Type III home sleep testing versus pulse oximetry: is the respiratory disturbance index better than the oxygen desaturation index to predict the apnoea-hypopnoea index measured during laboratory polysomnography?

Abstract

ObjectivesIn its guidelines on the use of portable monitors to diagnose obstructive sleep apnoea, the American Academy of Sleep Medicine endorses home polygraphy with type III devices recording at a minimum airflow the respiratory effort and pulse oximetry, but advises against simple pulse oximetry. However, oximetry is widely available and simple to use in the home. This study was designed to compare the ability of the oxygen desaturation index (ODI) based on oximetry alone with a stand-alone pulse oximeter (SPO) and from the oximetry channel of the ApneaLink Plus (ALP), with the respiratory disturbance index (RDI) based on four channels from the ALP to predict the apnoea–hypopnoea index (AHI) from laboratory polysomnography.DesignCross-sectional diagnostic accuracy study.SettingSleep medicine practice of a multispecialty clinic.ParticipantsPatients referred for laboratory polysomnography with suspected sleep apnoea. We enrolled 135 participants with 123 attempting the home sleep testing and 73 having at least 4 hours of satisfactory data from SPO and ALP.InterventionsParticipants had home testing performed simultaneously with both a SPO and an ALP. The 2 oximeter probes were worn on different fingers of the same hand. The ODI for the SPO was calculated using Profox software (ODISOX). For the ALP, RDI and ODI were calculated using both technician scoring (RDIMAN and ODIMAN) and the ALP computer scoring (RDIRAW and ODIRAW).ResultsThe receiver–operator characteristic areas under the curve for AHI ≥5 were RDIMAN 0.88 (95% confidence limits 0.81–0.96), RDIRAW 0.86 (0.76–0.94), ODIMAN 0.86 (0.77–0.95), ODIRAW 0.84 (0.75–0.93) and ODISOX 0.83 (0.73–0.93).ConclusionsWe conclude that the RDI and the ODI, measured at home on the same night, give similar predictions of the laboratory AHI, measured on a different night. The differences between the two methods are small compared with the reported night-to-night variation of the AHI.

Oxygen Desaturation Index Differs Significantly Between Types of Sleep Software

“…As a result, oximetry is the cornerstone of type 4, and many type 3, limited-channel home sleep test devices. The ODI is commonly used in some countries as a metric for diagnosing OSA [8][9][10][11][12][13] and/or as a marker for cardiovascular risk. [24][25][26][27][28] Implicit in the clinical utility of ODI is that the result is both accurate and reproducible.…”

“…ODI has validity in the diagnosis of OSA. 8 When there is a high clinical probability of OSA, an elevated ODI3% or ODI4% performs well at "ruling in" the diagnosis, [9][10][11][12][13] particularly in obese subjects, and has higher diagnostic utility in severe compared to moderatesevere OSA.…”

Oximetry use in obstructive sleep apnea

“…Dawson et al [59] developed a comparative study between ApneaLink and conventional oximetry alone using in-hospital PSG as gold standard. A small population was recruited and recordings showed several artifacts and signal loss.…”

Agreement Between Results of Home Sleep Testing for Obstructive Sleep Apnea with and Without a Sleep Specialist

“…Apnealink Plus® (type III), which has been previously validated, 14 was given to study subjects by research assistants who were not registered polysomnologists. Nasal airflow was recorded with a nasal cannula connected to a pressure transducer.…”