Impairment of pulmonary diffusion correlates with hypoxemic burden in central sleep apnea heart failure patients

Influence of Impaired Diffusing Capacity and Sleep-disordered Breathing on Nocturnal Hypoxemia and Health Outcomes in Men with and without Human Immunodeficiency Virus

Rationale: Nocturnal hypoxemia is common in sleep-disordered breathing (SDB) and is associated with increased morbidity and mortality. Although impaired diffusing capacity of the lung for carbon monoxide (DlCO) is associated with daytime hypoxemia, its influence on SDB-related nocturnal hypoxemia is not known. Objectives: To characterize the effects of DlCO impairment on SDB-related nocturnal hypoxemia and associated health outcomes. Methods: Data from a multicenter cohort of men with and without human immunodeficiency virus (HIV) infection, with concomitant measures of DlCO and home-based polysomnography (n = 544), were analyzed. Multivariable quantile regression models characterized associations between DlCO and several measures of SDB-related hypoxemia (e.g., total sleep time with oxygen saturation as measured by pulse oximetry [SpO2] < 90% [T90]). Structural equation models were used to assess associations of impaired DlCO and SDB-related hypoxemia measures with prevalent hypertension and type 2 diabetes. Results: DlCO impairment (<80% predicted) was associated with sleep-related hypoxemia. Participants with severe SDB (apnea-hypopnea index ⩾ 30 events/h) and impaired DlCO had higher T90 (median difference, 15.0% [95% confidence interval (CI), 10.3% to 19.7%]) and average SDB-related desaturation (median difference, 1.0 [95% CI, 0.5 to 1.5]) and lower nadir SpO2 (median difference, -8.2% [95% CI, -11.4% to -4.9%]) and average SpO2 during sleep (median difference, -1.1% [95% CI, -2.1% to -0.01%]) than those with severe SDB and preserved DlCO. Higher T90 was associated with higher adjusted odds of prevalent hypertension (odds ratio, 1.39 [95% CI, 1.14 to 1.70]) and type 2 diabetes (odds ratio, 1.25 [95% CI, 1.07 to 1.46]). Conclusions: DlCO impairment in severe SDB was associated with sleep-related hypoxemia, prevalent hypertension, and type 2 diabetes. Assessment of SDB should be considered in those with impaired DlCO to guide testing and risk stratification strategies.

Surgical Treatment for Central Sleep Apnea due to Occipitocervical Compression Myelopathy in a Patient with Klippel-Feil Syndrome

BACKGROUND

Central sleep apnea (CSA) due to occipitocervical compression myelopathy is an extremely rare condition. Here we report a case of surgical treatment for CSA due to occipitocervical compression myelopathy in a patient with Klippel-Feil syndrome.

CASE DESCRIPTION

A 60-year-old man had become aware of a gradually progressive clumsiness and gait disturbance without any cause of injury 5 years before. He had complicated respiratory discomfort during sleep for the previous month and visited our hospital. Neurologic examination revealed severe myelopathy. Polysomnography showed CSA and Cheyne-Stokes respiration. Imaging findings showed C2-3 vertebral fusion and severe spinal cord compression caused by hypoplasia of the C1 posterior arch complicated by an anomaly of the vertebral artery. We diagnosed the patient with CSA due to occipitocervical compression myelopathy complicated by Klippel-Feil syndrome. After a simulation using a full-scale 3-dimensional model, resection of the C1 posterior arch and C4-5 laminoplasty was performed. After surgery, both clumsiness and gait disturbance gradually improved. Polysomnography 1 month after surgery showed that the CSA and the Cheyne-Stokes respiration disappeared.

CONCLUSIONS

Although a recent report has indicated the cause of sleep apnea in patients with rheumatoid arthritis and occipitocervical disorders as obstructive sleep apnea, a significant improvement of CSA was observed with decompression surgery in this case. Appropriate surgical planning resulted in a favorable outcome.

Intermittent hypoxia in preterm infants: Measurement using the desaturation index

OBJECTIVE

The aims of this study were to: (i) Determine in preterm infants at neonatal discharge the prevalence of intermittent hypoxia (IH), as measured by the oxygen desaturation index (DSI) recorded by pulse oximetry and (ii) Determine the change in values for very preterm infants at 1-month post discharge.

METHODS

Preterm infants were recruited from the Wellington regional neonatal intensive care unit (NICU) and 24-h pulse oximetry recordings performed immediately before discharge. Infants born <32 weeks gestational age (GA) had repeat oximetry 1-month post discharge. Oxygenation measures included the 3% and 4% desaturation (DSI 3%, DSI 4%) indices.

RESULTS

At discharge from the neonatal unit the median and interquartile range (IQR) for DSI 4% was 51 (31-74) events per hour with normal mean SpO₂ (median of 97.9% [97.2-98.8 IQR]). Episodes of IH 1 month post discharge decreased with improvements of between 42% and 57% seen for the three DSI measures. Infants <32 weeks GA had higher median DSI 3 and 4% values at discharge but differences when compared with late preterm infants were not significant.

CONCLUSIONS

Preterm infants have frequent episodes of IH as measured by the 3% and 4% DSI when deemed otherwise ready for discharge home. Further research in a larger cohort of very preterm infants and also in term infants is needed to determine the significance of this finding.