PEEP , or Positive End-Expiratory Pressure, is a key setting in mechanical ventilators that keeps airways open at the end of each breath. It applies positive pressure above atmospheric levels (typically 5-15 cm H₂O) to prevent alveoli collapse, improving oxygenation and lung function.

Core Definition

PEEP maintains pressure in the lungs during expiration, mimicking natural glottis closure in spontaneous breathing. There are two types: extrinsic PEEP (set deliberately on the ventilator) and intrinsic/auto-PEEP (unintended air trapping from incomplete exhalation, common in obstructive diseases). In practice, extrinsic PEEP starts at 5 cm H₂O and adjusts based on patient needs like ARDS.

Why PEEP Matters

Without PEEP, sick lungs suffer repeated collapse and reopening (atelectrauma), worsening damage and gas exchange. Benefits include:

  • Recruiting collapsed alveoli for better oxygen uptake.
  • Boosting functional residual capacity (FRC), the lung's reserve volume.
  • Reducing ventilation-perfusion mismatches.

Imagine alveoli as fragile balloons: PEEP acts like a gentle brace, keeping them inflated between breaths to avoid overwork.

Clinical Applications

In ARDS or pneumonia : Higher PEEP (up to 15+ cm H₂O) counters low compliance and edema.

Routine use : 3-5 cm H₂O prevents atelectasis post-surgery.

Manual ventilation uses PEEP valves on bag-valve masks for emergencies. Ventilators display and titrate it per mode (e.g., BiPAP).

Scenario| Typical PEEP Level| Goal 79
---|---|---
Healthy lungs/post-op| 3-5 cm H₂O| Prevent collapse
ARDS/hypoxemia| 8-15 cm H₂O| Recruit alveoli, improve PaO₂
Obstructive (COPD)| Low (avoid auto-PEEP)| Balance exhalation time
Heart failure/edema| 5-10 cm H₂O| Shift fluid, aid oxygenation 3

Risks and Adjustments

Too much PEEP raises intrathoracic pressure, cutting venous return and cardiac output—monitor hemodynamics. Auto-PEEP complicates this in high-rate ventilation. Clinicians titrate using FiO₂ tables (e.g., ARDSNet), best compliance, or driving pressure.

TL;DR : PEEP is ventilator pressure at breath's end to keep lungs open, enhancing oxygen delivery while minimizing injury—ubiquitous in critical care.

Information gathered from public forums or data available on the internet and portrayed here.