Utility of overnight pulse oximetry and heart rate variability analysis to screen for sleep-disordered breathing in chronic heart failure.
BACKGROUND
Sleep-disordered breathing (SDB) is under diagnosed in chronic heart failure (CHF). Screening with simple monitors may increase detection of SDB in a cardiology setting. This study aimed to evaluate the accuracy of heart rate variability analysis and overnight pulse oximetry for diagnosis of SDB in patients with CHF.


METHODS
180 patients with CHF underwent simultaneous polysomnography, ambulatory electrocardiography and wrist-worn overnight pulse oximetry. SDB was defined as an apnoea-hypopnoea index ≥15/h. To identify SDB from the screening tests, the per cent very low frequency increment (%VLFI) component of heart rate variability was measured with a pre-specified cutoff ≥2.23%, and the 3% oxygen desaturation index was measured with a pre-specified cutoff >7.5 desaturations/h.


RESULTS
173 patients with CHF had adequate sleep study data; SDB occurred in 77 (45%) patients. Heart rate variability was measurable in 78 (45%) patients with area under the %VLFI receiver operating characteristic curve of 0.50. At the ≥2.23% cutoff, %VLFI sensitivity was 58% and specificity was 48%. The 3% oxygen desaturation index was measurable in 171 (99%) patients with area under the curve of 0.92. At the pre-specified cutoff of >7.5 desaturations/h, the 3% oxygen desaturation index had a sensitivity of 97%, specificity of 32%, negative likelihood ratio of 0.08 and positive likelihood ratio of 1.42. Diagnostic accuracy was increased using a cutoff of 12.5 desaturations/h, with sensitivity of 93% and specificity of 73%.


CONCLUSIONS
The high sensitivity and low negative likelihood ratio of the 3% oxygen desaturation index indicates that pulse oximetry would be of use as a simple screening test to rule out SDB in patients with CHF in a cardiology setting. The %VLFI component of heart rate variability is not suitable for detection of SDB in CHF.
Clinical and Academic Department of Sleep and Breathing, National Heart and Lung Institute and NIHR Biomedical Research Unit, Royal Brompton Hospital and Imperial College, London, UK. neil.ward@nhs.net
Neil R
NR
Ward
Martin R
MR
Cowie
Stuart D
SD
Rosen
Vitor
V
Roldao
Manuel
M
De Villa
Theresa A
TA
McDonagh
Anita
A
Simonds
Mary J
MJ
Morrell
D000368:Aged; D000465:Algorithms; D002908:Chronic Disease; D015716:Electrocardiography, Ambulatory; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D010092:Oximetry; D017286:Polysomnography; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D006113:United Kingdom / Q000453:epidemiology