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Evaluation of the PhysioFlex closed-circuit anaesthesia machine.
1Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, Japan.
European Journal of Anaesthesiology
|August 6, 2000
Summary
The PhysioFlex closed-circuit anesthesia machine effectively controlled sevoflurane and oxygen levels. However, it did not adequately manage increasing nitrous oxide concentrations during patient anesthesia.
Area of Science:
- Anesthesiology
- Medical Engineering
Background:
- Closed-circuit anesthesia machines offer potential benefits in gas conservation and cost reduction.
- Accurate control of anesthetic gas concentrations is crucial for patient safety and effective anesthesia delivery.
Purpose of the Study:
- To evaluate the concentration control capabilities of the PhysioFlex closed-circuit anesthesia machine.
- To assess the dynamic response of sevoflurane, oxygen, and nitrous oxide concentrations within the PhysioFlex system.
Main Methods:
- Concentrations of nitrous oxide, sevoflurane, and oxygen were measured in the circle system of the PhysioFlex machine in seven patients.
- Gas settings were altered during anesthesia, and concentration changes were recorded to assess system response times.
Main Results:
- Induction required 80-510s for end-tidal sevoflurane to reach 2.0% and 920-2640s for oxygen to reach 30%.
- Changes in sevoflurane settings during anesthesia showed rapid adjustments (90-480s).
- Oxygen concentration adjustments were rapid when increasing (40-60s) but slow when decreasing (310-470s), and nitrous oxide control was inadequate.
Conclusions:
- The PhysioFlex machine demonstrated adequate control over sevoflurane and oxygen concentrations.
- The system's ability to manage increasing nitrous oxide concentrations was insufficient, indicating a limitation in its design or application.