A Primer for EEG Signal Processing in Anesthesia

AAA
: abdominal aortic aneurysm
ACEI
: angiotensin converting enzyme inhibitor
ACS
: acute coronary syndromes
AF
: atrial fibrillation
AKI
: acute kidney injury
AKIN
: Acute Kidney Injury Network
ARB
: angiotensin receptor blocker
ASA
: American Society of Anesthesiologists
b.i.d.
: bis in diem (twice daily)
BBSA
: Beta-Blocker in Spinal Anesthesia
BMS
: bare-metal stent
BNP
: B-type natriuretic peptide
bpm
: beats per minute
CABG
: coronary artery bypass graft
CAD
: coronary artery disease
CARP
: Coronary Artery Revascularization Prophylaxis
CAS
: carotid artery stenting
CASS
: Coronary Artery Surgery Study
CEA
: carotid endarterectomy
CHA2DS2-VASc
: cardiac failure, hypertension, age ≥75 (doubled), diabetes, stroke (doubled)-vascular disease, age 65–74 and sex category (female)
CI
: confidence interval
CI-AKI
: contrast-induced acute kidney injury
CKD
: chronic kidney disease
CKD-EPI
: Chronic Kidney Disease Epidemiology Collaboration
Cmax
: maximum concentration
CMR
: cardiovascular magnetic resonance
COPD
: chronic obstructive pulmonary disease
CPG
: Committee for Practice Guidelines
CPX/CPET
: cardiopulmonary exercise test
CRP
: C-reactive protein
CRT
: cardiac resynchronization therapy
CRT-D
: cardiac resynchronization therapy defibrillator
CT
: computed tomography
cTnI
: cardiac troponin I
cTnT
: cardiac troponin T
CVD
: cardiovascular disease
CYP3a4
: cytochrome P3a4 enzyme
DAPT
: dual anti-platelet therapy
DECREASE
: Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography
DES
: drug-eluting stent
DIPOM
: DIabetic Post-Operative Mortality and Morbidity
DSE
: dobutamine stress echocardiography
ECG
: electrocardiography/electrocardiographically/electrocardiogram
eGFR
: estimated glomerular filtration rate
ESA
: European Society of Anaesthesiology
ESC
: European Society of Cardiology
EVAR
: endovascular abdominal aortic aneurysm repair
FEV1
: Forced expiratory volume in 1 second
HbA1c
: glycosylated haemoglobin
HF-PEF
: heart failure with preserved left ventricular ejection fraction
HF-REF
: heart failure with reduced left ventricular ejection fraction
ICD
: implantable cardioverter defibrillator
ICU
: intensive care unit
IHD
: ischaemic heart disease
INR
: international normalized ratio
IOCM
: iso-osmolar contrast medium
KDIGO
: Kidney Disease: Improving Global Outcomes
LMWH
: low molecular weight heparin
LOCM
: low-osmolar contrast medium
LV
: left ventricular
LVEF
: left ventricular ejection fraction
MaVS
: Metoprolol after Vascular Surgery
MDRD
: Modification of Diet in Renal Disease
MET
: metabolic equivalent
MRI
: magnetic resonance imaging
NHS
: National Health Service
NOAC
: non-vitamin K oral anticoagulant
NSQIP
: National Surgical Quality Improvement Program
NSTE-ACS
: non-ST-elevation acute coronary syndromes
NT-proBNP
: N-terminal pro-BNP
O2
: oxygen
OHS
: obesity hypoventilation syndrome
OR
: odds ratio
P gp
: platelet glycoprotein
PAC
: pulmonary artery catheter
PAD
: peripheral artery disease
PAH
: pulmonary artery hypertension
PCC
: prothrombin complex concentrate
PCI
: percutaneous coronary intervention
POBBLE
: Peri-Operative Beta-BLockadE
POISE
: Peri-Operative ISchemic Evaluation
POISE-2
: Peri-Operative ISchemic Evaluation 2
q.d.
: quaque die (once daily)
RIFLE
: Risk, Injury, Failure, Loss, End-stage renal disease
SPECT
: single photon emission computed tomography
SVT
: supraventricular tachycardia
SYNTAX
: Synergy between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery
TAVI
: transcatheter aortic valve implantation
TdP
: torsades de pointes
TIA
: transient ischaemic attack
TOE
: transoesophageal echocardiography
TOD
: transoesophageal doppler
TTE
: transthoracic echocardiography
UFH
: unfractionated heparin
VATS
: video-assisted thoracic surgery
VHD
: valvular heart disease
VISION
: Vascular Events In Noncardiac Surgery Patients Cohort Evaluation
VKA
: vitamin K antagonist
VPB
: ventricular premature beat
VT
: ventricular tachycardia

