Pulse oximetry oxygen saturation during the 6-min walk test: a limit for stopping the test without resuming it.

The technical standard reports that one of the reasons that should lead the examiner to stop the 6MWT is a fall in pulse oximetry oxygen saturation (SpO2) to <80% and suggests resuming the test after the SpO2 recovers to >85%. This suggestion is based on a single study only [3] that reports instruction to resume walking if SpO2 rises above 80% (and not 85%), citing these two documents: “ATS statement: guidelines for six minute walk test” [4] and “ATS/ACCP Statement on cardiopulmonary testing” [5]. The former did not mention anything about the behaviour of SpO2 during the test, since its monitoring was optional; the latter examined a maximal exercise test, which is considerably different from a functional test such as 6MWT and, moreover, the indication to interrupt cardiopulmonary test is a fall in SpO2 to <80% when accompanied by symptoms and signs of severe hypoxaemia [4].