A Bourdon Gauge is the type of oxygen flowmeter used most often in emergency medicine. It is a sturdy apparatus that is unaffected by gravity and will therefore operate at any angle. However, there are several problems with this particular gauge:
- it is inaccurate at low flow rates.
- it can be unstable.
- it is unable to compensate for back pressure.
The most significant problem of the three is its inability to compensate for back pressure. This means that there is no indication of how much oxygen is actually being delivered if the tubing is kinked or obstructed in some way. The gauge itself also contains a filter which can become clogged. In both of these cases the gauge will indicate a higher oxygen flow than is actually being delivered to the patient.
Despite its drawbacks, this is (IMHO) the most appropriate gauge for use by EMS, since it will operate in any position. | 
