What is the role of diaphragmatic pacing in treating a paralyzed hemidiaphragm?

Diaphragmatic Pacing for Unilateral Hemidiaphragm Paralysis

Diaphragmatic pacing is NOT indicated for isolated unilateral hemidiaphragm paralysis and should not be used in this setting. 1, 2

Key Contraindications for Diaphragmatic Pacing in Hemidiaphragm Paralysis

The available guideline evidence specifically addresses diaphragmatic pacing requirements and makes clear that this intervention demands bilateral intact phrenic nerve-diaphragm axis integrity 3, 1. The fundamental problem with unilateral hemidiaphragm paralysis is that one phrenic nerve is non-functional, which violates the core patient selection criteria.

Patient Selection Criteria for Diaphragmatic Pacing

According to the American Thoracic Society, diaphragmatic pacing requires 3, 1:

• Intact phrenic nerve-diaphragm axis bilaterally
• No or mild intrinsic lung disease
• Non-obese status
• Presence of tracheostomy (at least initially)

The requirement for bilateral phrenic nerve electrode implantation is explicitly stated as necessary to achieve optimal ventilation 3, 1. This makes unilateral hemidiaphragm paralysis an absolute contraindication, as only one functional phrenic nerve exists.

Validated Indications for Diaphragmatic Pacing

The evidence demonstrates only two validated indications for diaphragmatic pacing 4, 5, 6:

1. High cervical spinal cord injury (above C3) with bilateral phrenic nerve integrity 4, 7, 5
2. Central hypoventilation syndromes (such as congenital central hypoventilation syndrome) 3, 5

Both conditions involve central respiratory drive failure with intact peripheral neuromuscular apparatus bilaterally, not peripheral phrenic nerve injury 4, 5.

Appropriate Treatment for Unilateral Hemidiaphragm Paralysis

Conservative Management First

• Minimum 6 months of conservative management before considering surgical intervention 8
• Most patients with unilateral paralysis do not require surgical treatment unless experiencing major functional effects 4

Surgical Options When Symptomatic

For peripheral phrenic nerve injury causing unilateral paralysis:

• Diaphragmatic plication is the recognized, safe, and effective procedure with approximately 100% long-lasting functional benefit 4
• Can be performed via lateral thoracotomy or video-thoracoscopy 4
• Low morbidity and mortality 4

For recent phrenic nerve injuries (within 6 months):

• Nerve reconstruction techniques may restore function to the paralyzed hemidiaphragm 8
• Options include neurolysis, interpositional grafting, or neurotization 8
• Eight of nine patients in one series experienced improvements in diaphragmatic function following nerve reconstruction 8

Critical Distinction: Bilateral vs. Unilateral Paralysis

Even in bilateral diaphragm paralysis, diaphragmatic pacing is not appropriate for most patients 2. The American Thoracic Society states that pacing is unsuitable when there is 2:

• Complete or near-complete paralysis
• Obesity
• Significant lung disease

For bilateral diaphragm paresis, the recommended treatment algorithm is 2:

1. Nocturnal non-invasive ventilation with BiPAP (first-line)
2. Extended non-invasive ventilation use (12-15 hours daily)
3. Diaphragmatic pacing only in highly selected patients with intact phrenic nerves

Common Pitfall to Avoid

Do not confuse the mechanism of unilateral hemidiaphragm paralysis (peripheral phrenic nerve injury) with central hypoventilation syndromes. Diaphragmatic pacing requires functional phrenic nerves bilaterally to deliver electrical stimulation 3, 1. A paralyzed hemidiaphragm by definition has a non-functional phrenic nerve on that side, making pacing impossible.