Abstract:
BACKGROUND:The bispectral index (BIS) monitor has been available for clinical use for >20 years and has had an immense impact on academic activity in Anesthesiology, with >3000 articles referencing the bispectral index. Despite attempts to infer its algorithms by external observation, its operation has nevertheless remained undescribed, in contrast to the algorithms of other less commercially successful monitors of electroencephalogram (EEG) activity under anesthesia. With the expiration of certain key patents, the time is therefore ripe to examine the operation of the monitor on its own terms through careful dismantling, followed by extraction and examination of its internal software. METHODS:An A-2000 BIS Monitor (gunmetal blue case, amber monochrome display) was purchased on the secondary market. After identifying the major data processing and storage components, a set of free or inexpensive tools was used to retrieve and disassemble the monitor's onboard software. The software executes primarily on an ARMv7 microprocessor (Sharp/NXP LH77790B) and a digital signal processor (Texas Instruments TMS320C32). The device software can be retrieved directly from the monitor's hardware by using debugging interfaces that have remained in place from its original development. RESULTS:Critical numerical parameters such as the spectral edge frequency (SEF), total power, and BIS values were retraced from external delivery at the device's serial port back to the point of their calculation in the extracted software. In doing so, the locations of the critical algorithms were determined. To demonstrate the validity of the technique, the algorithms for SEF and total power were disassembled, comprehensively annotated and compared to their theoretically ideal behaviors. A bug was identified in the device's implementation of the SEF algorithm, which can be provoked by a perfectly isoelectric EEG. CONCLUSIONS:This article demonstrates that the electronic design of the A-2000 BIS Monitor does not pose any insuperable obstacles to retrieving its device software in hexadecimal machine code form directly from the motherboard. This software can be reverse engineered through disassembly and decompilation to reveal the methods by which the BIS monitor implements its algorithms, which ultimately must form the definitive statement of its function. Without further revealing any algorithms that might be considered trade secrets, the manufacturer of the BIS monitor should be encouraged to release the device software in its original format to place BIS-related academic literature on a firm theoretical foundation and to promote further academic development of EEG monitoring algorithms.
journal_name
Anesth Analgjournal_title
Anesthesia and analgesiaauthors
Connor CWdoi
10.1213/ANE.0000000000005220subject
Has Abstractpub_date
2020-12-01 00:00:00pages
1923-1933issue
6eissn
0003-2999issn
1526-7598pii
00000539-202012000-00032journal_volume
131pub_type
杂志文章abstract::Dexmedetomidine hydrochloride is a potent, highly selective alpha-2 adrenergic receptor agonist, broadly used as a sedative drug in intensive care units. We describe the case of a 59-yr-old patient who experienced drug fever caused by dexmedetomidine hydrochloride. The patient was transferred to the intensive care uni...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/ane.0b013e31819f1985
更新日期:2009-05-01 00:00:00
abstract:BACKGROUND:In this prospective observational study, we compared changes in cardiac index (CI) during fluid challenge using photoplethysmography (PPG; Nexfin™) (CIPPG) versus esophageal Doppler (ED) (CIED) in major noncardiac surgery patients. METHODS:Measurements were obtained when the attending anesthesiologist decid...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/ANE.0000000000001113
更新日期:2016-02-01 00:00:00
abstract:UNLABELLED:Suppression of nitric oxide (NO) production alters the toxicity of cocaine and bupivacaine. We undertook this study to determine whether the systemic toxicity of two other local anesthetics that differ in antiarrhythmic activity, plasma clearance, and biotransformation are similarly affected by nitric oxide ...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1097/00000539-199904000-00003
更新日期:1999-04-01 00:00:00
abstract:UNLABELLED:Adjuncts to local anesthetics for peripheral plexus blockade may enhance the quality and duration of anesthesia and postoperative analgesia. The analgesic, tramadol, has a unique mechanism of action that suggests efficacy as such an adjunct. It displays a central analgesic and peripheral local anesthetic eff...
journal_title:Anesthesia and analgesia
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1213/01.ane.0000108966.84797.72
更新日期:2004-04-01 00:00:00
abstract:UNLABELLED:New neurological deficit after spinal surgery is a rare complication that requires a quick diagnostic and therapeutic approach to reduce the risk of permanent neurological disabilities. We report a patient who presented with transient neurologic deficit after surgery for lumbar disk herniation resulting from...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/01.ane.0000083371.57228.64
更新日期:2003-11-01 00:00:00
abstract::The cardiovascular responses of aortic cross-clamping and declamping with normal and high ventricular filling pressures were compared during epidural and nitrous oxide-morphine anesthesia in 32 male patients undergoing reconstructive aortic surgery. The patients were divided into four groups. Groups I and II had lumba...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/00000539-197909000-00005
更新日期:1979-09-01 00:00:00
abstract::Electroconvulsive therapy (ECT) is a highly effective treatment for severe depression. However, its use is associated with significant posttreatment cognitive impairment. Magnetic seizure therapy (MST) was developed as an alternative therapy that could reduce postseizure side effects through the induction of more "foc...
