Sleep Disorders Common in Cystic Fibrosis
Children with cystic fibrosis (CF) who are in stable clinical condition have high rates of obstructive sleep apnea, which holds implications for their overall well-being, Italian researchers reported.
Among a group of 40 children with CF, 70% had an apnea-hypopnea index greater than 2, indicating the presence of obstructive sleep apnea, according to Lucia Spicuzza, MD, PhD, and colleagues from the University of Catania in Italy.
In fact, the mean apnea-hypopnea index was 7.3 in the affected children compared with 0.5 in healthy age-matched controls (P<0.001), the researchers reported online in the Archives of Pediatrics and Adolescent Medicine.
“In children, [obstructive sleep apnea] has been associated with several neurocognitive and behavioral abnormalities. In 5- to 9-year-old children, these include lack of memory, reduced executive functioning, learning disability, language dysfunction, and a lower intelligence quotient,” they explained.
Sleep disorders have been documented among adults with longstanding CF, but data are scarce on sleep problems among children with the disease, particularly the youngest children, when airway inflammation and resulting breathing difficulties have not yet become prominent. In addition, previous studies of breathing during sleep in children have relied on nocturnal oximetry, so Spicuzza and colleagues undertook a study in which they performed polysomnography among a cohort of patients ages 6 months to 11 years who had stable disease, and 18 healthy matched controls. Lung involvement in the patients was mild, with forced expiratory volume in 1 second (FEV1) values of 72% to 98%. However, one in four already had chronic Pseudomonas aeruginosa pulmonary infections, 36% had chronic rhinosinusitis, and 26% had adenotonsillar hypertrophy, with about half having some degree of upper airway obstruction. A number of aspects of sleep architecture were abnormal in the CF children. For instance, total sleep time was lower, at 7 hours versus 7.4 hours (P<0.05), and sleep efficiency was less, at 80.4% compared with 87.8% (P<0.001). The CF children also had less rapid-eye-movement sleep (11.7% versus 13.1%, P<0.05) and more arousals per hour (11 versus 8.2, P<0.001). Daytime oxyhemoglobin saturation in both patients and controls was 98%, but this fell to 94.7% in the CF group compared with 97% in controls (P<0.001). Most of the children who had obstructive sleep apnea had mild to moderate involvement, but the highest apnea-hypopnea index was seen in children younger than 6. "This study provides evidence, to our knowledge for the first time, that sleep-disordered breathing, mainly obstructive apnea/hypopnea, may occur in an early stage of the life in children with CF and mild lung disease in stable clinical condition," the researchers wrote. Both tonsillar enlargement and nasal obstruction may contribute to obstructive sleep apnea in these children, with the nasal involvement possibly encouraging mouth breathing and airway inflammation. This inflammation, along with greater mucus secretion, also may worsen occlusion of the airway, according to the study authors. They also noted that, aside from neurocognitive difficulties that could result from sleep disorders, cardiovascular effects also may be associated with obstructive sleep apnea in children, with consequences such as hypertension and left ventricular hypertrophy. "Although further studies are necessary to assess the effect of sleep disorders on clinical outcomes, these data advise an early inclusion of nocturnal cardiorespiratory monitoring in the routine evaluation of these patients," Spicuzza and colleagues concluded.