Towards a standardized anaesthetic state using isoflurane and morphine

Area of Science:

• Anesthesiology
• Medical Engineering
• Surgical Care

Background:

• Maintaining stable hemodynamics, specifically systolic arterial pressure, is critical during major surgery.
• Isoflurane is a widely used volatile anesthetic agent, but its precise titration can be challenging.
• Automated control systems offer potential for improved anesthetic management.

Purpose of the Study:

• To evaluate a control system designed to maintain systolic arterial pressure at a predetermined level during major surgery.
• To assess the clinical acceptability and safety of anesthesia managed by this system.
• To determine the impact of this control strategy on anesthetic recovery time and awareness.

Main Methods:

• A closed-loop control system adjusted inspired isoflurane concentration in 34 patients undergoing major surgery.
• Systolic arterial pressure was the primary controlled variable.
• An empirical rule guided additional morphine administration when isoflurane demand was high.

Main Results:

• Satisfactory control of systolic arterial pressure was achieved in 31 out of 34 patients (91%).
• The anesthetic state was deemed clinically acceptable by an independent observer.
• No instances of intraoperative awareness were reported, with a mean recovery time of 9.6 minutes.

Conclusions:

• Automated control of systolic arterial pressure using isoflurane is feasible and effective during major surgery.
• This approach provides a clinically acceptable anesthetic state with rapid recovery and no awareness.
• The system demonstrated reliable control, indicating potential for enhanced anesthetic management.