Leukocyte Telomere Length Reflects Prenatal Stress Exposure, But Does Not Predict Atopic Dermatitis Development at 1 Year

PURPOSE: Prenatal maternal stress affects offspring's atopic dermatitis (AD) development, which is thought to be mediated by the oxidative stress. We aimed to evaluate the difference in leukocyte telomere length (LTL), a marker for exposure to oxidative stress, according to the prenatal stress exposure and the later AD development. METHODS: From a birth cohort (the COhort for Childhood Origin of Asthma and allergic diseases) that had displayed a good epidemiologic association between the exposure to prenatal stress and AD development in the offspring, we selected 68 pairs of samples from 4 subject groups based on the level of prenatal maternal stress and later AD development. The LTL was measured from both cord blood and 1-year peripheral blood, and their LTLs were compared between subject groups. Finally, the proportion of AD development was examined in the subject groups that are reclassified based on subjects' exposure to prenatal stress and there LTL. RESULTS: Cord-blood LTL was shorter in prenatally stressed infants than in unstressed ones (P = 0.026), which difference was still significant when subjects became 1 year old (P = 0.008). LTL of cord blood, as well as one of the 1-year peripheral blood, was not different according to later AD development at 1 year (P = 0.915 and 0.174, respectively). Shorter LTL made no increase in the proportion of later AD development in either prenatally high-stressed or low-stressed groups (P = 1.000 and 0.473, respectively). CONCLUSIONS: Cord-blood LTL may reflect subjects' exposure to maternal prenatal stress. However, the LTL shortening is not a risk factor of increasing AD development until the age of 1, and a longer investigation may be necessary for validation. Currently, the results doubt the role of LTL shortening as a marker for risk assessment tool for the prenatal stress associated with AD development in the offspring.

Multicenter Adherence Study of Asthma Medication for Children in Korea

PURPOSE: Adherence is a major component of successful medical treatment. However, non-adherence remains a barrier to effective delivery of healthcare worldwide. METHODS: Twenty healthcare facilities (secondary or tertiary hospitals) belonging to the Korean Academy of Pediatric Allergy and Respiratory Diseases (KAPARD) participated. Questionnaires were given to patients currently receiving treatment in the form of inhalant useor oral intake or transdermal patch for mild to moderate asthma. RESULTS: A total of 1,838 patients responded to the questionnaire. Mean age was 5.98 ± 3.79 years (range: 0-18 years). With help from their caregivers, the percentage of patients that answered “taking as prescribed” was 38.04% for inhalant users, 50.09% for oral medication users and 67.42% for transdermal users. Transdermal patch users had significantly greater adherence compared to the other 2 groups (P < 0.001). The 34.15% of inhalant users, 70.33% of oral medication users and 93.00% of transdermal patch users felt that their medication delivery system was “Easy” or “Very easy” to use (P < 0.001). “Method of administration” was deemed to be the most difficult part of the treatment regimen to follow, and 76.7% of patients preferred once-daily administration (i.e., “Frequency of administration”). CONCLUSIONS: Asthma medication adherence in young children was found to be better in the transdermal patch group. This may be due to requiring fewer doses and easy to follow instructions. From an adherence point of view, the transdermal patch seems more useful for long-term asthma control in children compared to oral or inhaled medicine.

The Korean Version of the Test for Respiratory and Asthma Control in Kids (TRACK): Reliability and Validity