journal_title:Anesthesia and analgesia
pub_type: 临床试验,杂志文章
doi:10.1213/01.ane.0000221182.71648.a3
更新日期:2006-07-01 00:00:00
abstract::In view of the overall experience regarding regional anesthetic techniques to control postoperative pain in infants and children, it is feasible that a similar efficacy and safety profile can be obtained when using such techniques after major orthopedic procedures such as anterior or posterior spinal fusion. I reviewe...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章,评审
doi:10.1213/01.ane.0000107938.80562.75
更新日期:2004-04-01 00:00:00
abstract:UNLABELLED:In the present study, we examined whether preincisional treatment with dextromethorphan (DM) provides preemptive analgesia. Ninety patients scheduled for laparoscopic cholecystectomy were included. Patients receiving chlorpheniramine maleate (CPM) 20 mg via an IM injection 30 min before skin incision were de...
journal_title:Anesthesia and analgesia
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1097/00000539-199906000-00025
更新日期:1999-06-01 00:00:00
abstract:UNLABELLED:Combined spinal-epidural anesthesia (CSE) is a popular technique for cesarean delivery. Regional blocks in obstetrics are often performed with the parturient in the sitting position because the midline may be recognized more easily than in the lateral decubitus position. When conventional spinal anesthesia i...
journal_title:Anesthesia and analgesia
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1097/00000539-199809000-00023
更新日期:1998-09-01 00:00:00
abstract::To determine the pharmacokinetics of local anesthetics after lumbar sympathetic blocks, total and free (unbound) plasma concentrations of bupivacaine in venous blood samples were measured in 12 patients using a high-performance liquid chromatography (HPLC) technique. Administration of 30 mL of plain bupivacaine 0.175%...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/00000539-199411000-00017
更新日期:1994-11-01 00:00:00
abstract::A 38-yr-old man with congenital right pulmonary artery agenesis, whose right lung was perfused with collateral systemic arterial blood, presented for right pneumonectomy. Because of a likely difference in gas exchange between the two lungs, we sampled end-tidal gases from each lung individually, as well as from the co...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/01.ane.0000226089.53300.7a
更新日期:2006-08-01 00:00:00
abstract:UNLABELLED:Thiamylal, a chiral thiobarbiturate, is marketed as a racemic product. We studied the serum protein binding and microsomal metabolism of thiamylal enantiomers in vitro. The unbound fraction of R(+)-thiamylal was greater than that of S(-)-thiamylal. The analysis of binding data revealed that both enantiomers ...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1097/00000539-200009000-00045
更新日期:2000-09-01 00:00:00
abstract::Because we have noticed dramatic hemodynamic responses in brain dead patients undergoing surgery for organ donation, we analyzed the anesthetic records of cadaver organ donors. Ten records contain complete data for heart rate, blood pressure, central venous pressure, and time of incision. Systolic pressure increased b...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:
更新日期:1985-02-01 00:00:00
abstract:BACKGROUND:Safe and effective alternatives are required in labor when epidural analgesia is not appropriate. We hypothesized that patient-controlled IV remifentanil labor analgesia would not be inferior to patient-controlled epidural labor analgesia. METHODS:This randomized nonblinded controlled noninferiority study i...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章,随机对照试验
doi:10.1213/ANE.0b013e3182a7cd1b
更新日期:2014-03-01 00:00:00
abstract::Median convulsant (CD50) and median lethal (LD50) doses of intraperitoneal lidocaine, bupivacaine, and etidocaine were determined in 149 mice. Another 496 mice were pretreated with intramuscular diazepam, lorazepam, or midazolam, 1 mg/kg. Fifteen minutes later, lidocaine, bupivacaine, or etidocaine was given intraperi...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:
更新日期:1981-06-01 00:00:00
abstract:BACKGROUND:The pattern and magnitude of the hyperglycemic response to surgical stress, the added effect of low-dose steroids, and whether these differ in diabetics and nondiabetics remain unclear. We therefore tested 2 hypotheses: (1) that diabetics show a greater increase from preoperative to intraoperative glucose co...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章,随机对照试验
doi:10.1213/ANE.0b013e318288416d
更新日期:2013-05-01 00:00:00
abstract::After it was learned that electroanesthesia (EA) could not be produced in a Rhesus monkey which had undergone a circumferential scalp block with 0.25% lidocaine, it was postulated that EA could be produced by electrostimulation of the sensory nerves of the scalp in the rhesus. The work reported here verifies that EA c...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/00000539-197607000-00018
更新日期:1976-07-01 00:00:00
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journal_title:Anesthesia and analgesia
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.1097/00000539-200002000-00031
更新日期:2000-02-01 00:00:00
abstract::The cold pressor test is often used to assess vasoconstrictive responses because it simulates the vasoconstrictive challenges commonly encountered in the clinical setting. With IRB approval, 12 healthy volunteers, aged 25--50 yr, underwent baseline plethysmographic monitoring on the finger and ear. The contralateral h...
