Different Approaches to Ultrasound-guided Thoracic Paravertebral Block: An Illustrated Review.

Given the fast development and increasing clinical relevance of ultrasound guidance for thoracic paravertebral blockade, this review article strives (1) to provide comprehensive information on thoracic paravertebral space anatomy, tailored to the needs of a regional anesthesia practitioner, (2) to interpret ultrasound images of the thoracic paravertebral space using cross-sectional anatomical images that are matched in location and plane, and (3) to briefly describe and discuss different ultrasound-guided approaches to thoracic paravertebral blockade. To illustrate the pertinent anatomy, high-resolution photographs of anatomical cross-sections are used. By using voxel anatomy, it is possible to visualize the needle pathway of different approaches in the same human specimen. This offers a unique presentation of this complex anatomical region and is inherently more realistic than anatomical drawings.

Ipsilateral brachial plexus block and hemidiaphragmatic paresis as adverse effect of a high thoracic paravertebral block.

BACKGROUND: Thoracic paravertebral block is regularly used for unilateral chest and abdominal surgery and is associated with a low complication rate. CASE REPORTS: We describe 2 patients with an ipsilateral brachial plexus block with Horner syndrome after a high continuous thoracic paravertebral block at T2-3. One patient also developed an ipsilateral hemidiaphragmatic paresis, an adverse effect that has not been reported before. Subsequent radiologic examination revealed a limited thoracic cephalad spread of the radiopaque dye and a laterally ascending spread from the thoracic paravertebral space toward and around the brachial plexus. We offer potential explanations for these phenomena. CONCLUSIONS: Brachial plexus block can occur by a route parallel to a nerve connecting the second intercostal nerve and T1 nerve, that is, Kuntz nerve. The hemidiaphragmatic paresis was attributed to the ascending spread of local anesthetic toward the area where the phrenic nerve bypasses the subclavian artery and vein.

Minimum effective volume of local anesthetic for shoulder analgesia by ultrasound-guided block at root C7 with assessment of pulmonary function.

BACKGROUND AND OBJECTIVES: This study was performed to determine the minimum effective volume of ropivacaine 0.75% required to produce effective shoulder analgesia for an ultrasound (US)-guided block at the C7 root level with assessment of pulmonary function. METHODS: Using the Dixon and Massey up-and-down method study design, 20 patients scheduled for elective open shoulder surgery under combined general anesthesia and continuous interscalene brachial plexus block were included. Initial volume of ropivacaine 0.75% was 6 mL; block success or failure determined a 1-mL decrease or increase for the subsequent patient, respectively. General anesthesia was standardized. A continuous infusion of ropivacaine 0.2% was started at a rate of 6 mL/hr at 2 hrs after completion of surgery. Ventilatory function was assessed using spirometry, and movement of the hemidiaphragm was assessed by US. RESULTS: The minimum effective volume of local anesthetic in 50% and 95% of the patients was 2.9 mL (95% confidence interval, 2.4-3.5 mL) and 3.6 mL (95% confidence interval, 3.3-6.2 mL), respectively. Ventilatory function and hemidiaphragmatic movement was not reduced up to and including 2 hrs after completion of surgery, but 22 hrs after start of the continuous infusion of ropivacaine 0.2%, ventilatory function and hemidiaphragmatic movement were significantly reduced (P < 0.001). CONCLUSIONS: The minimum effective volume of local anesthetic for shoulder analgesia for a US-guided block at the C7 root level in 50% and 95% of the patients was 2.9 and 3.6 mL, respectively. Pulmonary function was unchanged until 2 hrs after completion surgery, but reduced 22 hrs after start of a continuous infusion of ropivacaine 0.2%.

Ultrasound-guided continuous phrenic nerve block for persistent hiccups.

