Comparison of Adequacy of Anaesthesia (AoA) monitors with CONOX monitor regarding sevoflurane consumption during routine general anaesthesia: A randomised clinical trial.

BACKGROUND AND AIMS

Adequacy of Anaesthesia (AoA) and CONOX are combined monitors that assess levels of anaesthesia and analgesia and give a comprehensive score. No studies have measured and compared the total consumption of inhaled anaesthetic agents while using these monitors. We designed a study to compare AoA and CONOX in terms of sevoflurane usage, fentanyl usage and recovery from the effects of anaesthesia.

METHODS

A randomised trial was conducted in 58 patients. Group A ( = 31) patients were monitored with AoA, and Group C ( = 27) patients were monitored with CONOX. Sevoflurane was titrated to maintain a state entropy value of 40-60 in AoA and a Quantium consciousness index (qCON) value of 40-60 in CONOX. Similarly, fentanyl was titrated with bolus doses of 0.5 μg/kg to maintain a surgical pleth index value of 40-60 in AoA and Quantium noxious index (qNOX) value of 40-60 in CONOX. Intraoperative awareness was assessed postoperatively using a modified Brice questionnaire. The -test or Chi-square test was used to compare the parameters between the groups.

RESULTS

Mean sevoflurane consumption was similar between AoA and CONOX groups [13.2 (standard deviation {SD}: 3.9) (95% confidence interval {CI}:11.8, 14.5) versus 14.4 (SD: 3.7) (95% CI: 13.0, 15.7) ml/h] ( = 0.236). Fentanyl usage was higher in the AoA group compared to the CONOX group [146.2 (SD: 34.28) (95% CI: 134.13, 158.26) versus 128.2 (SD: 26.7) (95% CI: 118.12, 138.27) μg] ( = 0.031). The emergence time and haemodynamic instability events were similar between AoA and CONOX.

CONCLUSION

Both AoA and CONOX measure anaesthetic depth similarly. However, interpreting qNOX values requires caution, as the patient's consciousness status influences them.