Regional anesthesia; Post-surgical pain; Post-surgical pain

Regional anesthesia has become a mainstay for post-surgical pain control, especially in upper extremity surgery. The utility of the brachial plexus block has been supported throughout the literature for decades [1,2]. By providing intra-operative and post-surgical analgesia, peripheral nerve blocks have allowed for advances in ambulatory surgery due to decreased times to discharge secondary to improved pain control and decreased narcotic usage [3]. Some situations hinder the anesthesiologist’s ability to approach the nerve for blockade using typical techniques, such as poly-trauma patients with multiple sites of injury, morbid obesity, infections or wounds at the site of needle entry. Contraindications can include significant pulmonary or cardiovascular disease, cellulitis or abscess over the site of needle entry, allergy to local anesthetic, super morbid obesity, and of course patient refusal [4]. Other patients possess contraindications to the use of high brachial plexus blocks due to the close proximity of the phrenic nerve and the potentially deleterious effects of hemidiaphragmatic paresis. The incidence of hemidiaphragmatic paresis has been reported to be as high as 100% for interscalene blocks [5,6], 50% for supraclavicular blocks [7,8], and 25% for infraclavicular blocks [9]. For most healthy patients, unilateral phrenic nerve palsy does not result in clinically significant respiratory dysfunction, however, some medically complicated may develop acute respiratory distress. We report a case of a morbidly obese patient with a complex medical history and the utility of ultrasound-guided isolated radial, median and ulnar nerve blocks using liposomal bupivacaine for post-surgical pain control.

A 44-year-old, 174 kg (BMI 66) woman with heart failure secondary to non-ischemic cardiomyopathy, left ventricular ejection fraction (LVEF) of 20-25% and severe mitral regurgitation, prior episodes of ventricular tachycardia and ventricular fibrillation status post automated internal cardiac defibrillator (AICD) implantation, and a history of chronic hypoxemic respiratory failure on 2 liters per minute supplementary home oxygen presented for left mini thoracotomy for epicardial lead replacement for her AICD. The cardiovascular anesthesiologist elected to perform the operation under general anesthesia (GA) with the patient in the supine position. Intraoperatively, endotracheal intubation proved difficult and traumatic, requiring 3 attempts at laryngoscopy with a videolaryngoscope. Arterial line placement was challenging, with more than 5 attempts on each arm, until the right brachial artery was finally successfully accessed. The surgical procedure was completed without complication. On emergence the patient could not generate adequate tidal volumes for extubation, and she remained intubated and transferred to the heart failure intensive care unit (HFICU). Upon extubation on post-operative day one, she began noticing pain and swelling in her left wrist and shoulder. A chest x-ray revealed a left anterior fracture-dislocation of the humeral head and a left distal radius fracture that occurred during positioning under general anesthesia. She was taken back to the operating room for open reduction and internal fixation (ORIF) of the left radius with closed reduction of the left humerus under GA and did not meet extubation criteria, so she returned to the HFICU intubated and sedated. On postoperative day 2, she was extubated, and the acute pain service was consulted for narcotic sparing pain control. The complicated medical history had made medical management of pain difficult for the HFICU team, who had been unable to wean her off of intravenous (IV) hydromorphone. She was requiring IV hydromorphone 0.4 milligrams (mg) every 4 hours and hydrocodone-acetaminophen 10/325 one to two tablets every 6 hours for adequate pain control. When the patient was first examined by the acute pain service, she was dyspneic on 3 liters per minute (L/min) of supplementary oxygen via nasal cannula (NC) and maintaining position of her left arm close to her chest, using an abdominal binder around the arm as a sling (Figure 1). Her body habitus and history of chronic respiratory failure put her at risk for respiratory distress, and the need for reintubation in the setting of prior difficult intubation. Emergent difficult airway management was likely if either left hemidiaphragmic paresis or over-narcotization occurred.

These considerations called for an alternative to high brachial plexus blockade that could provide prolonged adequate analgesia without hemidiaphragmatic paresis. The first choice was an axillary brachial plexus block for wrist analgesia with the addition of a suprascapular nerve block for proximal humerus analgesia; both of these techniques have no reported cases of phrenic nerve involvement in the literature [6,10,11]. However, this patient was in significant pain and refused to move her arm away from her chest. Her body habitus also made positioning extremely difficult, as can be seen in Figures 1 and 2.

Figure 1: Shown is the position of the patient with the cast and binder in place over the left upper extremity.

Figure 2: The position of the patient’s arm after the abdominal binder was removed from the arm, and the subcutaneous fat of the upper arm was retracted. Patient in pain and unwilling to move her arm away from her side, even with help.

