Chart — Critical Care
ICU Ventilator Mode Comparison Chart
A side-by-side comparison of four major ventilator modes — Assist Control, SIMV, Pressure Support Ventilation, and CPAP — covering description, typical clinical use, key advantages, and limitations.
Educational use only. Ventilator mode selection and management require provider and respiratory therapist orders and expertise. This chart supports learning, not independent ventilator management decisions. 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.
Ventilator Mode Comparison
| Mode | Description | Typical Use | Advantages | Limitations |
|---|---|---|---|---|
| AC (Assist Control) | Delivers full breath support for every respiratory effort; guarantees minimum mandatory rate | Acute respiratory failure; post-operative; patients unable to sustain breathing work | Full respiratory muscle rest; reliable minute ventilation; reduces work of breathing | Auto-PEEP risk if RR very high; respiratory alkalosis if patient over-breathes; no muscle conditioning |
| SIMV | Set mandatory breath rate; spontaneous breaths between mandatory breaths are unsupported (unless PS added) | Transitional support; gradual weaning by reducing mandatory rate | Allows muscle conditioning; weaning flexibility; backup rate maintained | Unsupported spontaneous breaths may cause fatigue; slower weaning than PSV-based trials; dyssynchrony possible |
| Pressure Support (PSV) | Pressure boost assists patient-initiated breaths only; no mandatory rate; patient controls timing and RR | Weaning; spontaneous breathing trials (SBTs); compensation for ETT resistance | Preserves respiratory muscle function; improves synchrony; reduces sedation needs; preferred SBT modality | No backup rate (apnea alarm dependency); not suitable for apneic or hemodynamically unstable patients; Vt variable |
| CPAP | Continuous positive pressure throughout respiratory cycle; no ventilatory assistance; patient breathes independently | Pre-extubation trial; OSA; non-invasive acute cardiogenic pulmonary edema | Maintains alveolar recruitment; avoids intubation in select patients; oxygenation support | No CO₂ removal assistance; no backup breaths; mask discomfort (non-invasive); requires cooperative patient |
Patient Contribution at Each Mode
Understanding how much work the patient contributes helps anticipate fatigue, dyssynchrony, and weaning readiness:
Progression from left to right represents the weaning continuum — increasing patient effort as support is reduced. The goal is the minimum support needed to maintain adequate ventilation and oxygenation without fatigue.
Related Resources
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with AARC / ACCP Ventilator Guidelines. 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 →