Model-based administration of inhalation anaesthesia. 3. Validating the system model

Area of Science:

• Anesthesiology
• Medical Informatics
• Pharmacokinetics

Background:

• Quantified predictive performance of a computer model for inhalation anesthesia administration.
• Utilized a Datex-Ohmeda Modulus CD circle-absorber system for data collection.

Purpose of the Study:

• To evaluate the predictive accuracy of a computer model for inhalation anesthesia.
• To compare two versions of the model differing in inter-tissue diffusion parameters.

Main Methods:

• In 50 patients, desflurane anesthesia was maintained with low fresh-gas flow (FGF).
• Two model versions were tested, differing in visceral to adipose tissue blood flow ratio (0% vs. 3%).
• Model performance assessed by root mean squared error, bias, and scatter of predicted vs. measured gas concentrations.

Main Results:

• Model predictions showed reasonable to very good agreement with clinical data.
• Version 2 of the model outperformed version 1.
• Model accuracy was better during maintenance (stage 2) than induction (stage 1), particularly for desflurane.

Conclusions:

• Version 2 of the computer model is suitable for guiding inhalation anesthesia administration.
• Active patient monitoring remains essential when using this model.