journal_title:Anesthesia and analgesia
pub_type: 临床试验,杂志文章
doi:10.1097/00000539-200106000-00026
更新日期:2001-06-01 00:00:00
abstract::Acute angle closure glaucoma is a rare complication of general anesthesia. However, in case of delayed diagnosis, it may lead to blindness. We present a case of bilateral acute angle closure glaucoma after cervical spine surgery under general anesthesia in a hypermetropic patient. In this case, the most likely trigger...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/ANE.0b013e3182009ad6
更新日期:2011-01-01 00:00:00
abstract::A new mode of pulmonary ventilation called intratracheal pulmonary ventilation (ITPV) was studied. Briefly, a continuous flow of air/oxygen is introduced through a small catheter, the tip of which is positioned at the carina, with a diffuser mounted at its distal end. A timed expiration valve, when closed, provides fo...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/00000539-199403000-00006
更新日期:1994-03-01 00:00:00
abstract:BACKGROUND:Increasing evidence links postoperative cognitive dysfunction (POCD) to surgery and anesthesia. POCD is recognized as an important neuropsychological adverse outcome in surgical patients, particularly the elderly. This prospective cohort study aimed to investigate whether POCD is associated with impaired int...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/ANE.0000000000001803
更新日期:2017-03-01 00:00:00
abstract::Contulakin-G is a novel conopeptide with an incompletely defined mechanism of action. To assess nociceptive activity we delivered Contulakin-G as a bolus intrathecally (0.03, 0.1, 0.3, 3 nmol) or epidurally (10, 30, 89 nmol) in rats. Intrathecal Contulakin G significantly decreased Phase II and, to a lesser degree, Ph...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/01.ANE.0000219586.65112.FA
更新日期:2007-06-01 00:00:00
abstract::We investigated the anesthetic and analgesic effectiveness of adding dexamethasone to lidocaine for IV regional anesthesia (IVRA). Seventy-five patients undergoing ambulatory hand surgery were randomly assigned to one of three groups: group L received 3 mg/kg lidocaine, group LD received 3 mg/kg lidocaine + 8 mg dexam...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章,随机对照试验
doi:10.1213/01.ane.0000194944.54073.dd
更新日期:2006-02-01 00:00:00
abstract:BACKGROUND:The purpose of this study was to identify optimal target propofol and remifentanil concentrations to avoid a gag reflex in response to insertion of an upper gastrointestinal endoscope. METHODS:Patients presenting for endoscopy received target-controlled infusions (TCI) of both propofol and remifentanil for ...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章,随机对照试验
doi:10.1213/ANE.0000000000000756
更新日期:2015-07-01 00:00:00
abstract::If there is a genetic predisposition to excessive bleeding, there should be an association in excessive blood loss between multiple cardiac surgeries. We retrospectively determined in 174 patients the association of excessive bleeding between 2 cardiac surgeries with cardiopulmonary bypass between January 19, 1990 and...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/01.ane.0000198563.28246.00
更新日期:2006-04-01 00:00:00
abstract:UNLABELLED:Adenosine and adenosine analogs induce analgesia in humans and presumed antinociception in animal models when administered both systemically and intrathecally. In the present investigation in rats, we studied the effects of intrathecally administered adenosine analogs, with or without systemic coadministrati...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1097/00000539-199709000-00025
更新日期:1997-09-01 00:00:00
abstract::Patients with coronavirus disease 2019 (COVID-19) frequently experience a coagulopathy associated with a high incidence of thrombotic events leading to poor outcomes. Here, biomarkers of coagulation (such as D-dimer, fibrinogen, platelet count), inflammation (such as interleukin-6), and immunity (such as lymphocyte co...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章,评审
doi:10.1213/ANE.0000000000005147
更新日期:2020-11-01 00:00:00
abstract:BACKGROUND:We have recently shown that levetiracetam, administered systemically, exerts an antihyperalgesic effect in a rat inflammatory pain model. In this study, we examined whether levetiracetam has local peripheral antihyperalgesic/anti-edematous effects in the same model of localized inflammation and whether opioi...
journal_title:Anesthesia and analgesia
pub_type: 杂志文章
doi:10.1213/ANE.0b013e31826c7fc2
更新日期:2012-12-01 00:00:00