Statistical anaysis of the relationship between the nociception qNOX index and painful stimuli

Abstract

One of the aspects that should be controlled during general anaesthesia is analgesia since those patients who suffer less surgical stress have fewer complications in the postoperative period. The qNOX (Quantium Medical) is an index responsible for calculating the probability of movement as a response to nociception stimulus. It is extracted from a frequency and temporal analysis of the EEG. It has been analysed a database of 212 patients undergoing general anaesthesia during different interventions at the Hospital Clinic, Barcelona. We used a Minto model (1997) for remifentanil and a Schinder model (1999) for propofol supplied with Target-Controlled Infusion (TCI). The behaviour of the qNOX index as a predictor of movements in response to laryngeal mask (LMA), intubation, incision, electrocautery and suture was studied. The values of the index before and during the stimulus were considered. The analysis was repeated for all registered movement and non-movement times. We also analysed how the index evolved in interest points during surgery (loss of verbal response, loss of eyelid reflex, patient opens eyes and awake patient). Statistical significance has been obtained for the qNOX values 60 seconds before the stimuli when working with the whole set of stimuli. A significant difference has also been found between the values of the index before and during a movement and the value where there was no response. The analysis of the points of interest has also shown there is a change between the index prior to the event and the qNOX immediately after them.