Complex sentence: An analysis of arterial blood is used to determine the need for oxygen; this is recommended in those with an FEV1 less than 35%, those with a peripheral oxygen saturation of less than 92% and those with congestive heart failure.
Split into simpler sentences: An analysis of arterial blood is used to determine the need for oxygen. Testing is recommended in those with an FEV1 less than 35%, those with a peripheral oxygen saturation of less than 92% and those with congestive heart failure.