BACKGROUND: Phrenic nerve block can be performed and repeated if necessary for persistent hiccups, when conservative and pharmacological treatment is unsuccessful. We report the first description of an in-plane ultrasound (US)-guided phrenic nerve block (PhNB) with a catheter, after US investigation of the bilateral diaphragm, to treat hiccups while avoiding repeated PhNBs. CASE: A 36-year-old man had persistent postoperative hiccups not responding to conservative and pharmacological treatment. Bilateral diaphragmatic US evaluation showed abnormal right-sided movement. A right-sided in-plane US-guided PhNB with catheter was performed. Injection of local anesthetic stopped the hiccups, and a continuous infusion of local anesthetic was started for 24 hrs. After discontinuation of the infusion, the hiccups recurred. Restart of the continuous infusion of the local anesthetic through the catheter was performed, and after discontinuation 24 hrs later, no further hiccups occurred. No adverse effect occurred. CONCLUSIONS: An US-guided in-plane PhNB with catheter is feasible and avoids repeated PhNB when hiccups reoccur. Ultrasound investigation of the bilateral diaphragm should be performed before performing the nerve block.

In-plane ultrasound-guided thoracic paravertebral block: a preliminary report of 36 cases with radiologic confirmation of catheter position.

BACKGROUND AND OBJECTIVES: Thoracic paravertebral block (TPVB) can be used for unilateral surgical procedures. Modifications of the classic approach have been proposed to minimize the risk of pleural puncture. In this study, we evaluated the feasibility and success rate of a transverse in-plane ultrasound (US)-guided TPVB with radiologic confirmation of catheter position. METHODS: A total of 36 patients scheduled for unilateral surgery with a TPVB catheter were included in this prospective study. Ultrasonographically, the transverse process of the thoracic vertebra and rib were identified at the appropriate thoracic level. The transducer was moved cranially until an intercostal US view was obtained, indicated by visualization of the parietal pleura. An in-plane needle insertion approach from lateral to medial was used, and a total of 20 mL ropivacaine 0.75% was injected through the needle and a subsequently threaded catheter, while the spread of local anesthetic was observed. Sensory spread of the block was evaluated by loss of cold sensation in the dermatomes. Catheter position was radiologically evaluated with radiopaque dye. RESULTS: Block success rate was 100%. In all patients, correct radiologic thoracic paravertebral catheter position was confirmed; 1 patient also showed additional epidural spread. The median number of total dermatomal segments with loss of cold sensation was 6. No pneumothorax or contralateral loss of cold sensation occurred. CONCLUSION: An in-plane transverse US-guided TPVB using the described technique is feasible and has a high success rate. In all patients, correct catheter position in the thoracic paravertebral space was radiologically confirmed.

Ultrasound-guided low-dose interscalene brachial plexus block reduces the incidence of hemidiaphragmatic paresis.

BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block is associated with 100% incidence of hemidiaphragmatic paresis as a result of phrenic nerve block. We examined whether an ultrasound (US)-guided interscalene brachial plexus block performed at the level of root C7 versus a nerve stimulation interscalene brachial plexus block, both using 10 mL of ropivacaine 0.75%, resulted in a lower incidence of hemidiaphragmatic paresis. METHODS: In a prospective randomized controlled trial, 30 patients scheduled for elective shoulder surgery under combined general anesthesia and interscalene brachial plexus block were included. Interscalene brachial plexus block using the same dose was performed using either US or nerve stimulation guidance of ropivacaine for both groups. General anesthesia was standardized. Ventilatory function was assessed using spirometry, and movement of the hemidiaphragm was assessed by US. RESULTS: Two patients in the US group showed complete paresis of the hemidiaphragm, but in the nerve stimulation group, 12 patients showed complete and 2 patients had partial paresis of the hemidiaphragm (13% versus 93%, respectively; P < 0.0001). Ventilatory function (forced expiratory volume at 1 second, forced vital capacity, and peak expiratory flow) was significantly reduced in the nerve stimulation group compared with the US-guided group (P < 0.05). One block failure occurred in the nerve stimulation group compared with none in the US group. No adverse effects occurred in either group. CONCLUSIONS: Ultrasound-guided interscalene brachial plexus block performed at the level of root C7 using 10 mL of ropivacaine 0.75% reduces the incidence of hemidiaphragmatic paresis.

Hemidiaphragmatic paresis can be avoided in ultrasound-guided supraclavicular brachial plexus block.

BACKGROUND AND OBJECTIVES: Supraclavicular brachial plexus block is associated with 50% to 67% incidence of hemidiaphragmatic paresis as a result of phrenic nerve block. We examined whether ultrasound-guided compared with nerve stimulation supraclavicular brachial plexus block using 0.75% ropivacaine results in a lower incidence of hemidiaphragmatic paresis. METHODS: In a prospective randomized observer-blinded controlled trial, 60 patients scheduled for elective elbow, forearm, wrist, or hand surgery under supraclavicular brachial plexus block without sedation were included. Supraclavicular brachial plexus block was performed with 20 mL of 0.75% ropivacaine using either ultrasound or nerve stimulation guidance. Ventilatory function was assessed by ultrasound examination of hemidiaphragmatic movement and spirometry. RESULTS: None of the 30 patients in the ultrasound group showed complete or partial paresis of the hemidiaphragm (95% confidence interval, 0.00-0.14), whereas in the nerve stimulation group, 15 patients showed complete paresis of the hemidiaphragm and 1 patient showed partial paresis of the hemidiaphragm (0% versus 53%, respectively; P < 0.0001). Ventilatory function (forced expiratory volume 1, forced vital capacity, peak expiratory flow) was significantly reduced in the nerve stimulation group compared with the ultrasound-guided group (P < 0.05). Two block failures occurred in the nerve stimulation group compared with none in the ultrasound group (P = 0.49). No adverse effects occurred in either group. CONCLUSIONS: Ultrasound-guided supraclavicular brachial plexus block, using 20 mL of 0.75% ropivacaine with the described technique, is not associated with hemidiaphragmatic paresis.

Vertical infraclavicular brachial plexus block: needle redirection after elicitation of elbow flexion.

BACKGROUND: In vertical infraclavicular brachial plexus block, success depends on distal flexion or extension response. Initially, elbow flexion (lateral cord) is generally observed. However, specific knowledge about how to reach the medial or posterior cord is lacking. We investigated the mid-infraclavicular area in undisturbed anatomy and tested the findings in a clinical setting. METHODS: Along a length of 35 mm around the mid-infraclavicular point, cryomicrotomy sections of 5 shoulders from cadavers were used to determine the topography of the cords in relation to one another and the axillary artery. Based on the findings, the anesthesiologists were instructed on how to elicit a distal motor response after an initial elbow flexion response in single-shot, Doppler-aided, vertical infraclavicular block in a series of 50 consecutive patients. RESULTS: In the mid-infraclavicular area, the lateral cord always lies anterior to either the posterior or the medial cord and cranial to the axillary artery; the posterior cord was always cranial to the medial cord; and both cords were always located dorsal to the artery. In the clinical study, in 98% of the included patients, finger flexion or finger and/or wrist extension was elicited as predicted. The overall success rate was 92%. No vascular or lung puncture occurred. CONCLUSIONS: In the clinical study, in 98% of cases, the final stimulation response of posterior or medial cord was found as predicted by the findings of the anatomic study. Once elbow flexion is elicited, a further (ie, deeper) advancement of the needle will result in the proper distal motor response.

A simplified approach to vertical infraclavicular brachial plexus blockade using hand-held Doppler.

In this observational study, we used Doppler ultrasound during the performance of vertical infraclavicular brachial plexus blockade. The success rate at inserting the needle at the point where the sound of the subclavian artery via Doppler reached its maximum audibility was compared with that of the classical insertion point. In 89 of the 100 patients, the medial or posterior cord was found at first needle pass. Using the Doppler point for insertion resulted in a significantly more lateral entry point compared with the classical point (P < 0.001) and was associated with a high success rate of infraclavicular block.