12 Flashcards
Asthma Pathophysiology Symptoms Triggers Dx Asthma vs RAD
Pathophysiology
Asthma is a heterogeneous condition characterized by:
Airway inflammation
Mucus hypersecretion, and
Reversible airflow obstruction due to bronchoconstriction.
Although the occurrence of remodeling in asthma has been somewhat controversial, some evidence suggests that smooth muscle hyperplasia and hypertrophy develop in the setting of longstanding asthma.
Symptoms
In the majority of children, asthma is clinically manifested by recurrent coughing and/or wheezing that is responsive to bronchodilators (such as beta-agonists) and to anti-inflammatory medications (such as steroids).
Triggers
Acute episodes of bronchoconstriction in children are often triggered by upper respiratory tract infections, but can also be triggered by other factors such as allergies, cold air, exercise and smoke exposure.
Diagnosis
A child with symptoms of asthma who responds to therapy for asthma and has no other identifiable cause for wheezing has asthma by definition, regardless of age.
“Asthma” vs. “Reactive airways disease” (RAD)
A significant proportion of children with wheezing that presents early in life do not continue to wheeze beyond 2 to 3 years of age. Many physicians are therefore reluctant to make a diagnosis of asthma in very young children, fearing that a child would be persistently labeled as having asthma when in fact their symptoms of this condition have resolved. Some physicians prefer to use the term “reactive airways disease” (RAD) when children appear to have signs and symptoms of underlying airway hyperresponsiveness that is characteristic of asthma, but in whom a diagnosis of asthma is not yet definite. The use of this term has been somewhat controversial, and its validity as a distinct diagnosis has been questioned.
Oxygen saturation
In the clinical setting, the percent oxyhemoglobin saturation, or “O2 saturation,” is obtained by the use of a pulse oximeter. A normal O2 saturation is generally considered to be > 94% in an otherwise healthy patient, regardless of age.
Certain conditions such as methemoglobinemia (either congenital or acquired through ingestion of certain oxidants) or carboxyhemoglobinemia (from carbon monoxide poisoning) result in inaccurate pulse oximetry readings. In these conditions, the O2 saturation reading may be in the normal range, but the actual percentage saturation of oxyhemoglobin in the blood may be low.
Another pitfall in the interpretation of O2 saturation is to assume that a normal O2 saturation means normal ventilation (CO2 elimination). In fact, the O2 saturation gives no information about ventilation and can mislead the unwary. In patients with compensated asthma, hyperventilation will lead to a decrease in PCO2 of the blood. As a child begins to tire and can no longer maintain adequate ventilation, the PCO2 may normalize and even become elevated despite continued normal oxygenation. Thus, blood gas analysis can be helpful in distinguishing compensated from uncompensated asthma, and in predicting impending respiratory failure.
Signs of respiratory distress - 5
Paradoxical breathing
Paradoxical breathing is almost always a sign of very severe respiratory distress due to respiratory muscle fatigue.
Paradoxical breathing occurs when the force of contraction generated by the diaphragm exceeds the ability of the chest wall muscles to expand the rib cage. As a result, the chest is drawn inward with inspiration, and the abdomen rises due to downward displacement of abdominal contents. Paradoxical breathing is seen more commonly in infants and young children than in older individuals due to the greater compliance of the chest wall.
Tachypnea
Tachypnea may be mild, moderate, or severe depending on the severity of the underlying process. When assessing tachypnea, the depth and degree of effort should also be noted:
Hyperpnea (increased depth of respiration) without respiratory distress may suggest a non-pulmonary condition such as fever, acidosis or extreme anxiety (hyperventilation syndrome).
Hypopnea (reduced tidal volume) increases the proportion of each breath used to ventilate dead space, so may result in hypoventilation even in the setting of a normal or elevated respiratory rate.
Nasal flaring
Nasal flaring (enlargement of both nares during inspiration) is seen in small children with significant respiratory distress and indicates that accessory muscles are being used for respiration.
Head bobbing
Another sign of respiratory distress in young infants is head bobbing, which is also due to use of the accessory muscles of respiration (in this instance, the neck strap muscles). In synchrony with each inspiration, the head is noted to bob forward owing to neck flexion caused by use of the neck strap muscles. Head bobbing is best observed during sleep.
Grunting
Grunting, another sign of respiratory distress seen in infants, consists of forced expiration against a partially closed glottis and is thought to help infants generate the positive pressure necessary to stent airways open.
It is important to note that respiratory muscle fatigue will reduce the signs of respiratory distress even though a patient’s condition is in fact deteriorating. In this situation, a blood gas may reveal elevation of PCO2 indicative of hypoventilation.
