Considered among the more painful orthopedic surgical procedures, reverse shoulder arthroplasty requires a comprehensive perioperative analgesic plan. Unimodal analgesia consisting of opioid therapy is usually insufficient to manage the nociceptive input of these surgeries and is frequently limited by side effects, such as respiratory depression, sedation, pruritus, constipation, and inadequate analgesia because of the poor dynamic analgesia of opioids. Adequate shoulder analgesia can be achieved by regional blockade of the upper trunks, C5 and C6, of the brachial plexus via an interscalene block (ISB) with or without a perineural catheter. In patients with respiratory disease, phrenic nerve palsy could be consequential and highlights the need for alternative regional analgesia strategies.
Previous studies of the ISBs describe ipsilateral hemidiaphragmatic paresis in 100% of patients.1,2 According to Kessler et al.,3 at the level of the cricoid cartilage, the phrenic nerve is 2 mm from the brachial plexus; with each centimeter caudad, the distance increases by 3 mm. In healthy patients undergoing shoulder surgery with an ISB, Choromanski et al.4 found a 20% to 30% decrease in forced expiratory volume at 1 second and forced vital capacity.
Several studies have explored strategies to mitigate this phrenic nerve palsy. Applying digital pressure cephalad to the interscalene injection site does not prevent diaphragmatic paresis.5 Ultrasound-guided ISBs using small volumes have shown some promise, but respiratory compromise is not completely mitigated.6,7 Riazi et al.7 noted that an ISB at C5/C6 using volumes of 5 mL of 0.5% ropivacaine provided equal analgesia to patients receiving 20 mL of 0.5% ropivacaine; 45% of patients in the 5-mL group had hemidiaphragmatic paralysis. This was an improvement but still a risk that cannot be taken in patients with poor pulmonary reserve. Renes et al.8 examined pulmonary function using 10 mL of 0.75% ropivacaine moving caudal to the C7 nerve root where the phrenic nerve is further separated from the brachial plexus, undergoing shoulder surgery. This resulted in 13% of patients having hemidiaphragmatic paralysis. Renes et al. continued on to determine the minimal effective analgesic volume using a Dixon and Massey up-and-down method and concluded that the effective dose required to obtain an effect in 95% of the study population was 3.6 mL at the C7 nerve root with no resultant hemidiaphragmatic paralysis in their study group. After their initial blocks, the authors administered continuous perineural analgesia using ropivacaine 0.2% at 6 mL/h and after 22 hours 100% of subjects had hemidiaphragmatic paralysis.9 Burckett et al. described a successful case of a superior trunk block in a patient, but the overall risk of phrenic nerve palsy, as well as the precise distal distance and volume of injection, was not specified.10 Therefore, although ISBs are usually well tolerated and clinically benign, and despite recent suggestions to reduce pulmonary compromise, the risks are still too great to consider these options in everyday practice for patients with limited pulmonary reserve.
Regional anesthesia of the suprascapular nerve (SSN) via a posterior approach provides blockade of the distal branch of the C5 and C6 nerve roots.11 This nerve accounts for approximately 70% of sensation in the shoulder joint and may be a viable alternative to the ISB for shoulder surgeries.12 Several small studies and case reports have already validated SSNs as a bona fide opioid-sparing, pain-reducing technique for arthroscopic shoulder surgery, especially when combined with an axillary nerve block,12 although there are no descriptions of this block as a primary analgesic for more painful, open shoulder arthroplasty.13–16
Although efficacy of the SSN block has not been validated compared with the “gold standard” ISB in open shoulder arthroplasty, we are pleased to report a successful case. In this article, we report the use of an SSN and catheter in a patient with severe chronic obstructive pulmonary disease (COPD) and functional limitation who underwent reverse open shoulder arthroplasty. We obtained written consent for publication of this report from the patient.
A 70-year-old woman (weight 68 kg, body mass index 28 kg/m2), ASA physical status III, suffered a right humeral head fracture and anterior shoulder dislocation after a mechanical fall 1 week before. She presented to our perioperative department for humeral fracture repair and reverse shoulder arthroplasty. She was a former smoker with a 40-pack-year history. Her medical history included severe COPD (forced expiratory volume at 1 second/forced vital capacity ratio 0.61, 31% of predicted value)17 with baseline oxygen saturation between 94% and 97% receiving 2 to 4 L/min of supplemental oxygen continuously, hypertension, hyperlipidemia, anemia, and depression. Her COPD was controlled with albuterol, tiotropium, cromolyn, ipratropium, and budesonide inhalers; hypertension was controlled with spironolactone and valsartan; and depression was controlled with bupropion and escitalopram. A review of the patient’s systems was notable for 2.75 metabolic equivalent functional status, supplemental oxygen use during activity, baseline orthopnea, and a chronic productive cough.
Her physical examination was notable for a Mallampati class 3 airway, with poor air movement and rales in bilateral lung fields. Her preoperative shoulder pain level was 8 of 10 on a numeric pain rating scale (NPRS) and was managed with oxycodone 5 mg every 4 hours as needed, taking between 20 and 30 mg daily. Baseline laboratory analysis including complete blood count and basic metabolic panel were within normal limits.
Discussion with our hospital’s regional anesthesia team concluded that the patient would not tolerate hemidiaphragmatic paralysis given her frail baseline respiratory status; therefore, general anesthesia was induced with the goal of using systemic analgesia to see how she would fare. Surgery proceeded uneventfully, with a hemodynamically stable intraoperative course under general anesthesia with endotracheal intubation, maintained with sevoflurane, IV fentanyl (125 μg), IV hydromorphone (0.4 mg), and a single bolus IV administration of ketamine (20 mg). Blood loss was 450 mL, which was replaced with crystalloid solution. Her blood pressures near the end of surgery were noted to be elevated in the 160/50 range with heart rate in the range of 80 to 90 beats/min. She received several puffs of albuterol into her breathing circuit during the case.
On emergence in the postanesthesia care unit (PACU), the patient was complaining of severe, sharp right shoulder pain refractory to increasing doses of IV hydromorphone, receiving a total of 0.8 mg IV hydromorphone in divided doses >30 minutes in the PACU. The Acute Pain Service was consulted because the patient was becoming more somnolent because of opioid administration but was still complaining of 10/10 pain with a respiratory rate of 20 breaths/min. The Acute Pain Service was also concerned about phrenic palsy in this patient; despite recent literature presenting options to reduce this risk, the risk was still ever present. Therefore, the decision was made to provide SSN block and catheter placement for rescue postoperative analgesia and opioid sparing. The patient was informed of the risks, benefits, and alternatives of this procedure, highlighting a lack of evidence for its use for her situation, although such blocks are performed by interventional pain physicians for chronic shoulder pain, e.g., adhesive capsulitis, rotator cuff tendinitis, osteoarthritis, rheumatologic arthritis, cancer-related pain, or trauma-related pain. She was also informed that it would manage a portion of her pain. The axillary nerve, with the surgical dressings in place, would have been difficult to access. We could have attempted to address this nerve if she did not obtain enough relief from the SSN and was having side effects from opioids. She understood and wished to proceed.
Sonographic examination using a linear ultrasound probe (Sonosite™ Edge [Bothell, WA] B-mode with 40-mm linear high-frequency 13–6 MHz probe) with sterile sonographic gel was used to reveal the patient’s right suprascapular fossa and transverse ligament with the suprascapular artery seen on Doppler for localization of the SSN. With the patient in the sitting position, the skin and subcutaneous tissues at the targeted point were anesthetized with bicarbonated 1% lidocaine using a 27-gauge needle (Fig. 1). A 19-gauge 10-cm echogenic Tuohy Pajunk™ needle was advanced from medial to lateral by using an in-plane approach under ultrasound guidance until the needle tip was visualized adjacent to the suprascapular artery, a landmark adjacent to the SSN. Hydrodissection was performed with normal saline revealing the nerve. Then, an echogenic catheter was threaded into the space and was visualized with sonography. After negative aspiration, 5 mL of 0.2% ropivacaine was injected through the catheter under ultrasound guidance revealing the catheter appropriately adjacent to the nerve and local anesthetic surrounding the SSN and suprascapular artery. The catheter was secured to the patient as shown in Figure 2.