BACKGROUND: Test for Respiratory and Asthma Control in Kids (TRACK) questionnaires were developed and validated in various languages to monitor respiratory control in preschool-aged children. We aimed to assess the reliability and validity of the Korean version of the TRACK questionnaire. METHODS: We administered the linguistically validated TRACK questionnaires to caregivers of asthmatic preschool children on two separate visits 4–6 weeks apart. Each physician graded the level of the guideline-based asthma control, assessed the timing of symptoms, and adjusted the therapeutic level at each visit. RESULTS: A total of 137 children were enrolled in the study. Cronbach's alpha was 0.65 for a questionnaire as a whole. The test-retest reliability was 0.72. The median TRACK scores were significantly different between asthma control status categories, with the lowest scores in children classified as poorly controlled and the highest in the well-controlled group (P < 0.001). They were different among groups classified according to the physician adjusted therapeutic levels, with the lowest values in children prescribed step-up therapy (P < 0.001), and according to the recency of respiratory symptoms (P < 0.001). Finally, the changes in TRACK scores between visits were highest in subjects showing improved control, followed by unchanged, and worsened control. When we applied the traditional cut-off of 80 for a well-controlled condition, a sensitivity of 75.6% and a specificity of 70.9% were calculated. CONCLUSION: The Korean translated version of the TRACK questionnaire is valid and reliable to assess respiratory and asthma control in Korean preschool children with asthma symptoms.

Dyspnea Perception During Induced Bronchoconstriction Is Complicated by the Inhaled Methacholine in Children With Clinical Asthma

PURPOSE: Dyspnea is not widely utilized as an indicator of asthma provocation despite its universal presentation. We hypothesized that dyspnea severity was proportionate with the lung function decline, methacholine dose-step, and the degree of bronchial hyperresponsiveness (BHR). METHODS: We retrospectively analyzed 73 children's bronchial provocation test data with an assessment of dyspnea at every dose-step. Dyspnea severity was scored using a modified Borg (mBorg) scale. A linear mixed effect analysis was performed to evaluate the relationship between the mBorg scale, the percentage fall in the forced expiratory volume in 1 second (FEV1) (ΔFEV1%), the methacholine dose-step, and the degree of BHR (BHR grade). RESULTS: Subjects were divided into 5 BHR groups based on their last methacholine dose-steps. The mBorg scores did not differ significantly among BHR groups (P=0.596, Kruskal-Wallis test). The linear mixed effect analysis showed that ΔFEV1% was affected by the methacholine dose-step (P < 0.001) and BHR grade (P < 0.001). The mBorg score was affected by the dose-step (P < 0.001) and BHR grade (P=0.019). We developed a model to predict the mBorg score and found that it was affected by the methacholine dose-step and ΔFEV1%, elevating it by a score of 0.039 (χ² [1]=21.06, P < 0.001) and 0.327 (χ² [1]=47.45, P < 0.001), respectively. A significant interaction was observed between the methacholine dose-step and ΔFEV1% (χ² [1]=16.20, P < 0.001). CONCLUSIONS: In asthmatic children, inhaled methacholine, as well as the degree of BHR and lung function decline, may affect dyspnea perception during the bronchial provocation test. If we wish to draw meaningful information from dyspnea perception, we have to consider various complicating factors underlying it.

Comparison on the profiles of a modified Borg scale and the pediatric dyspnea scale during an induced bronchoconstriction in children with clinical asthma

PURPOSE: Dyspnea is the cardinal symptom of asthma, but it is difficult to quantify clinically. Although modified Borg (mBorg) scale has been successfully used in adult, but there has been some difficulties to apply in children. Recently, Pediatric Dyspnea Scale (PDS) was adequately designed and has been widely used. The aim of this study is to compare 2 evaluating scales of dyspnea provoked by induced-bronchoconstriction in childhood asthma. METHODS: Seventy-three clinically suspected children with asthma were enrolled in this study. Each ‘fractional exhaled nitric oxide (FeNO)’ was documented. Forced expiratory volume in 1 second (FEV₁), mBorg score and PDS score were recorded during methacholine provocation test. RESULTS: Mapping using canonical plot demonstrated global similarity between 2 scales with some distinctive features. Whereas mBorg score showed more diverse categories in low level of dyspnea, PDS score did in medium level of it. A distribution of dyspnea perception score at a 20% decrease in FEV₁ relative to baseline (PS₂₀), a perception score of dyspnea at 20% fall in FEV1 of 2 scales represented similar wide, biphasic feature. Statistical relevance was verified with spearman correlation (R(s)=0.903, P<0.001) and Bland-Altman analysis. PS₂₀ of both scores and FeNO had no statistical relationship. While relationship between PS20 by mBorg score and the concentration of methacholine at 20% fall in FEV₁ (PC₂₀) was not significant (R(s)=0.224, P=0.154), that between PS₂₀ by PDS and PC₂₀ was weak positive (R(s)=0.29, P=0.063). CONCLUSION: PDS had similar pattern to assess the dyspnea with the mBorg scale suggesting adequacy of PDS in evaluating pediatric clinical asthma. We expect these scales to help clinical practice in complementary ways.