Causes of wheezing in infants and toddlers
Most common 4
Less common 3
Most common Viral bronchiolitis Asthma Foreign body aspiration Gastroesophageal (GE) reflux
Less common
Extrinsic compression (due to vascular ring or sling, or other anatomic airway lesions)
Tracheomalacia
Cystic fibrosis
In order to distinguish between some of these causes, it is important to ask about:
The timing of the wheeze Association with feeding Change with position or activity, and Other exacerbating factors. It is important to find out if a child has wheezed in the past and, if so, whether the wheezing responded to treatment with a bronchodilator, such as albuterol, or steroids. If a child has a history of recurrent episodes of wheezing that respond to asthma therapy, regardless of whether a diagnosis of asthma has actually been made, a subsequent similar wheezing episode is quite likely to be an asthma exacerbation. In a child with previous episodes of wheezing, it is also important to ascertain the severity of the child's asthma by asking about prior hospitalizations, intensive care unit admissions and intubations.
Of course, other diagnoses always need to be considered as well. For a child’s first episode of wheezing, diagnoses other than asthma need to be higher on your differential diagnosis until the diagnosis becomes clear.
Causes of cough
Cough can be seen in a large variety of conditions, such as:
Viral upper respiratory tract illnesses
Pneumonia
Post-nasal drip due to allergies and/or sinusitis
Foreign body aspiration
GE reflux
As above, the timing of the cough and presence of exacerbating factors is helpful in distinguishing between these conditions.
Cough is often described as either dry or wet/junky. A dry cough is typical of chronic asthma, whereas a wet cough suggests the presence of secretions in the airway, whether due to a viral infection, post-nasal drip, gastroesophageal reflux or bronchiectatic disease such as cystic fibrosis.
Respiratory diseases 3
Bordetella Pertussis
Course
Pertussis has a triphasic course:
The initial catarrhal stage lasts 1-2 weeks and is characterized by upper respiratory tract infection symptoms.
The paroxysmal stage that follows lasts 4-6 weeks and is characterized by repetitive, forceful coughing episodes followed by massive inspiratory effort, which results in the characteristic “whoop.” Infants generally do not develop a “whoop” due to relative weakness of their inspiratory effort.
The paroxysms of cough gradually decrease in frequency and severity as the convalescent stage is entered. Episodic cough may persist for months.
Complications
Infants with pertussis tend to have more complications than older children with pertussis. They may have difficulty feeding because of their cough, and they can also have central nervous system complications such as apnea.
Immunization
The acellular pertussis vaccine is recommended for all children. However, even with full immunization, vaccine efficacy is only 70-90%. Additionally, protection from the vaccine wanes with time such that many adolescents are unprotected from pertussis unless reimmunized as is currently recommended.
Epiglottitis
Epiglottitis is uncommon thanks to widespread immunization, but is important to consider in any child with stridor and respiratory distress.
Etiology
Epiglottitis is a life-threatening emergency that has historically almost always been due to infection with Haemophilus influenzae type b (Hib). Invasive infections with Hib, such as acute epiglottitis and pneumonia, are no longer common since the introduction of the conjugate Hib vaccine in the late 1980s. However, rare cases of epiglottitis still occur and, in immunized populations, are more commonly due to staphylococcal or streptococcal organisms than Hib.
Epidemiology
Epiglottitis presents most often in children between the ages of 2 and 5 years.
Signs and symptoms The diagnosis should be considered in a child or adult of any age with the presence of: fever stridor drooling dysphonia dysphagia, and respiratory distress. Most patients will appear toxic and may position their airway in a sniffing position (sitting, leaning forward, with neck hyperextended and chin protruding).
Emergent intervention
When epiglottitis is suspected on clinical grounds, acute airway obstruction may be imminent and prompt intervention in a controlled environment is mandatory. This is most often accomplished in the operating room by individuals skilled in airway management, usually an anesthesiologist and either a general surgeon or otolaryngologist. While awaiting these individuals, the child should not be disturbed or examined due to the risk of acute deterioration.
Radiology
Airway films are usually not indicated and may put the patient at risk. If done, the films may show thickening of the epiglottis (the “thumb sign”) and thickening of the aryepiglottic folds.
Diphtheria
Although immunization has resulted in diphtheria being an uncommon disease in the U.S., this diagnosis should nonetheless be considered in a child with pharyngitis and a low-grade fever, particularly if stridor or hoarseness is present. The diagnosis is made when the characteristic gray pseudomembrane is seen in the pharynx. Your index of suspicion should be raised if the child is not immunized.
Retropharyngeal or parapharyngeal abscess can also cause pharyngitis with dysphagia and stridor.
Sounds on lung exam when examining infant with cough
Stridor
Due to airway narrowing above the thoracic inlet.
