INTRAOPERATIVE INTRAOPERATIVE NEUROPHYSIOLOGY AND NEUROPHYSIOLOGY AND NEUROMONITORING NEUROMONITORING Ramsis F. Ghaly, MD, FACS and Todd Sloan MD MBA PhD Todd Sloan MD MBA PhD University of Colorado Health Science University of Colorado Health Science Center Center
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INTRAOPERATIVE INTRAOPERATIVE NEUROPHYSIOLOGY AND NEUROPHYSIOLOGY AND
NEUROMONITORINGNEUROMONITORINGRamsis F. Ghaly, MD, FACS
and
Todd Sloan MD MBA PhDTodd Sloan MD MBA PhDUniversity of Colorado Health Science CenterUniversity of Colorado Health Science Center
EEG MONITORING UNDER EEG MONITORING UNDER ANESTHESIAANESTHESIA
VISUAL DIAGRAM (COMPRESSED SPECTRAL ARRAY)
ANALYSE (SPECTRA) COMPRESS AND SPPRESS SMOOTH (Delta Theta Alpha Beta in a diagram Time against Hz)
NUMERICAL VALUES BIS
Bispectral IndexBispectral IndexSet of features on EEG(bispectrum, etal)
combined and correlated with regression to clinical exam.
Bispectrum: A measure of the level of phase coupling in a signal, as well as the power in the signal
BISPECTRAL INDEX (BIS)BISPECTRAL INDEX (BIS)
DIGITALIZE RAW SURFACE EEG (15-30SEC) AND PROCESS FREQUENCY AND AMPLITUDE AND CORRELATE TO DEPTH OF ANESTHESIA
70-75% RECALL OF WORDS OR PICTURES DEPRESSED <70% EXPLICIT RECALL SIGNIFICANTLY DEPRESSED 60-40% GENERAL ANESTHESIA 40-60% TARGET IF OPIODS USED AND 35% IF NO OPIODS TIVA, HEMODYNAMIC INSTABILITY TO REDUSE ANESTHETIC DOSAGES,
SPEED RECOVERY, CLOSED-LOOP ANESTHESIA INTERFERENCE FROM EXTERNAL, MECHANICAL AND MUSCLE ACTIVITY SEIZURE SPIKE ERRONEOUS VALUES HYPNOTIC AGENTS MAY NOT HAVE LINEAR RELATIONSHIP e.g. N20,
KETAMINE, OPIODS, ETOMIDATE
ANESTHETIC EFFECTS ON ANESTHETIC EFFECTS ON EEGEEG
DRUG TYPE- DOSE-RELATED (DEPTH OF ANESTHESIA)
AMPILTUDE-FREQUENCY-PATTERN- HEMISPHERIC SYMMETRY
INTRAVENOUS AGENTS
FAST ACTIVITY- SLOW & HIGH VOLTAGE
EPILEPTIFORM ACTIVITY (KETAMINE-METHOHEXITAL)
INHALATIONAL AGENT (FAST-LOW) SUB-MAC: FAST ACTIVITY (15-30Hz) 1 MAC 4-8 Hz - 1.5 MAC 1-4 Hz - 2-2.5MAC BURST SUPPRESSION SPIKE WAVE EEG (ENFLURANE) ISOLECTRIC EEG
BISPECTRAL ANALYSIS (BIS) BIS guided anesthesia demonstrated superiority in monitoring depth of anesthesia, minimize awareness under anesthesia, reduction in anesthetic utilization, guide delivery, fast awakening. Spectral Entropy, a measure of disorder in EEG activity, is being evaluated.
Muscle RelaxationMuscle Relaxation Paralysis ok during intubation and some other
times (e.g. back incision) Full paralysis may be necessary to reduce EMG
interference near recording electrodes ( e.g. SSEP cervical response, epidural or neural response)
Full or partial paralysis may reduce patient movement with stimulation
Partial paralysis may be acceptable for electrically stimulated pathways
Absence of paralysis may be necessary with mechanical stimulation or with pathology
Motor Evoked Responses: Start Motor Evoked Responses: Start with TIVAwith TIVA
- Induction with appropriate medications (limit barbiturates and benzodiazepines) Using short to intermediate acting relaxantsPropofol 1-2 mg/kg Succinylcholine, vecuronium, rocuronium, etc.