Nocturnal Sleep-disordered Breathing Research Articles

The Effect of Dietary Nitrate on Nocturnal Sleep-Disordered Breathing and Arterial Oxygen Desaturation at High Altitude.

Patrician, Alexander, Harald Engan, David Lundsten, Ludger Grote, Helena Vigetun-Haughey, and Erika Schagatay. The effect of dietary nitrate on nocturnal sleep-disordered breathing and arterial oxygen desaturation at high altitude. High Alt Med Biol 19:21-27, 2018.-Sleep-disordered breathing and fluctuations in arterial oxygen saturation (SaO2) are common during sleep among lowlanders ascending to high altitude. Dietary nitrate (NO3-) supplementation has been shown to lower the O2 consumption in various conditions. Our objective was to investigate whether dietary NO3- could reduce sleep-disordered breathing and SaO2 desaturation during sleep at altitude. Cardiorespiratory responses during sleep were measured in 10 healthy lowlanders at 330 m and then again in the Himalayas at 3700-4900 m. Each subject received two 70 mL shots of either beetroot juice (BR; ∼5.0 mmol NO3- per shot) or placebo (PL: ∼0.003 mmol NO3- per shot) in a single-blinded, weighted order over two consecutive nights at altitude. At 2.5-4.5 hours into sleep at altitude, BR increased the SaO2 desaturation drop (4.2 [0.1]% with PL vs. 5.3 [0.4]% with BR; p = 0.024) and decreased the SaO2 desaturation duration (14.1 [0.9] seconds with PL to 11.1 [0.9] seconds with BR; p = 0.0.041). There was a reduction in breaths with flow limitation (p = 0.025), but no changes in Apnea-Hypopnea Index (AHI), mean and minimum SaO2. The study suggests BR supplementation does not improve AHI or oxygenation, but may increase fluctuations in arterial O2 saturation during sleep at altitude in native lowlanders.

Cephalometric evaluation of children with nocturnal sleep-disordered breathing

The present study aimed to assess the cephalometric features in children with sleep-disordered breathing (SDB). The subjects were 70 children (34 boys and 36 girls, mean age 7.3, SD 1.72, range 4.2-11.9 years) with habitual snoring and symptoms of obstructive sleep disorder for more than 6 months. On the basis of overnight polygraphic findings, the subjects were further divided into subgroups of 26 children with diagnosed obstructive sleep apnoea (OSA), 17 with signs of upper airway resistance syndrome (UARS), and 27 with snoring. A control group of 70 non-obstructed children matched for age and gender was selected. Lateral skull radiographs were taken and cephalograms were traced and measured. The differences between the matched groups were studied using t-test for paired samples. Differences between the subgroups were studied using analysis of variance followed by Duncan's multiple comparison method. Children with SDB were characterized by an increased antero-posterior jaw relationship (P = 0.001), increased mandibular inclination in relation to the palatal line (P = 0.01), increased total (P = 0.019) and lower (P = 0.005) anterior face heights, a longer (P = 0.018) and thicker (P = 0.002) soft palate, smaller airway diameters at multiple levels of the naso- and oropharynx, larger oropharyngeal airway diameter at the level of the base of the tongue (P = 0.011), lower hyoid bone position (P = 0.000), and larger craniocervical angles (NSL-CVT, P = 0.014; NSL-OPT, P = 0.023) when compared with the non-obstructed controls. When divided into subgroups according to the severity of the disorder, OSA children deviated significantly from the control children especially in the oropharyngeal variables. Children with UARS and snoring also deviated from the controls, but the obstructed subgroups were not confidently distinguishable from each other by cephalometric measurements. Logistic regression analysis indicated that UARS and OSA were associated with decreased pharyngeal diameters at the levels of the adenoids (PNS-ad1) and tip of the uvula (u1-u2), an increased diameter at the level of the base of the tongue (rl1-rl2), a thicker soft palate, and anteriorly positioned maxilla in relation to the cranial base. Lateral cephalogram may thus reveal important predictors for SDB in children. Attention should be paid to pharyngeal measurements. Systematic orthodontic evaluation of SDB children is needed because of the effects of obstructed sleep on the developing craniofacial skeleton.

Effect of nasal continuous positive airway pressure in uncontrolled nocturnal asthmatic patients with obstructive sleep apnea syndrome

The mechanisms of nocturnal asthma are intimately related to circadian rhythms, which influence inflammatory cells and mediators, hormone levels and cholinergic tone. Nocturnal airway narrowing in asthma is sometimes associated with sleep disorders, such as obstructive sleep apnea syndrome (OSAS). The aims of this study were to evaluate the association of nocturnal asthma and OSAS, and investigate the influence of continuous positive airway pressure (CPAP) therapy to improve nighttime symptoms in asthmatic patients with OSAS. Forty-three asthmatic patients who had nocturnal symptoms in spite of the optimal medical treatment according to the Global Initiative for Asthma guidelines and associated with snoring were studied. Pulmonary function tests (PFTs), asthma nighttime symptom scores, and polysomnography were performed on all patients. We treated the patients with an apnea-hypopnea index (AHI) 15 (moderate-severe OSAS) (n=16) with CPAP during 2 months. After 2 months, PFT, asthma nighttime symptom scores were reperformed. There was no significant difference in PFT values before and after CPAP treatment in OSAS patients. Asthma nighttime symptom scores were improved significantly (P<0.05) after CPAP treatment. In conclusion, in some patients with nocturnal asthma, OSAS may be responsible disease for nocturnal symptoms. In this condition, CPAP improves nocturnal symptoms without amelioration in PFT abnormalities.

Nocturnal Worsening of Asthma and Sleep-Disordered Breathing

Asthma has a tendency to destabilize and get worse at night, probably due to a nocturnal increase in airway inflammation and bronchial responsiveness. Nocturnal airway narrowing in asthma is often associated with sleep disorders, such as episodes of nocturnal and early morning awakening, difficulty in maintaining sleep, and daytime sleepiness. On the other hand, an association has been documented between nocturnal sleep-disordered breathing and asthma. This review highlights the causes of nocturnal worsening of asthma and examines the evidence pointing toward a causal relationship between nocturnal asthma and sleep-disordered breathing.