Component	Comments and Examples
Onset, duration, and chronicity	• Abrupt onset: suggests upper airway conditions such as foreign body, allergy, or irritant exposure • Gradual onset: more consistent with process such as infection or heart failure

Alleviating and provoking factors

• A child with respiratory distress caused by upper airway obstruction may have some degree of relief by assuming the “sniffing position” to maximize airway patency

Treatment attempted

• A child with wheezing secondary to asthma may respond readily to inhaled bronchodilators, but a child with wheezing caused by foreign body aspiration may continue to show symptoms after treatment

Respiratory symptoms

• Cold symptoms: may indicate viral upper respiratory infection

• Cough: “seal-like” or “barky” cough is commonly heard in patients with croup

• Eliciting descriptions of the difficulty breathing may provide clues to the underlying cause (e.g., supraclavicular or suprasternal retractions point to upper airway obstruction)

• Color change: pallor may indicate anemia; cyanosis is indicative of decreased oxygen content in the blood, as seen in some forms of congenital heart disease and in methemoglobinemia

• Respiratory effort: poor effort may be seen in patients with underlying muscular dystrophies

• Change in voice: whereas muffled or hoarse voice points to upper airway pathology, lower airway disease does not typically change the character of the voice

Systemic or associated symptoms

• Fever: presence suggests an infectious cause

• Hydration status, including intake and output (urine, emesis, diarrhea, excessive perspiration, or high respiratory rate)

• Weight loss or failure to gain weight: may indicate systemic process (e.g., inborn error of metabolism) or the severity of respiratory distress is impairing growth (as seen in congestive heart failure)

• Abdominal pain: may suggest abdominal pathology such as obstruction or appendicitis or may represent referred pain from diaphragmatic irritation (as in basilar pneumonia)

Past medical history

• Underlying disorders may predispose patients to certain conditions: for example, a patient with sickle cell disease and respiratory distress may be exhibiting signs of acute chest syndrome; a patient with known gastroesophageal reflux and coarse lung findings on examination could have an aspiration pneumonia

Exposures or environmental factors

• For example, a patient involved in a fire may not only be affected by thermal injury to the airways but also systemic toxins such as carbon monoxide and cyanide

• A patient with allergy and a potential exposure to the allergen could be showing signs of anaphylaxis

Trauma

• History of trauma suggests diagnoses such as pneumothorax, flail chest, cardiac tamponade, or abdominal injury

Immunization status

• Children with incomplete or lack of immunization against Haemophilus influenzae type B are at increased risk for this form of epiglottitis

Last oral intake

• If advanced airway management becomes necessary (e.g., positive-pressure ventilation), the presence of stomach contents may increase the risk of pulmonary aspiration

Physical Examination

Vital Signs

Vital signs, including temperature, heart rate, blood pressure, respiratory rate, and pain score, should be promptly obtained in all patients with respiratory distress. Pulse oximetry, although not classically part of the vital signs, should also be noted to detect hypoxia. Tachypnea (rapid breathing) is one of the most consistent findings among children with respiratory distress and may be caused by fever, hypoxemia, hypercarbia, metabolic acidosis, pain, or anxiety (Table 3-2). However, many children with significant respiratory disease may have normal respiratory rates. Bradypnea may also occur in response to hypoxia in younger infants or from respiratory fatigue, CNS depression, or increased intracranial pressure. Pulsus paradoxus, an exaggeration of the normal decrease in blood pressure during inspiration, of greater than 10 mm Hg correlates well with the degree of airway obstruction but is very difficult to assess in children and therefore not routinely measured.

Table 3-2 Definition of Tachypnea by Age

Age	Breaths per Minute
Younger than 2 months	>60
2-12 months	>50
1-5 years	>40
Older than 5 years	>20

The respiratory examination can give many clues as to the cause of respiratory distress because the clinical manifestations may be indicative of the location of the disease process within the upper or lower respiratory tract (or both) (Figure 3-1). Initially, observe the general appearance of the patient, specifically for depth, rhythm, and symmetry of respirations; color; increased work of breathing; perfusion; and mental status. Patients with complete upper airway obstruction have aphonia, which is no audible speech, cry, or cough secondary to lack of effective air movement caused by a foreign body, angioedema, or epiglottitis. The presence of nasal flaring indicates dyspnea or upper airway obstruction. Facial edema and urticaria may signify anaphylaxis. The patient may show signs of acute or chronic hypoxemia in the form of cyanosis or clubbing, respectively (Figure 3-2). Cyanosis is not evident until more than 5 g/dL of hemoglobin is desaturated, which correlates with an oxygen saturation of less than 70% to 75%. Cyanosis is a late finding in children with hypoxemia and is seen in children with low cardiac output as well as low arterial oxygen saturation. Cyanosis in the presence of normal oxygen saturation may be indicative of methemoglobinemia.

Figure 3-1 Physical examination findings in respiratory distress.

Figure 3-2 Physical examination findings demonstrating hypoxemia.

Sounds noted on auscultation are useful in localizing the source of respiratory distress. Stertor, a sound from the upper airways resembling snoring, may indicate a degree of adenotonsillar hypertrophy, nasal congestion, or neuromuscular weakness. Hoarseness points to laryngeal or vocal cord dysfunction. A barky cough results from subglottic or tracheal obstruction. Stridor indicates abnormal turbulent air flow through a partially obstructed extrathoracic airway and can occur in both phases of respiration; if occurring during inspiration, the obstruction is most likely in the glottic or subglottic region; if in the expiratory phase, the sound is generated from the carina or below; if present in both phases (biphasic), the trachea may be involved (see Chapter 36). Grunting is a means by which patients generate intrinsic end-expiratory pressure against a closed glottis; in children, this is a sign of hypoxia that may indicate lower airway disease such as pneumonia. Grunting may also be associated with pain or an intraabdominal process. Retractions, the inward collapse of the chest wall, are caused by high negative intrathoracic pressure with increased respiratory effort and are more obvious in children because of the high compliance of the chest wall. Supraclavicular and suprasternal retractions occur in patients with upper airway obstruction; intercostal retractions signify lower tract disease or obstruction. Subcostal retractions may be seen with either upper or lower airway obstruction. Thoracoabdominal dissociation, or paradoxical breathing in which the chest collapses on inspiration while the abdomen is protruding, is a sign of respiratory failure from weakness or fatigue. Wheezing is classically a sign of lower airway obstruction and usually occurs during expiration (see Chapter 37). It may be associated with underlying medical conditions such as asthma, bronchiolitis, congestive heart failure, and congenital malformations. Inspiratory wheezing may indicate upper airway extrathoracic obstruction secondary to a foreign body, edema, or a fixed intrathoracic obstruction. Crackles (or rales) indicate fluid in the small- to medium-sized airways and may be heard in pneumonia, bronchiolitis, or myocarditis with heart failure. Rhonchi (coarse rales) involve secretions in the larger bronchi. A friction rub is heard when the pleura are inflamed and may be heard in patients with pneumonia or lung abscess and with pleural effusions or empyema. Bronchophony, egophony, and whispered pectoriloquy, which may be difficult to elicit in pediatric patients, occur because of consolidations in or around the lung, as seen in patients with pneumonia or pleural effusion.

Palpation and percussion of the neck or chest may also reveal crepitus suggestive of subcutaneous emphysema secondary to an air leak, such as in a pneumothorax. Whereas hyperresonance on percussion suggests air trapping, dullness suggests consolidation, a mass, or pleural fluid.

Differential Diagnosis

The differential diagnosis of respiratory distress can be summarized by organ system (Box 3-1).

Box 3-1

Differential Diagnosis of Respiratory Distress *

Respiratory System

Upper airway (nasopharynx, oropharynx, larynx, trachea, bronchi)

• Anatomic: craniofacial abnormalities, choanal atresia, tonsillar hypertrophy, macroglossia, midface hypoplasia, micrognathia, laryngomalacia, tracheomalacia, hemangioma, webs, cysts, laryngoceles, laryngotracheal cleft, papilloma, subglottic stenosis, vocal cord paralysis, tracheal stenosis, fistula, bronchomalacia, bronchogenic cyst

• Infectious: nasal congestion, Ludwig’s angina, peritonsillar abscess, tonsillitis, croup, epiglottitis, retropharyngeal abscess, tracheitis, bronchitis

• Environmental or traumatic: chemical or thermal burn, aspiration of foreign body

• Mass, including malignancy

• Inflammatory: angioneurotic edema, anaphylaxis

Lower airway (bronchioles, acini, interstitium)

• Inflammatory: asthma, allergy, angioneurotic edema, meconium aspiration, near drowning, submersion, gastroesophageal reflux, aspiration

• Infectious: bronchiolitis, pneumonia (bacterial, viral, atypical bacterial, Chlamydia, pertussis, fungal, Pneumocystis spp.), abscess

• Congenital malformation: congenital emphysema; cystic adenomatoid malformation; sequestration; pulmonary agenesis, aplasia, or hypoplasia; pulmonary cyst

• Environmental or traumatic: chemical or thermal burn, smoke, carbon monoxide, cyanide, hydrocarbon, near drowning, drug-induced pulmonary fibrosis, bronchopulmonary traumatic disruption, pulmonary contusion, high-altitude pulmonary edema

• Other: persistent fetal circulation, transient tachypnea of the newborn, respiratory distress syndrome, bronchiectasis, interstitial lung disease, bronchopulmonary dysplasia, cystic fibrosis, pulmonary edema, hemorrhage, embolism, atelectasis, mass

Chest wall and intrathoracic

• Pneumothorax, tension pneumothorax

• Diaphragmatic hernia

• Cyst, mass

• Spinal deformity (kyphoscoliosis)

• Pectus excavatum or carinatum

• Rib fracture, flail chest

Central Nervous System

• Structural abnormality: agenesis, hydrocephalus, mass, arteriovenous malformation

• Infectious: meningitis, encephalitis, abscess, poliomyelitis

• Dysfunction or immaturity: apnea, hypoventilation, hyperventilation

• Inherited degenerative disease: spinal muscular atrophy

• Intoxication or toxins: alcohol, barbiturates, benzodiazepines, opiates, tetanus

• Seizure

• Trauma: hemorrhage, birth asphyxia, spinal cord injury, anoxic encephalopathy

• Other: transverse myelitis, acute paralysis, myopathy

Peripheral Nervous System

• Phrenic nerve injury

• Environmental or toxins: tick paralysis, heavy metal poisoning, organophosphates, botulism, snakebite

• Metabolic: inborn errors of metabolism, carnitine deficiency, porphyria

• Inflammatory: dermatomyositis, polymyositis

• Other: Guillain-Barré syndrome, multiple sclerosis, myasthenia gravis, muscular or myotonic dystrophy, muscle fatigue

Cardiovascular System

• Structural: congenital heart disease, pericardial effusion, pericardial tamponade, aortic dissection or rupture, mass, coronary artery dilation or aneurysm, pneumopericardium, great vessel anomalies

• Other: arrhythmia, myocarditis, myocardial ischemia or infarction, congestive heart failure

Gastrointestinal System

• Appendicitis

• Necrotizing enterocolitis

• Mass (including hepatomegaly, splenomegaly)

• Ascites

• Obstruction

• Perforation, laceration

• Hematoma

• Contusion

• Esophageal foreign body

Hematologic System

• Acute chest syndrome

• Anemia

• Polycythemia

• Methemoglobinemia

Metabolic and Endocrine

• Acidosis: exercise, fever, hypothermia, dehydration, sepsis, shock, inborn errors of metabolism, liver disease, renal disease, diabetic ketoacidosis, salicylates

• Electrolyte disturbances: hypo- or hyperkalemia, hypo- or hypercalcemia, hypophosphatemia, hypo- or hypermagnesemia

• Hypo- or hyperglycemia

• Mitochondrial disorders leading to disruption of oxygen metabolism

^* Common causes are italicized; life-threatening causes are in bold.

Reprinted with permission from Weiner DL: Synopsis of Pediatric Emergency Medicine, ed 4. Philadelphia, Lippincott Williams & Wilkins, 2002, pp 221-227.

Evaluation and Management

Algorithm

An algorithmic approach that merges history and physical examination findings is helpful in eliciting the underlying cause of respiratory distress while also providing guidance for further testing (Figures 3-3 and 3-4).

Figure 3-3 Approach to the child with respiratory distress.

Figure 3-4 Approach to the child with respiratory distress (continued).

Initial Management

The emergent evaluation of children with respiratory distress must first identify the respiratory status of the patient by ensuring the patency of the airway, breathing, and circulation (see Chapter 1) before proceeding. Patients in severe respiratory distress and impending respiratory failure should be evaluated immediately for the life-threatening causes of respiratory distress, which include complete or rapidly progressing partial airway obstruction, as in foreign body or epiglottitis, tension pneumothorax, and cardiac tamponade (Table 3-2 and Figure 3-4). Children with respiratory failure secondary to inadequate oxygenation or ventilation may exhibit pallor or central cyanosis; altered mental status; decreased chest wall movement; or marked tachypnea, bradypnea, or apnea.

