Nocturnal desaturation in patients with stable heart failure

Abstract

Objective: To determine the prevalence of sleep disordered breathing within a United Kingdom heart failure population.

Subjects: 104 patients and 21 matched normal volunteers.

Methods: Overnight home pulse oximetry with simultaneous ECG recording in the patient group; daytime sleepiness was assessed using the Epworth sleepiness scale (ESS); 41 patients underwent polysomnography to assess the validity of oximetry as a screening test for Cheyne-Stokes respiration.

Results: Home oximetry was a good screening test for Cheyne-Stokes respiration (specificity 81%, sensitivity 87%). Patients with poorer New York Heart Association (NYHA) classes had higher sleepiness scores (p < 0.005). Twenty three patients had "abnormal" patterns of nocturnal desaturation suggestive of Cheyne-Stokes respiration. The mean (SEM) frequency of dips in Sao2 exceeding 4% was 10.3 (0.9) per hour in the patients and 4.8 (0.6) in normal controls (p < 0.005). Ejection fraction correlated negatively with dip frequency (r = -0.5, p < 0.005). The patient subgroup with > or = 15 dips/hour had a higher mean (SEM) NYHA class (3.0 (0.2) v 2.3 (0.1), p < 0.05), and experienced more ventricular ectopy (220 (76) v 78 (21) beats/hour, p < 0.05). There was no excess of serious arrhythmia.

Conclusions: Nocturnal desaturation is common in patients with treated heart failure. Low ejection fraction was related to dip frequency. Lack of correlation between dips and ESS suggests that arousal from sleep is more important than hypoxia in the aetiology of daytime sleepiness in heart failure. Overnight oximetry is a useful screening test for Cheyne-Stokes respiration in patients with known heart failure.

Figure 1

Bland and Altman plot showing the short term reproducibility of overnight home pulse oximetry in patients with controlled heart failure. ζ_w = 1.3 dips/h; mean difference = −0.2 dips/h; coefficient of variation = 7.9.

Figure 2

Receiver-operator curve demonstrating the ability of pulse oximetry to discriminate between normal breathing and Cheyne-Stokes respiration in heart failure. *Indicates a desaturation index of 15 dips/h (see text).

Figure 3

Sample "normal" (upper panel) and "abnormal" (lower panel) overnight oximetry recordings.

Figure 4

Cumulative histograms showing frequency of disordered breathing in 104 patients with chronic heart failure and 21 normal volunteers.

Figure 5

Relation between ejection fraction and desaturation events in all subjects.