Respiratory failure (pediatrics): Clinical sciences

Respiratory failure occurs when the respiratory system cannot adequately oxygenate the blood, remove carbon dioxide from the blood, or both.

This life-threatening condition requires rapid recognition and management.

Underlying causes of respiratory failure include pulmonary or airway disease, as well as conditions affecting the chest wall, muscles of respiration, and central or peripheral chemoreceptors.

Respiratory failure can be categorized as hypoxemic, hypercapnic, or a combination of the two.

Now, if a pediatric patient presents with a chief concern suggesting respiratory failure, you should first perform an ABCDE assessment.

These patients are typically unstable, so you’ll need to immediately stabilize their airway, breathing, and circulation. Then, provide supplemental oxygen, and consider noninvasive positive pressure ventilation.

If your patient has poor respiratory effort, you may need to perform endotracheal intubation and begin mechanical ventilation.

Next, obtain IV access, and put your patient on continuous vital sign monitoring, including respiratory rate, pulse oximetry, and cardiac monitoring.

Once you’ve provided acute management, obtain a focused history and physical exam, and order a chest X-ray and an arterial blood gas, or ABG for short.

Verbal patients may describe shortness of breath, and their history may reveal cardiac or pulmonary disease, a neuromuscular disorder, recent illness, head trauma, or narcotic exposure.

On exam, most patients are tachypneic, with signs indicating increased work of breathing, such as nasal flaring, head bobbing, grunting, tracheal tugging, retractions, and accessory muscle use.

In other cases, patients may exhibit slow, shallow respirations, or even apnea. Your patient might appear somnolent or cyanotic, and pulse oximetry frequently reveals an oxygen saturation below 90 percent.

Depending on the underlying cause, the chest X-ray might demonstrate abnormal findings, such as a foreign body, pulmonary edema, or a focal consolidation.

Here’s our first clinical pearl! While many patients with acute respiratory failure initially present with tachypnea and clear signs of respiratory distress; over time, progressive respiratory muscle fatigue can result in less obvious signs, like shallow and ineffective breaths. It’s crucial to recognize these later signs, since prompt intervention can prevent cardiopulmonary arrest.

Now, at this point, you should suspect respiratory failure, but to confirm the diagnosis, you’ll need to assess the ABG findings.

If the arterial partial pressure of oxygen, or PaO2, is less than 60 millimeters of mercury, your patient has hypoxemic respiratory failure. This means that a failure of gas exchange within the lungs is causing hypoxemia.

Most of the time, hypoxemic respiratory failure is caused by a mismatch in alveolar ventilation and perfusion, or a V/Q mismatch. When alveoli are well-ventilated but poorly perfused, the ventilation-to-perfusion or V/Q ratio is high, and an absence of perfusion creates alveolar “dead space”.

Conversely, when alveoli are well-perfused but poorly ventilated, the V/Q ratio is low, and a complete absence of ventilation with normal perfusion is called an intrapulmonary shunt.

Finally, in some cases, hypoxemic respiratory failure is caused by impaired diffusion of oxygen across the alveolar-capillary membrane.

Some conditions that lead to hypoxemic respiratory failure include asthma or other causes of small airway obstruction, as well as interstitial edema or fibrosis, atelectasis, and pneumonia.