An update on diagnosis and management of obstructive sleep apnoea in the first 2†years of life.

The aim of this review is to summarise evidence that became available after publication of the 2017 European Respiratory Society statement on the diagnosis and management of obstructive sleep apnoea syndrome (OSAS) in 1- to 23-month-old children. The definition of OSAS in the first 2 years of life should probably differ from that applied in children older than 2 years. An obstructive apnoea-hypopnoea index >5 events·h-1 may be normal in neonates, as obstructive and central sleep apnoeas decline in frequency during infancy in otherwise healthy children and those with symptoms of upper airway obstruction. A combination of dynamic and fixed upper airway obstruction is commonly observed in this age group, and drug-induced sleep endoscopy may be useful in selecting the most appropriate surgical intervention. Adenotonsillectomy can improve nocturnal breathing in infants and young toddlers with OSAS, and isolated adenoidectomy can be efficacious particularly in children under 12 months of age. Laryngomalacia is a common cause of OSAS in young children and supraglottoplasty can provide improvement in children with moderate-to-severe upper airway obstruction. Children who are not candidates for surgery or have persistent OSAS post-operatively can be treated with positive airway pressure (PAP). High-flow nasal cannula may be offered to young children with persistent OSAS following surgery, as a bridge until definitive therapy or if they are PAP intolerant. In conclusion, management of OSAS in the first 2 years of life is unique and requires consideration of comorbidities and clinical presentation along with PSG results for treatment decisions, and a multidisciplinary approach to treatment with medical and otolaryngology teams.

Management of Persistent, Post-adenotonsillectomy Obstructive Sleep Apnea in Children: An Official American Thoracic Society Clinical Practice Guideline.

Background: Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder. Although adenotonsillectomy is first-line management for pediatric OSA, up to 40% of children may have persistent OSA. This document provides an evidence-based clinical practice guideline on the management of children with persistent OSA. The target audience is clinicians, including physicians, dentists, and allied health professionals, caring for children with OSA. Methods: A multidisciplinary international panel of experts was convened to determine key unanswered questions regarding the management of persistent pediatric OSA. We conducted a systematic review of the relevant literature. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate the quality of evidence and the strength of the clinical recommendations. The panel members considered the strength of each recommendation and evaluated the benefits and risks of applying the intervention. In formulating the recommendations, the panel considered patient and caregiver values, the cost of care, and feasibility. Results: Recommendations were developed for six management options for persistent OSA. Conclusions: The panel developed recommendations for the management of persistent pediatric OSA based on limited evidence and expert opinion. Important areas for future research were identified for each recommendation.

Effect of Hypertonic Saline on Lung Function as Add-on Treatment in People With Cystic Fibrosis Receiving Dornase Alfa: A Cystic Fibrosis Foundation Patient Registry Analysis.

BACKGROUND: Introduction of novel therapies for cystic fibrosis (CF) raises the question of whether traditional treatments can be withdrawn. Nebulized hypertonic saline (HS) potentially could be discontinued in patients receiving dornase alfa (DA). RESEARCH QUESTION: In the era before modulators, did people with CF who are F508del homozygous (CFF508del) and who received DA and HS have better preserved lung function than those treated with DA only? STUDY DESIGN AND METHODS: Retrospective analysis of the Cystic Fibrosis Foundation Patient Registry data (2006-2014). Among 13,406 CFF508del with data for at least 2 consecutive years, 1,241 CFF508del had spirometry results and were treated with DA for 1 to 5 years without DA or HS during the preceding (baseline) year. Absolute FEV1 % predicted change while receiving DA and HS, relative to treatment with DA only, was the main outcome. A marginal structural model was applied to assess the effect of 1 to 5 years of HS treatment while controlling for time-dependent confounding. RESULTS: Of 1,241 CFF508del, 619 patients (median baseline age, 14.6 years; interquartile range, 6-53 years) received DA only and 622 patients (median baseline age, 14.55 years; interquartile range, 6-48.1 years) were treated with DA and HS for 1 to 5 years. After 1 year, patients receiving DA and HS showed FEV1 % predicted that averaged 6.60% lower than that in patients treated with DA only (95% CI, -8.54% to -4.66%; P < .001). Lower lung function in the former relative to the latter persisted throughout follow-up, highlighting confounding by indication. After accounting for baseline age, sex, race, DA use duration, baseline and previous year's FEV1 % predicted, and time-varying clinical characteristics, patients treated with DA and HS for 1 to 5 years were similar to those treated with DA only regarding FEV1 % predicted (year 1: mean FEV1 % predicted change, +0.53% [95% CI, -0.66% to +1.71%; P = .38]; year 5: mean FEV1 % predicted change, -1.82% [95% CI, -4.01% to +0.36%; P = .10]). INTERPRETATION: In the era before modulators, CFF508del showed no significant difference in lung function when nebulized HS was added to DA for 1 to 5 years.

