Part of the ICU Emergencies Hub — browse every related guide in one place.
| Setting | Definition | Normal Range |
|---|---|---|
| Tidal Volume (Vt) | Volume of air delivered per breath | 6–8 mL/kg IBW (ideal body weight); lung-protective uses 6 mL/kg IBW |
| Respiratory Rate (RR/f) | Number of mandatory breaths per minute set by ventilator | 12–20 breaths/min; total rate = set + patient-triggered |
| FiO2 | Fraction of inspired oxygen (0.21 = room air; 1.0 = 100% O2) | Titrate to SpO2 92–98%; wean FiO2 to ≤0.5 (50%) as quickly as tolerated to prevent O2 toxicity |
| PEEP (Positive End-Expiratory Pressure) | Pressure maintained in airway at end of exhalation; keeps alveoli open; prevents alveolar collapse | 5 cmH2O standard ("physiologic"); higher in ARDS (8–18 cmH2O) |
| Peak Inspiratory Pressure (PIP) | Maximum pressure during inhalation; affected by airway resistance and lung/chest wall compliance | <40 cmH2O; high PIP = increased resistance (secretions, bronchospasm, biting tube) or decreased compliance |
| Plateau Pressure (Pplat) | Pressure during inspiratory hold; reflects alveolar pressure and compliance; PEEP + driving pressure | <30 cmH2O; >30 = risk of barotrauma; measure with inspiratory pause maneuver |
| Minute Ventilation (Ve) | Total volume of air per minute = Vt x RR | 5–8 L/min at rest; high Ve = respiratory compensation for metabolic acidosis or sepsis |
| I:E Ratio | Ratio of inspiratory time to expiratory time | Normal 1:2; COPD/asthma: 1:3 or 1:4 (longer expiratory time to allow air trapping to escape) |
| Mode | How it Works | When Used |
|---|---|---|
| Assist Control (AC) / Continuous Mandatory Ventilation | Ventilator delivers a mandatory breath at set Vt and rate; EVERY breath patient triggers also gets the full set Vt; patient cannot breathe below set rate but is supported above it | Full respiratory support; immediately post-intubation; respiratory failure; sedated patients |
| SIMV (Synchronized Intermittent Mandatory Ventilation) | Delivers set number of mandatory breaths synchronized with patient effort; breaths BETWEEN mandatory are unsupported (patient must work for spontaneous breaths unless pressure support added) | Weaning; allows patient respiratory muscle exercise between mandatory breaths |
| Pressure Support Ventilation (PSV) | Patient triggers every breath; ventilator provides a set pressure boost for each breath; no set rate — entirely patient-driven | Weaning trial; spontaneous breathing trial; comfortable, awake patients |
| CPAP (Continuous Positive Airway Pressure) | Constant pressure throughout breath cycle; patient breathes spontaneously; no mandatory breaths; same as PSV 0 + PEEP | Weaning; spontaneous breathing trial; sleep apnea (non-invasive) |
| APRV (Airway Pressure Release Ventilation) | Maintains high pressure most of the time with brief releases to low pressure; improves oxygenation in severe ARDS; allows spontaneous breathing throughout | Severe ARDS refractory to conventional modes |
| Alarm | Possible Cause | Nursing Action |
|---|---|---|
| High Pressure | Secretions/mucus plug (most common); patient biting tube; patient coughing; bronchospasm; pneumothorax; right mainstem intubation; kinked tubing; water in circuit | Suction; check tube position and circuit; auscultate; reassure patient; notify provider if pressure remains high; prepare for bronchoscopy or CXR |
| Low Pressure / Disconnect | Disconnection of circuit; cuff leak; tube cuff deflated; ET tube migration above cords; extubation | Check all connections; assess patient; check cuff pressure (goal 20–30 cmH2O); notify provider; prepare for re-intubation if extubation occurred |
| Low Minute Ventilation | Low rate + Vt; patient not triggering; leak; apnea | Assess respiratory effort; check settings; check for leak; increase sedation if patient agitated and fighting vent |
| High Respiratory Rate | Pain, agitation, fever, hypoxia, anxiety, metabolic acidosis (respiratory compensation), inadequate sedation | Assess for pain and comfort; check SpO2 and ABG; treat underlying cause |
| FiO2 Alarm | O2 source failure; blender malfunction | Manually ventilate with 100% O2 via BVM; call respiratory therapy immediately |
When a ventilated patient suddenly deteriorates (SpO2 drops, high-pressure alarms, hypotension):
For patients with ARDS, the ARDSnet protocol significantly reduces mortality:
VAP is the most common healthcare-acquired infection in the ICU. Prevention bundle (Institute for Healthcare Improvement):
| Bundle Element | Rationale | Nursing Action |
|---|---|---|
| Head of bed elevation 30–45 degrees | Reduces aspiration of gastric contents | Unless contraindicated (spinal injury, hemodynamic instability); document compliance; lower only for procedures then raise immediately |
| Daily sedation vacation (SAT) | Reduces days on ventilator (shorter = less VAP risk) | Coordinate SAT + SBT each morning; assess readiness criteria |
| DVT prophylaxis | Reduces PE risk in immobile ventilated patients | SCDs on lower extremities; anticoagulation per order |
| Peptic ulcer disease (PUD) prophylaxis | Stress ulcers common in critically ill | Sucralfate, H2 blockers, or PPIs per protocol |
| Oral care with chlorhexidine | Reduces oral bacterial colonization and aspiration | CHG oral swabs q4–6h; q2h mouth care; suction subglottic secretions per tube type |
| Subglottic secretion drainage | Drains pooled secretions above cuff before aspiration | Use ET tubes with subglottic suction port (EVAC tubes) when intubation >72 hr expected |
Place patient on PSV 5–8 cmH2O (pressure support) + PEEP 5 cmH2O, or CPAP, for 30–120 minutes. Patient is doing most of the work. Pass criteria:
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