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Bronchiolitis Caused by RSV: A Clinical Review VAPOTHERM The Standard in High Flow Therapy RSV and Bronchiolitis Etiology, Epidemiology and Pathophysiology Course Objectives • Define bronchiolitis and RSV • Understand the etiology, pathophysiology and epidemiology of bronchiolitis caused by RSV • Explain the clinical signs and symptoms of bronchiolitis • Understand how the characteristics of High Flow Therapy (HFT) play a role in the treatment of the symptoms of Bronchiolitis • Review key research on the application of High Flow Therapy in pediatric bronchiolitis patients Bronchiolitis • Acute inflammation of the bronchioles • characterized by swelling and mucus buildup • Typically caused by a viral infection such as RSV • Prevalent in young infants • The leading cause of infant hospitalization in the US Chest x-ray of infant with RSV (James Heilman, MD) Overview of Bronchiolitis Caused By RSV • In children under 1 year, RSV is the most common cause of bronchiolitis • All children get RSV in first 3 years of life but in a small % of them, it creates serious infection • Most common cause of lower respiratory tract infection in the first year of life 5 Bronchiolitis: Etiology Most cases result from a viral pathogen RSV Parainfluenza virus Influenza virus Adenovirus RSV is the most common 75% of children younger than 2 hospitalized for bronchiolitis. Bronchiolitis in the ED1 277 samples tested Positive for: RSV – 64% Rhinovirus - 16% Human metapneumovirus (hMPV) - 9% Influenza A virus - 6% 1. Mansbach JM, McAdam AJ, Clark S, Hain PD, Flood RG, Acholonu U. Prospective multicenter study of the viral etiology of bronchiolitis in the emergency department. Acad Emerg Med. Feb 2008;15(2):111-8. Respiratory Syncytial Virus: RSV RSV is an enveloped RNA virus Two strains (A & B ) are recognized RSV is from common viral family (Paramyxovirdae) RSV infection can be confirmed using a simple lab technique Direct Fluorescent Antibody detection (DFA), Transmission Electron Micrograph of RSV Transmission Highly contagious Spreads through: • nasal secretions • airborne droplets • Fomites RSV: Epidemiology Each year, nearly 125,000 children are hospitalized due to an RSV infection RSV is seasonal 93% of cases occurring between November and April Reinfection is common From CDC Bronchiolitis: Epidemiology More than 1/3 of children develop bronchiolitis in the first two years of life 3% of infants hospitalized in U.S. Low mortality with fewer than 400 deaths annually For infants under 6 months, 17 hospitalizations and 55 ED visits per 1000 children due to RSV Bronchiolitis: Pathophysiology The effects of bronchiolar injury include the following: Increased mucus secretion Bronchial obstruction and constriction Alveolar cell death, mucus debris, viral invasion Air trapping Atelectasis Labored breathing Pathophysiology in Infants Infants are affected because: • Small airways • High closing volumes • Insufficient collateral ventilation Recovery: • Regeneration of bronchiolar epithelium after 3-4 days • Cilia do not appear for as long as 2 weeks. Risk Factors Risk factors for the development of bronchiolitis include the following: Low birth weight Gestational age Lower socioeconomic group Crowded living conditions / daycare Parental smoking Risk Factors Chronic lung disease, particularly bronchopulmonary dysplasia Severe congenital or acquired neurologic disease CHD w/ pulmonary hypertension Congenital or acquired immune deficiency diseases Age less than 3 months Airway anomalies Diagnosis and Treatment Symptoms, Admissions Criteria and Treatment Clinical Signs & Symptoms Examination often reveals the following: Tachypnea Tachycardia Fever (38-39°C) Retractions / nasal flaring Fine rales / Diffuse, fine wheezing Hospital Admissions Criteria Respiratory Status Respiratory distress, apnea, Tachypnea (>70 br/min) and/or clinical evidence of increased work of breathing Patient requires oxygen supplementation Patient requires continuous clinical assessment of airway clearance and maintenance using bulb suctioning Nutritional Status Patient is dehydrated Patient is unable to maintain oral feedings at a level to prevent dehydration AHRQ national guidelines Complications • Acute respiratory distress syndrome (ARDS) • Bronchiolitis obliterans • Congestive heart failure • Secondary infection • Myocarditis • Arrhythmias • Chronic lung disease Treatment and Management No definitive treatment At present, only oxygen appreciably improves the condition of young children with bronchiolitis.7 Medications have a limited role in the