Microcirculation and haemodynamics after infraclavicular brachial plexus block using adrenaline as an adjuvant to lidocaine: a randomised, double-blind, crossover study in healthy volunteers.

We evaluated the effect of adrenaline on human skin microcirculation (nutritive and sub-papillary) and systemic cardiovascular variables after it was added to lidocaine in infraclavicular brachial plexus blocks. Twelve healthy, non-smoking male volunteers were included, each attending two study sessions 2 weeks apart, and they were studied using a crossover design. In both sessions, they received an ultrasound-guided infraclavicular brachial plexus block in the non-dominant arm with 0.4 ml.kg-1 lidocaine, 15 mg.ml-1 with or without adrenaline 5 µg.ml-1 . Microcirculation was assessed by laser Doppler fluxmetry (sub-papillary blood flow), capillary video microscopy (nutritive blood flow) and continuous temperature measurements. Heart rate and arterial pressure were recorded continuously and non-invasively. Median (IQR [range]) sub-papillary blood flow increased substantially 30 min after the brachial plexus block, from 8.5 (4.4-13.5 [2.9-28.2]) to 162.7 (111.0-197.8 [9.5-206.7]) arbitrary units with adrenaline (p = 0.017), and from 6.9 (5.3-28.5 [1.8-42.1] to 133.7 (16.5-216.7 [1.0-445.0] arbitrary units without adrenaline (p = 0.036). Nutritive blood flow (functional capillary density, capillaries.mm-2 , measured at the dorsal side of the hand) decreased in the blocked extremity when adrenaline was used as adjuvant, from median (IQR [range]) 45 (36-52 [26-59]) to 38 (29-41 [26-42]), p = 0.028, whereas no significant change occurred without adrenaline. Median finger skin temperature (°C) increased by 44% (data pooled) with no significant differences between the groups. No significant changes were found in the systemic cardiovascular variables with or without adrenaline. We conclude that lidocaine infraclavicular brachial plexus blocks caused an increase in skin sub-papillary blood flow. The addition of adrenaline produced stronger and longer lasting blocks, but decreased the nutritive blood flow.

A novel combination of peripheral nerve blocks for arthroscopic shoulder surgery.

BACKGROUND: Interscalene brachial plexus block is currently the gold standard for intra- and post-operative pain management for patients undergoing arthroscopic shoulder surgery. However, it is associated with block related complications, of which effect on the phrenic nerve have been of most interest. Side effects caused by general anesthesia, when this is required, are also a concern. We hypothesized that the combination of superficial cervical plexus block, suprascapular nerve block, and infraclavicular brachial plexus block would provide a good alternative to interscalene block and general anesthesia. METHODS: Twenty adult patients scheduled for arthroscopic shoulder surgery received a combination of superficial cervical plexus block (5 ml ropivacaine 0.5%), suprascapular nerve block (4 ml ropivacaine 0.5%), and lateral sagittal infraclavicular block (31 ml ropivacaine 0.75%). The primary aim was to find the proportion of patients who could be operated under light propofol sedation, without the need for opioids or artificial airway. Secondary aims were patients' satisfaction and surgeons' judgment of the operating conditions. RESULTS: Nineteen of twenty patients (95% CI: 85-100) underwent arthroscopic shoulder surgery with light propofol sedation, but without opioids or artificial airway. The excluded patient was not comfortable in the beach chair position and therefore received general anesthesia. All patients were satisfied with the treatment on follow-up interviews. The surgeons rated the operating conditions as good for all patients. CONCLUSION: The novel combination of a superficial cervical plexus block, a suprascapular nerve block, and an infraclavicular nerve block provides an alternative anesthetic modality for arthroscopic shoulder surgery.

Pre-operative brachial plexus block compared with an identical block performed at the end of surgery: a prospective, double-blind, randomised clinical trial.

We evaluated whether pre-emptive analgesia with a pre-operative ultrasound-guided infraclavicular brachial plexus block resulted in better postoperative analgesia than an identical block performed postoperatively. Fifty-two patients undergoing fixation of a fractured radius were included. All patients received general anaesthesia with remifentanil and propofol. Patients were randomly allocated into two groups: a pre-operative block or a postoperative block with 0.5 ml.kg-1 ropivacaine 0.75%. After surgery, all patients received regular paracetamol plus opioids for breakthrough pain. Mean (SD) time to first rescue analgesic after emergence from general anaesthesia was 544 (217) min in the pre-operative block group compared with 343 (316) min in the postoperative block group (p = 0.015). Postoperative pain scores were higher and more patients required rescue analgesia during the first 4 h after surgery in the postoperative block group. There were no significant differences in plasma stress mediators between the groups. Analgesic consumption was lower at day seven in the pre-operative block group. Pain was described as very strong at block resolution in 27 (63%) patients and 26 (76%) had episodes of mild pain after 6 months. We conclude that a pre-operative ultrasound-guided infraclavicular brachial plexus block provides longer and better analgesia in the acute postoperative period compared with an identical postoperative block in patients undergoing surgery for fractured radius.

