Tolerance to propofol's sedative effect in mechanically ventilated Rabbits

Area of Science:

• Anesthesiology
• Pharmacology
• Critical Care Medicine

Background:

• Propofol is a widely used sedative for mechanically ventilated patients.
• Long-term propofol administration can lead to tolerance, necessitating dose adjustments.
• Understanding tolerance mechanisms is crucial for optimizing sedation strategies.

Purpose of the Study:

• To investigate the development of propofol tolerance in rabbits during prolonged mechanical ventilation.
• To analyze changes in propofol infusion rates, plasma concentrations, and systemic clearance.
• To correlate these changes with the emergence of sedative tolerance.

Main Methods:

• Six rabbits received continuous intravenous propofol infusion for 48 hours to maintain sedation.
• Infusion rates were adjusted based on sedation assessments.
• Arterial plasma propofol concentrations and systemic clearance rates were measured.
• High-performance liquid chromatography was used for concentration measurements.

Main Results:

• All rabbits exhibited 100% mortality within 30.8 +/- 6.0 hours.
• Propofol infusion rates showed a 5-phase pattern, including increasing and decreasing phases.
• Propofol plasma concentrations and systemic clearance rates demonstrated dynamic changes over time.
• Tolerance to propofol's sedative effect developed within the initial hours of administration.

Conclusions:

• Propofol tolerance can develop rapidly during prolonged mechanical ventilation in rabbits.
• Changes in propofol's metabolic clearance are associated with the development of tolerance.
• These findings highlight the need for careful monitoring and dose titration in clinical settings.