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A More Complete Picture Starts with More Complete Data

SEDLine monitor scan

About SedLine

SedLine® brain function monitoring advances neuromonitoring technologies to improve the care of patients under anesthesia or sedation. The core product is a state-of-the-art EEG-based brain function monitor. Utilising 4 channels of information, the SedLine monitor measures the effects of anesthesia and sedation by monitoring both sides of the brain's electrical activity to enable more individualised titration and improve the care of patients under anesthesia or sedation.

In 2010, Masimo acquired SedLine, commercialised SedLine products through its worldwide distribution channels, and initiated next-generation brain function monitoring technology and product development.

EEG and Anesthesia

Quantitative EEG (QEEG) Measures of Brain Activity in Response to Sedation/Anesthesia Follow a Predictable Pattern

  • > As the brain falls asleep, EEG activity declines according to a specific, invariant pattern1
    • In general, this drop in activity begins in the frontal lobes and moves toward the back of the brain

Shifts in EEG Power at Induction and Loss of Consciousness (LOC)

Chart showing shifts in EEG power at induction and loss of consciousness

These VARETA images depict changes in Delta wave (i.e., 3 to 5 Hz) activity. Anesthesia (propofol shown here) spreads from the frontal lobes toward the back of the brain (note residual blue/white at induction). Even at LOC, the frontal lobes are more heavily anesthetised areas.

  • > When waking up, EEG activity increases across the brain in exactly the opposite sequence observed when falling asleep
  • > These activity patterns have been shown to be invariant across a range of patient types and sedative/anesthetic agents1
    • Propofol
    • Inhalation gas - Isoflurane, Sevoflurane and Desflurane
    • Nitrous/narcotic

PSI Guidelines

A Greater Volume of Data to Enhance Your Anesthetic Control

Brain function monitoring with SedLine helps the anesthesia provider deliver the desired level of targeted sedation throughout all phases of anesthesia. SedLine uses a sophisticated algorithm based on extensive EEG records to process EEG data and determine the PSI value as a measure of anesthetic depth. The PSI corresponds to a patient's current level of sedation/anesthesia along a scale of 0 to 100, where 100 represents being fully awake2. Guidelines for interpreting the full range of values are presented below. Read PSI 25-50 Range of Optimal Hypnotic State for General Anesthesia to learn more about the studies supporting the development of these guidelines.

The PSI values reflect loss of consciousness, arousals, emergence and response to noxious stimuli. For ease in use, the numeric PSI values are colour coded on the display to promote immediate assessment of patient status. 4-channel real-time EEG data is presented as waveforms and as a Density Spectral Array (DSA) to enable quick and easy confirmation of PSI values.

Chart of guidelines for PSI values
  • 1 John ER, Prichep LS, Kox W, et al. Invariant Reversible QEEG Effects of Anesthetics. Conscious Cogn.0 2001;10:165-183.
  • 2 Prichep LS, et al. The Patient State Index as an indicator of the level of hypnosis under general anesthesia. Br J Anaesth. 2004,92:393-399. Available online at

PDF Resources

Data Sheet
Brain Function Monitoring
Data Sheet