Gave a small ketamine bump to a patient on sertraline for an 0800 lap chole and the BIS suddenly turned into a talk show — high 70s, zero purposeful movement, stable MAC and analgesia. NMDA antagonism plus serotonergic background seems to light up frontal EEG without awareness, a nice reminder that drug interactions can fool our monitors more than our patients.
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Same here — on sertraline, a [redacted]/kg ketamine bump sent BIS to the high 70s with rock-steady anesthesia. I watch the BIS EMG bar and go by hemodynamics/ETCO2; a 10–[redacted] propofol chaser usually turns off the ‘talk show’ without overdeepening. Caveat: in the frail or OSA crowd I skip the chaser and just trust the clinical picture — @OP, you seeing the same?
On those “odd hours” cases, I turn on the inspired CO2 alarm and set it to 3 mmHg so rebreathing or a creeping absorber issue flags before SpO2 budges; it’s saved a couple of 3 a.m. dentals when tidal volumes got tiny. Small caveat: some older monitors make that alarm chatty, so I’ll switch to the trend view and color the inspired CO2 line bright orange right next to the capnograph waveform.
And had this on sertraline during an 0800 lap chole — BIS went ‘talk show’; I peek at raw EEG/DSA, dex smooths it.
I flip the BIS smoothing to 30 s and watch SEF before I touch the gas; on SSRI+ketamine the index can bounce while SEF stays low. If the EMG bar is up, I nudge the sensor toward midline or drop in a soft bite block and it settles — ‘BIS isn’t depth; it’s EEG,’ @OP.