Respiratory failure occurs when the respiratory system cannot maintain adequate gas exchange between air and blood. In practical terms this means insufficient oxygenation of arterial blood, excessive retention of carbon dioxide, or both. The underlying problem may involve the process of respiration, the tiny air sacs called alveoli, or structures of the lung that deliver oxygen (O2) to the circulation. Left untreated, severe respiratory failure can be fatal, which is why it is considered a medical emergency.

Types and clinical distinctions

Clinicians commonly separate respiratory failure into two main patterns. Hypoxemic respiratory failure (often called Type I) is characterized primarily by low arterial oxygen tension and inadequate oxygen transfer. Hypercapnic respiratory failure (Type II) involves elevated arterial carbon dioxide, reflecting inadequate ventilation. Respiratory failure can also be acute, developing over minutes to days, or chronic, with gradual changes that the body partly compensates for.

Common causes and mechanisms

Multiple processes can cause respiratory failure: intrinsic lung diseases that impair gas exchange (for example, severe pneumonia, acute respiratory distress syndrome, or chronic obstructive pulmonary disease), airway obstruction, disorders of the chest wall or respiratory muscles, and central nervous system depression from drugs or injury. Systemic problems such as sepsis or major trauma may precipitate or worsen failure by altering lung mechanics and circulation.

Presentation and diagnosis

Symptoms range from shortness of breath and rapid breathing to confusion, cyanosis, and reduced consciousness. Healthcare providers rely on bedside measures such as pulse oximetry and definitive tests like arterial blood gases to assess oxygen (PaO2) and carbon dioxide (PaCO2) levels, as well as chest imaging and blood tests to identify underlying causes. For more on gas exchange physiology see gas exchange and on blood testing see arterial blood measurements.

Treatment and importance

Treatment aims to restore adequate oxygenation and ventilation while addressing the underlying cause. Immediate measures include supplemental oxygen, noninvasive ventilation (such as CPAP or BiPAP), and, when necessary, endotracheal intubation with mechanical ventilation. Supportive care may involve fluids, antibiotics, bronchodilators, or reversal of drug effects. Because rapid intervention can prevent progression, respiratory failure is managed urgently in emergency and critical care settings; basic emergency measures overlap with cardiopulmonary resuscitation principles and advanced airway management (emergency treatment, resuscitation).

  • Key points: recognize symptoms early, use arterial blood gas testing, distinguish hypoxemic from hypercapnic patterns.
  • Treatment ranges from oxygen therapy to invasive ventilation, tailored to cause and severity.