What is the treatment for a patient experiencing difficulty breathing after a brachial plexus block?

Treatment for Difficulty Breathing After Brachial Plexus Block

Immediately assess airway patency, provide supplemental oxygen, and position the patient upright while determining the underlying cause—most commonly phrenic nerve paralysis causing hemidiaphragmatic dysfunction or, less commonly, bilateral recurrent laryngeal nerve involvement causing vocal cord dysfunction.

Immediate Management Steps

Primary Assessment and Stabilization

• Position the patient upright or semi-recumbent immediately to maximize respiratory mechanics and functional residual capacity 1
• Administer high-flow humidified oxygen via face mask or nasal cannula to maintain SpO2 >94% 1
• Monitor continuously with pulse oximetry, capnography (end-tidal CO2), respiratory rate, and vital signs 2, 3
• Ensure an anaesthetist remains immediately available (within 2 minutes) as per regional anaesthesia guidelines 2

Differential Diagnosis and Specific Interventions

For suspected phrenic nerve paralysis (most common):

• Occurs in 50% of supraclavicular blocks and 17% show reduced diaphragmatic movement 4
• Patients typically remain asymptomatic with normal oxygen saturation on room air despite significant pulmonary function decreases 4
• Supportive care with supplemental oxygen and upright positioning is usually sufficient 5, 4
• Consider M-mode ultrasonography to confirm ipsilateral hemidiaphragmatic paralysis if diagnosis is uncertain 5

For suspected vocal cord dysfunction (stridor, hoarseness):

• Perform direct or indirect laryngoscopy immediately to assess vocal cord position and movement 6
• If bilateral vocal cord involvement causes severe respiratory distress with stridor and SpO2 <90%:
  • Apply continuous positive airway pressure (CPAP) via face mask as first-line intervention 6
  • Prepare for emergency intubation if CPAP fails to maintain oxygenation 6
  • Have difficult airway equipment immediately available 1
• Administer nebulized epinephrine 1 mg if upper airway obstruction or stridor develops to reduce airway edema 1

For pneumothorax (chest pain, progressive dyspnea):

• More common with infraclavicular approach but can occur with any brachial plexus block 7
• Obtain chest radiograph if clinical suspicion exists 7
• Management ranges from conservative observation with supplemental oxygen to chest tube placement depending on size and symptoms 7

Block-Specific Considerations

• If continuous catheter is in place, remove it immediately if vocal cord paresis is suspected, as high concentrations of local anesthetic may worsen nerve blockade 8
• Supraclavicular and interscalene blocks carry highest risk of phrenic nerve involvement (50-100% incidence) 2, 4
• Axillary or infraclavicular approaches should be preferred over supraclavicular/interscalene blocks in patients at risk for respiratory complications 2

Critical Warning Signs Requiring Escalation

• Stridor or obstructed breathing pattern requires immediate laryngoscopy and preparation for airway intervention 6
• Progressive hypercapnia with altered consciousness may indicate severe hypoventilation from combined phrenic and intercostal nerve involvement 5
• SpO2 <90% despite supplemental oxygen necessitates advanced airway management 6
• Bilateral vocal cord involvement is a life-threatening emergency requiring immediate airway control 6, 8

Prevention and Risk Mitigation

• Thorough pre-operative airway evaluation is essential, particularly assessing for any history of neck surgery, radiation, or previous vocal cord injury 6, 8
• Use ultrasound guidance to reduce risk of complications including local anesthetic systemic toxicity and inadvertent nerve injury 2
• Calculate and use safe doses of local anesthetic with lower concentrations for continuous blocks (e.g., 0.2% ropivacaine rather than 0.75%) 2, 8
• Avoid supraclavicular/interscalene blocks in patients with contralateral vocal cord palsy or significant respiratory disease, as this is an absolute contraindication 6, 8

Monitoring Duration

• Remain immediately available for the first 15 minutes following block, then contactable within 2 minutes thereafter 2
• Most respiratory complications manifest within the first 30 minutes but can be delayed up to 24-48 hours (pneumothorax) 7, 5
• Patients should not be discharged until respiratory symptoms have stabilized and adequate oxygenation is maintained on room air 4