Translation and linguistic validation of Korean version of the Test for Respiratory and Asthma Control in Kids instrument

PURPOSE: We aimed to translate the Test for Respiratory and Asthma Control in Kids (TRACK) instrument into Korean, with subsequent linguistic validation. METHODS: The multistep process of forward translation, reconciliation, back-translation, cognitive debriefing, and proofreading of the Korean version of the TRACK was completed. RESULTS: Two bilingual medical personnel independently translated the original English version of the TRACK into Korean one. After moderating the translation into a single reconciled one, 4 other bilingual persons were invited to translate the Korean draft back into an English one. Discrepancies between the original English version and the back-translated one were reviewed, and the need to modify the reconciled Korean draft was discussed. Twenty caregivers of asthmatic children took part in interviews that examine the appropriateness of the Korean version of the TRACK. The feedback from caregivers were then reviewed by a panel of pediatric allergists and reflected in the final Korean version. The document was finally proofread to check the spelling, grammar, layout and formatting. CONCLUSION: Translation and linguistic validation of the Korean version of the TRACK instrument were completed.

Phenotype and endotype in pediatric asthma

Asthma is not a homogeneous disease presenting variable clinical features, but a complex disorder consisting of many different disease entities characterized by variable air-flow limitation. To date, there are little effective preventive-strategies for the development of asthma, and it has been emphasized that early identification and intervention are the best ways to reduce the associated morbidities, quality of life, and socioeconomic burden. Predicting the natural course of asthma is still difficult, although various phenotypic approaches and predictive scores are developed and widely used. The present phenotypes and predictive scores may be reliable in the population, but those appear to be unreliable in each individual in real practice. Either undertreatment or overtreatment in childhood asthma is an important issue, because they are associated with poor compliance, increments of socioeconomic burdens, and poor quality of life. There is no doubt about the clinical efficacy of inhaled corticosteroid (ICS) in childhood asthma, but the negative effect of long-term use of ICS on the height is emerging. Therefore general physicians should consider an individualized management using specific phenotypes and endotypes, and regularly re-evaluate the drug-response, level of control, and adherence/compliance to avoid inadequate treatment.

The prevalence of bronchial hyperresponsiveness in elementary school children and its associated factors

PURPOSE: We investigated the prevalence of bronchial hyperresponsiveness (BHR) and its associated factors in population-based elementary school children. METHODS: Methacholine bronchial provocation tests were performed on 1,151 elementary school children and BHR was defined as PC20 (provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second [FEV1]) or =25 ppb (aOR, 2.118; P=0.025), and sensitization to mites (aOR, 1.705; P=0.034) were associated with BHR. Preterm birth (aOR, 2.056; P=0.068) showed borderline significance. The associated factors for BHR with atopy were lower body mass index (aOR, 0.838; P=0.005), preterm birth (aOR, 4.361; P=0.003), and FeNO > or =25 ppb (aOR, 2.161; P=0.043). Younger age (aOR, 0.810; P=0.037) and higher blood eosinophil % (aOR, 1.296; P<0.001) were associated with BHR without atopy. CONCLUSION: The prevalence of BHR decreased with age in elementary school children. Younger age, preterm birth, eosinophilia, sensitization to mites, lower lung function, and higher FeNO level were independently associated with BHR.

