ER Basics for Rookies

You’ve just intubated a critically ill patient in the ED. The tube is in, waveform capnography confirms placement, sats are stabilizing… now comes the next rookie stress point: ventilator settings. What you dial in during the first minutes can stabilize the patient—or push them into further hypoxemia, hypotension, or barotrauma.

This guide breaks down a simple, physiology-first approach to initial ventilator settings in crashing patients.

Step 1: Know Your Modes (Keep It Simple)

• Volume Control (VC): You set tidal volume (VT) and rate; ventilator delivers consistent volume with variable pressure.
• Pressure Control (PC): You set pressure; volume varies depending on lung compliance.
• Assist-Control (AC): Every breath (spontaneous or machine-triggered) delivers full set VT or pressure.
• In the ED: AC-VC (assist-control volume control) is the standard default—predictable and simple for rookies.

Step 2: Choose Initial Settings

Tidal Volume (VT)

• 6–8 mL/kg of predicted body weight (PBW).
• Use ideal body weight, not actual (especially in obese).
• Lower VT (6 mL/kg) for ARDS, severe hypoxemia, risk of barotrauma.

Respiratory Rate (RR)

• Adults: 16–20 breaths/min.
• Adjust based on pH and PaCO₂: higher if acidotic, lower if alkalotic.

FiO₂ (Fraction of Inspired Oxygen)

• Start at 100%, then titrate down rapidly to maintain SpO₂ 92–96%.
• Avoid prolonged hyperoxia—it’s harmful.

PEEP (Positive End-Expiratory Pressure)

• Start at 5 cm H₂O in most patients.
• Increase (8–10 cm H₂O or more) in severe hypoxemia/ARDS.
• Use caution in hypotension, hypovolemia, or right heart failure.

Inspiratory:Expiratory Ratio (I:E)

• Default 1:2.
• For obstructive lung disease (asthma, COPD): extend expiratory time (I:E 1:3–1:4) to prevent air trapping.

Step 3: Adjust by Clinical Scenario

1. ARDS / Severe Hypoxemia

• VT: 6 mL/kg PBW (low tidal volume strategy).
• PEEP: higher (8–15 cm H₂O), titrate carefully.
• FiO₂: start 100%, titrate down as SpO₂ allows.
• Consider prone positioning and lung-protective strategies early.

2. Obstructive Lung Disease (Asthma, COPD)

• VT: 6–8 mL/kg.
• RR: lower (10–12) to allow long expiration.
• PEEP: 0–5 (don’t add too much—risk of dynamic hyperinflation).
• I:E ratio: prolonged expiration (1:3–1:4).
• Watch for auto-PEEP and rising plateau pressures.

3. Shock or Hypotension

• Avoid high PEEP (reduces venous return).
• VT: 6–8 mL/kg.
• FiO₂: 100%, titrate once perfusion stabilizes.
• Ensure fluids/pressors started before aggressive PEEP.

4. Neurological Injury (TBI, Stroke)

• VT: 6–8 mL/kg.
• RR: set to maintain normocapnia (PaCO₂ 35–40).
• Avoid hypoxia and avoid aggressive hyperventilation unless managing acute herniation.

Step 4: Monitor & Reassess

• EtCO₂ / ABG: check PaCO₂, pH, adjust RR.
• SpO₂ & FiO₂: titrate oxygen down quickly to avoid hyperoxia.
• Peak & Plateau Pressures:
  • Peak <30–35 cm H₂O, Plateau <30 cm H₂O.
  • High pressures = risk of barotrauma.
• Hemodynamics: watch BP closely—vent changes affect preload/afterload.

Common Rookie Mistakes

• Setting tidal volume based on actual body weight in obese patients (dangerously high volumes).
• Leaving FiO₂ at 100% for hours (risk of oxygen toxicity).
• Forgetting to extend expiratory time in asthma/COPD → auto-PEEP, hypotension.
• Ignoring plateau pressure—rookies focus only on peak pressures.
• Not reassessing ABG/EtCO₂—ventilator is not “set and forget.”

Quick Reference Table

Rookie Pearls

• Always calculate predicted body weight:
  • Male: 50 + 2.3 × (height in inches − 60).
  • Female: 45.5 + 2.3 × (height in inches − 60).
• Titrate FiO₂ down quickly once sats are safe.
• Reassess patient physiology every few minutes—vent settings are dynamic, not static.
• Think “lung protection first, oxygen second, CO₂ last”—this prevents rookie mistakes.

Take-Home Message

The ventilator is not just a machine—it’s a continuation of resuscitation. Rookies should keep it simple:

• Mode: AC-VC.
• VT: 6–8 mL/kg PBW.
• RR: 16–20 (adjust for pH).
• FiO₂: start 100%, titrate down.
• PEEP: start 5, adjust for physiology.

From there, adjust based on the patient’s condition: ARDS, asthma/COPD, shock, or neuro. The key is to reassess early and often.