A randomised placebo-controlled trial examining the effect on hand supination after the addition of a suprascapular nerve block to infraclavicular brachial plexus blockade.

Some surgeons believe that infraclavicular brachial plexus blocks tends to result in supination of the hand/forearm, which may make surgical access to the dorsum of the hand more difficult. We hypothesised that this supination may be reduced by the addition of a suprascapular nerve block. In a double-blind, randomised, placebo-controlled study, our primary outcome measure was the amount of supination (as assessed by wrist angulation) 30 min after infraclavicular brachial plexus block, with (suprascapular group) or without (control group) a supplementary suprascapular block. All blocks were ultrasound-guided. The secondary outcome measure was an assessment by the surgeon of the intra-operative position of the hand. Considering only patients with successful nerve blocks, mean (SD) wrist angulation was lower (33 (27) vs. 61 (44) degrees; p = 0.018) and assessment of the hand position was better (11/11 vs. 6/11 rated as 'good'; p = 0.04) in the suprascapular group. The addition of a suprascapular nerve block to an infraclavicular brachial plexus block can provide a better hand/forearm position for dorsal hand surgery.

Minimum effective volume of ropivacaine 7.5 mg/ml for an ultrasound-guided infraclavicular brachial plexus block.

BACKGROUND: Ultrasound guidance has been shown to reduce the minimum effective volume (MEV) of local anaesthetics for several peripheral nerve blocks. Although the lateral sagittal infraclavicular block (LSIB) is a well-established anaesthesia method, MEV for this technique has not been established. Our aim with this study was to determine the MEV using ropivacaine 7.5 mg/ml for the LSIB method. METHODS: Twenty-five adult American Society of Anesthesiologists physical status I-II patients scheduled for hand surgery received an ultrasound-guided LSIB with ropivacaine 7.5 mg/ml. A successful block was defined as anaesthesia or analgesia for all five sensory nerves distal to the elbow, 30 min after local anaesthetic injection. The MEV for a successful block in 50% of the patients was determined by using the staircase up-and-down method introduced by Dixon and Massey. Logistic regression and probit transformation were applied to estimate the MEV for a successful block in 95% of the patients. RESULTS: The patients received ropivacaine 7.5 mg/ml volumes in the range of 12.5-30 ml. The MEVs in 50% and 95% of the patients were 19 ml [95% confidence interval (CI), 14-27] and 31 ml (95% CI, 18-45), respectively. CONCLUSIONS: For surgery distal to the elbow, the MEV in 95% of patients for an ultrasound-guided LSIB with ropivacaine 7.5 mg/ml was estimated to be 31 ml (95% CI, 18-45 ml). Further studies should determine the factors that influence the volume of local anaesthetic required for a successful infraclavicular block.

High-resolution MRI demonstrates detailed anatomy of the axillary brachial plexus. A pilot study.

BACKGROUND: Axillary block is the most commonly performed brachial plexus block and may be guided by nerve stimulation or ultrasound. Magnetic resonance imaging (MRI) has proven to be beneficial in presenting anatomy of interest for regional anaesthesia and in demonstrating spread of local anaesthetic. The aim of this pilot study was to demonstrate the anatomy as shown by MRI of the brachial plexus in the axillary region. METHODS: Nine volunteers and nine patients were examined in a 3.0 Tesla MR. The patients had two different brachial plexus blocks. Subsequently, they were scanned by MRI and finally tested clinically for block efficacy before operation. Axial images, with and without local anaesthetics injected, were viewed in a sequence loop to identify the anatomy. RESULTS: With the high-resolution MRI, we obtained images of good quality, and cords and all terminal nerves could be identified. When local anaesthetics are injected, neurovascular structures are displaced, and the vein is compressed. Viewing the images in a sequence loop facilitates identification of the different nerves and has high instructive value (links S1-3 to these loops are enclosed). CONCLUSION: Clinical high-field 3.0 Tesla MRI scanner gives good visualization of brachial plexus in the axilla. The superior ability to detect local anaesthetics after it has been injected and the multiplanar imaging capability make MRI a useful tool in studies of the brachial plexus.

Ultrasound controlled nerve stimulation in the elbow region: high currents and short distances needed to obtain motor responses.

BACKGROUND: Electrical nerve stimulation is commonly used to perform peripheral nerve blocks. The purpose of this study was to investigate the relation between stimulating currents and the distance between the needle-tip and stimulated nerves. METHODS: In 18 volunteers the radial and ulnar nerves were stimulated in the elbow region from opposite directions. Needle-to-nerve distances were measured by high-frequency ultrasound when motor responses to electrical stimulation were elicited with currents of 5, 2, 1 and 0.5 mA and impulse widths of 0.1 ms. Additionally, current thresholds for nerve stimulation were identified when the needle-tip was in contact with the nerve. RESULTS: The ulnar nerves responded to electrical stimulation from a significantly greater distance than the radial nerves. Threshold levels at needle-to-nerve contact ranged from 0.4 to 4.5 mA for the radial nerve and from 0.32 to 2.0 mA for the ulnar nerve. They were significantly lower for the ulnar nerve than for the radial nerve. Currents required to obtain neuromuscular responses often exceeded the recommended current levels for nerve stimulation. CONCLUSIONS: Our results show significant differences in the ease of stimulation between the radial and ulnar nerves. High current thresholds and short nerve-to-needle distances were often needed to obtain neuromuscular responses in two nerves in the elbow region.

The supraclavicular lateral paravascular approach for brachial plexus regional anesthesia: a simulation study using magnetic resonance imaging.

UNLABELLED: In the supraclavicular lateral paravascular approach for brachial plexus regional anesthesia by Moorthy et al. (Moorthy's block), the patient is supine with the ipsilateral shoulder displaced anteriorly 5-8 cm. The needle direction is precisely defined in the coronal plane (using a Doppler flowprobe) but not in the sagittal plane. We sought to determine whether the block could be simplified by keeping the shoulder in a neutral position, if the needle direction in the sagittal plane could be more precisely described, and if the risk of pneumothorax appeared acceptably small. These questions were studied by magnetic resonance imaging in 10 volunteers. Volume datasets of the periclavicular region allowed precise positioning of simulated needles. In all volunteers, Moorthy's block could be performed with the shoulder in a neutral position. The optimal needle trajectory passed 5 mm posterior to the clavicle and was 25 degrees posterior to the coronal plane, never approaching the pleura closer than 18 mm. We conclude that Moorthy's block can be performed with the shoulder in a neutral position, that more precise instructions for the needle direction can be given, and that the risk of pneumothorax seems minimal. This should be confirmed by a clinical study. IMPLICATIONS: We studied an established method for brachial plexus block with needle advancement in the chest region in volunteers using magnetic resonance imaging. Our results suggest a simplification of the method and more guidelines for the needle angle to the skin, with a minimal risk for lung injury.

A magnetic resonance imaging study of modifications to the infraclavicular brachial plexus block.

A previously described infraclavicular brachial plexus block may be modified by using a more lateral needle insertion point, while the patient abducts the arm 45 degrees or 90 degrees. In performing the modified block on patients abducting 45 degrees, we often had problems finding the cords of the brachial plexus. Therefore, we designed an anatomic study to describe the ability of the recommended needle direction to consistently reach the cords. Additionally, we assessed the risk of penetrating the pleura by the needle. Magnetic resonance images were obtained in 10 volunteers. From these images, a virtual reality model of each volunteer was created, allowing precise positioning of a simulated needle according to the modified block, without exposing the volunteers to actual needle placement. In both arm positions, the recommended needle angle of 45 degrees to the skin was too shallow to reach a defined target on the cords. Comparing the two arm positions, target precision and risk of contacting the pleura were more favorable with the greater arm abduction. We conclude that when the arm is abducted to 90 degrees, a 65 degrees -needle angle to the skin appears optimal for contacting the cords, still with a minimal risk of penetrating the pleura. However, this needs to be confirmed by a clinical study.

Functional imaging of the thoracic outlet syndrome in an open MR scanner.

