How should diaphragmatic palsy (unilateral or bilateral) be diagnosed and managed in older patients, especially those with pre‑existing lung disease or recent thoracic/upper abdominal surgery?

Diagnosis and Management of Diaphragmatic Palsy in Older Patients

Diagnostic Approach

In older patients with suspected diaphragmatic palsy—especially those with pre-existing lung disease or recent thoracic/upper abdominal surgery—diagnosis should be confirmed using phrenic nerve stimulation with measurement of transdiaphragmatic pressure (Pdi,tw), where values below 15 cm H₂O indicate diaphragmatic dysfunction, supplemented by fluoroscopic sniff testing to detect paradoxical movement. 1

Clinical Presentation and Initial Suspicion

• Positional dyspnea is the hallmark symptom: patients report worsening breathlessness when supine and improvement when upright, which should immediately raise suspicion for diaphragmatic paralysis 2
• Orthopnea and dyspnea on submersion in water are characteristic presenting features that distinguish diaphragmatic palsy from other causes of dyspnea 2
• In post-surgical patients (especially after thoracic or upper abdominal procedures), new-onset dyspnea with paradoxical abdominal motion during inspiration suggests phrenic nerve injury 1, 3
• Older patients with chronic obstructive pulmonary disease may present with more severe symptoms due to reduced respiratory reserve 3, 4

Objective Diagnostic Testing

• Pulmonary function testing reveals a restrictive pattern with forced vital capacity (FVC) reduction that worsens significantly (typically >20%) when moving from upright to supine position 2, 5
• Arterial blood gas analysis typically shows moderate hypoxemia (PaO₂ around 73 mm Hg) even in unilateral cases 5
• Phrenic nerve stimulation with transdiaphragmatic pressure measurement (Pdi,tw) is the gold standard: bilateral stimulation should produce Pdi,tw above 15 cm H₂O with electrical stimulation or above 20 cm H₂O with cervical magnetic stimulation 1
• Values below these thresholds indicate diaphragmatic dysfunction, with severely reduced or negative values confirming paralysis 1
• Fluoroscopic sniff test demonstrates paradoxical upward movement of the paralyzed hemidiaphragm during rapid inspiration 6, 5
• M-mode ultrasonography provides a non-invasive alternative to fluoroscopy and can definitively diagnose diaphragm paralysis by demonstrating absent or paradoxical movement 2
• The ratio of gastric pressure (Pga) to transdiaphragmatic pressure (Pdi) helps quantify diaphragmatic contribution: a negative ratio indicates severe dysfunction 1

Imaging Considerations

• Chest radiography may show an elevated hemidiaphragm but misses up to 62% of diaphragmatic pathology 6
• CT scan is essential in post-traumatic or post-surgical cases to exclude diaphragmatic rupture with herniation (82% sensitivity, 87% specificity) 6
• Fluoroscopy distinguishes between paralysis and eventration, which is critical for treatment planning 6

Management Strategy

Unilateral Diaphragmatic Palsy

For unilateral diaphragmatic palsy in older patients without underlying lung disease, initial conservative management with observation is appropriate, but those with significant dyspnea, underlying pulmonary pathology, or persistent symptoms beyond 6-12 months should undergo video-thoracoscopic diaphragmatic plication. 7, 4, 5

Conservative Management (First-Line for Uncomplicated Cases)

• Most patients with unilateral paralysis tolerate the condition well if there is no underlying lung or chest wall pathology 3, 4
• Spontaneous recovery can occur but typically requires prolonged periods (months to years) 4
• Positioning strategies are critical: patients should sleep with the head of the bed elevated 30-45 degrees and avoid lying on the affected side 8
• Forward-leaning posture with arm support on an over-bed table optimizes diaphragmatic geometry and reduces work of breathing 8
• Pursed-lip breathing combined with forward-leaning position reduces respiratory rate and improves oxygenation 8

Surgical Intervention (For Symptomatic Cases)

