Acute bronchiolitis in children: everything you need to know


Web Team :
Acute bronchiolitis is a very common, acute chest (lower respiratory tract) infection in infants and toddlers. It is one of the most common reasons for nebulization of infants at hospitals and it is one of the most common ailments encountered by a 
pediatrician. This disease typically starts with cough and running nose, which may or may not progress to breathing difficulty (respiratory distress). Usually, infants are affected but this disease can present up to 2 years of age. The common causative organisms are viruses namely Respiratory syncytial virus (RSV), parainfluenza virus, adenovirus, and influenza viruses.In clinical practice, atypical organisms like Mycoplasma pneumoniae has also been seen as the causative agent for this disease. The infant generally acquires these viruses from family members through fomites or in other words, usually, there will be someone else in the family who has rhinitis.

Maternal antibodies cannot provide protection for the infants as the protective antibody for RSV is IgG3 subtype and it can’t cross placenta to reach the body of fetus. However, secretory antibody IgA which is present in breast milk is protective and hence the incidence of this disease among breastfed infants is far less than that of bottle-fed infants.

Pathogenesis


The viral infections initiates a cascade of inflammatory processes in the airway of lungs, leading to edema (swelling), thickening, formation of mucus plugs and cellular debris in the airways. The airways of infant is already tiny as compared to older children and this acute insult can lead to breathing difficulty in infants as there is reduction in airway radius due mucus plugs. Airway resistance is inversely related to the fourth power of the radius;even a slight decrement of radius can exponentially increase the airway resistance.During expiration, the bronchioles (smaller airways) are partially collapsed and expiration of air from the lungs is limited resulting in trapping of the air inside the alveoli causing over inflation of lungs. When obstruction becomes complete with these mucus plugs and cellular debris, the trapped air in the lungs may be absorbed causing atelectasis (collapse of lungs). All these changes eventually lead to decrease in oxygen levels in the body and accumulation of carbon dioxide.

Clinical Features, course and prognosis


After prodromal symptoms such as of cough and running nose, child develops fast breathing and breathing difficulty. A major chunk of infants recover infection within 7 days; even though cough may be present for another week. On auscultation, creptitationsand wheeze may be present. X-rays will show features resembling hyperinflation, atelectasis etc. Few infants will develop severe symptoms and may require oxygen supplementation and in-patient care. If symptoms are severe, breath sounds will be barely audible with a stethoscope, oxygen levels will fall and child may even require ventilator support.
Bronchiolitis is generally a self-limiting illness which will settle by nebulization with hypertonic saline and nasal decongestants, but it has a potential for grave outcomes. Antibiotics are not routinely given as it is a viral induced disease where antibiotics don’t have a role. The symptoms subside in three to seven days if the course is mild. Death may occur in one percent of the severely ill patients due to respiratory failure. One fourth of children who presented with this disease in early age will develop bronchial asthma later in life.

Advice to the patients on prevention

As it is transmitted by fomites, the best way to prevent the spread of these viruses to your kid’s body is hand washing. Wash your hands regularly if you are handling your infant, especially after touching your nose and mouth. The infective viruses present in your nostril may not cause any problem for you but it can trouble your kid a lot. Avoid contact of your child with other people who is known to have cough or rhinitis. For heaven’s sake, don’t resort to salbutamol nebulization at home for this disease as salbutamol is of no effect in this disease and in fact salbutamol can cause harm if not given along with oxygen. Take your kid to a pediatrician if the running nose and cough persists for 3 days or longer, or child develops respiratory distress. Nasal decongestants and nebulization using 3% saline is the primary modality of treatment for this disease which will be available even in primary health care centers. It is advisable to take influenza vaccine annually at least till 5 years so that incidences of upper airway and lower airway viral infections can be reduced.

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