Association between the clinical index and disease severity in infants with acute bronchiolitis

PURPOSE: We aimed to verify whether the formal clinical index derived from infants and toddlers have a good association with the disease severity when we confine subjects to only infants, who undergo profound changes physically and immunologically. METHODS: We retrospectively reviewed the medical records of hospitalized infants with acute bronchiolitis caused by respiratory syncytial virus between January 1, 2010 and December 31, 2011 in three hospitals. The age, respiratory rate, presentation of chest retraction, and percutaneous oxygen saturation upon admission; presentation of fever, use of oxygen therapy and inhaled corticosteroid within 24 hours after admission were investigated. We then examined the effect of clinical index on severity of acute bronchiolitis; the mean length of stay, mean duration of fever and oxygen therapy. RESULTS: A total of 172 infants were studied. The mean length of stay was longer in patients younger than 3 months (P=0.015), in those with fever (P=0.028) and chest retraction (P=0.014), and in those who needed oxygen supplement (P=0.000). In the patients with fever, the mean duration of fever was longer in those who needed the oxygen supplement than those who did not (P=0.046). CONCLUSION: Younger than 3 months of age, chest retraction upon admission; fever, need of oxygen supplement within 24 hours after admission may predict the severe course of infants with acute bronchiolitis.

Relationship Between Atopy and Bronchial Hyperresponsiveness

Both atopy and bronchial hyperresponsiveness (BHR) are characteristic features of asthma. They are also found among non-asthmatic subjects, including allergic rhinitis patients and the general population. Atopy and BHR in asthma are closely related. Atopy induces airway inflammation as an IgE response to a specific allergen, which causes or amplifies BHR. Moreover, significant evidence of the close relationship between atopy and BHR has been found in non-asthmatic subjects. In this article, we discuss the relationship between atopy and BHR in the general population, asthmatic subjects, and those with allergic rhinitis. This should widen our understanding of the pathophysiology of atopy and BHR.

Long-term asthma remission during adolescence

Asthma is a heterogeneous disorder with a variable course, characterized by episodes of cough, wheezing and shortness of breath, reversible airflow limitation, and bronchial hyperresponsiveness (BHR). It begins early in life in many subjects, and it is well recognized that over 50% of asthmatic children go into long-term clinical remission, defined as the complete absence of asthmatic symptoms and no asthma medication for at least 24 months, during adolescence. Several studies have shown spirometric abnormalities and BHR during clinical remission. It is unknown whether these functional abnormalities, which are supposed to be indicative of asthma severity with respect to symptomatic asthma, reflect persistent airway inflammation or merely indicate residual airway damage or are related to another mechanism such as a familial predisposition. It is likely that the nature of BHR in asthma remission is not same as that in symptomatic asthma. We have shown that the former condition is associated with lower levels of blood eosinophils and eosinophilic cationic protein, a lower degree of bronchial responsiveness to exercise, and a more common formation of plateau on the dose-response curve to high-dose inhaled methacholine (i.e., limited maximal airway narrowing), compared to the latter condition. It is still controversial whether BHR in adolescents with asthma remission is reduced by inhaled corticosteroids. Better understanding of the mechanisms that lead to asthma remission, especially that seen during adolescence, is likely to lead to significant advances in our understanding of asthma pathogenesis, and should provide insights into how remission might be induced with therapy. We still have minimal understanding of the mechanism underlying BHR in adolescents with asthma remission. Elucidation of this mechanism would be an important step towards new perspectives that see remission as the next therapeutic frontier in asthma.

A case of fat embolism syndrome in juvenile rheumatoid arthritis patient

Fat embolism syndrome is a serious complication that can occur after trauma or operation of the limbs. Clinical criteria are used for the diagnosis of fat embolism syndrome and sometimes radiologic findings are helpful. Fat embolism syndrome is known to occur less frequently in children than in adults, but there is an increased risk in children with connective tissue disease. However, there are only a few reported cases of fat embolism syndrome in juvenile rheumatoid arthritis which is the most common connective tissue disease in children. We report a case of fat embolism syndrome diagnosed in a 13-year-old boy with juvenile rheumatoid arthritis, which was treated with corticosteroid.

A Case of Pulmonary Hemosiderosis that was Dissolved by an Oral Prednisolone and the Milk Avoidance / 소아알레르기및호흡기학회지

A 29-month-old boy presented with fever, dyspnea, and paleness. He was initially diagnosed with pneumonia and severe sepsis. Although he was treated with intravenous antibiotics and high dose methylprednisolone, dyspnea and paleness recurred two times. Under suspicion of pulmonary hemosiderosis, we performed video-assisted thoracoscopic lung biopsy and bronchoalveolar lavage on him and found hemosiderin-laden macrophages in both specimens. Despite thorough history and laboratory examination, we could not find any pathologic or serologic evidence for primary and secondary causes of pulmonary hemosiderosis except for one that indicating Heiner's syndrome. After taking oral prednisolone he showed improvement of anemia and dyspnea, which was maintained by milk avoidance. Based on the history and the existence of immunoglobulin G antibodies against milk components, we are considering it as the case of Heiner's syndrome.

Early childhood wheezing: various natural courses and their relationship to later asthma / 소아과

Wheezing is one of the most frequent complaints that lead to the use of medical resources in younger children. Generally, wheezing is caused by bronchiolitis and resolves spontaneously without recurrence, but sometimes, wheezing can progress into asthma. Early data on the natural history of childhood wheezing was mostly obtained from retrospective reviews of medical records or from questionnaires, which made it difficult to exclude biases. Now that many cohort studies are available, reviewing the results of birth cohort studies makes it possible to understand the natural course of early childhood wheezing and the risk factors for asthma. In this study, we have reviewed the various phenotypes of early childhood wheezing and their natural courses to help select the most appropriate management modalities for the different types of early childhood wheezing.

Changes in the Indices of Bronchial Reversibility Assessed by the Office Spirometry and Their Relationship to Asthma Symptoms after Discontinuing Controller Medication in Children with Controlled Asthma: Pilot Study / 소아알레르기및호흡기학회지

PURPOSE: It is important to assess the level of control in asthmatic children who were well-controlled and thus discontinued controller medications. Office spirometry has been regarded to provide objective measures. We aimed to see time changes in lung function indices measured by the office spirometry and their relationship to clues for asthma exacerbation after discontinuation of controller medications. METHODS: As a pilot study, a total of 20 well-controlled children with persistent asthma were included. After discontinuing controller medications, each made follow-up visits at the 2nd, 6th, and 12th week. At each visit, spirometric values before and after bronchodilators were evaluated by the office-based spirometer. Time changes and their relationship to clues for asthma exacerbation were assessed. RESULTS: Among 20 children, 13 (65%) were successfully followed-up for 12 weeks with asthma kept stable. They presented similar spirometric values (forced expiratory volume in 1 second [FEV1], peak expiratory flow rate [PEFR], bronchodilator responses [BDRs] based on the FEV1 and PEFR) across all time-points. No differences in spirometric values were found between those who were stable and those who exhibited clues for asthma exacerbation. BDRs calculated from FEV1 values (BDRFEV1) correlated well with those calculated from PEFR values (BDRPEFR). CONCLUSION: When controller medications were discontinued in children with well-controlled asthma, many of them were able to maintain the stable condition. Since the spirometric measures including BDR failed to differentiate clues for asthma exacerbation, the usefulness of office spirometry needs to be reevaluated by the larger population of children with controlled asthma after discontinuing medications.

