Respiratory System_ b Flashcards
What is bronchiolitis?
Bronchiolitis is an infection and inflammation in the bronchioles (small airways of the lungs), most commonly occurring in winter months.
What is the most common cause of bronchiolitis?
. Respiratory syncytial virus (RSV) is the most common cause. Other causes include rhinovirus and adenovirus.
W hat age group is most affected by bronchiolitis?
Bronchiolitis generally affects infants under 1 year of age, with the highest incidence in infants under 6 months. It can be diagnosed in children up to 2 years, particularly in ex-premature babies with chronic lung disease
. What is the basic pathophysiology of bronchiolitis?
Inflammation, edema, and increased mucus production in the bronchioles cause airway narrowing, obstructing airflow. This leads to increased work of breathing and reduced oxygen saturation.
Why are infants particularly susceptible to significant symptoms with bronchiolitis?
Infants’ airways are very small, so even minimal narrowing can cause significant symptoms.
What is the typical course of RSV infection?
RSV infection usually starts with coryzal symptoms, with chest symptoms appearing 1-2 days later, peak symptoms on days 3-5, total duration of 7-10 days, and full recovery within 3 weeks.
What percentage of infants with RSV infection develop bronchiolitis?
Approximately 50% of infants with RSV infection go on to develop bronchiolitis.
What are the presenting symptoms of bronchiolitis?
Coryzal symptoms, dyspnea, tachypnea, reduced feeding, mild fever (under 39°C), apneas, and possible cyanosis.
What auscultation findings are typical in bronchiolitis?
Widespread harsh breath sounds, wheezes, and crackles.
List the signs of respiratory distress in an infant with bronchiolitis.
Raised respiratory rate, accessory muscle use, intercostal and subcostal recessions, nasal flaring, head bobbing, tracheal tug, and grunting.
What causes wheezing and when does it occur?
Wheezing is a whistling sound caused by airway obstruction, occurring during exhalation.
What is grunting and why does it occur?
Grunting is caused by exhaling with the glottis partially closed to create positive end-expiratory pressure, helping keep airways open during exhalation
What is stridor and is it a feature of bronchiolitis?
Stridor is a high-pitched inspiratory noise caused by upper airway obstruction. It is not typically a feature of bronchiolitis
What are reasons for hospital admission in bronchiolitis?
Age under 3 months, pre-existing conditions, reduced fluid intake, dehydration signs, respiratory rate above 70, oxygen saturation below 92%, severe respiratory distress, apneas, cyanosis, and difficulty managing at home.
What are the key management approaches for bronchiolitis?
Ensuring adequate fluid intake, saline nasal drops and suctioning, supplementary oxygen if needed, and ventilatory support if required.
Why might smaller, more frequent feeds be recommended?
A full stomach restricts breathing, so smaller and more frequent feeds may be better tolerated.
What treatments are NOT recommended for bronchiolitis according to guidelines?
Nebulized hypertonic saline, bronchodilators, steroids, and antibiotics.
What are the steps of respiratory support that may be required in severe bronchiolitis?
Low-flow oxygen, high-flow humidified oxygen, continuous positive airway pressure (CPAP), and intubation/ventilation.
What is the purpose of high-flow humidified oxygen?
It adds positive end-expiratory pressure (PEEP) to help maintain airways and prevent them from collapsing during exhalation.
What are the signs of inadequate ventilation on blood gas monitoring?
Rising pCO₂ and falling pH (respiratory acidosis).
When is the RSV vaccine recommended for pregnant women and how does it protect the baby?
From 28 weeks of gestation; it creates antibodies in the mother that pass through the placenta to provide protection for the first 6 months of the baby’s life.
What is palivizumab and who receives it?
Palivizumab is a monoclonal antibody targeting RSV, given as monthly injections to high-risk babies (e.g., ex-premature and those with congenital heart disease).
How does palivizumab differ from vaccines in terms of immunity?
Palivizumab provides passive protection by directly injecting antibodies against RSV. Unlike vaccines, it doesn’t stimulate the immune system to create new antibodies, and levels decrease over time requiring repeated doses.
What do the South African guidelines say about management of Bronchiolitis ?
-MEDICINE TREATMENT
For all hospitalised patients
Only if saturation < 92%:
Oxygen, humidified, 1–2 L/min via nasal prongs or nasal cannula.
o Ensure clear nasal passages and correctly position the nasal
prongs.
For outpatient-based therapy nebulise with:
Epinephrine (adrenaline) 1: 1 000, 1 mL diluted in 2–4 mL sodium
chloride 3% immediately and every 2–4 hours.
For inpatient therapy nebulise with:
Sodium chloride 3%, solution, 2–4 mL, 4–6 hourly.
Mix 3 mL of 5% sodium chloride with 2 mL water to make 3% solution.
If there is poor response or deterioration, change to:
Epinephrine (adrenaline) 1: 1 000, 1 mL diluted in 2–4 mL sodium
chloride 3% immediately and every 2–4 hours.
PLUS
Sodium chloride 3%, solution, 2–4 mL, 4–6 hourly.
Antibiotic therapy
Routine antibiotic therapy is not indicated. Only use antibiotics if there is:
» raised leukocyte count,
» persistent fever of 38.5 C, and/or
» a chest X-ray showing opacification suggestive of pneumonia.
For secondary bacterial infection:
Amoxicillin, oral, 30 mg/kg/dose, 8 hourly for 5 days.
Note:
There is no evidence that 2-agonists, anticholinergics, inhaled
corticosteroids or leukotriene receptor antagonists have any benefit in these
children. In severe disease requiring intensive care, oral corticosteroids may
be considered after specialist consultation.
REFERRAL
» Bronchiolitis with signs of respiratory failure.
