The Bain anaesthetic system. An assessment during controlled ventilation

Area of Science:

• Anesthesiology
• Respiratory Physiology
• Medical Device Engineering

Background:

• The Mapleson D circuit is a common anesthetic breathing system.
• Controlled ventilation requires careful management of fresh gas flow.
• Optimizing anesthetic delivery and waste gas management is crucial.

Purpose of the Study:

• To evaluate the performance of the Bain anaesthetic breathing system (modified Mapleson D) under controlled ventilation.
• To determine the relationship between fresh gas inflow and PaCO2 levels.
• To assess the system's suitability as a universal breathing circuit.

Main Methods:

• Evaluation of the Bain circuit in over 140 patients undergoing anesthesia with controlled ventilation.
• Adjustment of fresh gas inflow based on patient body weight.
• Measurement of PaCO2 levels at different fresh gas flow rates.

Main Results:

• A predictable PaCO2 was achieved by adjusting fresh gas inflow relative to body weight in patients >40 kg.
• Mean PaCO2 was 40.8 mmHg at 70 ml/kg/min and 34.3 mmHg at 100 ml/kg/min fresh gas inflow.
• The circuit's length did not impact performance, even when doubled.

Conclusions:

• The Bain anaesthetic breathing system allows for predictable PaCO2 control with appropriate fresh gas flow adjustments.
• The system is versatile, lightweight, and can be used with simple ventilators for all patient ages.
• The Bain circuit demonstrates potential as a universal breathing system due to its performance and features.