2 yr after drug-eluting stent (DES) placement and examined whether this risk of major adverse cardiac events (MACE) changed based on the time between percutaneous coronary intervention (PCI) and surgery. The frequency of MACE was not found to be significantly associated with the time between PCI and NCS (rate of MACE 6.4%, 5.7%, 5.9%, and 3.3% at 0-90, 91-180, 181-365, and 366-730 days after PCI with DES, respectively). This study confirms guidelines, which recommend delaying elective NCS for at least 1 yr after DES implantation. See the accompanying Editorial View on page 573
Back to Top | Article Outline
Time and Cardiac Risk of Surgery after Bare-metal Stent Percutaneous Coronary Intervention 588
This large, single-center retrospective study examined the relationship between complication rate in patients with bare-metal stents (BMS) undergoing noncardiac surgery (NCS) and the length of time between percutaneous coronary intervention (PCI) and NCS. Primary endpoints included in-hospital major adverse cardiac events (MACE). The frequency of MACE was 10.5% when NCS was performed less than 30 days after PCI with BMS, 3.8% when NCS was performed between 31 and 90 days after PCI with BMS, and 2.8% when NCS was performed more than 90 days after PCI with BMS. These data indicate that the incidence of MACE is lowest when NCS is performed at least 90 days after PCI with BMS and confirm guidelines, which recommend delaying elective NCS for at least 6 weeks after BMS implantation, and highlight the very high risk of adverse cardiac events if surgery is performed within 30 days of placement of these stents. See the accompanying Editorial View on page 573
The med students question is irrelevant assuming that the stented vessel is among those to be bypassed.
Yes. That is the point. You need to clarify the difference between Cardiac and non-cardiac surgery to the Medical Student; the risks/problems are very different.
Now, any comments about the Patient's medications prior to induction? Do you worry about other diabetic medications preoperatively like Avandia or Glyburide?
What about the Clonidine and ACE inhibitors? Diltiazem? Hytrin?
The reality is that most patients have a hard enough time remembering to stay NPO and take their pills.
Let's move along here. I have more "real world" cases to post. Where are the CA'3's?
Look, I promise not to bite you for any response; I will let you know my opinion and try to provide references.
I think these exotic side effects come from academic attendings blaming a poor anesthetic or unexpected reaction on a new medication. To my knowledge there is no solid data to support any of the hypotension/lactic acidosis theories.
So no i would not worry about what pre-op meds he took: if his pressure or glucose is low, well it can be fixed relatively easily.
Yes. Good Answer and the real world answer as well. But, for you young guys still facing the oral boards I would NOT answer the question quite that way.
In the real world the answer is it just doesn't matter a lot as you won't cancel the case over a routine medication the patient takes at home.
But, your Academic Oral Board Examiner may want a more "conservative" answer like the following:
I would prefer that the patient not have taken his Hytrin the morning of surgery. That medication may add to the risk of hypotension after induction on this patient. He is already taking a Calcium Channel Blocker, Ace Inhibitor and alpha two agonist; the last thing I may want to deal with is the additional effect of an alpha one blocker. However, it appears based on his blood pressure that all the anti-HTN medications were probably needed. I am ready to deal with the situation and have planned accordingly.
Remember when answering an oral board examiner to be humble AND confident at the same time. Being an arrogant SOB won't help you pass.
Okay, so what is your plan now for induction, monitors, etc.?
Ironically, one medication you say he stopped (aspirin off 5 days), is one we keep patients on. No need for the anti-hyperglycemics since all these patients get an insulin drip.
For rapid extubation: fentanyl 5-8mcg/kg total (normally give perfusionist 250mcg of this total). Midazolam ~5 mg (divided 3 on induction, 2 coming off pump). Have the perfusionist use at least 0.7 mac isoflurane. Can use any paralytic, some use cisatracurium, others use panc (normally only need 1 dose). Rewarm fully coming off of pump, have them reversed before leaving the room. Should meet extubation criteria quickly.
Slow down dude. In my part of the woods the Surgeon has a huge input as to the preoperative medications. He asked the patient to stop the aspirin. In addition, he told the patient to take all of his other medicines as usual the morning of surgery.
My point was that surgical cases can be performed safely in spite of remaining on those anti-hyperglycemics. As for the Insulin drip that is almost standard of care on pump cases these days (especially on diabetic patients).
Now, what monitors do you want to use? both invasive and non-invasive. What lines are you going to place pre-induction? Are you using ACTUAL body weight for your Fentany dose or Ideal body weight? What is your MAIN induction agent for this guy? I can tell you around here Midazolam 5 mg I.V. and Fentanyl 250 micrograms won't do the trick; you will need something a little more potent at the start.
Here is a more politically correct way of making my point:
The CRNA in the room decided to apply a BIS monitor. After giving the Midazolam 5 mg IV and Fentanyl 250 micrograms IV the patient has a BIS reading of 73. Now what?
I don't have an answer for IBW vs real. Do the case with a total of ~750mcg of fentanyl. For the purposes of early extubation, induction agent doesn't matter. What matters is total opioid dose. He would get etomidate, midazolam, fentanyl and NMB for induction. At this point in my training I would have an awake a line and 1 PIV. Not all of my attendings would want that (1 never does). Once he's asleep he'd get a double stick IJ introducer + 16 ga single lumen cath + TEE. I don't feel the need for a PA-C but maybe helpful in the ICU.
I don't have any experience with BIS and cardiac surgery. I'd turn the thing off and run 0.7 ET iso.
Our surgeons are the same with the meds. They know that keeping aspirin going is beneficial.
Thank you. But, what if the Group at your new private practice ALWAYS uses BIS And everyone in the room expects it. Are you going to refuse?
So, let's assume the patient gets the midazolam and fentany but the BIS remains high at 73. Now the CRNA wants to add an induction agent. She politely asks which one you prefer: Etomidate, Propofol or Pentothal. All three are available. The EF=35% plus remember the preop medications.
What is your decision? Please drop the aspirin thing as the SURGEON will make that decision in your new Group. He has decided that his personal bleeding is greater on the aspirin so he stops it. However, the OTHER Cardiac surgeon tells his patients to keep taking it.
Your decision to place the A-line on this patient preoperatively is sound. Based on the preoperative medication list an A-line is indicated prior to induction.
Now, please research BIS monitors and realize it is a very reasonable non-invasive monitor for Cardiac Surgery.
Pharmacokinetic mass of fentanyl for postoperative analgesia in lean and obese patients
K. Shibutani1, M. A. Inchiosa, Jr1,2,*, K. Sawada3 and M. Bairamian1
1 Department of Anesthesiology and 2 Department of Pharmacology, New York Medical College, Valhalla, New York, USA. 3 Department of Anesthesia and Intensive Care, Nagoya University, Nagoya, Japan
* Corresponding author: Department of Pharmacology, New York Medical College, Valhalla, NY 10595, USA. E-mail: [email protected]
Background. We previously proposed dosing weights for fentanyl, termed pharmacokinetic mass, that span the total body weight (TBW) range from 40 to 210 kg. In this study, we examined the relationships among fentanyl doses needed to achieve postoperative analgesia, corresponding plasma fentanyl concentrations, and pharmacokinetic mass in lean and obese patients undergoing abdominal surgery.
Methods. A total of 69 patients were studied, with TBW ranging from 48 to181 kg. Fentanyl infusion was used during surgery. After surgery, fentanyl infusion rates were titrated to achieve analgesia without significant respiratory depression. Plasma fentanyl concentrations were measured when an apparent steady analgesic state was obtained. Comparisons were made for dosing requirements and effective plasma concentrations for 37 lean patients (body mass index <30, TBW <85 kg) and 33 obese patients (body mass index >30, TBW 85 kg).
Results. The average fentanyl dose (µg h1) required to achieve and maintain analgesia over the 4 h postoperative period had a non-linear relationship to TBW; in comparison, fentanyl dose had a strong linear relationship to pharmacokinetic mass: dose (µg h1)=1.22[FONT=arial,helvetica]x.pharmacokinetic mass7.5; r = 0.741, P<0.001. Based on results from our earlier study, the corresponding values of TBW and pharmacokinetic mass are: 52 kg 52 kg; 70 kg 65 kg; 100 kg 83 kg; 120 kg 93 kg; 140 kg 99 kg; 160 kg 104 kg; 180 kg 107 kg; 200 kg 109 kg. In the group comparisons, there was no statistically significant difference in the postoperative fentanyl dose per unit of pharmacokinetic mass between lean and obese patients. The plasma concentration of fentanyl required for analgesia was approximately 1.5 ng ml1, and was similar in the two groups.