• Video-thoracoscopic plication is the gold standard surgical approach for symptomatic unilateral diaphragmatic paralysis, offering excellent safety profile with low morbidity and mortality 7
• Indications for plication include: moderate to severe dyspnea, orthopnea, impaired pulmonary function (FVC reduction >25%), or failure of conservative management after 6-12 months 5
• Surgical technique involves imbricating the diaphragm in layers using interrupted non-absorbable sutures (2-0 or 1-0 monofilament) to flatten and stabilize the hemidiaphragm 7, 5
• Post-plication outcomes are excellent: all patients show both subjective and objective improvement, with benefits maintained at 5-7 years follow-up 5
• Improvement includes resolution of dyspnea, increased FVC, improved oxygenation, and elimination of paradoxical movement 5

Bilateral Diaphragmatic Palsy

Bilateral diaphragmatic paralysis is a medical emergency requiring immediate respiratory support with non-invasive positive pressure ventilation (BiPAP) as first-line therapy, with consideration for diaphragmatic pacing in carefully selected patients who have intact phrenic nerve-diaphragm axis and no severe intrinsic lung disease. 1, 4, 9

Acute Respiratory Support

• Bilateral paralysis is usually symptomatic and may result in ventilatory failure, especially in older patients with underlying lung disease 3, 4
• Non-invasive ventilation (BiPAP) is the preferred initial respiratory support and can successfully manage many patients long-term 4
• Continuous positive airway pressure (CPAP) or mechanical ventilation with tracheostomy may be required in severe cases with ventilatory failure 3
• Patients require continuous monitoring with pulse oximetry and end-tidal CO₂ 1

Diaphragmatic Pacing (Selected Cases)

• Diaphragmatic pacing is optimal for carefully selected patients: those without severe intrinsic lung disease, not obese, with intact phrenic nerve-diaphragm axis integrity 1
• Bilateral implantation of phrenic nerve electrodes is required for adequate ventilation 1
• Conservative use of 12-15 hours per day is recommended to prevent diaphragmatic fatigue 1
• Critical caveat: obstructive apnea can complicate diaphragm pacing during sleep due to lack of synchronous upper airway muscle contraction 1
• Patients must have backup mechanical ventilation available and spare equipment at home 1

Surgical Considerations for Bilateral Cases

• In bilateral paralysis, unilateral plication of the more severely affected (paradoxical) hemidiaphragm can be performed after partial recovery of the contralateral side 9
• This staged approach allows weaning from mechanical ventilation without requiring tracheostomy 9
• Median ventilation time is 48 days (range 20-90 days) with this approach 9

Special Considerations for High-Risk Populations

Post-Surgical Patients

• Diaphragmatic paralysis following cardiac or thoracic surgery has an incidence of approximately 0.68% 9
• Early recognition is critical: monitor for new-onset dyspnea, paradoxical abdominal motion, and difficulty weaning from ventilation 1, 9
• Deep breathing exercises, incentive spirometry, and adequate pain control reduce postoperative pulmonary complications and may facilitate recovery 1
• Regional analgesia (epidural) is superior to systemic opioids for preserving diaphragmatic function postoperatively 1

Patients with Pre-Existing Lung Disease

• Older patients with COPD or restrictive lung disease have significantly worse outcomes with diaphragmatic palsy 3, 4
• These patients are more likely to develop ventilatory failure and cor pulmonale 3
• Lower threshold for surgical intervention (plication) should be considered in this population 4, 5
• Prognosis is generally poor in patients with advanced lung disease and bilateral paralysis 3

Prognostic Factors

• Unilateral paralysis has good prognosis, especially in the absence of underlying neurological or pulmonary disease 3
• Bilateral paralysis, advanced lung disease, and chronic demyelinating conditions portend poor prognosis 3
• Spontaneous recovery is possible but unpredictable and may take months to years 4
• Surgical plication provides durable long-term benefit with maintained improvement at 5-7 years 5

Common Pitfalls to Avoid

• Do not dismiss positional dyspnea as anxiety or deconditioning in older post-surgical patients—always consider diaphragmatic palsy 2
• Avoid relying solely on chest radiography, which misses the majority of diaphragmatic pathology 6
• Do not delay surgical consultation in symptomatic patients with unilateral paralysis and underlying lung disease 4, 5
• In bilateral cases, avoid attempting diaphragmatic pacing without confirming intact phrenic nerve function 1
• Ensure adequate backup ventilation is available before initiating diaphragmatic pacing 1