Med Note [1]: Respiratory Syncytial Virus

Chapter 1 – Respiratory Syncytial Virus (RSV)

v History & Physic’ Exam

o ~ present w/: fever (typic’ low grade); cough; tachypn’; cyanos’; retracti’; wheezi’; rales; & sepsislike presentati’ or apneic episodes (in very young infants).

o In infant, RSV can cause variety of ill’, presenti’ w/ cold-like ill’, sometimes (+) fever (can also (+) bronchit’, croup, & LRTI s.as (25-40% cases) (+) bronchiolit’ & pneumon').

o Infant w/ LRTI typic’ (+) runny nose, ↓ed appetite before (+) other sympt’, cough usu’ (+) at 1-3 days later, then ~ (+) sneezi’, fever, & wheezi’. In very young infant, ~ only (+) irritabil’, ↓ed activi’, & apnea.

o Phys’ exam’ of infant w/ RSV Lower Respiratory Tract Infection (LRTI) (+) evidence of diffus’ small airway ill’. 40% cases in child’, + related otitis media (~ viral & or bacterial). Hydrati’ status assessm’ (eg: via skin turgor, capillary refill, & mucous membran’) is importa’ at infant w/ bronchiolit’.

o In adults (particular’ (+) at healthcare workers & caretakers of small child’), usu’ lasts < 5 days usu’ w/ Upper RTI (URTI)-consistent sympt’ (can include rhinorrhea, pharyngit’, cough, headache, fatig’, & fever), but at high-risk Px (immunosupressed or (+) certain chronic ill’) ~ (+) more +++ sympt’ (LRTI-consistent) s.as pneumon’.

v Complicati’

o InPx RSV LRTI infant has higher risk (~ lasts > 10 years) for subseq’ wheezi’ & abnorm’ pulmon’ funct’.

v DDx

o High risk of for +++ RSV infec’, in:

o Prematu’ infant in 1st year of life (younger child at RSV season, the higher risk).

o Infant w/ chronic lung ill’ (eg: bronchopulmon’ dysplas’, or cystic fibrosis) during 1st 2 years of life.

o Child w/ hemodynamical’ signific’ congeni’ ♥ ill’, espec’ w/ ↑ed pulmon’ blood flow.

o Immunodefici’ Px.

o Child’ w/ metabol’ disord’, structur’ airway abnorm’, & neuromuscul’ disord’.

o Children of multiple births ( ≥ triplets).

o Adenoviruses

o Asthma

o Bronchiolitis

o Croup

o Human Metapneumovirus

o Influenza

o Neonatal Sepsis

o Other respiratory viruses

o Parainfluenza Virus

o Pediatric Bronchitis

o Pediatric Pneumonia

v Workup

o Lab studies

§ General’ Ø indicated @ in infant w/ bronchiolit’ who is comfortab’ in room air, well-hydrated, & feeding adequate’.

§ Øspecific lab studies: CBC (~ (+) normal or mild’ ↑ed WBC count & ↑ed % of band forms); blood culture (frequent’ obtained, rare’ (+) pathogen’ bacter’); Arterial Blood Gas (~ indicated if (+) concerni’ CO₂ retenti’); serum electrolyte concentrati’; urinalysis; O₂ saturati’ measurem’.

§ Specific lab studies (~ indicated for deciding of Tx (eg: withdrawi’ unnecessary antibiot’) needs of Px isolation, education for parents & staff) to confirm RSV infec’ are readi’ availab’ & performab’ on sample of secretion ((for virus) culture, antigen-reveali’ technic, or PCR) taken by washi’, suctioni’, or swabbi’ the nasopharynx (molecular probes to detect RSV at clinic’ specimen ~ more sensitive).

§ General’, Antigen-detecti’ & culture technic’re reliab’ in young child, less useful in older child & adults.

§ RT-PCR should be considered, espec’ toward older children & adult Pxs because their respirat’ specimens ~’ve low viral loads.

§ Antigen-detecti’ technic ~ (+) Dx w/in hours & obtained reliably w/o sophisticated virolo’ Lab. (Critical) Test performa’ monitoring to maintain appropriate sensitivity & specificity.

o Chest Radiography

§ Frequent’ obtained at child +++ RSV infec’. Typic’ (+) hyperinflated lung fields w/ diffuse ↑ in interstiti’ markings. 20-25% cases, (+) areas of atelectasis or pulmon’ infiltrates. General’, not specific & not course-predictive except if infant w/ addition’ find’ of atelectasis or pneumon’ (~ (+) +++ course).

o Histolo’ Find’

§ (In infant whose died of RSV bronchiolit’) (+) MN cell & neutrophil infiltrati’ of peribronchiol’ areas, necrosis of small airway epitheli’, plugging of lumens w/ exudat’ & edema, & atelectasis & hyperinflati’.