Conclusion. The relationship between dose and pharmacokinetic mass, compared with that of dose vs TBW, may provide confidence for the use of pharmacokinetic mass as a dosing approximation for fentanyl. Fentanyl dose based on TBW may cause overdosing in obese patients.
Presented in abstract form at the Annual Meeting of the American Society of Anesthesiologists, Las Vegas, October 26, 2004.
Etomidate, ketamine, thiopental, propofol. +/- can be argued for all of them, but the bottom line is that if you slowly titrate, all can be used to good effect in just about any patient. I would probably use more midazolam and titrate some ketamine in. Etomidate has some evidence against it showing adverse outcomes with even single dosing (it was in one of the thoracic journals CHEST? so I tend to avoid it. He may have some vasodilation from his home meds so you could argue to avoid thiopental and propofol although I think slow titration of these will be just fine.
Excellent answer and just what I was looking for. You showed flexibility, logic and understood the potential problem. So, you are going to add some ketamine to the mix. How much are you going to start with?
Of the three listed Propofol would probably be the worst choice in terms of SVR; but, if given in small increments of 30 mg or so it would be perfectly acceptable. How many of you know that Propofol was CONTRAINDICATED in this exact subgroup of patients when it was first released? Turns out people were slamming in a 100-150 mg of Diprivan (it was brand name then) and that was the primary issue.
Here is some BIS info FYI:
Comparison of Bispectral Index and Patient State Index during Induction of Anesthesia for Open Heart SurgeryAndreas Mappes, M.D.; Marcus Gruendel, M.D.; Hermann Kuppe, M.D.
Dept. of Anesthesiology, German Heart Institute, Berlin, GermanyIntroduction: The bispectral index (BIS) and the patient state index (PSI) have both been shown to correlate with the hypnotic effect of anesthetic drugs (1, 2). We compared BIS and PSI during induction of anesthesia for open heart surgery.
Methods: After ethical approval and written informed consent were obtained, 36 cardiac risk patients (NYHA III to IV, mean age 65 [35-81], SD +/- 11.6, male/ female = 25/11) were monitored during induction of anesthesia for open heart surgery. To collect information on the hypnotic depth, in each patient BIS was obtained by bifrontal montage of the electrodes (A 1000, version 3.31, Aspect Medical Systems) and in addition the PSI via the PSArray electrode (PSA 4000, version 2.11, Physiometrix). A standardized anesthetic drug regimen using etomidate, sufentanil and pancuronium for induction and optional isoflurane for maintenance (max. 0.5 MAC) was administered according to common clinical standards. Time points of special interest were: awake before induction, after injection of drugs, loss of consciousness (LOC), insertion of tracheal tube after 3 min, insertion of gastric tube after ca. 20 min. Both BIS and PSI were recorded simultaneously; impedances of all electrodes were permanently kept under 10 kW. All data were automatically stored online on a laptop computer; all clinical events were marked.
Results: After induction of anesthesia, PSI fell from 96.5 +/- 3 to 19.3 +/- 4.3 (ΔPSI 77.2 +/- 5.7). BIS fell from 95.9 +/- 1.4 to 38.5 +/- 6.2 (ΔBIS 57.3 +/- 6.3). After intubation we saw a rise in PSI from 19.5 +/- 6 to 35.3 +/- 13.5 (ΔPSI 15.8 +/- 10.5), BIS rose from 39.4 +/- 5.6 to 50.6 +/- 12 (ΔBIS 11.2 +/- 10.3). The intubation was reflected by a PSI rise > 20% in 24 patients, and by a BIS rise > 20% in 14 patients. In n=1 patient we saw no PSI change > 20% and in n=10 patients we found no BIS change > 20%. After insertion of the gastric tube we observed a rise in PSI from 22.5 +/- 8.9 to 44.7 +/- 18.7 (ΔPSI 22.2 +/- 14.9), respectively from 48.7 +/- 6.4 to 62.1 +/- 12.2 for the BIS (ΔBIS 13.4 +/- 8.1). In all patients there was a rise of PSI > 20% after insertion of the gastric tube, but only in n=13 there was a BIS increase > 20%. In n=11 there was no BIS rise > 20%. The response of the indices to intubation and insertion of the gastric tube is shown in a frequency table (only measurements without artifacts, etc. were included).
