Bronchiolitis Depends on Age
International University of Brcko District, Bosnia and Herzegovina
Correspondence to: Sinisa Franjic; International University of Brcko District, Bosnia and Herzegovina, E-mail: firstname.lastname@example.org
Received: November 21, 2019; Accepted: December 18, 2019; Published: December 24, 2019
Copyright: © 2019 Franjic S. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.View / Download Pdf
Bronchiolitis is a respiratory disease caused by a respiratory infection that affects tiny air channels, bronchioles, which lead to the lungs. When the canal inflammation occurs, they overturn and fill the mucus, thereby aggravating the breathing of the baby. The disease most commonly affects infants and young children, because their tiny air channels can easily clog up, which is not the case with older children and adults. Bronchiolitis usually occurs during the first two years of age with the highest incidence rate between three and six months of age. It occurs more often in boys, children who are not breastfeeding and children who live in overcrowded conditions. Kindergartens’ stay, and exposure to cigarette smoke may also increase the possibility that babies develop bronchiolitis.
Symptoms; Disorders; Cause; RSV
Bronchiolitis is a clinical syndrome that comprises a group of presumed viral lung infections in children . Although many cases are thought to be due to RSV, a substantial percentage of clinically indistinguishablecases test negative. As bronchiolitis is not a uniform disease, treatment responses are variable and the literature is varied with regard to treatment recommendations. Options include steroids, beta-agonists, and nebulized epinephrine. The effectiveness of steroids is thought to be highest in cases where the child has underlying reactive airway disease (usually bronchopulmonary dysplasia or asthma). For a child with allergies and eczema, steroids may be effective therapy if he or she has bronchiolitis. The dosing of the steroids is the same as for asthma: 2mg/kg/day once daily (or divided into two equal doses) for 5 days. Betaagonists seem to work for some children and not for others. A trial of two or three nebulized albuterol treatments may be undertaken in the ED. If effective, treatment may be continued as an outpatient using an inhaler with a spacer and mask or as an inpatient with a nebulizer. If ineffective, further treatments are not usually helpful. The use of nebulized epinephrine is currently controversial. Clinical experience suggests that some children respond well to nebulized epinephrine (at least transiently) while others do not. However, recently performed, well-designed studies have failed to show a significant benefit. Antiviral treatment (e.g. with ribavirin) has no role in the ED.
Infants and young children have relatively narrow airways, with high resistance . If the diameter of these small airways is decreased, the work of breathing can increase dramatically. The airways can narrow due to inflammation (e.g. asthma, chemical pneumonitis, bacterial tracheitis, croup), bronchospasm (e.g. asthma, bronchiolitis), extrinsic compression (e.g. esophageal foreign body, retropharyngeal abscess), excessive mucus and secretions with airway plugging (e.g. bronchiolitis, bacterial tracheitis, pneumonia) or mechanical obstruction (e.g. aspirated foreign body). Infants have a pliable chest wall and immature diaphragm which also contribute to respiratory fatigue and failure. Increased work of breathing may cause a child to be unable to feed with resultant dehydration or respiratory muscle fatigue leading to respiratory failure and mechanical ventilation.
The likelihood of some disorders depends greatly on age. For example, pertussis is primarily seen in infants less than 6 months of age who are partially immunized. Croup is a disease of young children, such as toddlers and preschool groups. Bronchiolitis is generally not diagnosed past the age of 2 years. Infants who do not yet crawl, usually less than 9 months of age, seldom aspirate foreign bodies.
The time course of the illness may be helpful. Abrupt-onset conditions include foreign body aspiration and chemical pneumonitis from hydrocarbon ingestion. Disorders such as bacterial tracheitis and epiglottitis may present after a few days of mild upper respiratory tract symptoms and then have a rapid worsening. Croup tends to begin with mild coughing for a day or two before the parents notice a relatively severe barking cough late in the evening. Bronchiolitis and asthma exacerbations typically worsen over a few days. Pertussis is usually associated with 7-10 days of rhinorrhea and upper respiratory tract symptoms, followed by 2-4 weeks of a relatively severe staccato cough often accompanied by posttussive vomiting and periods of cyanosis.
Bronchiolitis occurs in children under 2 years of age and most commonly presents in infants aged 3 to 6 months . It most frequently occurs in association with viral infections such as Respiratory Syncytial Virus (RSV) in around 75% of cases and is most prevalent in the winter and spring months.
Children most at risk of severe bronchiolitis include those with chronic lung disease, congenital heart disease, premature birth (particularly under 32 weeks), neuromuscular disorders, immunodeficiency and those aged less than 3 months at presentation.
