A non‐rebreathing coaxial anaesthesia system: dependence of end‐tidal gas concentrations on fresh gas flow and tidal volume
| Autor: | W. A. Tweed |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Adult
chemistry.chemical_element Oxygen Drug Administration Schedule chemistry.chemical_compound Tidal Volume medicine Humans Normocapnia Developing Countries Tidal volume Pulmonary Gas Exchange business.industry Equipment Design Carbon Dioxide respiratory system Dilution Fresh gas flow Volumetric flow rate Anesthesiology and Pain Medicine chemistry Anesthesia Anesthetics Inhalation Carbon dioxide Halothane Anesthesia Inhalation business medicine.drug |
| Zdroj: | Anaesthesia. 52:237-241 |
| ISSN: | 1365-2044 0003-2409 |
| Popis: | A non-rebreathing adaptation of the Bain coaxial anaesthesia circuit was developed in Nepal as a simple and economical anaesthetic system for underdeveloped countries. It was made by inserting a coaxial (Bain) tubing between an Ambu-E valve and an Ambu self-inflating bag. The present study examined the dependence of end-tidal gas concentrations on fresh gas flow and tidal volume during halothane/oxygen/air inhalation anaesthesia. Four levels of fresh gas flow with normocapnia (0.2-3 l.min-1) and three levels of tidal volume at a constant respiratory rate of 15 breath.min-1 (to achieve end-tidal carbon dioxide values of 4 +/- 0.5%, 5 +/- 0.5% and 6 +/- 0.5%) were introduced in random order. Twelve ASA class 1 and 2 adult patients having intra-abdominal or pelvic surgery were studied. With increasing fresh gas flow rates, there were proportionate increases in the end-tidal concentrations of oxygen and halothane; with decreasing tidal volume and therefore less air dilution, there were proportionate increases in the end-tidal concentrations of carbon dioxide, oxygen and halothane. Both effects were statistically and clinically significant. Thus, when this system is used as described, the end-tidal concentrations of oxygen and halothane are highly dependent upon both the fresh gas flow and the tidal volume. |
| Databáze: | OpenAIRE |
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