The patient soon achieved reduction in her NPRS from 10/10 down to 2/10 and was feeling comfortable soon after the block was placed in the PACU. She remained stable without signs or symptoms of respiratory distress or wheezing with oxygen saturations between 95% and 100% on 2 L nasal cannula and room air. Her respiratory rate was between 12 and 16 breaths/min from the PACU throughout the remainder of her hospitalization.
Analgesia was maintained via the suprascapular perineural catheter with a CADD-Solis™ (Smiths Medical, Dublin, OH) pump using programmed intermittent boluses, which was approved by the US Food and Drug Administration in January 2014, providing a 4-mL bolus of ropivacaine 0.2% every 60 minutes. After placement and activation of the SSN catheter, the patient received supplemental opioids: 15 mg oxycodone on postoperative day 0 (in addition to the 0.8 mg IV hydromorphone received in the PACU), and on the first postoperative day, she received a total of 0.4 mg IV hydromorphone and 60 mg oral oxycodone without any sedation or respiratory depression. She remained comfortable and functional (NPRS 2/10) with gabapentin, acetaminophen, and oxycodone. The surgeons requested that we avoid the use of cyclooxygenase inhibitor medications. The nerve catheter was removed on the evening of postoperative day 1 to accommodate the orthopedic surgeon’s plan to discharge the patient on the morning of postoperative day 2. Before removal, the catheter was bolused with a 5-mL solution containing 0.25% ropivacaine and 100 μg clonidine in an effort to prolong the duration of analgesia; there was no sedation or bradycardia during postinjection monitoring and the patient later told us that her analgesia subsided approximately 48 hours after this bolus. We were not able to obtain an ambulatory pump for home use because of insurance coverage authorization denial.
The patient was contacted 2 weeks postoperatively via telephone and stated her pain level as 4/10, which was manageable for her and better than her preoperative expectation. She was taking infrequent doses of oxycodone, 5 to 10 mg/day, to manage her pain and self-discontinued her opioids completely after 2 weeks postoperatively. Per the orthopedic surgeon’s recommendations, she remained with her right upper shoulder immobilized in a sling for 6 weeks postoperatively. She then participated in physical therapy without functional limitations and without worsening or exacerbations of her baseline COPD.
Conventional approaches to perioperative analgesia for shoulder arthroplasty, a plexus ISB and opioids, can lead to respiratory decompensation in susceptible patients with limited pulmonary reserve function. Although the literature is growing in how to selectively anesthetize the nerve roots without affecting the phrenic nerve, this remains a challenge. Other regional anesthetics distal to the roots may provide analgesia without impacting pulmonary function. Opioid mitigation and phrenic nerve sparing were paramount in this patient because of her severe COPD and risks of delirium from severe pain, opioids, age, etc. Although ideally our catheter would have been used preoperatively and for a longer duration, we were able to change her postoperative course and prevent potential complications from conventional therapies.
Given the known efficacy of SSN blocks in minimally invasive shoulder arthroscopic surgery and for chronic pain management, and the success of our case, we feel that further investigations into the potential benefits of suprascapular perineural catheters are important. We conjecture that the SSN block will not supplant the ISB because of reduced coverage, but it should be within the armamentarium of the regional anesthesiologists when pulmonary function cannot be compromised. Supplementation of analgesia with the axillary block may also prove useful when compared with the ISB for arthroplasty and we look forward to results of randomized clinical trials that compare the combination of SSN and axillary nerve blocks against ISB. We encourage further study into how to improve on reducing phrenic nerve palsy with ISBs and perineural analgesia, although the anatomy may be difficult to overcome given the nominal distance between these 2 structures. Aside from a close proximity to the phrenic nerve, the brachial plexus ISB is surrounded by many other critical structures (vertebral and carotid arteries, internal jugular vein, trachea, esophagus, neuraxial compartments, lungs, etc.) where life-threatening complications can quickly arise from misplacement of a needle and/or local anesthetic injection. The SSN’s relatively far distance from these structures compared with that of an ISB makes it an enticing choice in clinical scenarios that call for shoulder analgesia, preservation of respiratory function, and avoidance of cardiovascular compromise. Studies comparing postoperative pain, respiratory function, patient satisfaction, length of stay, and development of chronic pain after shoulder arthroplasty with SSN catheters with and without axillary block would be very interesting and have the potential to change the current practice paradigms.
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