Respiratory Failure

Respiratory failure represents a spectrum of illnesses that have led to the disruption of one’s ability to breathe normally. Oxygenation and ventilation are the two main components to breathing. Respiratory failure can refer to an acute or chronic disruption of oxygenation, ventilation, or both. Depending upon the type of respiratory failure, interventions can be short or long term. A better understanding of the terminology can help to understand the situation your child is experiencing.

Definitions:

• Oxygenation - the process of bringing oxygen in from the environment (air) to the alveoli, or gas exchange units of the lungs. Hypoxia is the term used to describe low oxygen saturations in the tissue (this is what is measured with pulse oximetry). Hypoxemia describes low oxygen saturations in the blood (this requires a blood gas to measure).

• Ventilation - the process of eliminating carbon dioxide (a metabolic waste product) in the gas exchange units of the lungs (alveoli). When ventilation is impaired, carbon dioxide typically rises. This can be referred to as hypercarbia. Carbon dioxide is measured on a blood gas and can be estimated using end tidal (exhaled) carbon dioxide measurements.

• Acute Respiratory Failure - a temporary loss in one’s ability to oxygenate or ventilate. Common causes include respiratory infections, ingestions or trauma.

• Chronic Respiratory Failure - a persistent loss in one’s ability to oxygenate or ventilate. Common causes include neurologic impairments, chronic lung diseases such as bronchopulmonary dysplasia or interstitial lung disease.

One typically uses a combination of the above terms to describe a patient’s respiratory status. For example, an otherwise healthy child with a new pneumonia with low oxygen saturations may be described as acute hypoxic respiratory failure. A child with a chronic respiratory condition, such as a neuromuscular condition typically requiring non-invasive ventilator support during sleep who suddenly develops a pneumonia may be described as an acute on chronic hypoxic and hypercarbic respiratory failure.

Causes of Respiratory Failure:

There are many causes of respiratory failure, some brief (acute) and others more long lasting (chronic). Below is a non-exhaustive list for some etiologies of respiratory failure.

Acute Respiratory Failure

• Pneumonia/Infections

• New neurologic insults (e.g. trauma, stroke)

• Overdose (e.g. narcotics)

• Aspiration

• Asthma (severe exacerbations)

Diagnosing Respiratory Failure:

Children who develop respiratory failure either have a clear inciting event (e.g. trauma) or have a slow onset or progression of symptoms depending upon the nature of their underlying condition. Others can transition from acute respiratory failure (such as a premature baby born with neonatal respiratory distress syndrome) to chronic respiratory failure (bronchopulmonary dysplasia).

Acute respiratory failure typically presents with shortness of breath (such as in an asthmatic with a severe exacerbation) or limited respiratory effort (such as in a child with a brain injury). Either way, the child will have low oxygen as measured through a pulse oximeter. The child with shortness of breath will often have nasal flaring, chest wall retractions and will likely be breathing very rapidly (tachypneic). Children in these scenarios require emergent medical attention.

Chronic respiratory failure can either begin acutely and transition to a more long term challenge or onset may be a bit more ominous with a slow, gradual progression of the underlying disease process. These children will often appear to be at their baseline, however laboratory testing may reveal a slightly elevated carbon dioxide in the blood or a sleep study (polysomnogram) will demonstrate notable hypoxia (desaturations in oxygen) or hypercarbia (increased carbon dioxide) with sleep. These signs of respiratory failure may only be evident during sleep in the early phases of disease progression and often require a higher index of suspicion to identify. For children with known conditions associated with chronic respiratory failure, disease specific guidelines typically recommend routine screening for respiratory failure.

Tests for respiratory failure:

Treating Respiratory Failure:

The treatment for respiratory failure typically depends on the cause and expected duration of the condition. Treating the underlying cause of acute respiratory failure is paramount to a successful recovery. In other words, if your child needs supplemental oxygen because they have a bacterial pneumonia, antibiotics should help solve the problem. To support challenges with oxygenation, one can supplement oxygen via a nasal cannula, a face mask (venturi or non-rebreather), high flow nasal cannula, continuous positive airway pressure (CPAP), bi-level non-invasive support (NIV, such as BiPAP) or more invasive ventilatory support via an endotracheal tube (intubation). Typically, the expectation in acute respiratory failure is a short term process that will resolve in time. If this is not the case, and a longer duration of respiratory support is required, particularly CPAP, bi-level NIV or invasive ventilatory support, a tracheostomy may be considered.

A tracheostomy is a surgically placed opening between the environment and the trachea. A tracheostomy tube is a breathing tube that is placed into a trachea via the tracheostomy and provides a connection for a respiratory device (supplemental oxygen, CPAP or mechanical ventilation) to help deliver its support. A tracheostomy tube is fixed to the neck by “neck ties” and allows children to socialize, interact, participate in therapies and cares all while continuing on their necessary level of respiratory support. Many children can be discharged from the hospital to home, on ventilatory support, through a tracheostomy if the child is stable and providers are trained to troubleshoot the tracheostomy tube (and respiratory support). It’s also important to note that a tracheostomy tube is not always a permanent intervention. For children who eventually recover from their chronic respiratory failure, a tracheostomy can be reversed/closed.

Resources:

• Columbia University’s “When a child may use a ventilator for a long time” by Jeffrey Edwards, MD MA MAS and others (publication in Pediatric Pulmonology)