Diagnosis of a Respiratory Disorder

Introduction

Respiratory disorders are the commonest causes of morbidity and mortality among children of all ages. The presentation may vary from trivial to life threatening symptoms. While a carefully conducted history and physical examination are vital for a correct diagnosis, various laboratory and radiological investigations aid in finally clinching the diagnosis.

This chapter focuses on clinical assessment of the respiratory system in children. There is much overlap between the respiratory examination and that of other systems, and it is assumed that the reader has mastered basic physical examination skills.

History

The evaluation of a child with respiratory disorder should start with the history of present illness, significant past history, family history as well as antenatal and birth histories. The parent should be asked the chief complaint that prompted the consultation, along with the circumstances at onset, frequency, duration, and severity. History of prior treatment should be obtained. History of past illness will include all previous respiratory and other complaints. These include history of recurrent pneumonia (suggesting immunodeficiency, cystic fibrosis, anatomic abnormality, or bronchiectasis) known allergy and malnutrition. The family/ environmental history will provide information about history of contact or that suggestive of asthma in relatives, nutritional and financial status of the family, and history of exposure to allergens. Following are important clinical pointers in the history:

1. Recurrent pneumonia: points towards immunodeficiency, cystic fibrosis, anatomic abnormality (gastroesophageal reflux), dysfunctional swallowing, or bronchiectasis. The child with a history of tracheoesophageal fistula repair is prone to tracheomalacia and gastroesophageal reflux–related disease.
2. Atopy: eczema, atopic dermatitis, hay fever, or known allergies, may be important in the child with chronic cough or recalcitrant asthma.
3. Failure to thrive, frequent infections, blood product transfusion, parental substance abuse, or poor growth may be a clue to an underlying immunodeficiency.
4. History of contact with a case of tuberculosis
5. Environmental history: exposure to dust due to construction in the house/neighbourhood, presence of pet animals or birds, exposure to smoke, either from tobacco use or use of wood for heating, cooking, or both.
6. Associated complaints: Headache may be a sign of sinus disease or, especially if occurring in the early morning, a result of obstructive sleep apnea.

Ocular symptoms such as conjunctivitis and blepharitis, as well as nasal symptoms, may indicate an atopic predisposition or in the young infant a chlamydial infection. Recurrent mouth ulcers or thrush can be associated with immunodeficiency, as may chronic or recurrent ear drainage. Poor feeding, edema, shortness of breath, and exercise tolerance can be clues to the presence of congestive heart failure. Stool characteristics, abdominal bloating, and fatty food intolerance are important features of cystic fibrosis. Neurologic symptoms such as seizures or developmental delay are important in evaluating the child with apparent life-threatening events or suspected chronic or recurrent aspiration.

PHYSICAL EXAMINATION

A thorough general physical examination is extremely important in the approach to a child with respiratory disorder. Recording the anthropometry is as important as are the presence of cyanosis, pallor and clubbing. Use of accessory muscles of respiration may indicate severity of respiratory distress and intercostal recession may point towards airway obstruction and a non-compliant lung. Supraclavicular and cervical lymph nodes should form part of the exanination routinely.

Upper Airway

An examination of the upper airway will indicate presence of nasal foreign body or infection, tonsillar enlargement, or narrowing of the glottis. The position of the trachea should be noted during examination of the neck. Deviation to one side may be seen with pneumothorax, neck mass, unilateral pulmonary agenesis or hypoplasia, or unilateral hyperinflation (as seen with foreign body or congenital cystic lung disorders).

Chest

Inspection

Inspection forms the first component of chest examination. Presence or absence of any deformity should be noted, as should the general shape of the chest. A barrel chest (increased anteroposterior dimension) denotes obstructive lung disease. The severity of this deformity shows increased lung volumes (functional residual capacity, residual volume, total lung capacity, functional residual capacity/total lung capacity ratio, and residual volume/total lung capacity ratio) and is associated with radiographic findings of hyperinflation in children with poorly controlled asthma. Pectus carinatum (“pigeon breast”) or pectus excavatum (“funnel chest”) may be seen in patients who have chronically increased work of breathing, as in pulmonary fibrosis, cystic fibrosis, or poorly controlled asthma. The respiratory rate, preferably noted with the child at rest or asleep, is a very important indicator of pulmonary illness (though fever and metabolic acidosis can have an increased respiratory rate in the absence of pulmonary disease).

Nasal flaring to reduce nasal resistance to airflow and the use of accessory muscles of respiration such as the sternocleidomastoid muscles indicates respiratory distress as do retractions or indrawing of the skin of the neck and chest. Respiratory distress may also be seen in children with neuromuscular disorders. An objective way of assessing the degree of dyspnea is asking the child to count and noting the highest number reached in a single breath.