Usually heard with inspiration, but can be biphasic if obstruction is severe.
Wheezing
Typically due to airway narrowing below the thoracic inlet.
With mild airway obstruction, wheezing is usually heard only in expiration.
With increasing obstruction, wheezing may become biphasic and may even disappear altogether when obstruction is severe.
Although typically diffuse, focal wheeze may be heard in some settings such as mucus plugging.
Wheezing can also be characterized as polyphonic or monophonic: Polyphonic wheeze is characterized by multiple pitches and is typical of asthma; monophonic wheeze is characterized by only a single pitch and is typical of focal airway obstruction.
Rhonchi
Coarse, low-pitched rattling sounds heard best in expiration.
Thought to be due to secretions and narrowing of airways.
Crackles
Finer breath sounds heard on inspiration.
Associated with either fluid in the alveoli or with opening and closing of stiff alveoli (as in interstitial disease).
Sometimes described as either coarse or fine. (Coarse crackles are usually thought to be associated with purulent secretions in the alveoli as with pneumonia; fine crackles are often associated with pulmonary edema or interstitial lung disease.
Air entry
The amount of air entry should be noted during every lung exam.
Decreased air entry can be a sign of consolidation, atelectasis, pneumothorax, pleural effusion or airway obstruction.
Bronchial breath sounds
Lower in pitch and more hollow-sounding than normal breath sounds.
Caused by air moving through areas of consolidated lung.
Evaluation for foreign body aspiration
PA and lateral chest films are a good choice as part of your initial workup, because you know she has asymmetric breath sounds and you want to see whether there are radiographic findings to account for the asymmetry.
Bilateral decubitus or inspiratory/expiratory chest films are used to evaluate whether obstruction of the larger airways, such as that due to a foreign body, is present. Decubitus chest films are performed with the child lying on her side. The concept of the lateral decubitus film is that the dependent lung should deflate slightly compared to the non-dependent lung due to the effect of gravity. If each lung deflates slightly when dependent as expected, there is less likelihood of an obstruction in a large airway. If one side does not deflate as expected, this suggests an obstruction in a large airway. The rationale for inspiratory/expiratory films is similar to that for decubitus films. The airway containing an obstruction does not allow the distal lung to deflate fully and results in asymmetric deflation with expiration. The advantage of decubitus films over inspiratory/expiratory films is that decubitus films do not require the patient to be able to hold a breath in inspiration or expiration. The disadvantage is that the abnormal finding, if present, is more subtle than on inspiratory/expiratory films. Chest fluoroscopy (E) is an excellent radiographic test to evaluate for airway foreign body in an infant or toddler because it does not require the child to hold her breath. Also, it is a dynamic evaluation that allows visualization of the airways over several breaths rather than a single breath, as is the case with decubitus or inspiratory/expiratory films. However, it is performed with continuous and real-time imaging of the chest by the radiologist and is therefore generally available only during hours that a radiologist is immediately available. An additional drawback to fluoroscopy is the additional radiation typically administered during the test compared with plain films.
Soft-tissue neck films (A) are not the best choice at this time. Anna has no stridor to suggest croup or another supra- or subglottic abnormality.
Although albuterol (B) is a reasonable choice to see if Anna’s wheezing improves, there are other tests that are more likely to be diagnostic. If you decide to give the aerosol while you’re waiting for the next test to be performed, you would find that her wheezing is unchanged by the aerosol.
Bronchoscopy (F) is typically not performed as the initial diagnostic test for foreign body given that it requires that a physician trained in the procedure is on-site with the necessary equipment. In most cases, some type of airway imaging (x-rays or fluoroscopy) is usually obtained first unless the history and exam are extremely suggestive of an aspirated foreign body.
Asthma
X ray findings
Tx
Radiographic findings
Chest x-ray findings in asthma include hyperinflation due to air trapping, increased interstitial markings and patchy atelectasis.
The primary goals of asthma therapy are to:
Reduce airway inflammation and
Dilate the airways
Treatment
Acute exacerbation
The mainstays of treatment for an acute episode are anti-inflammatory therapy with corticosteroids and bronchodilation with beta-2 agonists such as albuterol, together with supportive care for hypoxemia or dehydration.
Maintenance therapy
Choice of therapy for chronic asthma is based on the frequency, severity and type of symptoms, as well as by other comorbidities.
A common approach is to use an inhaled corticosteroid as a daily, controller medication, with an inhaled beta-agonist such as albuterol as needed for breakthrough symptoms.
Alternative and additional medications (such as montelukast) are also used under appropriate circumstances.
Prognosis
Prognosis is generally good but is highly dependent on ongoing medical management and patient adherence to therapy.