Abnormal vital signs should also be noted given that several simple interventions can promptly lessen the degree of the patient’s distress. For example, for a patient with a fever that may be contributing to respiratory distress, antipyretics are indicated. For a patient who has tachycardia caused by dehydration that is contributing to respiratory distress, an intravenous bolus of isotonic fluid can provide intravascular volume repletion and normalization of the tachycardia. Increased respiratory rate and hypoxia on pulse oximetry may indicate a need for supplemental oxygen.

A patient with respiratory distress of any degree may have an obstruction in the airway that should be managed with measures such as repositioning to maximize the patency of the airway, suctioning of excessive secretions, and inspection for a foreign body. Physical examination findings such as drooling, stridor, change in cry or voice, and dysphagia likely signify an upper airway condition. The presence of fever in these children indicates an infectious cause such as epiglottitis, croup, tracheitis, retropharyngeal abscess, or peritonsillar abscess. Absence of fever favors alternate diagnoses, such as vocal cord dysfunction or angioedema secondary to anaphylaxis.

If signs such as crackles or wheezing are present by auscultation, respiratory distress is likely attributable to a process located in the lung parenchyma (e.g., pneumonia) or larger lower airways (e.g., asthma). As with upper airway disease, the presence of fever favors infectious causes.

Simple tachypnea without other lung findings may still indicate infectious causes (i.e., pneumonia, empyema, or sepsis), anatomic abnormalities (i.e., pneumothorax or congenital heart disease), or even underlying metabolic and CNS causes that interfere with the normal mechanisms of respiration.

Diagnostic Studies

Radiographs

In the younger age groups, the physical examination, including the respiratory examination, may not clearly elucidate the underlying disease process. Radiographs may be helpful in these cases and in other instances to corroborate physical examination findings. A child who exhibits a barking cough suspicious for laryngotracheobronchitis (more commonly known as croup) may have the pathognomonic “steeple sign,” the radiographic projection of the narrowing of the subglottic trachea on a neck radiograph. Croup is usually a diagnosis made only on clinical grounds, but radiographs may be helpful when the diagnosis is in question or the presentation is unusual. In a child who exhibits fever, drooling, and is sitting upright in the “sniffing position” (neck flexed and head mildly extended), a lateral neck radiograph may show prevertebral widening classically seen in retropharyngeal abscess. Chest radiographs, both anteroposterior and lateral projections, are also helpful in evaluating for heart size, which may signify an underlying cardiac anomaly; consolidations in the lung fields, which may represent infection, atelectasis, or effusion; and inadequate lung expansion, which may be present with pneumothorax, foreign body, or poor external muscle strength.

If the history and physical examination indicate an obstructive component, neck radiographs or lateral decubitus chest radiographs can aid in the diagnosis. Lateral and anteroposterior radiographs of the neck are useful for the diagnosis of retropharyngeal abscess, epiglottitis, foreign body aspiration, or tracheitis in stable children. Abdominal radiographs may reveal intestinal obstruction or perforation causing respiratory distress from abdominal competition. Other advanced imaging studies to consider based on the clinical situation include barium swallow, airway fluoroscopy, computed tomography, and magnetic resonance imaging. A ventilation-perfusion scan or pulmonary angiography of the chest may also be helpful in the diagnosis of entities such as pulmonary embolus.

Blood Tests

Blood tests may also be useful to guide further therapy. A blood gas analysis, ideally an arterial sample, will reflect oxygenation, ventilation, and acid–base status, all of which may be amenable to immediate treatment (Figure 3-5). A venous blood gas analysis can provide some information about ventilation but is less useful in assessing oxygenation. Blood chemistry analysis that includes electrolytes and total carbon dioxide may provide evidence of a metabolic acidosis that could be contributing to the patient’s respiratory distress. Other tests such as carboxyhemoglobin or methemoglobin levels may be useful if the clinical history and physical examination raise suspicion. A complete blood count can indicate an elevated white blood cell count that may support a diagnosis of infection or may show anemia or polycythemia, both of which may lead to tachypnea. A toxicology screen may be useful in a child with altered mental status, respiratory depression (opiate overdose), or unexplained tachypnea (metabolic acidosis). Specimens should be sent for microbiologic culture as deemed necessary.