The respiratory pattern and depth may also point towards a particular pathology. Shallow and rapid respiration is seen in children with restrictive lung disease. Similarly, rapid and deep respiration (hyperpnea), can be seen in children with hypoxia and metabolic acidosis while alkalosis results in slow, shallow breaths. Hyperpnea alternating with apnea (Biots respiration) is associated with central nervous lesions involving the respiratory centers. Cheyne-Stokes respirations seen in comatose patients is marked by gradually increasing and decreasing respirations.

Likewise, the relative length of the respiratory phases (the inspiratory/expiratory ratio) is important. As the inspiratory and expiratory phases are roughly equal, a prolonged expiration may indicate obstructive diseases such as bronchiolitis, acute exacerbations of asthma, and cystic fibrosis. While some abdominal breathing, is normal up to 6 or 7 years of age, conspicuous respirations of this type in a child, however, generally reflect a pulmonary abnormality such as pneumonia, or respiratory muscle weakness.

Palpation:

Although more generally thought of in terms of the abdominal examination, palpation is important in the respiratory examination as well. It is used to confirm the visual observations of chest wall shape and excursion. Palpation is performed by placing the entire hand on the chest and feeling with the palm and fingertips. Friction rubs may be felt as high-frequency vibrations in synchrony with the respiratory pattern. Tactile fremitus, the transmission of vibrations associated with vocalization, is at times difficult to assess in children because of a lack of cooperation and a higher-pitched voice; lower-pitched vocalization is more effectively transmitted. It is best felt with the palmar aspects of the metacarpal and phalangeal joints on the costal interspaces. Decreased fremitus suggests airway obstruction, pleural fluid, or pleural thickening, whereas increased fremitus is associated with parenchymal consolidation. Occasionally a “thud” can be felt high in the chest or in the neck, a finding suggestive of a free tracheal foreign body. One can also assess chest excursion by placing the hands with the fingertips anterior and thumbs posterior and noting the degree of chest wall movement, comparing excursion of one side with the other by noting the movement of the thumbs away from the midline (the spinous processes). The point of maximal impulse, frequently shifted to the left in cardiac disease, may be shifted inferiorly and to the right in severe asthma, a large left-sided pleural effusion, or a tension pneumothorax. With massive left-sided atelectasis, it may be shifted to the left.

Percussion

:

Percussion should be performed with the child upright with the head in neutral position, and using the indirect method (a single finger from one hand strikes on a finger of the other hand placed on an interspace). A gentle force should be used so as to avoid causing injury, especially in a young child). Sounds commonly elicited by percussion of the chest are as follows:

• Tympany : Normally heard with percussion of the abdomen, is seen in the chest with a massive pneumothorax.
• Resonance: This is the normal state in the chest; it is sometimes called
  
  vesicular resonance.
  
• Hyperresonance: Accentuation of the normal percussion is seen with states of hyperinflation like emphysema, asthma, or free intrapleural air.
• Coin test: A resonant metallic sound heard with a stethoscope when tapping a coin that is held flat against the chest with another coin; it indicates a pneumothorax.
• Dullness: A flat, thud-like sound, this sound is associated with pleural fluid or parenchymal consolidation.
• Flatness: This sound can be mimicked by percussing over muscle; its presence in the chest suggests massive pleural effusion.

Auscultation:

Auscultation of the chest should be performed with the age appropriate stethoscope (with chest pieces for premature infants, infants, children, and adolescents/adults). The diaphragm of the chest piece (pressed tightly against the skin) is used to filter out low-pitched sounds, thereby isolating high-pitched sound, and the bell (held lightly on the chest) is used preferentially to isolate low-pitched sounds.

The upper lobes are best heard by listening anteriorly in the infraclavicular regions, the lower lobes by listening posteriorly below the scapulae, and the right middle lobe and lingula by listening anteriorly lateral to the lower third of the sternum. All lobes can be heard in the axillae.

It is also important to specify the timing (continuous, early, or late), pitch (high, medium, or low), and character (fine, medium, or coarse) of sounds. These sounds can be divided into breath sounds (produced by the movement of gas through the airways), voice sounds (modifi cations of phonation not heard distinctly in the normal state), and adventitious sounds (neither breath or voice sounds).

Breath Sounds

Vesicular breath sounds are the sounds heard during respiration in a healthy individual. They are low-pitched, with a relatively longer inspiratory phase and a shorter expiratory phase and are louder on inspiration. These sounds emanate from the lobar and segmental airways and are then transmitted through normal parenchyma.

