Worakamol Tiyaprasertkul

A Multicenter Randomized Comparison Between Intravenous and Perineural Dexamethasone for Ultrasound-Guided Infraclavicular Block.

Background and Objectives This multicenter, randomized trial compared intravenous (IV) and perineural (PN) dexamethasone for ultrasound (US)-guided infraclavicular brachial plexus block. Our research hypothesis was both modalities would result in similar durations of motor block. Methods One hundred fifty patients undergoing upper limb surgery with US-guided infraclavicular block were randomly allocated to receive IV or PN dexamethasone (5 mg). The local anesthetic agent (35 mL of lidocaine 1%-bupivacaine 0.25% with epinephrine 5 &mgr;g/mL) was identical in all subjects. Patients and operators were blinded to the nature of IV and PN injectates. During the performance of the block, the performance time, number of needle passes, procedural pain, and complications (vascular puncture, paresthesia) were recorded. Subsequently, a blinded observer assessed the success rate (defined as a minimal sensorimotor composite score of 14 of 16 points at 30 minutes), onset time as well as the incidence of surgical anesthesia (defined as the ability to complete surgery without local infiltration, supplemental blocks, IV opioids, or general anesthesia). Postoperatively (at 24 hours), the blinded observer contacted patients with successful blocks to enquire about the duration of motor block, sensory block, and postoperative analgesia. The main outcome variable was the duration of motor block. Results No intergroup differences were observed in terms of technical execution (performance time/number of needle passes/procedural pain/complications), onset time, success rate, and surgical anesthesia. However, compared to its IV counterpart, PN dexamethasone provided 19% to 22% longer durations for motor block (15.7 ± 6.2 vs 12.9 ± 5.5 hours; P = 0.009), sensory block (16.8 ± 4.4 vs 13.9 ± 5.4 hours; P = 0.002), and postoperative analgesia (22.1 ± 8.5 vs 18.6 ± 6.7 hours; P = 0.014). Conclusions Compared with its IV counterpart, PN dexamethasone (5 mg) provides a longer duration of motor block, sensory block, and postoperative analgesia for US-guided infraclavicular block. Future dose-finding studies are required to elucidate the optimal dose of dexamethasone.

Analgesia for clavicular fracture and surgery: a call for evidence.

Abstract The sensory innervation of the clavicle remains controversial. The supraclavicular, subclavian, and long thoracic/suprascapular nerves, alone or together, may be responsible for pain transmission after clavicular fracture and surgery. Peripheral nerve blocks used to anesthetize the clavicle include superficial cervical plexus blocks, interscalene blocks, and combined superficial cervical plexus-interscalene blocks. Future (randomized) trials are required to determine which constitutes the best option for emergency department (fracture) and operating room (surgical fixation) settings.

Reliability of Waveform Analysis as an Adjunct to Loss of Resistance for Thoracic Epidural Blocks.

Background The epidural space is most commonly identified with loss of resistance (LOR). Although sensitive, LOR lacks specificity, as cysts in interspinous ligaments, gaps in ligamentum flavum, paravertebral muscles, thoracic paravertebral spaces, and intermuscular planes can yield nonepidural LOR. Epidural waveform analysis (EWA) provides a simple confirmatory adjunct for LOR. When the needle is correctly positioned inside the epidural space, measurement of the pressure at its tip results in a pulsatile waveform. In this observational study, we set out to assess the sensitivity, specificity, as well as positive and negative predictive values of EWA for thoracic epidural blocks. Methods We enrolled a convenience sample of 160 patients undergoing thoracic epidural blocks for thoracic surgery, abdominal surgery, or rib fractures. The choice of patient position (sitting or lateral decubitus), approach (midline or paramedian), and LOR medium (air or normal saline) was left to the operator (attending anesthesiologist, fellow, or resident). After obtaining a satisfactory LOR, the operator injected 5 mL of normal saline through the epidural needle. A sterile tubing, connected to a pressure transducer, was attached to the needle to measure the pressure at the needle tip. A 4-mL bolus of lidocaine 2% with epinephrine 5 &mgr;g/mL was then administered and, after 10 minutes, the patient was assessed for sensory blockade to ice. Results The failure rate (incorrect identification of the epidural space with LOR) was 23.1%. Of these 37 failed epidural blocks, 27 provided no sensory anesthesia at 10 minutes. In 10 subjects, the operator was unable to thread the catheter through the needle. When compared with the ice test, the sensitivity, specificity, and positive and negative predictive values of EWA were 91.1%, 83.8%, 94.9%, and 73.8%, respectively. Conclusions Epidural waveform analysis (with pressure transduction through the needle) provides a simple adjunct to LOR for thoracic epidural blocks. Although its use was devoid of complications, further confirmatory studies are required before its routine implementation in clinical practice.

A randomized comparison between ultrasound- and fluoroscopy-guided c7 medial branch block.

Background Because of its location in the lower neck and anatomical variability, the C7 medial branch represents a challenging target for local anesthetic blocks. Although ultrasound (US) guidance offers an alternative to fluoroscopy for C3 to C6 cervical medial branch blocks (CMBBs), its use at the C7 level has not been examined. We hypothesized that US, using a biplanar imaging technique, could provide a shorter performance time than conventional fluoroscopy for C7 CMBB. Methods Fifty patients undergoing C7 CMBB were randomized to fluoroscopy or US guidance. A 0.6-mL mixture of local anesthetic and radiographic contrast was injected in both groups. The primary outcome was performance time. Secondary outcomes included success rate, pain levels preblock and postblock, and incidences of aberrant spread and procedure-related complications. Results Compared to fluoroscopy, US guidance was associated with a shorter performance time (233.6 ± 80.4 vs 390.6 ± 142.4 seconds; P < 0.001) and fewer needle passes (2 vs 4; P < 0.001). However, both imaging modalities provided similar success rates (92%–96%). Furthermore, no intergroup differences were found in preblock and postblock pain scores. In the fluoroscopy group, intravascular and intra-articular spreads were seen in 20% and 4% of cases, respectively. In the US group, a blood vessel was visualized overlying the target area and successfully avoided during needle insertion in 40% of patients. No procedure-related complications occurred in either group. Conclusions Ultrasound guidance using a biplanar approach provides a similar success rate to fluoroscopy for C7 CMBB. However, US is associated with improved efficiency (decreased performance time and fewer needle passes).

A prospective validation of biplanar ultrasound imaging for C5-C6 cervical medial branch blocks.

Background Ultrasound (US) guidance offers an alternative to fluoroscopy for medial branch blocks of the upper cervical spine, but it may be less accurate for blocks at the C5 and C6 levels. We hypothesized that a modified technique using biplanar US imaging would facilitate level identification and provide greater accuracy for the lower cervical spine. Methods Forty patients with chronic neck pain underwent US-guided blocks of the C5 and C6 medial branches. For each level, 0.3 mL of a local anesthetic/iodinated contrast mixture was injected. Posterolateral in-plane needle placement was carried out in a transverse view, and the position of the needle tip was verified in the coronal plane using the C7 transverse process as a sonographic landmark. Contrast distribution, as assessed by a blinded observer on anteroposterior and lateral x-ray views, constituted the primary outcome. Secondary outcomes were performance time and pain relief 30 minutes after the blocks. Results One hundred percent and 97.5% of C5 and C6 levels, respectively, demonstrated appropriate contrast distribution. The C7 transverse process was readily identified in the coronal plane in all but 2 subjects. Performance time was 248.8 ± 82.7 seconds; the mean percentage of relief provided by the blocks was 76.9% ± 25.5%. In 30% of patients, a blood vessel was visualized crossing the C6 articular pillar and successfully avoided during needle insertion. Conclusions Ultrasound guidance using a biplanar approach is a reliable imaging modality for C5 and C6 medial branch blocks.

Real-Time Detection of Periforaminal Vessels in the Cervical Spine: An Ultrasound Survey.

