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Published on: February 20, 2017
Evaluation of the Humphrey A.D.E. breathing system
1Department of Anesthesiology, University of Washington School of Medicine, Seattle 98195.
Canadian Journal of Anaesthesia = Journal Canadien D'Anesthesie
|September 1, 1987
Summary
The Humphrey A.D.E. breathing circuit requires specific fresh gas flows (FGF) for controlled and spontaneous ventilation. While satisfactory for controlled breathing, the recommended FGF for spontaneous breathing may risk hypercapnia, necessitating CO2 monitoring or higher flows.
Area of Science:
- Anesthesiology
- Respiratory Physiology
- Medical Device Evaluation
Background:
- Breathing circuits are crucial for anesthesia delivery.
- Optimizing fresh gas flow (FGF) is essential for maintaining normocapnia.
- The Humphrey A.D.E. breathing circuit's performance needed evaluation.
Purpose of the Study:
- To determine optimal fresh gas flow (FGF) for the Humphrey A.D.E. breathing circuit in adults.
- To assess end-expired CO2 (PECO2) levels at specific FGF settings.
- To evaluate the reliability and sensitivity of recommended FGF settings for controlled and spontaneous ventilation.
Main Methods:
- Evaluated the Humphrey A.D.E. double lever model breathing circuit in adult patients.
- Measured FGF required for normocapnia (controlled ventilation) and to induce rebreathing (spontaneous ventilation).
- Analyzed PECO2, FGF reliability (standard deviation), and system sensitivity to FGF variations.
Main Results:
- FGFs for normocapnia (controlled) and just-induced rebreathing (spontaneous) were 67 ± 10 and 52 ± 7 ml/kg/min, respectively.
- PECO2 levels were 36.0 ± 0.3 mmHg (controlled) and 41.6 ± 3.9 mmHg (spontaneous).
- Controlled ventilation showed low reliability but low sensitivity; spontaneous ventilation had low reliability and high sensitivity at lower FGFs, risking hypercapnia.
Conclusions:
- The Humphrey A.D.E. circuit's recommended FGF for controlled ventilation is satisfactory.
- The recommended FGF for spontaneous ventilation may lead to hypercapnia.
- Using a higher routine FGF (66 ml/kg/min) or CO2 monitoring with lower flows is advised for spontaneous ventilation.
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