Symptoms due to thoracic outlet syndrome may present only in abduction, a position that cannot be investigated in conventional MR scanners. Therefore, this study was initiated to test MRI in an open magnet as a method for diagnosis of thoracic outlet syndrome. Ten volunteers and 7 patients with a clinical suspicion of thoracic outlet syndrome were investigated at 0.5 T in an open MR scanner. Sagittal 3D SPGR acquisitions were made in 0 and 90 degrees abduction. In the patients, a similar data set was also obtained in maximal abduction. To assess compression, the minimum distance between the first rib and the clavicle, measured in a sagittal plane, was determined. In the neutral position, no significant difference was found between patients and controls. In 90 degrees abduction, the patients had significantly smaller distance between rib and clavicle than the controls (14 vs 29 mm; p < 0.01). On coronal reformatted images, the compression of the brachial plexus could often be visualised in abduction. Functional MR examination seems to be a useful diagnostic tool in thoracic outlet syndrome. Examination in abduction, which is feasible in an open scanner, is essential for the diagnosis.

Axillary brachial plexus block with ropivacaine 7.5 mg/ml. A comparative study with bupivacaine 5 mg/ml.

BACKGROUND: Ropivacaine is less cardiotoxic than bupivacaine and may be used in higher doses in order to increase the quality of a block. The aim of this study was to compare the efficacy and safety of 40 ml ropivacaine 7.5 mg/ml (300 mg) and 40 ml bupivacaine 5 mg/ml (200 mg) for axillary plexus block. METHODS: One hundred and four adult patients were included in a prospective, double-blind study. Sensory and motor block were tested for the five main terminal nerves of the arm at 10-min intervals until start of surgery and every second hour there-after until full resolution of the block. RESULTS: The overall evaluation of the block by the surgeon and the anesthesiologist showed a significantly better quality in the ropivacaine patients, regarding both anesthesia and motor block. There were no differences in the time to onset and duration of the block. Except for one patient, who had seizures after an accidental IV injection of ropivacaine, there were no major side effects. CONCLUSION: Ropivacaine 7.5 mg/ml, 40 ml, produces axillary plexus block of similar onset and duration but better quality than 40 ml of bupivacaine 5.0 mg/ml.

Magnetic resonance imaging demonstrates lack of precision in needle placement by the infraclavicular brachial plexus block described by Raj et al.

UNLABELLED: The infraclavicular brachial plexus block first described by Raj et al. was supposed to anesthetize all the main peripheral nerves of the brachial plexus without the risk of pneumothorax. However, in performing the block, we have had difficulties finding the nerves at the cord level. Therefore, we questioned whether the recommended needle direction (the "Raj line") guides the needle close enough to the cords. We therefore designed an anatomic study to answer this question and to assess the risks of entering the pleura and axillary vein. Ten volunteers were examined noninvasively in an open model magnetic resonance scanner. The Raj line deviated greatly from a defined location on the cords by a mean of 26 (range 14-39) mm, always caudad, and posterior to the target in nine cases. Further, the needle trajectory's shortest distance to the pleura was only 10 (0-27) mm, and in one case, it hit the pleura. Finally, the Raj line's distance to the axillary vein was also short, 11 (0-18) mm. We conclude that a modification of the method is necessary to guide the needle closer to the cords and further away from the pleura and the axillary vein. A more lateral needle insertion seems beneficial. IMPLICATIONS: Using a magnetic resonance scanner, the anatomical basis of Raj's infraclavicular method for brachial plexus blockade was examined in volunteers. The results show that the method should be modified to make it more precise and to provide less risk of complications.

[Capnography. A new monitoring method may improve patient safety during anesthesia and in the recovery room]. / Kapnografi. Ny monitorering som kan bedre pasientsikkerheten ved anestesi og i overvåkingsavdeling.

This review describes the diagnostic possibilities of capnography: the graphic presentation of carbon dioxide concentrations in respiratory gas during the entire respiratory cyclus. The monitoring may confirm that the tube used for intubating the patient's trachea is positioned in the patient's airway, and indicates dysfunction of the tube or of the ventilator. Capnography can also rapidly provide important information about a patient's ventilation, circulation and metabolism. This may improve patient safety during anaesthesia and in the intensive care unit. Patients without artificial airways may also be monitored by capnography. The method may reduce the number of arterial blood gases required to check the degree of ventilation.

Acute epiglottitis in children. Review of 27 patients.

Of 27 children treated for acute epiglottitis, 26 survived. Eighteen patients treated by nasotracheal intubation were devoid of sequelae, whereas of six patients in whom tracheotomy was performed, one developed an ugly scar and two had slight tracheal stenosis at the tracheostomy site. In 22 of the 27 children the diagnosis of the referring physician was wrong, causing serious delay in securing the airway. We conclude that short-term nasotracheal intubation and antibiotic prophylaxis is the optimal treatment for acute epiglottitis in children. However, such patients are often in a critical condition, and it is essential that a well-planned procedure for examination and treatment is established in each hospital.