Respiratory Failure and Mechanical Ventilation
Respiratory failure is the syndrome that arises when the respiratory system can no longer maintain adequate gas exchange, producing hypoxemia (failure of oxygenation), hypercapnia (failure of ventilation), or both. Mechanical ventilation is the principal organ-support technology used in the intensive care unit to substitute for or assist failing respiratory function while the underlying cause is treated. Together these topics form one of the central pillars of critical care medicine.
Definition
Respiratory failure denotes inadequate gas exchange by the respiratory system, conventionally divided into hypoxemic (type 1) failure, characterised by low arterial oxygen, and hypercapnic (type 2) failure, characterised by carbon dioxide retention; mechanical ventilation is the application of positive-pressure breaths by a ventilator to support or replace spontaneous breathing.
Scope
This area orients the reader to the spectrum of acute respiratory failure and to the technology used to support it. It links to detailed topic entries on the acute respiratory distress syndrome, the modes and strategies of invasive mechanical ventilation, ventilator-induced lung injury, weaning and extubation, and noninvasive positive-pressure ventilation. It is a reference and educational overview, not a bedside protocol.
Sub-topics
Core questions
- What distinguishes hypoxemic from hypercapnic respiratory failure, and why does the distinction matter for support?
- When does a patient with respiratory failure need invasive versus noninvasive ventilatory support?
- How can mechanical ventilation support the lungs without itself causing injury?
- How is readiness to liberate a patient from the ventilator assessed?
Key concepts
- Hypoxemic (type 1) respiratory failure
- Hypercapnic (type 2) respiratory failure
- Gas exchange and the alveolar-arterial oxygen gradient
- Positive-pressure ventilation
- Lung-protective ventilation
- Ventilator-induced lung injury
- Ventilator liberation (weaning)
Mechanisms
Adequate gas exchange requires matched alveolar ventilation and pulmonary perfusion across a functional alveolar-capillary membrane. Respiratory failure follows when this is disrupted by ventilation-perfusion mismatch, shunt, diffusion impairment, alveolar hypoventilation, or pump (neuromuscular and chest-wall) failure. Mechanical ventilation delivers positive-pressure breaths that recruit collapsed lung, augment alveolar ventilation, and reduce the work of breathing; positive end-expiratory pressure keeps alveoli open at end-expiration to improve oxygenation. Because the same positive pressure that supports gas exchange can also overdistend and repeatedly open and close lung units, modern practice frames ventilation around minimising ventilator-induced lung injury while the primary disease resolves (Slutsky-Ranieri-2013; Tobin-2013-textbook).
Clinical relevance
Acute respiratory failure is among the commonest reasons for intensive care admission, and mechanical ventilation is one of the defining interventions of critical care. Understanding how respiratory support works, and how it can both help and harm the lung, underpins evidence appraisal across this area. This entry describes concepts and evidence and is not a source of individualised diagnostic or treatment instructions.
Epidemiology
Large international observational cohorts show that mechanical ventilation is used in a substantial proportion of intensive care admissions worldwide, with acute respiratory failure, postoperative care, coma, and exacerbations of chronic lung disease among the leading indications, and with mortality varying by indication and severity (Esteban-2002).
Evidence & guidelines
The modern evidence base for this area is built on randomised trials and professional-society guidelines addressing lung-protective tidal volumes, positive end-expiratory pressure strategy, prone positioning, weaning practice, and the role of noninvasive support, which are detailed in the individual topic entries. This overview points to that evidence rather than restating specific thresholds.
History
Positive-pressure mechanical ventilation entered routine clinical use during the poliomyelitis epidemics of the mid-twentieth century, when manual and then mechanical positive-pressure ventilation dramatically reduced mortality from ventilatory failure and helped give rise to the intensive care unit. Over subsequent decades attention shifted from simply restoring gas exchange to recognising that the ventilator itself can injure the lung, reframing the field around protective ventilation (Slutsky-Ranieri-2013).
Key figures
- Arthur Slutsky
- V. Marco Ranieri
- Martin J. Tobin
- Laurent Brochard
- Andres Esteban
Related topics
Seminal works
- slutsky-ranieri-2013
- esteban-2002
- tobin-2013-textbook
Frequently asked questions
- What is the difference between type 1 and type 2 respiratory failure?
- Type 1 (hypoxemic) failure is dominated by a low arterial oxygen level with normal or low carbon dioxide, typically from ventilation-perfusion mismatch or shunt; type 2 (hypercapnic) failure is dominated by carbon dioxide retention from inadequate alveolar ventilation or pump failure.
- Does mechanical ventilation cure respiratory failure?
- No. Mechanical ventilation supports gas exchange and reduces the work of breathing to buy time, but it is a supportive therapy; recovery depends on treating the underlying cause of the respiratory failure.