Bronchial breath sounds are usually louder than vesicular sounds and have short inspiratory and long expiratory phases. They are higher pitched and louder during expiration. They may be the result of consolidation or compression (i.e., airlessness) of the underlying parenchyma. A similar sound can be heard by listening directly over the trachea.

Bronchovesicular breath sounds, as the name implies, are intermediate between vesicular and bronchial sounds. The respiratory phases are roughly equal in length. This sound is felt to be indicative of a lesser degree of consolidation or compression (airlessness) than bronchial sounds. Bronchovesicular (and sometimes bronchial) breath sounds can occasionally be heard in normal individuals in the auscultatory triangle (the area in the back bound by the lower border of the trapezius, the latissimus dorsi, and the rhomboideus major muscles) and the right upper lobe.

Wheezes are continuous musical sounds, more commonly expiratory in nature, and usually associated with short inspiratory and prolonged expiratory phases. They can be of single (monophonic) or multiple (polyphonic) pitches, which are higher pitched than vesicular sounds. These can often be very difficult to distinguish from snoring and upper airway sounds such as stridor.

Stridor is a musical, monophonic, often high-pitched sound, usually thought of as inspiratory in nature; it can be expiratory as well, such as when produced by partial obstruction of a central, typically extrathoracic airway. Its presence in both inspiration and expiration suggests severe, fixed airway obstruction.

Voice Sounds

The normal lung parenchyma filters vocalization so that whispered sounds are not usually heard during auscultation and normally spoken syllables are indistinct. Bronchophony is the distinct transmission of spoken syllables as the result of an underlying consolidation or compression. More severe consolidation or compression results in the transmission of whispered sounds or whispered pectoriloquy. Egophony is very similar to bronchophony but has a nasal quality as well. It may reflect an underlying effusion, consolidation or compression, or both conditions.

Adventitious Sounds

Fine crackles are thought to be the result of the explosive reopening of alveoli that closed during the previous exhalations. These occur exclusively during inspiration and are associated with conditions such as bronchitis, pneumonia, pulmonary infarction, and atelectasis. They can also be normal when heard in the posterior lung bases during the first few breaths on awakening. They may be imitated by rolling several strands of hair between the thumb and forefinger in front of the ear or by pulling apart Velcro. Hamman’s sign, also called a

mediastinal crunch,

is the finding of crackles associated with systole and is suggestive of pneumomediastinum.

Coarse crackles are popping sounds likely produced by the movement of thin fluids in bronchi or bronchioles. They occur early in inspiration and occasionally in expiration as well, may be audible at the mouth, and may clear or change pattern after a cough. They can sometimes be heard in the anterior lung bases during exhalation to residual volume. An example of these sounds is the crackles typically heard in patients with cystic fibrosis. Rhonchi (sometimes more descriptively called

large airway sounds

) are gurgling or bubbling sounds usually heard during exhalation. These sounds are the result of movement of fluid within larger airways. In individuals with pleural inflammation, a pleural friction rub may be heard. This loud, grating sound may come and go over a short period of time. It is usually associated with a subpleural parenchymal inflammatory process.

OTHER SIGNS AND SYMPTOMS

Clubbing:

Clubbing is the broadening and thickening of the ends of the fingers and toes that occur as the result of connective tissue hypertrophy and hyperplasia and increased vascularity in the distal phalanges, in response to chronic hypoxia. It can be confirmed clinically by checking for Schamroth’s sign. Causes of clubbing are as follows:

• Bronchiectasis
• Severe pneumonia, lung abscess, or empyema
• Interstitial lung disease (autoimmune and infectious)
• Pulmonary arteriovenous malformation
• Hepatopulmonary syndrome
• Pulmonary malignancy
• Cyanotic congenital heart disease
• Bacterial endocarditis
• Inflammatory bowel disease
• Thyrotoxicosis
• Familial

Cyanosis:

The use of cyanosis as a clinical indicator of hypoxemia is confounded by a number of factors such as skin pigmentation, poor lighting, the presence of nail polish, or hypothermia. Cyanosis occurs when the concentration of reduced arterial hemoglobin exceeds 3 g/dL. Clinical impression of cyanosis should be verified by arterial blood gas analysis or pulse oximetry.

Pulsus paradoxus:

Pulsus paradoxus (fluctuation in systolic blood pressure with respiration) may sometimes be associated with obstructive pulmonary disease. The arterial pressure falls during inspiration and rises with exhalation. It is quantified as the difference between the systolic pressures measured during inspiration and expiration. Pulsus paradoxus is useful in evaluating children with cystic fibrosis and asthma, in which a value of more than 15 mm Hg has been found to

INVESTIGATION: