Impulse Oscillometry to Evaluate Lung Function in Young Children Under Five Years with Sickle Cell Disease

• Published in: Blood 2019-11, Vol.134 (Supplement_1), p.4853-4853
• Main Authors: Enokekwa, Lawson, Ngo, Tony, McKie, Kathleen, Badamosi, Nnenna R
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2019-121349

BACKGROUND Young children with sickle cell disease (SCD) aged 2 - 5 years old are at the highest risk of acute chest syndrome (ACS), a leading cause of morbidity and mortality. In addition to severe forms of SCD (HbSS and HbSβ0 thalassemia), asthma and airway hyper-responsiveness are also known risk factors for ACS, and are three to five times more prevalent in older children and adults with SCD. However in SCD children under 5 years there are only a few studies describing airway function, due to limitations in spirometry and other common pulmonary function tests (PFTs). Impulse oscillometry, a passive, non-invasive technique to evaluate airway function via pulmonary resistance and reactance, has been validated in children as young as 3 years, but has not been used widely in children with SCD. OBJECTIVE We sought to describe baseline airway function in children under 5 years with SCD using impulse oscillometry, as part of an ongoing observational study to evaluate lung function in young SCD children over time. METHOD Following IRB approval, participation in the ongoing prospective study was offered to patients aged 3 - 5 years old with HbSS and HbSβ0 thalassemia followed at the Pediatric Sickle Cell Clinic at Augusta University. Parents of the consented patients completed a modified ISAAC questionnaire assessing reported asthma symptoms and tobacco smoke exposure. Baseline IOS was obtained within 6 months of consent, with other clinical data obtained from medical records. Airway function was assessed using airway resistance at 5Hz and 20Hz (R5, R20), and reactance at 5Hz (X5). Percent predicted values were computed using NHANES (National Health and Nutrition Examination Survey) reference criteria for age, height, gender and ethnicity. RESULTS Out of 9 consented patients, 7 completed the ISAAC questionnaire and 6 successfully performed IOS. One patient consented but deferred participation to next visit and 1 patient with HbSC was excluded from analysis. All remaining patients had sickle cell anemia (HbSS). Age range at study enrolment was 3.7 - 5.4 years (mean 4.6 years). All participants were African American, 4/7 were male. Four out of 7 survey participants were already on Hydroxyurea therapy for their disease with therapy duration ranging from 2 - 41 months. None had preceding history of ACS. One survey respondent reported asthma symptoms (wheezing, dry cough at night) in preceding 12 months and 1 reported passive tobacco exposure. None reported a prior