Symptoms of bronchiolitis in children include breathing difficulties, cough, poor feeding, irritability and, in the very young, apnoea. Signs may include wheezing and/or crepitations on auscultation and mild pyrexia. Symptoms usually peak between days 3 and 5 of the illness.
Do not routinely perform blood tests/gases or chest radiographs in children with bronchiolitis unless you suspect another diagnosis or the patient is deteriorating. Rapid virological PCR testing is recommended if admitting the patient. This helps with cohorting patients with the same virus strains into the same bay on the ward.
The mainstay of treatment is supportive care. Consider upper airway suctioning in patients with secretions and associated respiratory distress or feeding difficulties. Oxygen supplementation is required if saturations persistently fall below 92% in air.
The child may need high flow oxygen therapy (e.g. Optiflow) or Continuous Positive Airway Pressure (CPAP) if there are signs of worsening respiratory failure. Commence fluids by nasogastric or orogastric tube if the child cannot take sufficient amounts orally, and consider intravenous fluids if they cannot tolerate this or if they have impending respiratory failure.
Signs of impending respiratory failure include exhaustion (laboured breathing), recurrent apnoea or failure to maintain adequate oxygen saturations despite oxygen supplementation.
Typically, a child with bronchiolitis will have a prodrome of an upper respiratory tract infection . There will often be a family or contact history of upper respiratory tract infection.
On physical examination, hyperventilation, as a compensatory response for hypoxia secondary to the ventilation-perfusion mismatching, is common. Respiratory rates of 70 to 90/min or greater are not uncommon. Flaring of the nasal alae and use of intercostal muscles may also be present. Respirations are shallow because of persistent distension of the lungs by the trapped air. Wheezing, prolonged expiration, and musical rales are common. The chest is often hyperexpanded and hyperresonant due to the air trapping. The liver and spleen may be displaced downward because of the hyper inflation and flattening of the diaphragm.Thoracoabdominal asynchrony may be present with breathing and correlates with the degree of obstruction. Fever is present in two-thirds of children with bronchiolitis. Despite these findings, the patient often has a nontoxic appearance.
Respiratory fatigue may occur, since the bronchiolitic infant may increase the work of breathing up to sixfold. Apnea is not uncommon (18 to 20 percent of those hospitalized with RSV bronchiolitis), especially in very young and premature infants. Hospitalized patients should be placed on a cardiac/apnea monitor and watched carefully for apneic episodes.
RSV is the principal etiologic agent of bronchiolitis and viral pneumonia in infants and young children worldwide . Influenza viruses also contribute to significant number of hospitalizations among children. While the clinical manifestations are similar, there are remarkable differences in terms of their immune responses. In a simplified comparison, RSV does not induce protective immunity, there is no available vaccine, and it is associated with recurrent wheezing. In contrast, influenza does induce a more effective protective immune response, vaccines are quite effective, and it is not associated with longterm wheezing. This provides an ideal setting for a comparative analysis of the immune responses of children with these two viral infections. Dendritic cells (DCs) constitute a complex system of cells with a unique ability to induce primary immune responses. In addition, emerging evidence indicates that DCs control cytokine production by T cells and regulate the Th1/Th2 balance of the immune responses.
The clinical presentation of a patient with bronchiolitis is variable, depending on the point in course at which the patient presents and the progression of disease . The patient may be a smiling interactive child with mild tachypnea or an infant in severe respiratory distress.
The patient's history will include several days of coryza and congestion representing the upper airway time of the disease. This is followed by a progressive history of increasing tachypnea, cough, increased work of breathing, and decreased ability to feed. Fever is usually present earlier in the disease but is mild to moderate (<38.3° C). Smaller infants may exhibit episodes of apnea, lethargy or irritability, tachypnea, and retractions.
RSV in particular seems to cause only a low-grade fever. Higher temperatures may be seen with the other viruses.
Broncholitis Obliterans Syndrome
Bronchiolitis obliterans syndrome (BOS) is a dreaded complication of lung transplantation . Despite the fact that over 50% of lung transplant recipients will eventually be diagnosed with BOS, it remains a challenging diagnosis to make with complete certainty. This diagnostic dilemma is a product of the inherent limitations of spirometry, the parameter upon which the diagnosis relies, as well as the many confounding diagnoses that must be considered and excluded before the diagnosis of BOS can be made.