Relationship between Bronchial Hyperresponsiveness and Development of Asthma in Preschool Children with Cough Variant Asthma / 소아알레르기및호흡기학회지

PURPOSE: A significant proportion of patients with cough variant asthma (CVA) eventually develops asthma. The aim of this study was to investigate the relationship between bronchial hyperresponsiveness (BHR) and development of asthma in preschool children with CVA. METHODS: We reviewed the medical records of children aged 5 to 7 years who presented with chronic cough and had regular check-up by the school age. All children had methacholine bronchial challenge test (MBCT) at preschool age with a modified auscultation method. The end-point was defined as the appearance of wheezing and/or oxygen desaturation. Positive BHR was defined as end-point concentration (EPC)< or =8 mg/mL. MBCT was performed at the school age with spirometric method. Positive BHR was defined as PC20< or =8 mg/mL. We collected information on the development of wheezing or dyspnoea from the medical records. RESULTS: Thirty-six children with CVA were analyzed. During follow-up (2.1+/-0.9 years), 9/36 children developed wheezing or dyspnoea (group A), and 27/36 children did not (group B). EPC (geometric mean, 95% confidence interval) was significantly lower in group A than group B (1.59 mg/mL, 0.93 to 2.70 mg/mL vs. 3.43 mg/mL, 2.34 to 5.03 mg/mL; P=0.02, respectively). The prevalence of positive BHR at school age was significantly higher in group A than group B (77.8% vs. 22.2%, P<0.01). CONCLUSION: These results suggest that the increase and the persistence of BHR may have an important role in the development of asthma during the course of CVA in preschool children.

Coagulopathy as a Prognostic Factor of Acute Lung Injury in Children

The coagulation cascade and inflammatory process are known to be associated with the pathophysiology of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). We retrospectively investigated laboratory values indicating coagulopathy obtained within 24 hr from diagnosis of ALI/ARDS in 79 children who received mechanical ventilation between 2008 and 2009 and their final outcomes. Prothrombin time (PT) (P = 0.001) and activated partial thromboplastin time PTT (APTT) (P = 0.001) were more prolonged in non-survivors than survivors (mean; 1.57 vs 1.33; 63 vs 57). In multivariate analysis with stratification by oxygenation-index ( or = 14.5), prolonged PT (> or = 1.46 international normalized ratio, [INR]) (hazard ratio; 2.043, 1.027-4.064) was associated with lower non-pulmonary-organ-failure-free survival rate (FFS), and prolonged APTT (> or = 50 seconds) (2.062, 1.031-4.121; 2.422, 1.227-4.781) was associated with lower overall survival rate (OS) and lower FFS. In stratification by ventilation-index ( or = 40), prolonged PT (2.232, 1.095-4.540; 2.177, 1.092-4.342) and prolonged APTT (2.574, 1.230-5.386; 3.089, 1.500-6.360) were associated with lower OS and lower FFS. Prolonged PT and APTT are associated with mortality in mechanically ventilated children with ALI/ARDS. We suggest PT and APTT as prognostic factors of ALI/ARDS in children.

Predisposing Factors Associated With Chronic and Recurrent Rhinosinusitis in Childhood

PURPOSE: There is currently no information regarding predisposing factors for chronic and recurrent rhinosinusitis (RS), although these are considered to be multifactorial in origin, and allergic diseases contribute to their pathogenesis. We evaluated the predisposing factors that may be associated with chronic and recurrent RS. METHODS: In this prospective study, we examined patients with RS younger than 13 years of age, diagnosed with RS at six tertiary referral hospitals in Korea between October and December, 2006. Demographic and clinical data related to RS were recorded and analyzed. RESULTS: In total, 296 patients were recruited. Acute RS was the most frequent type: 56.4% of the patients had acute RS. The prevalences of other types of RS, in descending order, were chronic RS (18.9%), subacute RS (13.2%), and recurrent RS (11.5%). Factors associated with recurrent RS were similar to those of chronic RS. Patients with chronic and recurrent RS were significantly older than those with acute and subacute RS. The prevalences of allergic rhinitis, atopy, and asthma were significantly higher in patients with chronic and recurrent RS than those with acute and subacute RS. CONCLUSIONS: An association between atopy and chronic/recurrent RS, compared to acute and subacute RS, suggests a possible causal link.

