Vitamin D and BronchiolitisChris Prestel, MD10/30/12

L'enfant a une bronchiolite

What is it?• Acute inflammation of the bronchioles• Usually seen about 1 week after exposure from minor URI of an

adult• mild URI with sneezing and rhinorrhea decreased appetite

and possible fever respiratory distress with wheezing, cough, dyspnea, and irritability• Often tachypneic which can interfere with feeding• Young infants/premature infants may present with apnea• Usually does not include other systemic complaints

• Physical exam dominated with wheezing, tachypnea, increased work of breathing, crackles, prolonged expiratory phase and even poorly audible breath sounds or hyperinflation of the lungs

What is it? • RSV responsible for >50% of cases• Parainfluenza, adenovirus, and Mycoplasma are other culprits• No evidence of bacterial cause, but can have superinfections

• RSV causes eosinophil degranulation cationic protein cytotoxic to airway epithelium bronchiolar obstruction with edema, mucus and cellular debris• r^4 Poiseuille's equation – small changes = big results• Resistance is greater on expiration often causing air trapping

leading to atelectasis hypoxemia due to ventilation-perfusion mismatch possible hypercapnea

How we treated it in Burundi• There was one oxygen compressor for the entire hospital• Had to choose who needed oxygen more and who had the best

chance of survival• Minimal stimulation and elevated positioning• Often could not feed; tried to give fluids• Suctioned with bulb syringe

• Standard is cool, humidified oxygen with chest/neck elevation, nasogastric feeds, suctioning of secretions, possible intubation if further increased work of breathing ensues.

Role of Vitamin D• Essential nutrient which is known to regulate over 1000 genes

and most cells have receptors designed to fit Vitamin D. • 40% of pregnant women and 50% of newborns and infants

have vitamin D insufficiency. • Related to diseases in offspring such as Type 1 Diabetes, MS,

schizophrenia and acute respiratory infections• Thought to protect against severe RSV by possibly decreasing

inflammatory response of airway epithelial cells without jeopardizing viral clearance

Question• P: Newborns/infants with Bronchiolitis

• P: Vitamin / Nutrient level

• C: Nutrient deficient vs. nutrient replete

• O: Increased or decreased incidence of bronchiolitis

Search Strategy• Source: Pubmed• Search Terms: Bronchiolitis + Vitamin (39)• Bronchiolitis + Vitamin + Newborn (16)

• Bronchiolitis + Vitamin + Newborn + Free Full Text (4)

Search Results• Vitamin D intake in young children with acute lower respiratory

infection• Prenatal prevention of respiratory syncytial virus bronchiolitis• Cord blood Vitamin D deficiency is associated with respiratory

syncytial virus bronchiolitis• Vitamin D receptor polymorphisms and risk of acte lower respiratory

tract infection in childhood

Study Design – Prospective Birth Cohort

Characteristics of Study Population

Outcomes• Primary defined as parent-reported RSV LRTI• LRTI symptoms and presence of RSV RNA in a nose-throat swab

specimine• Symptoms recorded in journal • Then reviewed by two researches

• Moderate to severe cough or wheeze of any severity lasting for at least 2 days. Swab obtained on second day of every episode. Then underwent real-time PCR for dection

• Secondary was “physcian atteneded RSV LRTI”• Infant with respiratory symptoms was seen by general

practitioner or pediatrician who did a nose-throat swab and was positive for RSV RNA

Analysis• Cord blood plasma Vitamin D (25-0HD) concentration normally

distrubted and compared using Student’s t test• Used when scaling term is unknown and replaced by an estimate

scale• χ2 used to analyze association between categorical variables• Due to limited number of RSV LRTI there was restricted

number of potential confounders that could be analyzed • Birth month adjustment• “Deseasonalization” – “Predicted 25-OHD concentrations based on

birth month for each subject, derived from the sinusoidal model, were subtracted from the actual observed value. Subsequently, the overall mean was added and the resulting deseasonalized 25-OHD concentrations were analyzed using logitistic regression analysis, also adjusting for maternal ethnicity and birth weight”

References• http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional

/ (Vitamin D table)• Nelsons Textbook of Pediatrics• UpToDate