A portable automated assessment tool for sleep apnea using a combined Holter-oximeter.
OBJECTIVE
Resource limitations have raised interest in portable monitoring systems that can be used by specialist sleep physicians as part of an overall strategy to improve access to the diagnosis of sleep apnea. This study validates a combined electrocardiogram and oximetry recorder (Holter-oximeter) against simultaneous polysomnography for detection of sleep apnea.


METHODS
Prospective study.


METHODS
A dedicated sleep disorders unit.


METHODS
59 adults presenting for evaluation of suspected sleep apnea.


METHODS
NA.


RESULTS
An automated algorithm previously developed for sleep apnea detection was applied to the electrocardiogram and oximetry measurements. The algorithm provides (a) epoch-by-epoch estimates of apnea occurrence and (b) estimates of overall per-subject AHI. Using separate thresholds of AHI > or =15 and AHI <5 for defining clinically significant and insignificant sleep apnea, sensitivity, specificity, and likelihood ratios, conditional on positive or negative (but not indeterminate) test results were used to assess agreement between the proposed system and polysomnography. Sensitivity of 95.8% and specificity of 100% was achieved. Positive and negative likelihood ratios were >20 and 0.04 respectively, with 16.7% of subjects having intermediate test results (AHI 5-14/h). Regardless ofAHI, 85.3% of respiratory events were correctly annotated on an epoch-by-epoch basis. AHI underestimation bias was 0.9/h, and the antilogs of log-transformed limits of agreement were 0.3 and 2.7. Correlation between estimated and reference AHI was 0.95 (P <0.001).


CONCLUSIONS
Combined Holter-oximeter monitoring compares well with polysomnography for identifying sleep apnea in an attended setting and is potentially suitable for home-based automated assessment of sleep apnea in a population suspected of having sleep apnea.
School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Dublin, Ireland. conor.heneghan@ucd.ie
Conor
C
Heneghan
Chern-Pin
CP
Chua
John F
JF
Garvey
Philip
P
de Chazal
Redmond
R
Shouldice
Patricia
P
Boyle
Walter T
WT
McNicholas
D000328:Adult; D000368:Aged; D000465:Algorithms; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation*; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010092:Oximetry / Q000295:instrumentation*; D017286:Polysomnography / Q000295:instrumentation*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*