Obliterative bronchiolitis (OB) was first described in heart?lung transplant recipients in 1984 and is well recognized as a major cause of morbidity and mortality after lung transplantation. It is largely felt to be the pathologic correlate of chronic allograft rejection, although there is increasing recognition of non-alloimmune causes, such as chronic gastroesophageal reflux disease. BOS was proposed as a clinical entity in 1993 to describe progressive airflow limitation resulting from small airway obstruction (OB) after lung transplantation. The definition of BOS relies upon pulmonary function rather than histology owing to the unacceptably low sensitivity of histology for the detection of OB. BOS as a clinical syndrome is defined as a decrement of 20% or more in forced expiratory volume in 1s (FEV 1 ) compared to post-transplant baseline FEV 1 individualized for each patient. By definition, 3 or more months must have elapsed from the time of transplantation before the diagnosis of BOS can be made. Progressive stages of BOS are defined according to the magnitude of the decrease in FEV 1. The classification system for BOS was refined in 2002 to include a ?potential BOS stage? to identify patients with a 10?20% drop in FEV 1 and/or a >25% drop in mid-expiratory fl ow rate (FEF 25?75 ) who are at risk for progression to BOS in order to facilitate earlier detection and potential intervention. For the most part, however, BOS is characterized by irreversible loss of lung function for which there is no effective treatment.
Regular bronchoscopy with transbronchial biopsy is an integral component of surveillance of lung transplant recipients, as it can detect both acute rejection and respiratory infection . When suspicious symptoms are present, this investigation is clinically indicated and uncontroversial, but the optimal frequency and duration of surveillance bronchoscopy (i.e. in asymptomatic individuals) remains unclear. Challenges specific to pediatric subjects relate to the size of instruments that can be used for transbronchial biopsy and the challenge of getting adequate samples for processing and grading. Broadly speaking, there are two different transbronchial biopsy forcep options for use in the pediatric age range: radial jaw forceps with a cup volume of 2.0 ?L, which can fit down a 2 mm working channel; and smooth oval cup forceps with a cup volume of 0.5 ?L, which can be used with a 1.2 mm working channel. The smallest flexible bronchoscopes currently available with 2.0- and 1.2 mm working channels have an outer diameter of 4.0 mm and 2.8 mm, respectively, although actual diameter of a 4.0 mm scope is 4.4 mm beyond the tip. Flexible bronchoscopes can also vary significantly from the manufacturers specifications. Obtaining adequate samples is challenging with smaller instruments. In a retrospective analysis at one institution, adequate samples were obtained in 97% and 84% of specimens collected with the radial and oval cup forcep equipment set-ups, respectively, defined as a minimum of five alveolar tissue fragments or if a specific diagnosis (i.e., treatable grade of ACR or infection) was possible. The presence of bronchial tissue for B grading of biopsies for ACR was not assessed in this study. The overall complication rate (bleeding>150 mL, bleeding that required a transfusion, pneumothorax, or septicemia) was 2%, which is consistent with complication rates quoted in the adult literature.
Clinical diagnostic criteria for chronic allograft dysfunction have been developed due to the patchiness of the disease process and the relative insensitivity of transbronchial biopsy . Although raw (or actual) values for spirometry test results are commonly used for adults, this is inappropriate in children. Specifically, the challenge within the pediatric population is that somatic growth is an ongoing process, and measures of lung function need to take account of concurrent changes in lung volume and airway caliber.
Tidal breathing lung function tests, such as the forced oscillation technique and inert gas washout, have strong feasibility across the pediatric age range but have not been systematically evaluated to date. Air trapping or mosaic pattern on expiratory slice HRCT is a marker of small airway disease, but studies have yet to demonstrate strong clinical utility in BOS surveillance due to poor specificity despite reports of good sensitivity. Concerns about the cumulative radiation dose associated with surveillance CT scanning protocols are less relevant in a population with shortened life expectancy. However, relative radiation risk is inversely proportional to age and highest in infancy. Therefore, risk of cumulative radiation exposure needs to be taken into account.
The diagnosis of bronchiolitis is a clinical one based on presenting symptoms and severity . Complete Blood Count (CBC) is usually not necessary unless the infant or child has high fever or toxic appearance and more serious bacterial illness is suspected. Testing for RSV can be useful because it causes most cases of bronchiolitis. Nasal wash or aspirate is preferable to nasal swab for RSV antigen or immunofluorescence. It has a sensitivity of 90% and specificity of 95%, and results usually are available within hours.Viral culture and serology have little clinical utility because of the length of time needed to get results. Chest x-ray is not needed unless there are clinical signs and symptoms of pneumonia. Children with severe respiratory disease or cyanosis should have pulse oximetry. The differential diagnosis includes asthma, pneumonia, foreign body aspiration, and chronic conditions such as bronchopulmonary dysplasia.
