Automatic Gas Control Mode Versus Manual Minimal-flow and Medium-flow Anaesthesia in Breast Surgery: A Comparative Study.

OBJECTIVE

This study compared automatic gas control (AGC) mode with manual minimal-flow and manual medium-flow techniques in elective breast surgery, evaluating sevoflurane consumption, cost, hemodynamics, and recovery.

METHODS

Following ethics approval, 90 American Society of Anaesthesiologists I-II patients (age 18-65 years) undergoing elective breast surgery were randomized to AGC mode (Group AGC, n = 30), manual minimal-flow control (Group ManCo, n = 30), or manual medium-flow control (Group ModFA, n = 30). All received standard induction after preoxygenation, with maintenance via sevoflurane and remifentanil infusion in a mixture of oxygen and medical air. After reaching a minimum alveolar concentration of 1.0, sevoflurane was adjusted to maintain a bispectral index of 40-60. Mean arterial pressure (MAP), heart rate, peripheral capillary oxygen saturation, bispectral index, inspired sevoflurane fractions and expired sevoflurane fraction, end-tidal carbon dioxide, temperature, and instantaneous sevoflurane consumption were recorded pre-induction and every 15 minutes. Extubation time, recovery time, surgery duration, and total anaesthesia time were documented. Total sevoflurane consumption and cost were calculated postoperatively.

RESULTS

Sevoflurane consumption and related costs were significantly lower in Group AGC versus Groups ManCo and ModFA (both P <0.001) and lower in Group ManCo than in Group ModFA (P <0.001). MAP and recovery times did not differ significantly among groups (P >0.05). Pre-extubation temperature was higher in Group AGC compared to Group ManCo (P=0.014) and Group ModFA (P=0.002). Extubation time was longer in Group ManCo versus Groups AGC and ModFA (P <0.001).

CONCLUSION

AGC mode significantly reduces sevoflurane consumption and cost compared to both manual minimal-flow and manual medium-flow techniques, without adversely affecting hemodynamics or recovery.