Respiratory support comprises a spectrum of therapeutic interventions designed to maintain adequate oxygenation, ventilation, and gas exchange in patients with acute or chronic respiratory compromise. It is a cornerstone of emergency medicine, respiratory medicine, anaesthesia, perioperative care, and intensive care medicine, providing physiological support while the underlying cause of respiratory failure is identified and treated.
The level of respiratory support required varies according to the severity of respiratory dysfunction, underlying pathology, and the patient’s physiological response to treatment. Management ranges from supplemental oxygen therapy to advanced invasive mechanical ventilation and is guided by clinical assessment, oxygenation, ventilation, haemodynamic status, and objective physiological measurements.
Supplemental Oxygen Therapy
Supplemental oxygen is the most frequently used form of respiratory support and is indicated for the treatment of hypoxaemia. Oxygen therapy increases the fraction of inspired oxygen (FiO₂), thereby improving arterial oxygenation and tissue oxygen delivery.
Common oxygen delivery devices include:
- Nasal cannulae
- Simple face masks
- Venturi masks
- Non-rebreather masks
- High-flow nasal oxygen (HFNO)
Selection of the appropriate delivery device depends on the patient’s oxygen requirements, work of breathing, and underlying respiratory pathology. Oxygen therapy should be titrated to achieve recommended target oxygen saturation ranges while avoiding both inadequate oxygenation and unnecessary hyperoxia. Particular care is required in patients at risk of hypercapnic respiratory failure, including selected individuals with chronic obstructive pulmonary disease (COPD).
Non-Invasive Ventilation
Non-invasive ventilation (NIV) provides positive pressure ventilatory support without the need for endotracheal intubation. Ventilation is delivered via a tightly fitting face or nasal interface and may reduce the work of breathing, improve alveolar ventilation, and enhance gas exchange.
The two principal forms of NIV are:
- Continuous Positive Airway Pressure (CPAP)
- Bi-level Positive Airway Pressure (BiPAP)
Non-invasive ventilation is widely used in the management of acute exacerbations of chronic obstructive pulmonary disease, acute cardiogenic pulmonary oedema, selected forms of hypoxaemic respiratory failure, obesity hypoventilation syndrome, and postoperative respiratory insufficiency. Successful treatment requires careful patient selection, close physiological monitoring, and timely recognition of treatment failure.
Invasive Mechanical Ventilation
Patients who remain unable to maintain adequate oxygenation or ventilation despite less invasive measures may require invasive mechanical ventilation. This involves placement of an endotracheal tube or tracheostomy connected to a mechanical ventilator capable of partially or completely supporting respiratory function.
Common indications include:
- Acute respiratory distress syndrome (ARDS)
- Severe pneumonia
- Sepsis-associated respiratory failure
- Major trauma
- Neurological impairment affecting airway protection or ventilation
- Respiratory muscle weakness or neuromuscular disease
- Postoperative respiratory failure
Ventilator management is individualised according to the patient’s underlying pathology and physiological requirements. Ventilator settings are adjusted using clinical examination, arterial blood gas analysis, respiratory mechanics, lung-protective ventilation strategies, and evidence-based critical care practice.
Clinical Assessment
Patients receiving respiratory support require continuous clinical reassessment to evaluate treatment effectiveness and identify deterioration. Monitoring typically includes:
- Peripheral oxygen saturation (SpO₂)
- Respiratory rate
- Fraction of inspired oxygen (FiO₂)
- Arterial blood gas (ABG) analysis
- Partial pressure of arterial oxygen (PaO₂)
- PaO₂/FiO₂ ratio
- Work of breathing
- Heart rate and blood pressure
- Level of consciousness
These parameters assist clinicians in determining whether respiratory support should be escalated, maintained, or gradually weaned as the patient’s condition evolves.
Respiratory Support in Clinical Scoring Systems
Objective assessment of respiratory function is supported by several validated clinical calculators and scoring systems. Commonly used tools include the PaO₂/FiO₂ Ratio, the Sequential Organ Failure Assessment (SOFA) Score, and the National Early Warning Score 2 (NEWS2). These instruments assist in quantifying respiratory dysfunction, monitoring disease progression, and supporting evidence-based clinical decision-making.
Although clinical calculators provide valuable objective information, they should always be interpreted alongside comprehensive clinical assessment, diagnostic investigations, and professional judgement.
Clinical Significance
Respiratory support remains a fundamental component of modern acute and critical care medicine. Appropriate selection of oxygen therapy, non-invasive ventilation, or invasive mechanical ventilation can improve oxygen delivery, reduce the work of breathing, support gas exchange, and prevent progression of respiratory failure. When integrated with ongoing clinical assessment and treatment of the underlying disease process, respiratory support contributes significantly to improved patient outcomes across a wide range of medical and surgical specialties.