Mechanical Ventilation for ICU Nurses: A Practical Bedside Guide

Medical Disclaimer: This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols or a provider's orders. Always follow your facility's policies and a provider's orders.

Updated 2026  |  More nurse finance guides →

The ventilator is the most important piece of equipment in the ICU, and the ICU nurse's relationship to it is one of the things that separates critical care practice from any other nursing specialty. Here's what you need to know — and be able to do — at the bedside.

Ventilator Modes — What You're Actually Setting

Volume-Controlled Ventilation (VCV/AC)

You set: tidal volume, respiratory rate, PEEP, FiO2, I:E ratio (or inspiratory time). The ventilator delivers exactly the tidal volume you set on every breath. Pressure varies.

Use when: You need guaranteed tidal volume delivery — ARDS, neuromuscular failure, initial post-op management.

Watch for: High peak pressures. If peak pressure >40 cmH2O, investigate: bronchospasm? Mucus plug? Pneumothorax? Decreased compliance?

Pressure-Controlled Ventilation (PCV)

You set: inspiratory pressure, rate, PEEP, FiO2. The ventilator delivers a constant pressure, and tidal volume varies with lung compliance. Safer for lungs with variable compliance.

Use when: Patients with fluctuating compliance (ARDS, bronchospasm) where volume control is generating excessive pressures.

Watch for: Tidal volume drift. A patient who was getting 450 mL is now getting 300 mL — lung compliance has changed, call the team.

SIMV (Synchronized Intermittent Mandatory Ventilation)

Delivers a set number of mandatory breaths, synchronized with patient effort. Patient can breathe spontaneously between mandatory breaths. Often combined with pressure support.

Less common now — most evidence suggests AC or PSV weaning is superior.

Pressure Support Ventilation (PSV)

Patient triggers every breath; ventilator provides a set amount of pressure support to augment each breath. Used in weaning. Patient must have adequate drive and strength.

SBT (spontaneous breathing trial) is often conducted on low-level PSV (5-8 cmH2O) or CPAP.

Key Ventilator Settings and Their Clinical Meaning

• Tidal Volume (TV): 6 mL/kg of ideal body weight for lung-protective ventilation in ARDS. Use PREDICTED body weight based on height, not actual weight.
• PEEP: Positive end-expiratory pressure. Keeps alveoli open at end-expiration. Standard ARDS protocol starts at 5 cmH2O and titrates based on FiO2 needs. Maximum varies by protocol.
• FiO2: Fraction of inspired oxygen. Target SpO2 92-96% in most patients (ARDS targets vary — Surviving Sepsis suggests SpO2 ≥92%). Higher FiO2 = more oxygen toxicity risk over time.
• Rate: Set respiratory rate. In ARDS, permissive hypercapnia may require you to accept higher CO2 to protect lungs — don't reflexively increase rate to normalize PaCO2.

Pressures You Monitor Every Hour

Peak Inspiratory Pressure (PIP): The highest pressure during the breath. Reflects airway resistance. High PIP with normal plateau = airway problem (bronchospasm, mucus, kinked tube).

Plateau Pressure: Measured at end-inspiration with an inspiratory hold. Reflects alveolar pressure. Target <30 cmH2O in ARDS. If plateau is high, you have a compliance problem — notify MD.

Auto-PEEP (Intrinsic PEEP): Air trapping in patients with obstructive lung disease. Check with an expiratory hold. If significant, reduce RR, increase expiratory time, or consider sedation to reduce breathing effort.

Common Alarms and What They Mean

• High pressure alarm: Patient coughing, biting tube, secretions, bronchospasm, pneumothorax. Assess patient first, then equipment.
• Low minute volume: Patient not triggering, circuit disconnection, cuff leak.
• Low PEEP: Circuit leak, accidental extubation.
• Apnea alarm: Patient not breathing above set rate. Check sedation level, neurologic status. In PSV mode, this means the patient may need more respiratory support.

Daily Ventilator Assessment — The SAT/SBT Bundle

The ABCDEF bundle requires daily assessment for weaning readiness:

1. SAT (Spontaneous Awakening Trial): Hold sedation daily (if meets safety criteria). Patient should be arousable and following commands.
2. SBT (Spontaneous Breathing Trial): Place on low PS (5-8 cmH2O) or T-piece for 30-120 minutes. Failure criteria: RR >35, SpO2 <88%, HR >140 or >20% change from baseline, respiratory distress signs.
3. Extubation readiness: Patient awake, following commands, adequate cough, secretion manageable, hemodynamically stable.

What Nurses Actually Need to Be Doing

You're not just watching the numbers — you're the first person to notice when they change. Significant ventilator changes require a call to the provider. What's "significant"? Trending plateau pressure above 28, sudden FiO2 requirement increase, auto-PEEP development in a previously non-obstructive patient, any pressure alarm that doesn't resolve with routine suctioning.

Know when your patient last had an ABG, and know what it showed. Every shift starts with: what's the ventilator doing, what's the ABG saying, and how are those two things related?