Even more interestingly, OSA diagnosis, characterized by ODI - as detected using the oximeter and, by AHI - as detected using the flow transducer - was no different. Most morbidity - cardiovascular and metabolic- in sleep apnea is believed to be related primarily to the burden of intermittent hypoxia. Use of single channel recorders to detect reductions in flow with or without concomitant oximetry has gained credence as a method of screening or possible even diagnosing sleep apnea in appropriately selected high-risk patients or patients with high pre-test probability for OSA.
The question arises - does nasal airflow measurements add significantly more to a simpler and more cost-effective continuous nocturnal oximetry recording with a finger oximeter.
A study from Australia seems to have an answer. About 100 patients had laboratory PSG, and 2 sets of 3 consecutive nights on each device; nasal airflow and oximetry at home in random order.
Measurements of nasal airflow had high accuracy when compared to lab based PSG for not only severe OSA (AUC 0.92) but also any OSA (AUC 0.87)!
Cost to diagnose by the three modalities would be $1500:$500:$50.
Cost to diagnose per 1,00,000 general population assuming a 10% testing rate in order to diagnose 6% of the disease -$15 milion; $5 million; $0.5 million
The results are intriguing and add to the (slowly) growing body of literature that support a parsimonious approach to a diagnosis of sleep apnea is feasible.
