High volume and low concentration of anaesthetic solution in the perivascular interscalene sheath determines quality of block and incidence of complications.

BACKGROUND AND OBJECTIVE: In the perivascular sheath of the brachial plexus, the volume of anaesthetic solution determines the quality of anaesthetic cover. Fibrous septa may divide the perivascular space into compartments, leading to inadequate diffusion of the anaesthetic solution. The aim of our study was to obtain good anaesthesia and less complications using high volume of low concentration anaesthetic solution, overcoming the obstacle of the septa with a double approach to the scalene sheath. METHODS: Sixty patients scheduled for shoulder capsuloplasty received both Winnie interscalene brachial plexus block and Pippa proximal cranial needle approach. The patients were randomly assigned to two groups. A constant dose of local anaesthetic was administered to each group: Group I (30 patients) received high volume (60 mL of anaesthetic solution) and Group II (30 patients) received low volume of solution (30 mL of anaesthetic solution). Sensory and motor block in the upper limb and complications were evaluated. RESULTS: In all the patients the quality of anaesthesia obtained at the surgical site was excellent. In Group I also the areas supplied by the medial cutaneous nerves of the arm and forearm, ulnar, median and radial nerves were blocked (P < 0.002). Complications were only observed in Group II and consisted of bradycardia and hypotension (66% of the patients) and phrenic nerve paresis (27% of the patients). CONCLUSIONS: The lower concentration of the anaesthetic solution avoids complications while increased volume provides good analgesic cover. The combination of the Winnie interscalene plexus block and the Pippa proximal cranial needle approach should contribute to fill up the scalene sheath overcoming the septa obstacles.

Brachial plexus block using a new subclavian perivascular technique: the proximal cranial needle approach.

We describe the proximal cranial needle approach for brachial plexus blockade; clear surface markings and cranial direction of the needle lead to satisfactory results with a low incidence of complications.

Preferential channelling of anaesthetic solution injected within the perivascular axillary sheath.

Preferential channelling of anaesthetic solution injected into the perivascular axillary sheath was investigated in 40 patients undergoing elective orthopaedic upper-limb surgery. Three needles, with different approaches and inclinations, were inserted near the three main terminal branches of the brachial plexus using an axillary approach. Separate boluses of anaesthetic solution (12 ml of a mixture of equal parts of 0.5% bupivacaine with 1:200,000 adrenaline and 2% lignocaine) were injected in random order through each needle, and back flow through the other two needles was noted. Back flow was observed, mainly in the needle nearest to the radial nerve during injection of the anaesthetic solution in the superior and inferior aspects of the brachial artery, and in the needle close to the ulnar nerve when the injection was performed posterior to the artery, near the radial nerve. These results could be related to the trapping of anaesthetic solution in unconnected compartments and to the slope of the needle injecting the anaesthetic solution which spreads preferentially along a gradient following the needle shaft direction.

Effect of injection speed on anaesthetic spread during axillary block using the orthogonal two-needle technique.

One hundred patients undergoing scheduled upper limb orthopaedic surgery were studied to determine if the speed of injection of the local anaesthetic solution could modify the extent and depth of anaesthesia with the axillary approach to the brachial plexus. The blocks were performed using the 'orthogonal two-needle technique' in which two needles are positioned on the upper and on the lower aspect of the axillary artery, orthogonal to the neurovascular bundle and directed towards the fascial compartment containing the radial nerve. The patients were randomly assigned to one of three groups to receive one of three injection rates (10, 20 and 30 s) (n = 30). In consequence to the results obtained in these patients, a further group of 10 patients was a posteriori added for whom the injection time for each single shot of anaesthetic solution was increased to 1 min. In each group the same mixture and volume of anaesthetic solution (a 30 mL mixture of equal parts of 0.5% bupivacaine with adrenaline 1:200,000 and 2% lignocaine) was injected in two separate boluses of 15 mL each through the two positioned needles. A significant association was found between the injection rate and the anaesthetic spread for all tested areas with the exception of the regions supplied by the median nerve. A greater speed of injection was associated with less anaesthetic spread and more frequent block failure. A clear association between the anaesthetic spread to all branches of the brachial plexus and a slower injection rate of the local anaesthetic was found.

The orthogonal two-needle technique: a new axillary approach to the brachial plexus.

Ninety-eight patients scheduled for elbow, forearm, wrist or hand surgery were allocated randomly to one of two different techniques of brachial plexus block, both using the axillary approach. The blocks were all performed at the level of the insertion of the lateral margin of the pectoralis major muscle on the humerus. The same mixture and volume of anaesthetic solution (30 mL of a mixture of equal parts of 0.5% bupivacaine with adrenaline 1:200 000 and 2% lignocaine) was injected through two needles positioned above and below the axillary artery, in the fascial compartments containing the median and ulnar nerves, respectively. Confirmation of correct needle placement was obtained by elicitation of paraesthesias. In one group of patients (n = 40) the needles were inserted parallel to the axillary artery pathway and the anaesthetic solution was injected toward the apex of the axilla. In a second group (n = 58) the needles were inserted orthogonally with respect to the neurovascular bundle pathway, aimed towards the posterior fascial compartment containing the radial nerve. Using the second technique, all the terminal branches of the brachial plexus were more frequently involved in the block, including the distribution of the musculocutaneous nerve. It seems likely that the inclination of the needles causes a preferential spread of the anaesthetic solution which follows the direction of the needle shaft.

