The use of cutaneous oximetry in the prescription of long-term oxygen therapy.

Using current Medicare guidelines for the prescription of long-term oxygen therapy, we studied the impact on decision-making of substituting cutaneous oxyhemoglobin saturation measurements (SaO 2 ) for direct arterial oxygen tension measurements (PaO 2 ). Fifty-five patients with chronic lung disease and resting hypoxemia were studied. More than 80 percent of patients with a resting PaO 2 of 7.33 kPa (55 mm Hg) or less had a cutaneous oximetry SaO 2 greater than 85 percent. These patients would not have met the guidelines for long-term oxygen therapy if the cutaneous oximetry measurements were used instead of direct PaO 2 measurements. Substituting a threshold criterion of 88 percent instead of 85 percent resulted in fewer patients being denied oxygen therapy but also included patients with PaO 2 values greater than 7.33 kPa (55 mm Hg). We conclude that cutaneous oximetry cannot be substituted equivalently for PaO 2 measurements in prescribing long-term oxygen therapy.