British journal of anaesthesia
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The probability to tolerate laryngoscopy (PTOL) and its derivative, the noxious stimulation response index (NSRI), have been proposed as measures of potency of a propofol-remifentanil drug combination. This study aims at developing a triple drug interaction model to estimate the combined potency of sevoflurane, propofol, and remifentanil in terms of PTOL. We compare the predictive performance of PTOL and the NSRI with various anaesthetic depth monitors. ⋯ The triple interaction model estimates the potency of any combination of sevoflurane, propofol, and remifentanil expressed as either PTOL or NSRI.