Guidelines summarize and evaluate all available evidence, at the time of the writing process, on a particular issue with the aim of assisting health professionals in selecting the best management strategies for an individual patient with a given condition, taking into account the impact on outcome, as well as the risk–benefit ratio of particular diagnostic …

/pdf/2014-esc-esa-guidelines-on-non-cardiac-surgery-bbdr0c4n87.pdf

2014 ESC/ESA Guidelines on non-cardiac surgery: cardiovascular assessment and management: The Joint Task Force on non-cardiac surgery: cardiovascular assessment and management of the European Society of Cardiology (ESC) and the European Society of Anaesthesiology (ESA).

Background:The bispectral index (BIS), a value derived from the electroencephalograph (EEG), has been proposed as a measure of anesthetic effect. To establish its utility for this purpose, it is important to determine the relation among BIS, measured drug concentration, and increasing levels of seda

Bispectral Analysis Measures Sedation and Memory Effects of Propofol, Midazolam, Isoflurane, and Alfentanil in Healthy Volunteers

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(04)16300-9.pdf

Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial

Background:Intraoperative hypotension may contribute to postoperative acute kidney injury (AKI) and myocardial injury, but what blood pressures are unsafe is unclear. The authors evaluated the association between the intraoperative mean arterial pressure (MAP) and the risk of AKI and myocardial inju

Relationship between intraoperative mean arterial pressure and clinical outcomes after noncardiac surgery: toward an empirical definition of hypotension.

The goal of much effort in recent years has been to provide a simplified interpretation of the electroencephalogram (EEG) for a variety of applications, including the diagnosis of neurological disorders and the intraoperative monitoring of anesthetic efficacy and cerebral ischemia. Although processed EEG variables have enjoyed limited success for specific applications, few acceptable standards have emerged. In part, this may be attributed to the fact that commonly usedsignal processing tools do not quantify all of the information available in the EEG. Power spectral analysis, for example, quantifies only power distribution as a function offrequency, ignoring phase information. It also makes the assumption that thesignal arises from alinear process, thereby ignoring potential interaction betweencomponents of the signal that are manifested asphase coupling, a common phenomenon in signals generated fromnonlinear sources such as the central nervous system (CNS). This tutorial describes bispectral analysis, a method of signal processing that quantifies the degree of phase coupling between the components of a signal such as the EEG. The basic theory underlying bispectral analysis is explained in detail, and information obtained from bispectral analysis is compared with that available from thepower spectrum. The concept of abispectral index is introduced. Finally, several model signals, as well as a representative clinical case, are analyzed using bispectral analysis, and the results are interpreted.

An introduction to bispectral analysis for the electroencephalogram

Background: Low mean arterial pressure (MAP) and deep hypnosis have been associated with complications and mortality. The normal response to high minimum alveolar concentration (MAC) fraction of anesthetics is hypotension and low Bispectral Index (BIS) scores. Low MAP and/or BIS at lower MAC fractions may represent anesthetic sensitivity. The authors sought to characterize the effect of the triple low state (low MAP and low BIS during a low MAC fraction) on duration of hospitalization and 30-day all-cause mortality. Methods: Mean intraoperative MAP, BIS, and MAC were determined for 24,120 noncardiac surgery patients at the Cleveland Clinic, Cleveland, Ohio. The hazard ratios associated with combinations of MAP, BIS, and MAC values greater or less than a reference value were determined. The authors also evaluated the association between cumulative triple low minutes, and excess length-of-stay and 30-day mortality. Results: Means(SD)definingthereference,low,andhigh stateswere875mmHg(MAP),464(BIS),and0.56 0.11 (MAC). Triple lows were associated with prolonged lengthofstay(hazardratio1.5,95%CI1.3–1.7).Thirty-day mortality was doubled in double low combinations and quadrupled in the triple low group. Triple low duration 60 min quadrupled 30-day mortality compared with 15 min. Excess length of stay increased progressively from 15 min to 60 min of triple low. Conclusions: The occurrence of low MAP during low MAC fraction was a strong and highly significant predictor

Hospital Stay and Mortality Are Increased in Patients Having a “Triple Low” of Low Blood Pressure, Low Bispectral Index, and Low Minimum Alveolar Concentration of Volatile Anesthesia

EEG leads are connected to a patient's head (14) by a set of surface electrodes which transmit signals over a patient cable (16) to a 19-channel EEG data acquisition system (12). Data acquisition system (12) filters, amplifies and digitizes the EEG waveforms and sends the digitized data to the microcomputer (18) via high speed synchronous serial line (26). Microcomputer (18) processes the serial data stream to generate computed data arrays. These arrays are then used in conjunction with predetermined reference arrays derived from clinical studies to produce diagnostic indices. These indices are displayed on graphics display (20). Printed output of the diagnostic index is available on the hard copy output device (22) which is connected to the microcomputer (18). Interaction between the operator and the system is provided by means of a keyboard (24) and a pointing device (28) with feedback provided by graphics display (20).

