Bronchiolitis Caused by RSV: A Clinical Review

VAPOTHERM

The Standard in High Flow Therapy

RSV and BronchiolitisEtiology, 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)

5

• 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

Overview of Bronchiolitis Caused By RSV

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: PathophysiologyThe 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 TreatmentSymptoms, 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 PatientsMild Cases:

Cardio-respiratory Monitoring

Pulse Oximetry

Oxygenation Supplementation

Maintenance of Hydration

Moderate & Severe Cases:

CPAP

Humidification

High flow nasal cannula

Mechanical ventilation

Traditional Respiratory Support

Low Flow Oxygen

Non-Invasive Ventilation

Intubation

High Flow TherapyRespiratory Support for Bronchiolitis

Accepted standard of care:

Humidity

Effects of High Flow Therapy via Nasal Cannula on Bronchiolitis:

Flush out of dead space removes CO2

Creates internal reservoir of desired FiO2

Decreases work of breathing

Setting flow rates to exceed the patients inspiratory demand:

Patient breathes through own airway instead of from external source (ie: mask)

How High Flow Therapy Impacts Bronchiolitis:

Why is heat and humidity important?

•Improves mucocilliary process

•Allows tolerability of higher flow rates

•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 ImpactBy instituting High Flow Therapy:

Secretion Management

Provide precise FiO2

Reduce WOB with dead space flush

Allows for better feeding tolerance

Improving Patient Tolerance & ComfortNot 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 ReviewHigh 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.

Overall298 infants <24 months of age received HFT. 36 infants (12%) required escalation to MVNo 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.

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.

Schibler et al. Intensive Care Med. 2011;37(5):847-52.

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