Anaes · Medical gases & gas supply
Medical gases and gas supply
Also known as Medical gas supply · Cylinder · Pipeline · Pin-index · Gas laws · Entonox
The medical gas supply provides the oxygen, the nitrous oxide, the medical air and the carbon dioxide used in anaesthesia. The framework rests on four exam-critical ideas: the two supply systems — the hospital pipeline (the primary, at 4 bar) and the cylinders (the backup, at up to 200 bar, identified by the colour code and the pin-index); the pressure regulation that reduces the high cylinder pressure to the 4 bar working pressure; the gas laws (the Boyle, the Charles, the universal gas law) that govern the cylinder content and the flow; and the safety systems (the pin-index, the Schrader probe, the colour code, the oxygen failure device) that prevent the wrong gas being delivered to the patient. Built on the AAGBI checking guidelines (2012), the anaesthetic machine assessment (Tiviraj 2016), and the closed-circuit review (Parthasarathy 2013).
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Meet the patient
Halfway through a laparotomy the oxygen supply alarm sounds and the pipeline pressure gauge falls. The registrar freezes; the consultant is already opening the cylinder oxygen and switching to the reserve supply. The case continues, the surgeon is told, and engineering is called — in that order.[1]
The two questions that decide every gas-supply crisis are the two the topic turns on: is the gas the right gas? (identity, protected by pin index, connectors and the analyser) and is there enough of it? (continuity, protected by pipeline, cylinders and the changeover manifold). Hold those two and the safety systems below fall into place.[1]
You have read the opening of this topic. The complete unit — every section and its primary-source references — is part of the Anaesthesia fellowship atlas.
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- [1]Hartle A, Anderson E, Bythell V, et al. Checking anaesthetic equipment 2012: association of anaesthetists of Great Britain and Ireland Anaesthesia, 2012.PMID 22563957
- [2]Tiviraj S, et al. Development of An Assessment Test for An Anesthetic Machine J Med Assoc Thai, 2016.PMID 27501622
- [3]Parthasarathy S The closed circuit and the low flow systems Indian J Anaesth, 2013.PMID 24249885