Predictors of Mortality and Complication in Pediatric Patients Who Require Continuous Renal Replacement Therapy in Pediatric Intensive Care Unit / 대한구급학회지

BACKGROUND: The objective of this study is to analyze the factors associated with mortality and complication in children requiring continuous renal replacement therapy (CRRT) in a pediatric intensive care unit. METHODS: We retrospectively analyzed 96 patients who required CRRT at a pediatric intensive care unit in Seoul National University Hospital between April 2005 and April 2011. We evaluated the clinical features, diagnosis, mortality risk factors and complications related to CRRT. RESULTS: Univariate and multivariate analyses were performed to analyze the mortality risk factors of patients requiring CRRT. The overall mortality was 56.3%, the median age was 8 years, and the ages ranged from 4 days to 22 years. The median weight of the patients was 7.9 kg, and the weights ranged from 3.6-72.9 kg. 16 patients were diagnosed with primary renal disease, and the remainder with other underlying diseases. Mortality was higher in children who received stem cell transplantation and in children with a diagnosis of imunologic disease and neurologic disease. The Pediatric Risk of Mortality (PRISM) III score at initiating CRRT was 17.8 +/- 8.9 and the degree of fluid overload at CRRT (FO%) was 12.9 +/- 16.0. The PRISM III score at the start of CRRT and low uric acid level were the factors associated with an increased risk of mortality. Of the 96 children, 13 (13.53%) presented problems of venous catheterization. Hypotension during connection to CRRT was detected in 28 patients (29.2%). Clinically significant hemorrhage occurred in 10 patients (10.4%). CONCLUSIONS: Children who require CRRT have a high mortality rate. The higher score of PRISM III at the starting time of CRRT and the lower uric acid level are the factors associated with a higher mortality. The most frequent complication of CRRT was hypotension on connection to CRRT.

Atelectasis and the Risk Factors in the Patients Admitted to Pediatric Intensive Care Unit / 대한구급학회지

BACKGROUND: Atelectasis is a state of a collapsed and non-aerated region of the lung parenchyma, which is otherwise normal. This condition is usually associated with pulmonary disorders. The purpose of this study is to analyze the incidence and risk factors of atelectasis in patients admitted to the pediatric intensive care unit (PICU). METHODS: We retrospectively analyzed the clinical characteristics and chest radiography of 280 PICU patients under 18 years old. We analyzed the incidence and pattern of atelectasis and compared the incidence according to the phase and mode of mechanical ventilation. We compared the incidence of ventilator care need and respiratory disease in 93 atelectasis patients. RESULTS: Atelectasis incidence was 33.2%. The age (4.9 +/- 4.4 years) was younger and the admission-duration (17.8 +/- 25.1 days) was significantly longer in atelectasis patients (p < 0.01). Ventilator care need and respiratory disease in atelectasis patients (86.0%, 66.7% respectively) was significantly higher than in non-atelectasis patients (62.6%, 43.3% respectively) (p < 0.01). Atelectasis incidence in ventilator-required patients and respiratory-diagnosed patients (40.6%, 43.4% respectively) was significantly higher than that in non ventilator-required patients and non respiratory-diagnosed patients (15.7%, 22.6% respectively) (p < 0.01). Atelectasis was more common in the right upper lobe (55.6%) and during or after ventilator care (62.6%) (p < 0.05). Atelectasis incidence in ventilator care did not differ between the assist-control and intermittent mandatory ventilation modes. CONCLUSIONS: In the PICU, atelectasis incidence was higher in patients with ventilator care and respiratory disease. Atelectasis was more common in the right upper lobe and in the phase after ventilator initiation. Atelectasis incidence in ventilator care did not differ between ventilation modes.