A Comparison of Propofol- and Dexmedetomidine-induced Electroencephalogram Dynamics Using Spectral and Coherence Analysis

Abstract

Background Electroencephalogram patterns observed during sedation with dexmedetomidine appear similar to those observed during general anesthesia with propofol. This is evident with the occurrence of slow (0.1–1 Hz), delta (1–4 Hz), propofol-induced alpha (8–12 Hz), and dexmedetomidine-induced spindle (12–16 Hz) oscillations. However, these drugs have different molecular mechanisms and behavioral properties, and are likely accompanied by distinguishing neural circuit dynamics. Methods We measured 64-channel electroencephalogram under dexmedetomidine (n = 9) and propofol (n = 8) in healthy volunteers, 18–36 years of age. We administered dexmedetomidine with a 1mcg/kg loading bolus over 10 minutes, followed by a 0.7mcg/kg/hr infusion. For propofol, we used a computer controlled infusion to target the effect-site concentration gradually from and 0 µg/mL to 5 µg/mL. Volunteers listened to auditory stimuli and responded by button-press to determine unconsciousness. We analyzed the electroencephalogram using multitaper spectral and coherence analysis. Results Dexmedetomidine was characterized by spindles with maximum power and coherence at ~13 Hz, (mean±std; power, −10.8dB±3.6; coherence, 0.8±0.08), while propofol was characterized with frontal alpha oscillations with peak frequency at ~11 Hz (power, 1.1dB±4.5; coherence, 0.9±0.05). Notably, slow oscillation power during a general anesthetic state under propofol (power, 13.2dB±2.4) was much larger than during sedative states under both propofol (power, −2.5dB±3.5) and dexmedetomidine (power, −0.4dB±3.1). Conclusion Our results indicate that dexmedetomidine and propofol place patients into different brain states, and suggests that propofol enables a deeper state of unconsciousness by inducing large amplitude slow oscillations that produce prolonged states of neuronal silence.

Electroencephalogram Similarity Analysis Using Temporal and Spectral Dynamics Analysis for Propofol and Desflurane Induced Unconsciousness

“…These EEG dynamics similarities between them are in line with the findings that GABAergic neural circuit mechanisms behave [3,26,31]. This implies that highly structured thalamocortical oscillations that communicate with cortical information processing, as well as slow oscillations in cortical activity [9,32], which are responsible for this phenomenon.…”

Clinical Electroencephalography for Anesthesiologists

“…Higher index values cause concern as to whether the patients are unconscious. At the other extreme, dexmedetomidine can produce profound slow electroencephalogram oscillations 43 and low index values consistent with the patient being profoundly unconscious. However, the patient can be easily aroused from what is a state of sedation rather than unconsciousness.…”

“…However, the patient can be easily aroused from what is a state of sedation rather than unconsciousness. 43,44 …”

“…43,47 The signatures are readily visible as oscillations in the unprocessed electroencephalogram and its spectrogram. We relate these oscillations to the actions of the anesthetics at specific molecular targets in specific neural circuits.…”

“…6D, minute 7.1) The electroencephalogram change is dramatic as the slow-oscillation amplitudes can be 5 to 20 times larger than the amplitudes of the gamma and beta oscillations seen in the electroencephalogram of an awake patient. 43 …”