Fix the Patient, Not the Ventilator

Fix the Patient, Not the Ventilator

How to Use PIP, Plateau Pressure, and Compliance to Diagnose Acute Respiratory Deterioration

When a ventilated patient suddenly worsens, the ventilator isn’t the problem—it’s the messenger. This tool walks clinicians through how to interpret what the ventilator is telling us so we can rapidly identify the underlying pathology and intervene appropriately.

Key principle: The ventilator reflects changes in airway resistance and lung compliance. Your job is to determine which one changed—and why.

Step 1: Start With Peak Inspiratory Pressure (PIP)

PIP = pressure needed to push gas through the airways

It reflects:

• Endotracheal tube

• Bronchi

• Circuit resistance

• Flow demand

Normal target: ≤ 35 cm H₂O

What changes in PIP mean:

• ⬆ PIP → Something is making it harder to move air

• ⬇ PIP → Possible leak

• No change → Look elsewhere (not airway or lung mechanics)

Step 2: Interpret PIP Changes

🔽 PIP Decreased

Think air leak

• Circuit disconnect

• ETT cuff leak

• ETT dislodgement

➖ PIP No Change

Consider non-mechanical causes

• Pulmonary embolism

• Reduced perfusion without airway/lung change

🔼 PIP Increased

Now you must check Plateau Pressure (Pplat) to determine why.

Step 3: Measure Plateau Pressure (Pplat)

Pplat = pressure in the alveoli (static pressure)Measured with an inspiratory hold

Target: ≤ 30 cm H₂O

Pplat answers one critical question:

Is the problem airway resistance or lung compliance?

Step 4: Compare PIP vs Pplat

🔼 PIP with Normal Pplat

➡ Airway Resistance Problem

The lungs themselves are okay—the air just can’t get there easily.

Common causes:

• Secretions

• Mucus plug

• Bronchospasm

• Kinked or bitten ETT

• Ventilator dyssynchrony

What to do:

• Suction

• Bronchodilators

• Fix the tube

• Improve synchrony

• Adjust inspiratory flow

🔼 PIP with ⬆ Pplat

➡ Decreased Lung Compliance

The lungs (or chest wall) are stiff.

Common causes:

• ARDS

• Pulmonary edema

• Pneumothorax

• Pleural effusion

• Atelectasis

• Abdominal distention

• Auto-PEEP

• Chest wall injury or burns

This is where lung-protective strategy matters most.

Step 5: Use Static Compliance (Cstat) to Confirm

Cstat = VT ÷ (Pplat − PEEP)It tells you how stiff the lungs are.

Cstat	Meaning	Examples
50–70 mL/cm H₂O	↑ Compliance (air trapping)	COPD, emphysema
50–60 mL/cm H₂O	Normal	Healthy/post-op
35–45 mL/cm H₂O	↓ Compliance	ARDS, edema, fibrosis

Step 6: Ventilator Strategy Based on the Problem

If Airway Resistance is the Issue:

• ↓ Respiratory rate

• ↓ Inspiratory time (I-time ~0.6–0.8 sec)

• Ensure Pplat ≤ 35

• Treat the obstruction, not just the numbers

If Decreased Compliance (Restrictive Physiology):

• ARDSnet principles

• ↓ Tidal volume

• ↑ PEEP (≤ 20 cm H₂O if oxygenation requires)

• Accept permissive hypercapnia

• Protect the lung from further injury

Why This Tool Matters

This framework prevents:

• Blindly turning up pressures

• Missing pneumothorax or auto-PEEP

• Treating airway problems like lung disease (and vice versa)

It trains clinicians to pause, interpret, and act with intention.

The ventilator doesn’t fail the patient. Misinterpretation does. Fix the Patient, Not the Vent!

Educational Disclosure:

This content is intended for educational purposes only. It is not a substitute for medical advice, clinical judgment, or institutional protocols. Clinical decisions should always be made in accordance with local guidelines, medical direction, and patient-specific circumstances.