Urates in exhaled breath condensate of children with obstructive sleep apnea.

BACKGROUND: Urate levels may be a marker of oxidative stress. The aim of the present study was to find out are there any differences in urate concentrations in exhaled breath condensate (EBC) between children with obstructive sleep apnea (OSA) and healthy children. MATERIALS AND METHODS: EBC was collected in children with obstructive sleep apnea (OSA) and clinically healthy children. Urate measurements in EBC and serum were performed by enzymatic color test. RESULTS: The higher concentration of urates in EBC of children with OSA than clinically healthy children indicate the oxidative stress in their airways. Since there was no significant difference in serum concentration of urates between children with OSA and healthy children, it could be considered that urates are sintetized in the airways of children with OSA. CONCLUSIONS: The present study indicated that urates in EBC (but not in serum) may be used as a marker of local synthesis of antioxidant compounds, but definitive conclusion must be supported by investigations involving larger number of participants.

Sleep disordered breathing in children in a general population sample: prevalence and risk factors.

STUDY OBJECTIVES: Assess the prevalence based on clinically meaningful criteria (i.e., blood pressure) and identify risk factors of sleep disordered breathing (SDB) in a representative sample of elementary school children. DESIGN: A random sample of the local elementary school children (K-5) were assessed using a two-phased strategy. In phase I a brief questionnaire was completed by a parent of each child in local elementary schools (N = 5,740), with a response rate of 78.5%. In phase II, randomly selected children and their parent spent a night in our sleep laboratory (N = 700) with a response rate of 70.0%. SETTING: University sleep laboratory. PARTICIPANTS: Children enrolled in local elementary schools. INTERVENTION: None. MEASUREMENT & RESULTS: Each child was assessed with a full polysomnogram and completed a history/physical examination including an electrocardiogram, otolaryngology examination, and pulmonary evaluation. The prevalence of moderate SDB (apnea-hypopnea index > or = 5) was 1.2%. The independent risk factors included nasal abnormalities and minority associated only with mild (1 < AHI < 5) SDB and snoring and waist circumference associated with all levels of SDB. Tonsil size, based on visual inspection, was not an independent risk factor. CONCLUSION: The prevalence of AHI > or = 5 was 1.2% in a representative sample of elementary school children. Risk factors for SDB included waist circumference, nasal abnormalities (e.g., chronic sinusitis/rhinitis), and minority. The strong linear relationship between waist circumference and BMI across all degrees of severity of SDB suggests that, as in adults, metabolic factors may be among the most important risk factors for SDB in children.

Blood pressure associated with sleep-disordered breathing in a population sample of children.

The current criteria for sleep-disordered breathing (SDB) in children are not based on a clinically relevant outcome. The purpose of this study was to assess the association of blood pressure with SDB in a random sample of the local elementary school children (kindergarten through grade 5) using a 2-phased strategy. During phase 1, a brief questionnaire was completed for all of the children (N=5740) with a response rate of 78.5%. During phase 2, 700 randomly selected children from phase 1 with a response rate of 70.0% were assessed with a full polysomnograph and a history/physical, including an ECG; ear, nose, and throat; and pulmonary evaluation. We observed a significantly elevated systolic blood pressure associated with the apnea hypopnea index (AHI): AHI >or=1 (2.9 mm Hg); AHI >or=3 (7.1 mm Hg); and AHI >or=5 (12.9 mm Hg). The SDB and blood pressure association remained significant after adjusting for age, sex, race, body mass index percentile or waist circumference, sleep efficiency, percentage of rapid eye movement sleep, and snoring. In addition, older age, body mass index percentile, waist circumference, and snoring were significantly associated with blood pressure, independent of SDB. Based on these findings, our study suggests that SDB is significantly associated with higher levels of systolic blood pressure in children aged 5 to 12 years even after adjusting for the various confounding factors. Clinically, the data support the threshold of AHI >or=5 for the initiation of treatment for SDB. Additional research is indicated to assess the efficacy of SDB treatment on reducing blood pressure.

Effect of prenatal nicotine exposure on biphasic hypoxic ventilatory response and protein kinase C expression in caudal brain stem of developing rats.

Current evidence suggests that maternal smoking is associated with decreased respiratory drive and blunted hypoxic ventilatory response (HVR) in the newborn. The effect of prenatal nicotine exposure on overall changes in HVR has been studied; however, there is limited data on the effect of nicotine exposure on each component of biphasic HVR. To examine this issue, 5-day timed-pregnant Sprague-Dawley rats underwent surgical implantation of an osmotic minipump containing either normal saline (Con) or a solution of nicotine tartrate (Nic) to continuously deliver free nicotine at 6 mg.kg of maternal weight(-1).day(-1). Rat pups at postnatal days 5, 10, 15, and 20 underwent hypoxic challenges with 10% O(2) for 20 min using whole body plethysmography. At postnatal day 5, Nic was associated with attenuation of peak HVR; peak minute ventilaton increased 44.0 +/- 6.8% (SE) from baseline in Nic pups, whereas that of Con pups increased 62.9 +/- 5.1% (P < 0.05). Nic pups also had a reduction in the magnitude of ventilatory roll-off; minute ventilation at 15 min decreased 7.3 +/- 7.1% in Nic pups compared with 27.3 +/- 4.0% in Con pups (P < 0.05). No significant difference in HVR was noted at postnatal days 10, 15, and 20. Hypercapnic response was similar at all ages. We further investigated the effect of prenatal nicotine exposure on PKC expression in the caudal brain stem (CB) of developing rats. At postnatal day 5, Nic was associated with increased expression of PKC-beta and PKC-delta in CB, whereas other PKC isoforms were not affected. It is concluded that prenatal nicotine exposure is associated with modulation of biphasic HVR and a selective increase in the expression of PKC-beta and PKC-delta within the CB of developing rats.

Periodic limb movements in sleep and iron status in children.

STUDY OBJECTIVES: To assess potential relationships between serum iron and ferritin levels and the severity of periodic limb movement in sleep (PLMS) in a pediatric population, and to evaluate the response to supplemental iron therapy. DESIGN: A prospective study of all consecutively diagnosed children with PLMS (periodic limb movement index [periodic limb movements per hour of total sleep time, [PLMI] > 5) who underwent overnight polysomnographic evaluation. In all patients, complete blood count and serum iron and ferritin levels were obtained. Patients with serum ferritin concentrations less than 50 microg/L were prescribed iron sulfate at 3 mg/kg of elemental iron per day for 3 months. At the end of treatment, serum iron and ferritin levels and sleep studies were repeated. SETTING: Comprehensive Sleep Medicine Center, Tulane University Health Sciences Center, and Kosair Children's Hospital Sleep Medicine and Apnea Center. PATIENTS: Twenty boys and 19 girls with PLMS with a mean age of 7.5 +/- 3.1 years. INTERVENTION: Iron therapy. RESULTS: Twenty-eight (71.8%) patients had ferritin levels less than 50 microg/L. There was no significant correlation between serum ferritin concentration and PLMS severity as indicated by the PLMI (r = -0.19). The PLMI in patients with serum ferritin levels less than 50 microg/L (29.9 +/- 15.5 PLM/h) was higher than in patients with serum ferritin levels greater than 50 microg/L (21.9 +/- 11.8 PLM/h); however, the difference did not achieve statistical significance (P = 0.09). In contrast, serum iron was significantly correlated with PLMI (r = -0.43, P < 0.01). Indeed, patients with serum iron concentrations less than 50 microg/dL had a higher PLMI compared to patients with serum iron concentrations greater than 50 microg/dL (42.8 +/- 18.3 PLM/h and 23.1 +/- 10.1 PLM/h, respectively; P = 0.02). Twenty-five out of the 28 PLMS patients with serum ferritin levels less than 50 microg/L received treatment with iron sulfate, and 19 (76%) responded favorably. Among the responders to iron therapy, PLMI decreased from 27.6 +/- 14.9 PLM per hour to 12.6 +/- 5.3 PLM per hour after 3 months of iron supplements (P < 0.001) and coincided with increases in serum ferritin levels (pre: 40.8 +/- 27.4 microg/L vs post: 74.1 +/- 13.0 microg/L; P < 0.001). CONCLUSIONS: In children, the presence of PLMS is frequently associated with low serum iron and a tendency toward low serum ferritin levels. In addition, iron therapy is associated with clinical improvement in most of these patients.