Nocturnal oximetry parameters as predictors of sleep apnea severity in resource-limited settings.

Nocturnal oximetry is an alternative modality for evaluating obstructive sleep apnea syndrome (OSAS) severity when polysomnography is not available. The Oxygen Desaturation (≥3%) Index (ODI3) and McGill Oximetry Score (MOS) are used as predictors of moderate-to-severe OSAS (apnea-hypopnea index-AHI >5 episodes/h), an indication for adenotonsillectomy. We hypothesised that ODI3 is a better predictive parameter for AHI >5 episodes/h than the MOS. All polysomnograms performed in otherwise healthy, snoring children with tonsillar hypertrophy in a tertiary hospital (November 2014 to May 2019) were analysed. The ODI3 and MOS were derived from the oximetry channel of each polysomnogram. Logistic regression was applied to assess associations of ODI3 or MOS (predictors) with an AHI >5 episodes/h (primary outcome). Receiver operating characteristic (ROC) curves and areas under ROC curves were used to compare the ODI3 and MOS as predictors of moderate-to-severe OSAS. The optimal cut-off value for each oximetry parameter was determined using Youden's index. Polysomnograms of 112 children (median [interquartile range] age 6.1 [3.9-9.1] years; 35.7% overweight) were analysed. Moderate-to-severe OSAS prevalence was 49.1%. The ODI3 and MOS were significant predictors of moderate-to-severe OSAS after adjustment for overweight, sex, and age (odds ratio [OR] 1.34, 95% confidence interval [CI] 1.19-1.51); and OR 4.10, 95% CI 2.06-8.15, respectively; p < 0.001 for both). Area under the ROC curve was higher for the ODI3 than for MOS (0.903 [95% CI 0.842-0.964] versus 0.745 [95% CI 0.668-0.821]; p < 0.001). Optimal cut-off values for the ODI3 and MOS were ≥4.3 episodes/h and ≥2, respectively. The ODI3 emerges as preferable or at least a complementary oximetry parameter to MOS for detecting moderate-to-severe OSAS in snoring children when polysomnography is not available.

Inflammation and Infection in Cystic Fibrosis: Update for the Clinician.

Inflammation and infection play an important role in the pathophysiology of cystic fibrosis, and they are significant causes of morbidity and mortality in CF. The presence of thick mucus in the CF airways predisposes to local hypoxia and promotes infection and inflammation. A vicious cycle of airway obstruction, inflammation, and infection is of critical importance for the progression of the disease, and new data elucidate the different factors that influence it. Recent research has been focused on improving infection and inflammation in addition to correcting the basic gene defect. This review aims to summarize important advances in infection and inflammation as well as the effect of new treatments modulating the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. New approaches to target infection and inflammation are being studied, including gallium, nitric oxide, and phage therapy for infection, along with retinoids and neutrophil elastase inhibitors for inflammation.

Adenotonsillectomy: the good, the bad and the unknown.

PURPOSE OF REVIEW: Adenotonsillar hypertrophy is the most common pathogenetic contributor to obstructive sleep apnea syndrome (OSAS) in childhood, and adenotonsillectomy is the standard initial treatment. Here, we summarize the most recent evidence on the efficacy and complications of adenotonsillectomy and explore knowledge gaps in clinical management. RECENT FINDINGS: Favorable adenotonsillectomy effects have been reported in children with very severe OSAS [apnea-hypopnea index (AHI) >20 episodes/h] and extremely severe OSAS (AHI >100 episodes/h), without postoperative mortality, need for endotracheal intubation, prolonged hospital stay or re-admission after hospital discharge. However, the risk of residual OSAS after adenotonsillectomy, which may reach 30-60%, has not been thoroughly established. Behavior, OSAS-related symptoms and quality of life improve postoperatively even in children with AHI 1-5 episodes/h. Natural history of enuresis resolution is accelerated postadenotonsillectomy and office-based systemic blood pressure is decreased in OSAS and hypertension. However, which children younger than 2 years should undergo adenotonsillectomy instead of adenoidectomy only to prevent recurrence of OSAS symptoms and revision surgery remains unclear. Adenotonsillectomy in children with Prader-Willi syndrome is frequently accompanied by postoperative residual OSAS while complications are not uncommon. SUMMARY: In the last 2 years, several studies have provided evidence supporting the efficacy and safety of adenotonsillectomy as treatment intervention for otherwise healthy children with OSAS.