Cerebral biopotential analysis system and method

BACKGROUND: Bispectral analysis is a signal-processing technique that determines the harmonic and phase relations among the various frequencies in the electroencephalogram. Our purpose was to compare the accuracy of a bispectral descriptor, the bispectral index, with that of three power spectral variables (95% spectral edge, median frequency, and relative delta power) in predicting patient movement in response to skin incision during propofol-nitrous oxide anesthesia. METHODS: Forty-four adult patients scheduled for elective noncranial surgery were studied. Gold cup electroencephalographic electrodes were placed on each patient in a frontoparietal montage (Fp1, Fp2, P3, and P4) referred to Cz, and the electroencephalogram was recorded continuously and processed off-line. Conventional frequency bands were used to describe power spectrum variables. Anesthesia was induced with propofol (1.5-3.0 mg-1.kg-1) and maintained with 60% nitrous oxide in oxygen and with propofol at one of three randomized infusion rates (100, 200, or 300 micrograms.kg-1.min-1). Inadequate anesthetic depth was defined as patient movement in response to a 2-cm skin incision at the planned site of surgery. Plasma propofol concentrations were measured within 2 min after skin incision. RESULTS: Complete data were available for 38 patients, of whom 17 moved in response to skin incision. Analysis of the area under the receiver operating characteristic curves showed that only for bispectral index and drug dose group was there a significant predictive relation (area > 0.5). Furthermore, the bispectrum was significantly predictive even after stratification by dose group. CONCLUSIONS: The bispectral index of the electroencephalogram is a more accurate predictor of patient movement in response to skin incision during propofol-nitrous oxide anesthesia than are standard power spectrum parameters or plasma propofol concentrations.

Bispectral analysis of the electroencephalogram correlates with patient movement to skin incision during propofol/nitrous oxide anesthesia.

Background:Hospitals are increasingly required to publicly report outcomes, yet performance is best interpreted in the context of population and procedural risk. We sought to develop a risk-adjustment method using administrative claims data to assess both national-level and hospital-specific performance. Methods: At otal of 35,179,507 patient stay records from 2001‐2006 Medicare Provider Analysis and Review (MEDPAR) files were randomly divided into development and validation sets. Risk stratification indices (RSIs) for length of stay and mortality endpoints were derived from aggregate risk associated with individual diagnostic and procedure codes. Performance of RSIs were tested prospectively on the validation database, as well as a single institution registry of 103,324 adult surgical patients, and compared with the Charlson comorbidity index, which was designed to predict 1-yr mortality. The primary outcome was the C statistic indicating the discriminatory power of alternative risk-adjustment methods for prediction of outcome measures. Results:A single risk-stratification model predicted 30-day and 1-yr postdischarge mortality; separate risk-stratification models predicted length of stay and in-hospital mortality. The RSIs performed well on the national dataset (C statistics formedianlengthofstayand30-daymortalitywere0.86and 0.84).TheyperformedsignificantlybetterthantheCharlson comorbidity index on the Cleveland Clinic registry for all outcomes.TheCstatisticsfortheRSIsandCharlsoncomorbidity index were 0.89versus0.60 for median length of stay, 0.98versus0.65forin-hospitalmortality,0.85versus0.76for

/pdf/broadly-applicable-risk-stratification-system-for-predicting-2fqplybfj5.pdf

Nassib G. Chamoun

Papers

An introduction to bispectral analysis for the electroencephalogram

Hospital Stay and Mortality Are Increased in Patients Having a “Triple Low” of Low Blood Pressure, Low Bispectral Index, and Low Minimum Alveolar Concentration of Volatile Anesthesia

Cerebral biopotential analysis system and method

Bispectral analysis of the electroencephalogram correlates with patient movement to skin incision during propofol/nitrous oxide anesthesia.

Broadly applicable risk stratification system for predicting duration of hospitalization and mortality