Timing and Symptoms of Pneumothorax After Interscalene Nerve Block
Pneumothorax after interscalene nerve block most commonly presents acutely during or immediately after the procedure (within the first hour), with ipsilateral chest pain and dyspnea being the most common symptoms. 1
Timing of Presentation
- 98% of pneumothoraces are detectable on chest radiographs taken either immediately or within 1 hour post-procedure, making the immediate post-procedural period the critical window for detection 1
- The acute presentation typically occurs during or immediately after the block procedure with sudden onset of symptoms 1
- Delayed presentations beyond 24 hours are documented but remain exceptional, even in higher-risk procedures like lung biopsies where pneumothorax risk substantially exceeds that of nerve blocks 1
- One case report documented a tension pneumothorax developing during shoulder arthroscopy after an ultrasound-guided interscalene block, emphasizing that complications can manifest intraoperatively 2
Most Common Symptoms
The classic presentation includes:
- Ipsilateral chest pain - the predominant and most consistent symptom 1, 3
- Dyspnea (shortness of breath) - typically acute in onset 1, 2
- Diminished breath sounds on the affected side upon auscultation 1
- In severe cases, patients may experience panic and a sense of impending doom, as described in one case where a patient "felt as if her life was in jeopardy" 4
Clinical Monitoring Recommendations
- Patients must remain in a monitored setting for at least the first hour after the block, as this captures the vast majority of potential pneumothorax complications 1
- Staff should be immediately alerted if patients develop any new chest pain or breathlessness during this observation period 1
- Early postoperative chest x-ray is recommended if chest pain presents after interscalene block to rule out pneumothorax, atelectasis, or pleural effusion 3
Incidence Context
- The overall incidence of pneumothorax from interscalene block is extremely low at 0.2% when performed with standardized technique 5
- This contrasts with intercostal nerve blocks, which carry a substantially higher pneumothorax risk of 1.4% per individual nerve blocked 6
Discharge Instructions
All patients discharged after interscalene block must receive explicit instructions to return immediately for any new-onset breathlessness or chest pain, as rare delayed presentations have been documented in procedural literature 1