Phenotypic variance in pediatric obstructive sleep apnea.

It is crucial that clinicians understand what underpins the considerable phenotypic variance in pediatric obstructive sleep apnea syndrome (OSAS), if they are to implement individually tailored phenotype-based approaches to diagnosis and management. This review summarizes the current literature on how disease severity, comorbidities, genetic and environmental/lifestyle factors interact to determine the overall OSAS phenotype. The first part discusses the impact of these factors on OSAS-related morbidity in the context of otherwise healthy children, whilst the second half details children with complex conditions, particularly focusing on the anatomical and functional abnormalities predisposing to upper airway obstruction unique to each condition. One can then understand the need for a multidimensional assessment strategy for pediatric OSAS; one that incorporates the history, physical examination, sleep study results, and biomarkers to enable precise stratification, so vital for effective determination of the timing and the nature of the therapeutic interventions required.

Lung hyperinflation quantitated by chest CT in children with bronchiolitis obliterans syndrome following allogeneic hematopoietic cell transplantation.

OBJECTIVES: Bronchiolitis obliterans syndrome (BOS) diagnosis in children following allogeneic hematopoietic stem cell transplantation (post-HSCT) is based on detection of airway obstruction on spirometry and air-trapping, small airway thickening or bronchiectasis on chest CT. We assessed the relationship between spirometry indices and low-attenuation lung volume at total lung capacity (TLC) on CT. METHODS: Data of children post-HSCT with and without BOS were analyzed. An age-specific, low-attenuation threshold (LAT) was defined as average of (mean-1SD) lung parenchyma attenuation of 5 control subjects without lung disease matched to each age subgroup of post-HSCT patients. % CT lung volume at TLC with attenuation values

Triage for Malnutrition Risk among Pediatric and Adolescent Outpatients with Cystic Fibrosis, Using a Disease-Specific Tool.

Malnutrition prevails in considerable proportions of children with Cystic Fibrosis (CF), and is often associated with adverse outcomes. For this, routine screening for malnutrition is pivotal. In the present cross-sectional study, we aimed to assess the risk for malnutrition in pediatric outpatients with CF. A total of 76 outpatients (44 girls, 11.9 ± 3.9 years old, 39.5% adolescents) were recruited and anthropometric, clinical, dietary and respiratory measures were collected. All outpatients were screened for malnutrition risk with a validated disease-specific instrument. Most children exhibited a low risk for malnutrition (78.9%), whereas none of the participants were characterized as having a high malnutrition risk. In the total sample, malnutrition risk was positively associated with age (r = 0.369, p = 0.001), and inversely related to the body mass index (r = -0.684, p < 0.001), height z-score (r = -0.264, p = 0.021), and forced expiratory volume (FEV1%, r = -0.616, p < 0.001). Those classified as having a low malnutrition risk were younger (p = 0.004), heavier (p < 0.001) and taller (p = 0.009) than their counterparts with a moderate risk. On the other hand, patients in the moderate risk group were more likely pubertal (p = 0.034), with a reduced mid-upper arm fat area (p = 0.011), and worse pulmonary function (p < 0.001). Interestingly, none of the children attaining ideal body weight were classified as having a moderate malnutrition. risk, whereas 37.5% of the patients allocated at the moderate risk group exhibited physiological lung function. In this cohort of outpatients with CF that were predominantly well-nourished and attained physiological lung function, malnutrition risk was identified only in small proportions of the sample. Our data support that patients that are older, pubertal, or have diminished fat mass are at greater risk for malnutrition.

Adherence to Dietary Recommendations, Nutrient Intake Adequacy and Diet Quality among Pediatric Cystic Fibrosis Patients: Results from the GreeCF Study.

Nutrition is an important component of cystic fibrosis (CF) therapy, with a high-fat diet being the cornerstone of treatment. However, adherence to the dietary recommendations for CF appears suboptimal and burdensome for most children and adolescents with CF, leading to malnutrition, inadequate growth, compromised lung function and increased risk for respiratory infections. A cross-sectional approach was deployed to examine the degree of adherence to the nutrition recommendations and diet quality among children with CF. A total of 76 children were recruited from Aghia Sophia's Children Hospital, in Athens, Greece. In their majority, participants attained their ideal body weight, met the recommendations for energy and fat intake, exceeding the goal for saturated fatty acids consumption. Carbohydrate and fiber intake were suboptimal and most participants exhibited low or mediocre adherence to the Mediterranean diet prototype. It appears that despite the optimal adherence to the energy and fat recommendations, there is still room for improvement concerning diet quality and fiber intake.