Bronchiolitis Pathophy Symptoms X rays Tx
Acute bronchiolitis is a viral disease of the lower respiratory tract of infants and represents the most common cause of wheezing in infants.
Pathophysiology
It is characterized by bronchiolar obstruction due to edema, mucus, and cellular debris. Respiratory syncytial virus (RSV) is the most common cause, but other viruses such as influenza and parainfluenza may cause bronchiolitis as well.
Signs and symptoms
There is a wide spectrum of disease. Most children initially have mild upper respiratory tract symptoms and often a fever of 38.5-39 C. Respiratory symptoms can progress to cough, wheezing, dyspnea and irritability.
Radiographic findings
Chest radiographs may show hyperinflation, increased interstitial markings, peribronchial cuffing, and scattered atelectasis from bronchial obstruction.
Treatment
Treatment of bronchiolitis is supportive, aimed at maintaining adequate oxygenation and hydration.
The use of additional therapies such as corticosteroids, bronchodilators, and hypertonic saline has been controversial, with some physicians adhering to the principle that they are ineffective and other believing that they can be helpful under certain circumstances (such as a strong family history of asthma).
Antibiotics may be indicated if there is evidence of secondary bacterial pneumonia.
Pneumonia Pathophy Etiology Symptoms X ray - 2 causes differentiated Tx
Pathophysiology
Pneumonia is due to inflammation of the lung parenchyma. It is generally caused by microorganisms, but non-infectious causes include aspiration of gastric contents or hydrocarbons.
Etiology
The most common cause of pneumonia in children is a respiratory virus, including:
Adenovirus
RSV
Parainfluenza
Influenza
Bacterial infections are less common causes of pneumonia than viruses but tend to be more severe:
In the neonatal period, bacteria transmitted from the maternal genital tract must be considered, including Group B streptococcus, E.Coli, and Klebsiella.
Pneumonia due to Chlamydia pneumoniae usually presents with a staccato cough between 4 and 12 weeks of age.
Streptococcus pneumoniae is the most common bacterial cause of pneumonia in the U.S. among infants beyond the neonatal period and children up to 5 or 6 years of age.
In school-aged and older children, Mycoplasma pneumoniae is the predominant cause, followed by S. pneumoniae.
Signs and symptoms
The symptoms of viral pneumonia begin with a prodrome of upper respiratory tract infection symptoms including cough and rhinorrhea. The cough frequently progresses, and is accompanied by fever, tachypnea, and crackles on chest exam.
Bacterial pneumonia may present abruptly or be preceded by a viral prodrome. Presentation varies, depending on the age of the patient and the etiology, but typically fever, cough, and signs of respiratory distress (dyspnea, tachypnea, retractions, etc.) are present. On chest examination, crackles or decreased breath sounds may be noted.
Radiographic findings
Radiographic findings
Findings of viral pneumonia on chest x-ray are variable and may show diffuse or patchy interstitial infiltrates, hyperinflation and small pleural effusions.
Chest x-rays in bacterial pneumonia typically show airspace disease with lobar or segmental consolidation and air bronchograms.
Lab findings
In viral pneumonia, peripheral white blood cell counts tend to be normal or only slightly elevated. Viral antigen testing of respiratory secretions may be helpful in making the diagnosis but is usually not necessary.
In bacterial pneumonia, peripheral white blood cell counts are usually elevated and have a neutrophilic predominance.
Treatment of viral pneumonia
Treatment of viral pneumonia is supportive, and the majority of children recover without sequelae.
Treatment of bacterial pneumonia
Treatment of bacterial pneumonia includes appropriate antibiotics and supportive care. Prognosis for treated patients is usually excellent in previously healthy children, but varies depending on the bacterial etiology.
Radio graphic findings in foreign body aspiration
Pa film
Decubitus
These are the findings you would expect with an aspiration obstructing the right airway:
PA film (with the child in a sitting position): Right hemidiaphragm is flattened, suggesting unilateral hyperexpansion on the right. Right decubitus: With child on her right side, the mediastinal structures remain in the midline, rather than shifting towards the right lung due to gravity, further demonstrating the fixed hyperinflation of the right lung. Left decubitus: With child on her left side, the mediastinal structures shift towards the left lung as expected. Hyperinflation is seen in those foreign body aspirations that result in a "ball valve" effect, in which the aspirated object creates a partial obstruction to airflow during inspiration but fully obstructs the airway during exhalation. The result is air trapping with each breath.
Alternatively, when an aspirated object causes a complete airway obstruction, the result is a total lack of airflow to the bronchus, which can lead to atelectasis and signs of volume loss on x-ray (e.g., mediastinal shift towards the affected side or elevation of the hemidiaphragm on the affected side).
