What is Positive Expiratory Pressure (PEP) therapy?

What is PEP Therapy?

PEP (Positive Expiratory Pressure) therapy is a nonpharmacologic airway clearance technique that involves breathing out against resistance of 5-20 cm H₂O, typically delivered through a facemask, to improve mucus clearance by increasing gas pressure behind secretions through collateral ventilation and preventing airway collapse during expiration. 1

Mechanism of Action

PEP therapy works through two primary physiological mechanisms:

• Collateral ventilation enhancement: The positive pressure during expiration increases gas pressure behind mucus plugs, helping to mobilize secretions from peripheral to central airways where they can be cleared by coughing or huffing 1
• Prevention of airway collapse: The expiratory resistance prevents premature airway closure during expiration, particularly important in patients with abnormally compliant airways 1
• Temporary increase in functional residual capacity: PEP can transiently increase lung volumes, though this effect is more pronounced with mask delivery than mouthpiece delivery 2, 3

Clinical Application and Technique

The technique is typically performed using a facemask rather than a mouthpiece to avoid air leaks via the upper airways and mouth, which is critical for achieving the desired physiological effects. 2

Standard Protocol:

• Pressure range: 5-20 cm H₂O resistance 1, 4
• Typical session duration: 20 minutes 1
• Frequency: Usually performed twice daily (bid) 1
• Combined with: Breathing exercises, forced expiration technique (huffing), and coughing as needed 1, 4

Primary Clinical Indications

Cystic Fibrosis (Strongest Evidence)

In patients with CF, PEP is recommended over conventional chest physiotherapy because it is approximately as effective as chest physiotherapy, and is inexpensive, safe, and can be self-administered (Grade B recommendation). 1

• A Cochrane review of 20 studies in CF patients showed no differences between physiotherapy and PEP in short-term effects on airway clearance and FEV₁ 1
• Long-term studies (≥1 month) showed patients consistently preferred PEP over conventional chest physiotherapy 1, 2
• High-quality evidence demonstrates significantly fewer respiratory exacerbations when PEP with mask is used for at least one year compared to other techniques 2

COPD and Chronic Bronchitis (Limited Evidence)

When COPD patients have copious secretions, PEP devices should be added to huffing techniques, as they improve mucus clearance. 4

• In chronic bronchitis patients, one study showed PEP combined with forced expirations resulted in less cough, less mucus production, fewer exacerbations, and reduced antibiotic use after 5-12 months 1, 4
• However, this study lacked blinding of subjects and investigators, limiting the validity of conclusions 1
• One study found no demonstrable effect on regional lung clearance in chronic bronchitis patients 5

Atelectasis

• PEP therapy opens airways while promoting removal of secretions in patients with plate-like atelectasis 6

Key Advantages

• Self-administered: Can be performed independently without caregiver assistance 1
• Inexpensive: Low-cost device compared to other airway clearance technologies 1, 4
• Safe: Minimal adverse events reported across studies 2
• Patient preference: Consistently preferred over conventional chest physiotherapy in long-term studies 1, 2

Important Caveats and Pitfalls

Device Selection Matters

The mask delivery system is critical—mouthpiece PEP has not demonstrated the same increase in functional residual capacity and may be less effective. 2 In three studies where mouthpiece was used, results were less consistent, and one study reported no difference in respiratory exacerbations 2.

Not a Universal Solution

• Evidence is strongest in CF patients; data in other conditions (COPD, chronic bronchitis, bronchiectasis) is limited and of lower quality 1, 4
• One study in bronchiectasis found no formal assessment of PEP effectiveness, though it did not increase gastroesophageal reflux 1
• Long-term outcome data on mortality, quality of life, and hospitalization rates remain unknown for most conditions 4

Proper Instruction is Essential

Different breathing patterns during PEP can increase or reduce expiratory flow and affect lung volumes, so precise instructions tailored to the desired physiological effect are necessary. 3 Supervised "self-administered" treatments in studies may lead to better performance than truly unsupervised home use 1.

Treatment Individualization

There is no consensus on optimal treatment frequency and number of cycles per session—these must be adjusted based on sputum production, patient tolerance, and clinical response 3.

Comparison to Other Techniques

• Versus conventional chest physiotherapy: Approximately equivalent effectiveness in CF, but PEP is preferred by patients and allows independence 1, 2
• Versus oscillatory devices: Conflicting evidence; oscillatory devices should be considered only as alternatives when standard techniques fail in COPD 4
• Versus high-frequency chest wall oscillation (HFCWO): High-quality evidence shows PEP with mask results in fewer pulmonary exacerbations and fewer lower airway adverse events compared to HFCWO in CF patients 2

Evidence Quality Summary

The evidence base has significant limitations: most studies assess only short-term effects on sputum characteristics or radioaerosol clearance rather than clinically important endpoints like exacerbations, hospitalizations, or mortality 1. The majority of high-quality studies were conducted exclusively in CF patients, limiting generalizability to other conditions 1, 4.