Guide — Critical Care
Ventilator Basics
Mechanical ventilation supports or replaces the work of breathing when a patient cannot maintain adequate oxygenation or ventilation independently. This guide covers indications, essential settings, nursing monitoring responsibilities, and common complications.
11 min read · Critical Care
Educational use only. Mechanical ventilation management requires advanced training, licensed supervision, and institutional protocols. Ventilator settings are always individualized by the provider or respiratory therapist. This content supports learning, not clinical decision-making. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Purpose of Mechanical Ventilation
Mechanical ventilation serves two primary physiological goals:
- Oxygenation: Delivering adequate oxygen to the alveoli and bloodstream when spontaneous breathing is insufficient. Supported through FiO₂ and PEEP adjustments.
- Ventilation: Removing carbon dioxide (CO₂) through controlled or assisted breathing cycles. Supported through rate and tidal volume settings.
Mechanical ventilation does not treat the underlying cause — it buys time while the primary condition is addressed.
Common Indications
- Respiratory failure: Hypoxemic (PaO₂ < 60 mmHg on FiO₂ ≥ 0.60) or hypercapnic (PaCO₂ > 50 mmHg with acidemia)
- Airway protection: Altered mental status (GCS ≤ 8), aspiration risk, or inability to manage secretions
- Increased work of breathing: Severe respiratory distress with accessory muscle use, paradoxical breathing, or fatigue
- Post-operative: Following major surgery, particularly cardiac, thoracic, or prolonged procedures
- Apnea or respiratory arrest: Any condition causing complete cessation of breathing
- Specific conditions: ARDS, severe pneumonia, exacerbated COPD, pulmonary edema, septic shock with respiratory compromise
Ventilator Terminology
| Term | Definition |
|---|---|
| FiO₂ | Fraction of inspired oxygen (0.21–1.0). Goal is lowest FiO₂ that achieves SpO₂ ≥ 92–95%. |
| Tidal Volume (Vt) | Volume delivered per breath. Lung-protective: 6–8 mL/kg of ideal body weight. Higher volumes risk barotrauma. |
| Respiratory Rate (RR) | Breaths per minute delivered by the ventilator. Adjusted to control PaCO₂. |
| PEEP | Positive End-Expiratory Pressure. Prevents alveolar collapse at end of expiration. Typically 5–10 cmH₂O. |
| Peak Inspiratory Pressure (PIP) | Highest pressure generated during inhalation. Monitored for trends indicating changes in compliance or resistance. |
| Plateau Pressure (Pplat) | Pressure at end of inhalation with no airflow. Reflects alveolar pressure and lung compliance. Goal < 30 cmH₂O. |
| Minute Ventilation (MV) | Total volume of air moved per minute: Vt × RR. Determines CO₂ elimination. Normal: 5–8 L/min. |
| I:E Ratio | Inspiratory-to-expiratory time ratio. Normal is 1:2. Prolonged expiration (1:3 or 1:4) used in obstructive disease to prevent air trapping. |
Basic Ventilator Settings Overview
Initial settings are ordered by the provider and adjusted based on ABG results, SpO₂, and patient response. Typical starting ranges for an adult on volume-controlled AC mode:
Settings are continuously individualized. Lung-protective ventilation uses lower tidal volumes to reduce ventilator-induced lung injury (VILI), especially in ARDS.
Nursing Monitoring Considerations
Continuous Assessment
- Bilateral breath sounds — equality, adventitious sounds
- Chest rise symmetry — unilateral movement suggests ETT malposition or pneumothorax
- SpO₂ and ETCO₂ (end-tidal CO₂) continuously
- Peak inspiratory pressure (PIP) trends — sudden increase suggests obstruction or decreased compliance
- Ventilator waveforms and alarms — never silence an alarm without assessing the patient first
ETT Position and Security
- Document ETT cm marking at lip/teeth each shift and after repositioning
- Confirm CXR verification of placement (tip should be 3–5 cm above carina)
- Secure tube to prevent accidental extubation — two-nurse procedure for repositioning
- Cuff pressure: maintain 20–30 cmH₂O to prevent aspiration and tracheal injury
Sedation and Comfort
- Assess sedation level using RASS or SAS every 2–4 hours
- Target lightest sedation level that maintains patient comfort and ventilator synchrony
- Daily spontaneous awakening trials (SATs) and spontaneous breathing trials (SBTs) per protocol
- Pain assessment using CPOT for non-verbal patients
Ventilator-Associated Complications
Ventilator-Associated Pneumonia (VAP)
Most common infectious complication. Prevention: VAP bundle — HOB elevation 30–45°, oral care every 2–4 hours with chlorhexidine, subglottic suctioning, hand hygiene, daily extubation readiness assessment.
Barotrauma
Alveolar rupture due to excessive airway pressures. Can lead to pneumothorax, pneumomediastinum, or subcutaneous emphysema. Monitor plateau pressures — keep < 30 cmH₂O.
Oxygen Toxicity
Prolonged high FiO₂ (> 0.60 for > 24–48 hours) can injure alveolar membranes. Wean FiO₂ to the lowest level that maintains acceptable SpO₂.
Ventilator-Induced Diaphragm Dysfunction (VIDD)
Prolonged full ventilator support can cause diaphragm atrophy. Spontaneous breathing modes preserve diaphragm strength and support weaning.
Hemodynamic Effects
Positive pressure ventilation increases intrathoracic pressure, reducing venous return and cardiac output. PEEP magnifies this effect. Monitor BP, HR, and perfusion closely after ventilator changes.
Related Resources
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with Society of Critical Care Medicine (SCCM) · Surviving Sepsis Campaign · American Association of Critical-Care Nurses (AACN). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →