49th Annual Regional Anesthesiology and Acute Pain Medicine Meeting

Post-Operative Increased Work of Breathing Following Interscalene Catheter Placement for Reverse Total Shoulder Arthroplasty

Introduction

The interscalene approach to the brachial plexus is a common peripheral nerve block for surgeries of the proximal upper extremity and shoulder. If prolonged analgesia is preferred, a catheter can be placed.

Anatomy:

Brachial plexus visualized at C6 vertebral level between anterior and middle scalene muscles targeting the C5-C7 roots/trunks1

C8-T1 typically spared with this block

The phrenic nerve runs superficial to the interscalene groove at the level of the cricoid cartilage and runs in a caudad direction on top of the anterior interscalene muscle3

Complications:

Phrenic nerve is anesthetized almost 100% of the time resulting in ipsilateral hemidiaphragm weakness.

Intervascular injection, seizures, stellate ganglion block (Horner’s syndrome), recurrent laryngeal nerve block, pneumothorax5

Case Presentation

HPI

63-year-old female 5’5”, 111kg with BMI of 40.45 presented with right rotator cuff tear arthropathy

PMH: Type II diabetes mellitus, obstructive sleep apnea on CPAP, hypertension, hyperlipidemia, hypothyroidism, and morbid obesity

Surgical Procedure: right reverse total shoulder arthroplasty

Pre-Operative:

Right interscalene peripheral nerve block with catheter placement under ultrasound guidance. Tolerated procedure well.

Skin local: 1mL of 1% lidocaine

Initial bolus: 20mL of 0.5% ropivacaine

Sedation: 1mg IV midazolam, 50mcg IV fentanyl

Intraoperative:

General anesthesia with endotracheal intubation in the beach chair position

No immediate complications. Extubated to simple face mask

Postoperative:

Patient noted to have an increased work of breathing in PACU, stated she was unable to inspire deeply

Interscalene catheter flushed with 10mL of normal saline and subsequently removed

CPAP with her home setting of 11 ordered

Shortly after flushing the catheter, the patient noted a drastic improvement of her symptoms

Admitted overnight by surgical team

Post-op day 2- patient reported good control of her pain and no episodes of increased work of breathing overnight

Discussion

Interscalene peripheral nerve block causes weakness in the ipsilateral hemidiaphragm

This can be observed using M-mode on an ultrasound as seen in Figure 5.2

This often goes unnoticed in healthy patients

In patients with respiratory comorbidities (asthma, COPD, OSA, pneumonectomy) it can increase work of breathing and result in respiratory compromise

Relevant Research:

A randomized, double blinded study was conducted at Stanford University to investigate the effectiveness of saline washout on improving FVC

Results: significant improvement in the FVC 30 minutes after the saline washout, suggesting a reversal of the phrenic nerve paralysis.2

A clinical trial was conducted across multiple medical facilities that investigated effects of saline washout on hemidiaphragm paralysis

They found no significant difference in reversal of paralysis, but there were more patients in the intervention group that only progressed to partial paralysis

Secondary outcomes showed no difference in pain scores, PACU opioid requirement, and sensory/motor exam between the two groups4

Conclusion

Saline wash-out following placement of an interscalene catheter is a fast, safe, and reliable way to decrease respiratory symptoms caused by phrenic nerve paralysis

The analgesia from the interscalene nerve block appears to be preserved following saline washout, further increasing the usefulness of this treatment

If encountered again, we will consider leaving the catheter in place for continued pain relief

49th Annual Regional Anesthesiology and Acute Pain Medicine Meeting

POST-OPERATIVE INCREASED WORK OF BREATHING FOLLOWING INTERSCALENE CATHETER PLACEMENT FOR REVERSE TOTAL SHOULDER ARTHROPLASTY

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