The optimal dose of local anaesthetic in the orthogonal two-needle technique. Extent of sensory block after the injection of 20, 30 and 40 mL of anaesthetic solution.

Ninety patients undergoing scheduled upper limb orthopaedic surgery were studied to determine the optimal anaesthetic dose using the 'orthogonal two-needle technique'. The patients were randomly assigned to one of three groups to receive one of three different volumes (20, 30 and 40 mL) (n = 30) of anaesthetic solution (a mixture of equal parts of 0.5% bupivacaine with adrenaline 1:200,000 and 2% lignocaine). A significant correlation was found between the volume injected and the anaesthetic spread for all tested areas. A better analgesic spread to all the major branches of the plexus was obtained when increased volumes of anaesthetic solution were injected. The comparisons between the 20 mL group and the other two groups are significant in all the tested areas, as well as the comparisons between 30 and 40 mL groups in the areas innervated by radial and musculocutaneous nerves. Only the area innervated by the axillary nerve showed a weaker volume-analgesia relation, confirming the elusiveness of this area to anaesthesia in the axillary approaches. The improved results observed using greater amounts of anaesthetic solution might result from a higher intrasheath pressure with disruption of sheath septa, or from a greater availability of drug for all the terminal branches of brachial plexus, or both.

How many interscalenic blocks are there? A comparison between the lateral and posterior approach.

This study compares the areas of analgesia obtained with the lateral and posterior approaches to the interscalene space after injection of equal volumes of anaesthetic solution (40 ml of a mixture of 0.5% bupivacaine with adrenaline 1:200,000 and 2% lignocaine in equal parts). There was a significant difference in the distribution of the areas of analgesia between the two approaches. With the posterior approach, the region supplied by the radial, medial and ulnar nerves and the post-axial border of the upper limb were more frequently involved, whilst with the lateral approach the area of analgesia was usually confined to the regions supplied by the most caudal roots of the cervical plexus and the upper trunk of the brachial plexus (pre-axial border of the upper limb). On these grounds it appears that two different types of interscalene block are possible.

Fentanyl and bupivacaine mixture for extradural blockade in orthopaedic surgery: effects on haemodynamic responses and pain related to the use of thigh tourniquet.

Analgesic and haemodynamic changes due to tourniquet application were investigated in a prospective double-blind study on orthopaedic patients submitted to extradural lumbar blockade with a bupivacaine and fentanyl mixture. The study was carried out in 161 healthy patients undergoing limb surgery with a thigh tourniquet. Patients were randomly assigned to two groups: each group received treatment with bupivacaine 0.5% containing 1:200,000 adrenaline. Normal saline (B:F o group) or 200 micrograms fentanyl (B:F 200 group) was added to this solution. An immediate increase in systolic and diastolic blood pressure (SBP and DBP) was provoked by tourniquet application in all patients, whilst heart rate (HR) showed no modification and the rate-pressure product (RPP) was hardly influenced in the B:F 200 group. A dramatic reduction in intra-operative supplemental analgesic needs was observed in the B:F 200 group. This group of patients also complained less of tourniquet pain than their counterparts, for the first 30 min of application. Our study underlines the value of fentanyl addition to bupivacaine in extradural blockade in orthopaedic surgery.

Postspinal headache in Taylor's approach: a comparison between 21- and 25-gauge needles in orthopaedic patients.

A randomized study was carried out on 160 patients aged 30-60 years with the aim of finding a method of preventing postdural puncture headache (PDPH). In Taylor's lumbosacral approach to the subarachnoid space, two different needle sizes were used (21-gauge versus 25-gauge) for injecting the anaesthetic solution. Our results show an overall incidence of PDPH in nearly 8% of patients, with no significant difference related to the size of the needle employed. Patients with PDPH showed mild symptoms which disappeared in a short time and none needed epidural blood patching. The possibility of using larger needles, facilitating the execution of the block without increasing PDPH incidence, renders this technique particularly attractive in patients where the midline approach is not feasible, or when pencil-point needles are not available.

[Fibromyalgia and trigger points]. / Fibromialgia e trigger points.

Trigger points in chronic pain and myofascial syndromes are often localized at a distance from the painful area. Infiltration of trigger points with Bupivacaine 0.5% greatly reduces pain and can eliminate it with no need of any other analgesic therapy.