management of RSV and bronchiolitis Treatment & Management in Hospitalized Patients Mild Cases: Moderate & Severe Cases: Cardio-respiratory Monitoring CPAP Pulse Oximetry Oxygenation Supplementation Maintenance of Hydration Humidification High flow nasal cannula Mechanical ventilation Traditional Respiratory Support Low Flow Oxygen Non-Invasive Ventilation Intubation High Flow Therapy Respiratory Support for Bronchiolitis Accepted standard of care: Humidity Effects of High Flow Therapy via Nasal Cannula on Bronchiolitis: Setting flow rates to exceed the patients inspiratory demand: Flush out of dead space removes CO2 Creates internal reservoir of desired FiO2 Patient breathes through own airway instead of from external source (ie: mask) Decreases work of breathing How High Flow Therapy Impacts Bronchiolitis: Why is heat and humidity important? •Allows tolerability of higher flow rates •Improves mucocilliary process •Decreases energy expenditure Effects of HFT on Bronchiolitis: Inflammed bronchiole as a result of bronchiolitis Ideally heated and humidified gas improves and facilitates airway conductance Once open, much needed oxygen can now reach the alveoli, allowing for proper gas exchange The Importance of Humidification: Damaged cilia Mucus collection The Importance of Humidification: Heated and humidified gas restores cilia to its natural state, allowing for secretion clearance Clinical Impact By instituting High Flow Therapy: Secretion Management Provide precise FiO2 Reduce WOB with dead space flush Allows for better feeding tolerance Improving Patient Tolerance & Comfort Not a mask therapy, resolves: Tolerance and adherence issues Feeding issues High flow cannula provides: simple interface Improves comfort / tolerance Less skin trauma Decreased acuity of care The Simplicity of the Nasal Cannula Research Review High Flow Therapy and Bronchiolitis Reduced intubation rates for infants after introduction of high-flow nasal prong oxygen delivery Schibler A, Pham TM, Dunster KR, Foster K, Barlow A, Gibbons K, Hough JL. Intensive Care Med. 2011; 37(5):847-52. A retrospective chart review to: Describe the change in PICU ventilatory practice after adoption of HFT. Identify the patient subgroups requiring escalation of therapy. Schibler et al. Intensive Care Med. 2011;37(5):847-52. Overall 298 infants <24 months of age received HFT. 36 infants (12%) required escalation to MV No adverse events Subgroup - viral bronchiolitis Of 167 infants, only 6 (4%) required escalation to MV. Rate of intubation reduced from 37% to 7%, corresponding to an increase in the use of HFT. Schibler et al. Intensive Care Med. 2011;37(5):847-52. Conclusions: HFNP therapy has dramatically changed ventilatory practice in infants <24 months of age Appears to reduce the need for intubation in infants with viral bronchiolitis. High Flow Nasal Cannulae Therapy in Infants with Bronchiolitis McKiernan C, Chua LC, Visintainer PF, Allen H Journal of Pediatrics. 2010; 156(4):634-638. A retrospective chart review to of infants <24 months old with bronchiolitis Goal to determine if the introduction HFT was associated with decreased rates of intubation McKiernan et al. Journal of Pediatrics. 2010; 156(4): 634-638. Season after the introduction of HFT vs Season prior: Decrease in intubation from 23% to 9% (p < 0.05) HFNC therapy resulted in a greater decrease in respiratory rate compared with other forms of respiratory support infants with the greatest decrease in respiratory rate were least likely to be intubated Median PICU length of stay decreased from 6 to 4 days McKiernan et al. Journal of Pediatrics. 2010; 156(4): 634-638. HFT appears to decreases rates of intubation in infants with bronchiolitis by decreasing the respiratory rate and work of breathing Provides a comfortable and well-tolerated means of noninvasive ventilatory support. Summary of Study Conclusions High flow therapy has been shown to reduce intubation rates in infants with bronchiolitis High flow therapy is well tolerated High flow therapy administered with heliox further improved respiratory scores Thank You ! Questions? Resources: Clinical Practice Guidelines American Academy of Pediatrics, Diagnosis and Management of Bronchiolitis, 2006 Cincinnati Children's Hospital Medical Center (CCHMC). Evidence-based care guideline for management of first time episode bronchiolitis in infants less than 1 year of age. Cincinnati, OH Scottish Intercollegiate Guidelines Network (SIGN). Bronchiolitis in children. A national clinical guideline. Edinburgh (Scotland): Scottish Intercollegiate Guidelines Network (SIGN); 2006 Nov. 41 p