Bronchiolitis is a disease of the lower respiratory tract most prevalent in children less than two years of age . Respiratory syncytial virus is a common cause, although other viruses such as human metapneumovirus and human rhinovirus have also been implicated. The clinical respiratory effects stem from damage of epithelial cells in the terminal bronchi leading to edema, inflammation, excessive mucous production, and epithelial cell sloughing. This cascade causes widespread obstruction of bronchioles from mucous plugging and causes atelectasis resulting in varying levels of respiratory distress. Symptoms may range from mild nasal congestion, to copious secretions, wheezing, and/or rales (crackles). Ventilationperfusion mismatch due to obstruction causes hypoxia, rather than the smooth-muscle contraction of airways seen in reactive airway disease.
Management of pediatric BOS is extrapolated from adult data, and there is no current evidence to suggest that the underlying disease process fundamentally differs from that seen in the adult transplant population .
Augmentation of immunosuppression is controversial and should only be attempted if there is evidence of under-immunosuppression (e.g. through repeated ACR episodes), because the disadvantage of increased infections is likely to outweigh any benefit. Experience with sirolimus or everolimus is increasing, but use of these agents within the pediatric population remains limited according to registry data. Azithromycin is well tolerated within the pediatric population, and it tends tobe started once children fulfill BOS diagnostic criteria due to the beneficial results that have been described in adult transplant BOS populations. The characteristics of pediatric responders have not been described to date, and it is unknown whether the benefits of early commencement of azithromycin therapy during BOS stage 0p or in those with neutrophilic airway inflammation are also present in younger subjects. Montelukast, which has been suggested to be beneficial in recipients with BOS stage 2 who lack significant BAL neutrophilia (either on or off azithromycin therapy), is also readily available for administration to recipients in the pediatric age range, both as granules for children aged less than 2 years and as chewable tablets for older children.
Increased use of statins in pediatric patients has been triggered by adult data describing an association with reduced acute rejection rates and delayed progression to chronic kidney disease. Statins are generally well tolerated by recipients in the pediatric age range, although pediatricspecific data showing benefit are lacking. Pediatric guidelines for familial hyperlipidemia recommend that statins should not be used in children until they have attained Tanner stage II or higher in pubertal development.
Other therapeutic options include fundoplication and Total Lymphoid Irradiation (TLI), and gastric fundoplication has been shown to improve lung function in adult cohorts when GERD is present. Although fundoplication is feasible in children, it is unclear from currently available, published pediatric data whether fundoplication can lead to improved pulmonary outcomes and lower BOS rates. Published experience with TLI is limited to the adult transplant literature, although TLI has been used at our own center in children with BOS with varying success.
Bronchiolitis treatment is supportive; supplemental oxygen, nasal suctioning, and hydration . There is no evidence to support the routine use of bronchodilators, steroids, or antivirals in the ED. Studies addressing the combined use of these agents, as well as nebulized hypertonic saline, are inconclusive. Children with bronchiolitis and a moderate work of breathing after nasal suctioning are often trialed with a bronchodilator. Albuterol leads to clinical improvement in only 20% to 30% of patients, likely those who have a ?reactive component? similar to asthma. Alternatively, albuterol may worsen ventilation/perfusion mismatch and exacerbate hypoxemia. Nebulized epinephrine may be slightly more effective, likely due to vasoconstrictive effects; since there is no outpatient equivalent, it should only be used for admitted patients.
Careful and frequent clinical assessment of the child is essential to the successful treatment of bronchiolitis . Cardiac and respiratory rate monitoring should be initiated in hospitalized patients. Oxygen saturations should also be monitored to assure oxygenation saturations are at acceptable levels. Premature infants, infants with underlying chronic conditions, and infants less than 3 months of age who contract RSV are at particular risk of severe complications such as apnea or respiratory failure. Furthermore, several studies have reported more severe progression of the disease in children with bronchiolitis who present with low initial oxygen saturations.
A sick child usually has symptoms of upper respiratory tract infection with progressive respiratory distress characterized by tachipnea, inlet and dry cough. Small children may have recurrent apnea attacks, which after 24 to 48 hours follow more typical signs and symptoms. Signs of distress are cyanosis around the mouth, all the stronger indentation and the whistling sound. The fever is frequent but is not always present. In the beginning, children are healthy and without distractions, in spite of the tachypnea and the indentation, but with the progression of the disease they can become more lethargic. Vomiting and reduced food intake can lead to dehydration. With fatigue, breathing can become low and ineffective, leading to respiratory acidosis. Auscultation is heard by whistles, prolonged expiration, and often, tiny humidity rattles. Many children have secondary inflammation of the middle ear.
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