Background and Objectives Compared with the thoracic and lumbar spine, transforaminal epidural injections and medial branch blocks in the cervical spine are associated with a higher incidence of neurological complications. Accidental breach of small periforaminal arteries has been implicated in many instances. In this observational study, using ultrasonography, we surveyed the incidence of periforaminal bloods vessels in the cervical spine. Methods Patients undergoing ultrasound-guided cervical medial branch blocks were scanned using color power and pulsed wave Doppler. Five levels from C2/C3 to C6/C7 were studied. Incidental blood vessels located between the anterior tubercles of the transverses process and the posterior borders of the articular pillars were included for analysis. We recorded the diameter and position of arteries relative to contiguous bony landmarks as well the number of veins. Results In 102 patients, we performed a total 201 scans (1005 cervical levels). Of the 363 incidental vessels identified, 238 were arteries (mean diameter, 1.25 ± 0.45 mm). The latter were most commonly found at the posterior foraminal aspects of C5, C6, and C7 (13%, 11%, and 16% of scans, respectively); the transverse processes of C5 and C6 (10% and 16% of scans, respectively); and the articular pillars of C6 and C7 (19% and 16% of scans, respectively). Conclusions Small periforaminal arteries are prevalent along the lateral aspect of the cervical spine, adjacent to areas commonly targeted by nerve block procedures. Further trials are required to determine if ultrasound guidance can reduce the incidence of complications related to accidental vascular breach.

A Randomized Comparison Between Single- and Triple-Injection Subparaneural Popliteal Sciatic Nerve Block.

Background and Objectives This prospective randomized trial compared ultrasound-guided single-injection (SI) and triple-injection (TI) subparaneural popliteal sciatic nerve block. We hypothesized that multiple injections are not required when local anesthetic (LA) is deposited under the paraneurium because the latter entraps LA molecules, ensuring circumferential spread around the nerve. Therefore, in addition to comparable success rates, we also expected similar total anesthesia-related times (sum of performance and onset times) and designed this study as an equivalency trial. Methods Ultrasound-guided subparaneural posterior popliteal sciatic nerve block was carried out in 100 patients. In the SI group, LA was deposited at a single location between the tibial and peroneal nerves. In the TI group, LA was injected between the tibial and peroneal divisions, medial to the tibial nerve, and lateral to the common peroneal nerve. The total LA volume (15 mL) and mixture (lidocaine 1%–bupivacaine 0.25%–epinephrine 5 &mgr;g/mL) were identical in all subjects. The performance time, number of needle passes, and adverse events (paresthesia, neural edema) were recorded by the (nonblinded) investigator supervising the block. A blinded observer evaluated the success rate (sensorimotor composite score ≥6/8 points at 30 minutes) as well as the onset time and contacted patients 7 days after the surgery to inquire about persistent numbness or motor deficit. Results Both techniques provided comparable success rates (92%) and total anesthesia-related times (17.1–19.7 minutes). Expectedly, the SI group required fewer needle passes (1 vs 3; P < 0.001) and a shorter needling time (3.0 ± 2.3 minutes vs 4.0 ± 2.3 minutes; P = 0.025). The TI group displayed a shorter onset time (12.5 ± 7.9 minutes vs 15.8 ± 7.9 minutes; P = 0.027). The performance time, procedural discomfort, and incidence of paresthesia (14%–20%) were similar between the 2 groups. Sonographic neural swelling was detected in 2 subjects in the SI group. In both cases, the needle was carefully withdrawn and the injection was completed uneventfully. Follow-up of the 100 subjects 1 week after surgery revealed no residual numbness or motor deficit. Conclusions Ultrasound-guided SI and TI subparaneural popliteal sciatic nerve blocks result in comparable success rates and total anesthesia-related times. Expectedly, the SI technique requires fewer needle passes.

Injection of steroids before radiofrequency ablation has a negative impact on lesion size.

Radiofrequency (RF) ablation of medial branches for facetogenic pain is performed extensively for chronic pain management and is therefore useful in the study of patient outcomes and RF techniques. The benefits of RF ablation in terms of pain relief and functional improvement have been demonstrated sufficiently in the management of lumbar and cervical facet pain. Current knowledge supports that the key to a clinically successful RF neurotomy lays on (1) careful patient selection, (2) precise cannula placement, and (3) effective thermocoagulation of the targeted nerve structure: