• asbestos
• oxygenation
• asbestosis

The publication of “Radiographic (ILO) readings predict arterial oxygen desaturation during exercise in subjects with asbestosis” by YCG Lee et al from the Sir Charles Gardiner Hospital in Perth¹ presents no new information and fails to reference an earlier paper on the same subject which included more patients with clinical asbestosis and four different control groups.² This paper actually measured the P(A−a)O₂ rather than estimating it from the oxygen saturation. Furthermore it correlated the change in A−a O₂ gradient with the amount of work performed during exercise by measuring the P(A−a)O₂/VO₂ ratio which was more specific and sensitive than the P(A−a)O₂ gradient. The estimate of the true oxygen tension by measuring pulse oximetry is fraught with potential error well understood by most pulmonary physiologists, including motion artifact, vasoconstriction, hypotension, carboxyhaemoglobinaemia, methaemoglobinaemia and anaemia.³ The same information …