Implications of revised AASM rules on scoring apneic and hypopneic respiratory events in patients with heart failure with nocturnal Cheyne-Stokes respiration

Effect of Varying Definitions of Hypopnea on the Diagnosis and Clinical Outcomes of Sleep-Disordered Breathing: A Systematic Review and Meta-Analysis

STUDY OBJECTIVES

Various criteria have been used for scoring hypopneas, leading to difficulties when comparing results in clinical and research settings. We conducted a systematic review and meta-analysis to assess the effect of different hypopnea definitions on the diagnosis, severity, and clinical implications of sleep-disordered breathing (SDB).

METHODS

Ovid MEDLINE, Embase, and Scopus databases were queried for English-language publications from inception through March 7, 2017. Studies that directly compared various hypopnea definitions were eligible. The hierarchical summary receiver operating characteristic model was used to jointly estimate diagnostic performance for comparisons between criteria.

RESULTS

The initial search yielded 2,828 abstracts; 28 met inclusion criteria. After reviewing reference lists and expert review, five additional articles were identified. Most of the studies were cross-sectional or retrospective in nature. Eleven studies compared 2007 recommended criteria with 2012 criteria; 6 of these (evaluating 6,628 patients) were suitable for inclusion in the meta-analysis. Using the 2012 definition (≥ 3% desaturation or arousal) as the reference standard, the 2007 definition (≥ 4% desaturation) showed a sensitivity of 82.7% (95% confidence interval 0.72-0.90) and specificity of 93.2% (95% confidence interval 0.82-0.98). Although 2007 criteria were found to be associated with prevalent cardiovascular (CV) disease and increased risk of CV death, the 2012 criteria appeared to correspond better with intermediate CV risk markers based on two abstracts.

CONCLUSIONS

As expected, 2012 hypopnea scoring criteria resulted in a greater prevalence and severity of SDB. Data regarding the effect of varying hypopnea definitions on clinical outcomes, quality of life, health care costs, and mortality rates are limited.

COMMENTARY

A commentary on this article appears in this issue on page 683.

Effect of Continuous Positive Airway Pressure on Airway Inflammation and Oxidative Stress in Patients with Obstructive Sleep Apnea

Background. Airway inflammation and oxidative stress may be linked in obstructive sleep apnea (OSA) patients. We determined the effectiveness of continuous positive airway pressure (CPAP) therapy in reducing fractional exhaled nitric oxide (FeNO) and malondialdehyde (MDA) levels in OSA patients. Methods. Thirteen patients with OSA and 13 normal controls were recruited. FeNO and MDA levels were measured in the controls and in OSA patients before and after three months of CPAP therapy. Results. FeNO and MDA levels were higher in the patients compared to the age and gender matched controls (FeNO: 25.9 ± 5.0 versus 17.5 ± 5.9 ppb, P < 0.001; MDA: 14.6 ± 7.8 versus 2.1 ± 0.3 μmol/L, P < 0.001). FeNO and MDA levels were lower post-CPAP compared to pre-CPAP (FeNO: 25.9 ± 5.0 versus 17.0 ± 2.3 ppb, P < 0.001; MDA: 14.6 ± 7.8 versus 10.0 ± 6.4 μmol/L, P < 0.01). Apnea-hypopnea index (15.9 ± 6.6 versus 4.1 ± 2.1/h, P < 0.001) and mean arterial pressure (P < 0.01) decreased following CPAP treatment. Daytime mean SpO₂ (P < 0.05) increased. Conclusion. Our study demonstrates that CPAP therapy yields clinical benefits by reducing upper airway inflammation and oxidative stress in OSA patients.

Photoplethysmographic Signal to Screen Sleep-Disordered Breathing in Hospitalized Heart Failure Patients: Feasibility of a Prospective Clinical Pathway

OBJECTIVES

The purpose of this study was to evaluate the plethysmographic signal-derived oxygen desaturation index (ODI) as an inpatient screening strategy to identify sleep-disordered breathing (SDB) in patients with congestive heart failure (CHF).

BACKGROUND

SDB is highly prevalent among patients hospitalized with CHF but is widely underdiagnosed. We evaluated overnight photoplethysmography as a possible screening strategy for hospitalized patients with CHF.

METHODS

Consecutively admitted heart failure patients with high clinical suspicion of SDB and ODI ≥5 were offered outpatient polysomnography (PSG), which was completed within 4 weeks of discharge. PSG was considered positive if the apnea hypoxia index (AHI) was ≥5. A Bland-Altman plot was used to assess agreement between ODI and AHI. Receiver-operator characteristics were determined for ODI ≥5 and AHI ≥5.

RESULTS

A screening questionnaire identified 246 of 282 consecutive patients with positive symptoms for SDB. Of these patients, 105 patients were offered further evaluation and 86 had ODI ≥5 (mean ODI 17 ± 17). Among these 86 patients, 68 underwent outpatient PSG within 4 weeks of discharge. PSG showed that 64 (94%) had SDB, with a mean AHI of 28. Inpatient ODI correlated well with PSG-derived AHI. The area under the curve was 0.82 for AHI ≥5. The Bland-Altman plot revealed no major bias. Matthew's correlation coefficient revealed that the optimal cut-off for ODI is 5.

CONCLUSIONS

Screening hospitalized patients with heart failure using targeted inpatient ODI identifies a cohort of patients with a high prevalence of SDB. Our screening strategy provides a potentially cost-effective method for early detection and treatment of SDB.