Monday, February 6, 2023

Pediatric Respiratory Failure

Practice Essentials

Pediatric respiratory failure develops when the rate of gas exchange between the atmosphere and the blood is unable to match the body’s metabolic demands. Acute respiratory failure remains an important cause of morbidity and mortality in children. Cardiac arrests in children frequently result from respiratory failure. See the image below.

Bilateral airspace infiltrates on chest radiograph

Bilateral airspace infiltrates on chest radiograph film secondary to acute respiratory distress syndrome that resulted in respiratory failure.

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Signs and symptoms

Patients may be lethargic, irritable, anxious, or unable to concentrate. Children with respiratory distress commonly sit up and lean forward to improve leverage for the accessory muscles and to allow for easy diaphragmatic movement. Children with epiglottitis sit upright with their neck extended and head forward while drooling and breathing through their mouth.

The respiratory rate and quality can provide diagnostic information, as exemplified by the following:

Bradypnea: Most often observed in central control abnormalities

Tachypnea: Fast and shallow breathing is most efficient in intrathoracic airway obstruction; it decreases dynamic compliance of the lung

The patient should also be evaluated for the following:

Stridor (an inspiratory sound)

Wheezing (an expiratory sound)

Crackles

Decreased breath sounds (eg, alveolar consolidation, pleural effusion)

Paradoxical movement of the chest wall

Accessory muscle use and nasal flaring

Cardiovascular signs in patients with respiratory failure can include the following:

Tachycardia and hypertension: May occur secondary to increased circulatory catecholamine levels

Gallop: Suggestive of myocardial dysfunction leading to respiratory failure

Bradycardia: Age-specific bradycardia associated with decreased or shallow breathing and desaturations indicates the need for emergent positive-pressure ventilation

See Clinical Presentation for more detail.

Diagnosis

Blood and pulmonary studies

Arterial blood gas (ABG) measurement: Can be used to define acute respiratory failure

Complete blood count (CBC): Polycythemia suggests chronic hypoxemia

Electrolyte abnormalities: Hypokalemia, hypocalcemia, and hypophosphatemia can impair muscle contraction

Alveolar-arterial oxygen difference ([A-a]DO2): In children, (A-a)DO2 is normally 5-10

PaO2/ fractional concentration of inspired oxygen (FiO2): Indicates gas exchange

Oxygen index: (PaO2 x FiO2/mean airway pressure) x 100

Dead-space volume to tidal gas volume (VD/VT)

Intrapulmonary shunt fraction (Qs/Qt)

Imaging studies

Common radiographic findings associated with respiratory failure include the following:

Focal or diffuse pulmonary disease (eg, pneumonia, acute respiratory distress syndrome [ARDS])

Bilateral hyperinflation (eg, asthma)

Asymmetrical lung expansion suggesting a bronchial obstruction

Pleural effusion

Cardiomegaly

Bronchoalveolar lavage and lung biopsy

Bronchoalveolar lavage (BAL) is performed to identify a specific infectious pulmonary pathogen; it can also be used to isolate lipid-laden macrophages (suggestive of recurrent aspiration) or pulmonary hemorrhage.

Lung biopsy may be indicated if BAL does not reveal a pathogen and is also helpful in the diagnosis of sarcoidosis and other granulomatous conditions.

See Workup for more detail.

Management

For partial upper-airway obstruction (eg, from anesthesia or acute tonsillitis), place a nasopharyngeal airway to provide a passageway for air. An oropharyngeal airway can be used temporarily in the unconscious patient.

For extrathoracic airway obstruction, as in croup, the following measures may be helpful:

Inspired humidity: To liquefy secretions

Heliox (helium and oxygen gas mixture): To decrease the work of breathing

Racemic epinephrine 2.25% (an aerosolized vasoconstrictor)

Systemic corticosteroids: To decrease airway edema

Nebulized hypertonic (3%) saline

Lung and respiratory pump support

Oxygen therapy: Supplemental oxygen is the initial treatment for hypoxemia

Humidified high-flow nasal cannula therapy (HHFNC): May be effective in the treatment of some neonatal respiratory conditions

Continuous positive airway pressure (CPAP): May be indicated if lung disease results in severe oxygenation abnormalities

Noninvasive positive-pressure ventilation (NPPV): To decrease the work of breathing and provide adequate gas exchange

Conventional mechanical ventilation: For acute hypercapnia and severe hypoxemia

Inverse ratio ventilation: A nonphysiologic pattern for breathing

Airway pressure release ventilation (APRV): A form of inverse-ratio ventilation that allows the patient to breathe spontaneously throughout the ventilatory cycle

High-frequency oscillatory ventilation (HFOV): Improves the occurrence and treatment of air-leak syndromes associated with neonatal and pediatric acute lung injury; research suggests, however, that it may lead to poorer outcomes than conventional mechanical ventilation in pediatric acute respiratory failure

Adjunctive therapies for severe hypoxemia

Prone positioning: Reduces compliance of the thoracoabdominal cage by impeding the compliant rib cage

Inhaled nitric oxide (NO): Potential benefit of NO is to improve ventilation-to-perfusion matching by enhancing pulmonary blood flow to well-ventilated parts of the lung

Exogenous surfactant: Improves respiratory mechanics and oxygenation in neonatal respiratory distress syndrome (RDS)

Extracorporeal life support (ECLS): Therapy in which blood is removed from the patient, passed through an artificial membrane where gas exchange occurs, and returned to the body by either the arterial (venoarterial [VA]) or venous (venovenous [VV]) system

See Treatment and Medication for more detail.

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