Nebulizer Care and Inhalation Technique in Children with Cystic Fibrosis.

Nebulizers are used by the great majority of cystic fibrosis patients for delivery of cornerstone treatments. Inhalation technique and adequate disinfection and maintenance are important for optimizing medication delivery. In this study, inhalation technique and nebulizer disinfection/maintenance were assessed in cystic fibrosis patients by direct observation in clinic and completion of a scoring sheet. A total of 108 patients were recruited. The maximum inhalation technique score was attained by 30.5% and adequate inhalation technique score by 74.08% of patients. The inhalation technique score was best with the vibrating mesh nebulizer (p = 0.038), while patient age and number of nebulized medications did not affect ITS significantly (p > 0.05). Nebulizer disinfection/maintenance score was excellent in only 31.48%. Most families kept the nebulizer clean and used appropriate disinfection method, but only half of them replaced the nebulizer and nebulizer cup at the recommended time intervals. Nebulizer disinfection/maintenance score was positively affected by a number of nebulized medications and negatively by years of equipment use (p = 0.009 and p = 0.001, respectively). Even though inhalation technique and disinfection/maintenance practices were found to be adequate in a large proportion of cases, there is still a need for regular review and education. The type of nebulizer was associated with improved inhalation technique, but more data are required before making specific recommendations.

Measures of nocturnal oxyhemoglobin desaturation in children with neuromuscular disease or Prader-Willi syndrome.

OBJECTIVES: Evidence for nocturnal oximetry interpretation in patients with abnormal neuromuscular function is limited. We aimed to compare children with neuromuscular disease (NMD) or Prader-Willi syndrome (PWS) to otherwise healthy subjects with obstructive sleep-disordered breathing (SDB) or without respiratory disorder (controls) regarding nocturnal oximetry parameters. METHODS: We analyzed recordings from children with: (a) NMD; (b) PWS; (c) snoring and adenotonsillar hypertrophy and/or obesity (SDB); and (d) controls. Outcomes included: (a) basal SpO2 ; (b) proportions of subjects with McGill oximetry score (MOS) >1 (clusters of desaturations); and (c) desaturation index (SpO2 drops ≥3%/h-ODI3). RESULTS: Data of 12 subjects with NMD (median age, 5.2 years; IQR, 2.7, 8.2), 14 children with PWS (5 years; 2.3, 6.9), 21 children with SDB (5.8 years; 4.6, 9.6), and 20 controls (6.2 years; 5.4, 11.2) were analyzed. Children with NMD, PWS, and SDB had lower basal SpO2 than controls (95.6% [94.5%, 96.9%], 96.2% [95.1%, 97.4%], 96.1% [95.8%, 97.5%] vs 97.8% [97.2%, 97.9%], respectively; (P < .01). NMD and PWS showed the greatest negative effect on basal SpO2 (P < .05). Children with SDB or PWS had a higher risk of MOS >1 than patients with NMD (OR, 25.9 [95% CI, 3.4-200.4] and 9.5 [1.5-62.6]). NMD, PWS, and SDB were similar regarding ODI3, which was elevated compared to ODI3 in controls (P < .05). Frequent desaturations predominated in NMD, while periods of sustained desaturation were noted in NMD and PWS. CONCLUSION: PWS and NMD have a negative effect on basal SpO2 , while clusters of desaturations are prevalent in patients with PWS or obstructive SDB.

Frequency of moderate-to-severe obstructive sleep apnea syndrome among children with snoring and blood pressure in the hypertensive range.