Conclusions: Both indices followed the clinical endpoint LOC time synchronously and without delay. Deep hypnosis (mainly no burst suppression) monitored by the PSI could be observed around 19.3 +/- 4 and corresponded to a BIS of 38.5 +/- 6.2. Especially during the very first minutes after induction, a homogenous deep sedation could be documented with both indices. After intubation, and particularly after the insertion of the gastric tube, a greater scatter of PSI and BIS values could be observed due to the intraindividual pharmacodynamics of the anesthetic drug boli, with an apparent more distinct response of the PSI. In this period a more shallow anesthesia was administered, maintained only by maximum 0.5 MAC of isoflurane. We conclude that BIS and PSI both reflect reliably the loss of consciousness during the induction phase of anesthesia for cardiac risk patients and that both indices closely followed the changes in hypnotic levels.
References: 1) J Cardiothorac Vasc Anesth 2000; 14: 693-7. 2) Memory and Awareness in Anaesthesia IV, Imp College Press, London 2000, 144-52.
Anesthesiology 2001; 95:A279intubationPSIBISgastric tubePSIBISrise > 20%2414rise > 20%2413rise < 20%110rise < 20%011n2524n2424Copyright © 2008, American Society of Anesthesiologists.
All rights reserved.
[FONT=Arial, Helvetica, sans-serif][SIZE=+2]Anesthesia Awareness and the Bispectral Index[/SIZE].
[SIZE=+1]Michael S. Avidan, M.B., B.Ch., Lini Zhang, M.D., Beth A. Burnside, B.A., Kevin J. Finkel, M.D., Adam C. Searleman, B.S., Jacqueline A. Selvidge, B.S., Leif Saager, M.D., Michelle S. Turner, B.S., Srikar Rao, B.A., Michael Bottros, M.D., Charles Hantler, M.D., Eric Jacobsohn, M.B., Ch.B., and Alex S. Evers, M.D. [/SIZE]
[FONT=arial, helvetica]Background Awareness during anesthesia is a serious complication with potential long-term psychological consequences. Use of the bispectral index (BIS), developed from a processed electroencephalogram, has been reported to decrease the incidence of anesthesia awareness when the BIS value is maintained below 60. In this trial, we sought to determine whether a BIS-based protocol is better than a protocol based on a measurement of end-tidal anesthetic gas (ETAG) for decreasing anesthesia awareness in patients at high risk for this complication. .
[FONT=arial, helvetica]Methods We randomly assigned 2000 patients to BIS-guided anesthesia (target BIS range, 40 to 60) or ETAG-guided anesthesia (target ETAG range, 0.7 to 1.3 minimum alveolar concentration [MAC]). Postoperatively, patients were assessed for anesthesia awareness at three intervals (0 to 24 hours, 24 to 72 hours, and 30 days after extubation). .
[FONT=arial, helvetica]Results We assessed 967 and 974 patients from the BIS and ETAG groups, respectively. Two cases of definite anesthesia awareness occurred in each group (absolute difference, 0%; 95% confidence interval [CI], –0.56 to 0.57%). The BIS value was greater than 60 in one case of definite anesthesia awareness, and the ETAG concentrations were less than 0.7 MAC in three cases. For all patients, the mean (±SD) time-averaged ETAG concentration was 0.81±0.25 MAC in the BIS group and 0.82±0.23 MAC in the ETAG group (P=0.10; 95% CI for the difference between the BIS and ETAG groups, –0.04 to 0.01 MAC). .
[FONT=arial, helvetica]Conclusions We did not reproduce the results of previous studies that reported a lower incidence of anesthesia awareness with BIS monitoring, and the use of the BIS protocol was not associated with reduced administration of volatile anesthetic gases. Anesthesia awareness occurred even when BIS values and ETAG concentrations were within the target ranges. Our findings do not support routine BIS monitoring as part of standard practice. (ClinicalTrials.gov number, NCT00281489 [ClinicalTrials.gov] .) .