Henderson C L, Rosen H D, Arney K L
Department of Anaesthesia, St. Paul's Hospital, University of British Columbia, Vancouver, Canada.
Can J Anaesth. 1996 Jun;43(6):636-9. doi: 10.1007/BF03011779.
Since many operating theatres do not have distinct oxygen flowmeters, flow rates of oxygen were measured via nasal prongs at several settings and attachments to three anaesthetic machines.
Oxygen-flow rates were measured using a Timeter RT-200 Calibration Analyzer at three, five and eight L.min-1 via nasal prongs attached to a distinct flowmeter, the common gas outlet (CGO) and the Y-piece of a circle system with the adjustable pressure release (APL) valve closed, open and partially open at circuit pressures of 10 and 20 cm H2O.
The most accurate delivery of oxygen from a distinct flowmeter and the CGO (mean difference 0.2 +/- 0.2 and 0.4 +/- 0.4 respectively). Differences between the flowmeter and CGO were not significant (P = 0.1). Accuracy of flows via the Y-piece were worse than via the flowmeter and CGO (P < 0.0001). Flows via the Y-piece were less than those dialed, especially at high rates. With a partially open APL valve, flow depended upon pressure in the anaesthetic circuit, not upon the flow set. With the APL valve completely open, no flow occurred.
To deliver supplemental oxygen in the operating theatre when there are no distinct flowmeters, nasal prongs should be attached to the CGO of the anaesthetic machine or a flowmeter on a portable E-tank oxygen cylinder. Connecting nasal prongs to the Y-piece of a circle system should be avoided since oxygen delivery is less than dialed, especially when the APL valve is open.
由于许多手术室没有独立的氧气流量计，因此在几种设置下通过鼻导管对连接到三台麻醉机的不同附件的氧气流速进行了测量。
使用Timeter RT - 200校准分析仪，通过连接到独立流量计、共用气体出口（CGO）以及在回路压力为10和20 cm H₂O时可调压力释放（APL）阀关闭、打开和部分打开的环路系统的Y形管的鼻导管，测量在3、5和8 L·min⁻¹时的氧气流速。
来自独立流量计和CGO的氧气输送最为准确（平均差异分别为0.2±0.2和0.4±0.4）。流量计和CGO之间的差异不显著（P = 0.1）。通过Y形管的流速准确性比通过流量计和CGO的要差（P < 0.0001）。通过Y形管的流速低于设定值，尤其是在高流速时。当APL阀部分打开时，流速取决于麻醉回路中的压力，而不是设定的流速。当APL阀完全打开时，没有气流。
在没有独立流量计的手术室中输送补充氧气时，鼻导管应连接到麻醉机的CGO或便携式E型氧气筒上的流量计。应避免将鼻导管连接到环路系统的Y形管，因为氧气输送量低于设定值，尤其是当APL阀打开时。
