Respiratory insufficiency

respiratory failure is a clinical syndrome characterized by the body's inability to maintain arterial levels of oxygen (O₂) and carbon dioxide (CO ₂) suitable for the demands of cellular metabolism.

Concept

Acute respiratory failure is the inability of the respiratory system to perform its basic function, which is the gaseous exchange of oxygen and carbon dioxide between ambient air and circulating blood, culminating in failure of the body's cellular metabolism..

According to its medical heading, it is defined as:

It fails to properly provide oxygen to the cells of the body and remove excess carbon dioxide from it. (Stedman, 25th ed)

MeSH Term for Respiratory Insufficiency

In medical terms, respiratory failure is defined as the presence of arterial hypoxemia (PaO₂ less than 60 mmHg) at rest, at sea level and breathing room air. This criterion may be accompanied by hypercapnia (PaCO₂ greater than 45 mmHg). For practical purposes, an oxygen saturation between 90 and 95 can be understood to be equivalent to a PaO₂ of 60 and 80 mmHg.

Classification

Based on arterial blood gas values, respiratory failure is classified into two subtypes:

• Partial respiratory insufficiency: It is defined as the decrease in partial oxygen pressure below 60 mmHg. (P_O2 60 mmHg
• Global respiratory insufficiency: It is defined as the decrease in partial oxygen pressure below 60 mmHg plus the increase in partial carbon dioxide pressure above 45 mmHg. (P_O2 60 mmHg + P_CO2  45 mmHg)

According to the time of onset, respiratory failure is classified as:

• Acute
• Chronic
• chronicled

Pathophysiology

Hemoglobin dissociation curve, depending on the oxygen saturation.

The choice of 60 mmHg PaO₂ as the threshold for the diagnosis of respiratory failure is based on the shape of the dissociation curve of hemoglobin where, above this level, oxygen saturation stands tall and stable; however, below this level, any slight reduction can result in a noticeable decrease in oxygen saturation.

Treatment

Mechanical ventilator

Treatment of the underlying cause is necessary, if possible. Treatment of acute respiratory failure may include medication such as bronchodilators (for airway disease), antibiotics (for infections), glucocorticoids (for many causes), diuretics (for pulmonary edema), among others. Respiratory failure resulting from an opioid overdose can be treated with the antidote naloxone. In contrast, most benzodiazepine overdoses do not benefit from its antidote, flumazenil. Respiratory Therapy/Respiratory Physiotherapy] may be beneficial in some cases of respiratory failure.

Type 1 respiratory failure may require oxygen therapy to achieve adequate oxygen saturation. Failure to respond to oxygen may indicate other modalities such as heated humidified high-flow therapy, continuous positive airway pressure, or (if severe) endotracheal intubation and mechanical ventilation.

Type 2 respiratory failure often requires noninvasive ventilation (NIV) unless medical therapy can improve the situation. Immediate mechanical ventilation or otherwise is sometimes indicated if NIV fails. Respiratory stimulants such as doxapram are now rarely used.

There is tentative evidence that in those with respiratory failure identified before hospital arrival, continuous positive airway pressure may be helpful when initiated before transfer to hospital.

Related diseases

• Asma
• Bronquitis
• Broncholitis
• Pulmonary emphysema
• Pneumonia
• Medical breathing