BACKGROUND: It is recommended that children with hypertension and loud snoring should be referred for polysomnography. We aimed to compare the frequency of moderate-to-severe obstructive sleep apnea syndrome (OSAS) among snorers with and without hypertension. Thus, it was hypothesized that systolic or diastolic hypertension among children with snoring is a risk factor for moderate-to-severe OSAS. METHODS: Data of children with snoring and adenotonsillar hypertrophy and/or obesity referred for polysomnography were retrospectively analyzed. Blood pressure (BP) was measured three times in the morning after polysomnography and percentiles were calculated for the average of the second and third measurement. Association of systolic or diastolic hypertension with moderate-to severe OSAS (apnea-hypopnea index-AHI > 5 episodes/h) adjusted for age and obesity was assessed by logistic regression. RESULTS: Data of 646 children with snoring (median age, 6.5 years; 3-14.9 years; 25.7% obese) were analyzed. Prevalence of systolic or diastolic hypertension was 14.1% and 16.1%, respectively and frequency of AHI > 5 episodes/h was 18.3%. Systolic hypertension was a significant predictor of moderate-to-severe OSAS (OR 1.87; 95% CI 1.10 to 3.17; P = 0.02) after adjustment for age and obesity, but diastolic hypertension was not (OR, 0.96; 0.55 to 1.67; P > 0.05). Odds of AHI > 5 episodes/h prior to considering systolic hypertension was 0.25 and after considering its presence, increased to 0.46 (Bayes' theorem), or for every three children with systolic hypertension and snoring tested, one had AHI > 5 episodes/h. CONCLUSIONS: In the context of systolic hypertension and snoring, referral for polysomnography to rule out moderate-to-severe OSAS is a clinically productive practice.

Comparison of International Growth Standards for Assessing Nutritional Status in Cystic Fibrosis: The GreeCF Study.

OBJECTIVE: The aim of the study was to compare 3 international growth references and explore their differences in assessing growth in Greek school-aged patients with cystic fibrosis (CF). METHODS: Sample included 114 patients (50 boys, age 11.5 ±â€Š3.9 years), provided care at Aghia Sofia Children's Hospital, Greece. Anthropometrics and predicted forced expiratory volume in 1 second (FEV1%) were measured. Body mass index (BMI) and height z scores were computed according to the Centers for Disease Control and Prevention (CDC), World Health Organization (WHO), and International Obesity Task Force (IOTF) references. Agreement between methods was analyzed with kappa statistics, repeated-measures analysis of variance, and Bland-Altman analysis. The relationship between FEV1% and BMI was explored with linear regression. RESULTS: Mean CDC BMI z score was the lowest (0.06 ±â€Š1.08), followed by WHO (0.17 ±â€Š1.14) and IOTF (0.35 ±â€Š1.05) (P ≤ 0.001 for all). The CDC and WHO growth references highly agreed for most weight status strata and stunting; all other comparisons produced lower agreements. Except for CDC and IOTF BMI z scores, all other comparisons produced wide levels of agreement and proportional bias. CDC reference classified more children as attaining low or normal weight, against WHO or IOTF (P ≤ 0.001 for all). Lowest prevalence of ideal and excess weight was recorded by CDC, compared to all other standards (P ≤ 0.001 for all). All BMI z scores provided moderate associations with FEV1%. CONCLUSION: Large variations across weight status classification were present when employing 3 growth standards in school-aged patients . Given than BMI z-scores from all references provided comparable associations with pulmonary function, our data indicate that no studied reference is better than others in assessing growth in CF.

Pancreatitis in A Patient with Cystic Fibrosis Taking Ivacaftor.

Pancreatitis is rare in pancreatic insufficient cystic fibrosis patients. While pancreatic insufficiency has been considered irreversible until now, in the current era of new therapies with modulators of the Cystic Fibrosis Transmembrane Regulator CFTR channel, there are reports of improvement of pancreatic exocrine function. We describe the case of an adolescent with cystic fibrosis who developed pancreatitis after the partial recovery of pancreatic function while taking ivacaftor. This case adds to the limited body of evidence that CFTR modulators lead to the improvement of pancreatic exocrine function in cystic fibrosis.

Assessing the need for adenotonsillectomy for sleep-disordered breathing in a community setting: A secondary outcome measures analysis of a randomized controlled study.