The patient was unable to abduct or externally rotate the arm for axillary brachial plexus block; isolated blockade of the left superficial branch of the radial, ulnar and median nerves was performed, just distal to the antecubital fossa. The first of these nerves to be identified was the left superficial branch of the radial nerve, as this provides the sensory innervation of the radial head and dorsum of the hand, which ran adjacent to the radial artery [12]. Figure 3 shows the ultrasound image of the left superficial branch of the radial nerve blockade with a 21-gauge echogenic blunt-tipped needle (BBraun, Bethlehem, Pennsylvania, USA) using an in-plane technique and a high-frequency linear ultrasound probe (Sonosite, Bothell, Washington, USA) placed in a transverse orientation 1-2 cm distal to the antecubital fossa.

Figure 3: This shows the superficial branch of the radial nerve (RN) running alongside the radial artery (RA). Also seen is the local anesthetic (LA) spreading around the nerve and artery. The nerve was approached from lateral to medial with the LUE held close to the chest in pronation. The tip of the needle can be seen entering the neurovascular bundle about 1-2 cm distal to the antecubital fossa.

The ulnar nerve was found by tracing the ulnar artery proximally from the patient’s cast until it separated from the ulnar nerve. This ultrasound image can be seen in Figure 4. Finally, the median nerve was found by identifying the brachial artery in the antecubital fossa and following it immediately distal to the fossa. The ultrasound imaging can be seen in Figure 5. Each block was performed with 3 mL of 0.25% bupivacaine hydrochloride with 3 mL of 1.3% liposomal bupivacaine. The patient reported experiencing anesthesia of her wrist and hand within 25 minutes of the block procedure and stated the anesthesia and associated pain relief lasted nearly 22 hours.

Figure 4: This shows the ulnar nerve (UN) separated from the ulnar artery (UA), which runs closer to the ulnar artery as you scan distally along the arm using a high-frequency linear ultrasound probe in a transverse position (Sonosite, Bothell, Washington, USA). However, in this image, 2 cm distal to the antecubital fossa, the UN has separated from the UA, allowing for an easier needle approach. The 21-gauge echogenic blunt-tipped needle (BBraun, Bethlehem, Pennsylvania, USA) was advanced in-plane from lateral to medial.

Figure 5: The median nerve (MN) can be seen here running along the radial (RA) and ulnar (UA) arteries which have just branched off of the brachial artery. Local anesthetic (LA) can be seen around the median nerve. This block was also performed using an in-plane technique, with the needle advanced from lateral to medial, entering the neurovascular bundle just superficial to the RA.

Analgesia of the proximal humerus fracture was unable to be provided via peripheral nerve blockade due to patient refusal to reposition for this procedure. Therefore, analgesia was provided to the proximal humerus using a medication regimen consisting of: 1 gm acetaminophen every 6 hours, gabapentin 300mg every 8 hours, oxycodone 10-15 mg every 4 hours as needed, and a once daily rescue dose of IV hydromorphone. The patient was also offered tramadol, but refused it due to a history of side effects. She was weaned off her IV hydromorphone the day following the nerve blocks and found her pain to be better controlled with oral (PO) medications.

This case report provides an example of a patient in which nontraditional regional techniques were used due to contraindications to high brachial plexus blockade and inability to position for axillary brachial plexus block and suprascapular blocks. The upper extremity is innervated by the brachial plexus and the intercostobrachial nerve. Choices for peripheral nerve blockade of the upper extremity are limited to brachial plexus and selective terminal branches of the brachial plexus which are field blocks and have a limited duration of action of 6 to 8 hours. Because this was the only technique we could offer to this patient, liposomal bupivacaine was chosen for this procedure as the duration of subcutaneous infiltration has been reported to last up to 72 hours [13].

The extent of the clinical effects of hemidiaphragmatic paresis on respiratory function is determined by the patient’s baseline pulmonary status [14]. The diaphragm accounts for 75% of inspiration, while the intercostal, scalene and sternocleidomastoid muscles account for the other 25% [15]. Unilateral phrenic nerve palsy after interscalene block reduces the forced expiratory volume in 1 second (FEV1) by 16 to 40%, the forced vital capacity by 13 to 40%, and the peak expiratory flow rates by 15 to 43% [16,17]. Therefore, loss of a hemidiaphragm can significantly affect respiratory mechanics and ability to maintain acceptable oxygen saturation. In one study, brief episodes of oxygen saturation less than 85% following interscalene block with 20-28 mL of 0.25% bupivacaine hydrochloride were seen in 4 out of 10 patients, 3 of whom were obese [18]. Several case reports have also been published which report symptomatic dyspnea and clinically significant hypoxemia, and each one of the reported patients was obese; several also had underlying pulmonary disease [19-26].

This case supports the utility of isolated nerve blocks in patients who have relative contraindications to the use of brachial plexus blocks. Isolated nerve blocks are a useful technique for anesthesiologists to remember when treating a patient with contraindications to blockade at the brachial plexus.