OBJECTIVE: To assess whether children with sleep-disordered breathing (SDB) symptom severity above a certain level, measured by a validated questionnaire, improve after adenotonsillectomy (AT) compared to no intervention. METHODS: Children with snoring and tonsillar hypertrophy (4 to 10-years old), who were candidates for AT, were randomly assigned to two evaluation sequences (baseline and 3-month follow-up): (a) evaluation immediately before AT and at 3 months postoperatively (AT group); or (b) evaluation at the initial visit and at the end of the usual 3-month waiting period for surgery (control group). Outcomes were (a) Pediatric Sleep Questionnaire sleep-related breathing disorder scale (PSQ-SRBD); (b) modified Epworth Sleepiness Scale (mESS); and (c) proportion of subjects achieving PSQ-SRBD <0.33 (low-risk for apnea-hypopnea index ≥5/h) if they had score ≥0.33 at baseline. RESULTS: Sixty-eight children were assigned to the AT and 72 to the control group and two-thirds of them had PSQ-SRBD ≥0.33. The AT group experienced significantly larger improvement between follow-up and baseline than controls (between-group difference [95% CI] for PSQ-SRBD: -0.31 [-0.35 to -0.27]; and mESS: -2.76 [-3.63 to -1.90]; P < .001 for both). Children with baseline PSQ-SRBD ≥0.33 in the AT group had an eight-times higher probability of achieving PSQ-SRBD <0.33 at follow-up than controls with similar baseline score (risk ratio [95% CI]: 8.33 [3.92-17.54]; P < .001). CONCLUSION: Among children with snoring, tonsillar hypertrophy, and clinical indications for AT, those with preoperative PSQ-SRBD score ≥0.33 show measurable clinical benefit postoperatively.

Nocturnal oximetry in children with obstructive lung disease or sleep-disordered breathing.

OBJECTIVES: Although progress has been made in the standardized interpretation of nocturnal oximetry in children with obstructive sleep-disordered breathing (SDB), no evidence exists on oximetry abnormalities in other respiratory disorders. We aimed to compare obstructive lung disease (OLD) and SDB regarding nocturnal oximetry parameters. METHODS: We analyzed oximetry recordings from children with (i) OLD (obliterative bronchiolitis; cystic fibrosis); (ii) snoring and adenotonsillar hypertrophy (SDB); and (iii) no respiratory disorder (controls). The three groups were compared regarding: (i) oxygen desaturation of hemoglobin index (SpO2 drops ≥3%/h-ODI3) and (ii) basal SpO2 (average SpO2 between SpO2 drops). The associations of oximetry parameters (natural logarithm) with study group were tested using linear regression including age as covariate. RESULTS: Data of 16 subjects with OLD (median age: 7.3 years; Q25, Q75: 5.4, 12), 22 children with SDB (6.3 years; 4, 9) and 22 controls (6.8 years; 5.6, 10.3) were analyzed. Children with OLD or SDB had significantly lower basal SpO2 than controls (91.9% [90.8, 93.4] vs 96.3% [96, 97.4] vs 97.6% [97.1, 97.9]; P < 0.01). No subjects in the SDB or control groups had basal SpO2 < 95%. Children with SDB had significantly higher ODI3 than children with OLD or controls [8.4 episodes/h (6.2, 16.6) vs 4.4 episodes/h (3.6, 6.6) vs 2 episodes/h (1.3, 2.7); P < 0.01]. OLD had the greatest negative effect on basal SpO2 (R2 = 0.62; P < 0.001) and SDB the greatest positive effect on ODI3 (R2 = 0.34; P < 0.001). CONCLUSION: OLD is associated mostly with reduced basal SpO2 , whereas SDB is characterized by elevated ODI3.

Urine concentrations changes of cysteinyl leukotrienes in non-obese children with obstructive sleep apnea undergoing adenotonsillectomy.

OBJECTIVE: The main objective of the study was to compare preoperative to postoperative levels of urine-Cysteinyl leukotrienes (uCysLT) in children undergoing adenotonsillectomy (AT) for obstructive sleep apnea (OSA) in order to investigate whether exaggerated leukotriene activity is the cause or consequence of OSA. METHODS AND MATERIALS: A prospective study was conducted on non-obese children (4-10 years old) referred for overnight PSG. Children with moderate/severe OSA treated with AT were included. A second PSG study performed 2 months postoperatively to confirm OSA resolution, and those with residual OSA were excluded. Morning urine specimens after both PSG studies were obtained and pre-operative uCysLT levels were compared to postoperative levels. RESULTS: 27 children fulfilled the criteria and underwent a post-operative PSG study with three exclusions for residual OSA (postop-AHI>2), so the study group consisted of 24 children (mean age: 5.7 ±â€¯2.1 years). Mean preoperative and postoperative AHI was 10.96 ±â€¯5.93 and 1.44 ±â€¯0.56 respectively. Mean preop-uCysLT were 21.14 ±â€¯4.65, while after AT they significantly reduced to 12.62 ±â€¯2.67 (P < 0.01). CONCLUSION: uCysLT levels are significantly reduced after AT in non-obese children with moderate/severe OSA, suggesting that exaggerated leukotriene activity is mainly a consequence of OSA.