Comparison of ultrasound-guided supraclavicular block according to the various volumes of local anesthetic

A randomised trial comparing block characteristics of a mixture versus sequential injections of lignocaine and ropivacaine for supraclavicular brachial plexus nerve block in patients undergoing upper limb surgery

Background and Aim

There is no consensus on the appropriate use of mixtures of local anaesthetic drugs in various combinations for nerve blocks. We intended to compare short-acting lignocaine and long-acting ropivacaine as a mixture versus undiluted sequential injections on block characteristics of ultrasound-guided (USG) supraclavicular brachial plexus block for upper limb surgeries.

Methods

A double-blinded randomised study was conducted on 64 adult patients scheduled for upper limb surgery who received 15 mL each of 2% lignocaine with adrenaline and 0.75% ropivacaine as a 1:1 mixture in the mixed group (Group M) or sequential injections in the sequential group (Group S) by using a USG technique. The primary outcome was the percentage of participants with complete four nerve sensory blocks at 10 minutes post block injection. Secondary outcomes were sensory and motor block characteristics till 30 minutes, total duration of analgesia, sensory and motor block, and complications.

Results

Demographic characteristics and time taken for the procedure were similar. The percentage of participants with a complete four-nerve sensory block at 10 minutes was higher in Group S (69%) versus Group M (41%) (P = 0.04). Complete sensory and motor block rates were similar at 30 minutes. The block procedure time, total duration of analgesia, and sensory and motor block were similar in both groups. There were no major complications.

Conclusion

Sequential lignocaine-ropivacaine, compared to the mixed injection technique, has a higher initial rate of sensory and motor block onset with a similar total block duration.

Ultrasonographic evaluation of incidence of diaphragmatic paralysis following different volumes of supraclavicular brachial plexus block- A prospective randomized double blinded study

Background:

Ipsilateral diaphragmatic paralysis occurs following supraclavicular blocks such as interscalene blocks, supposedly attributable to the backward diffusion of the local anesthetic (LA) inside the neural sheath. Hence, we have made an attempt to assess diaphragmatic paralysis with ultrasonogram (US) following different volumes of supraclavicular brachial plexus blocks (SCB).

Aim:

To compare the incidence of diaphragmatic paralysis with different volumes of supraclavicular brachial plexus block using ultrasonogram.

Methods:

Sixty patients with American Society of Anesthesiologists (ASA) Physical Status I and II were randomized to receive 20, 25, or 30 mL of 0.375% bupivacaine in a double-blinded fashion, and supraclavicular block was performed using ultrasound guidance in an in-plane technique. Diaphragmatic excursion and velocity were studied using a curvilinear 3.5 MHz transducer before and 20 min after giving the block.

Results:

The incidence of reduction in diaphragmatic excursion and velocity in the group receiving 30 mL was 45% and 45%, respectively, which was higher, whereas it was 47.5% and 32.5% in the 25 mL group and 40% and 25% in the 20 mL group, respectively, which were still lower. Pre- and post-block data were studied using T-test, Kruskal–Wallis test, and Mann–Whitney U test. The probability of reduction in diaphragmatic excursion and velocity in each group was <0.05, which was statistically significant.

Conclusion:

Our results suggest that there is a greater risk of inadvertent phrenic nerve blockade even in supraclavicular brachial plexus block. The resulting hemidiaphragmatic paralysis is volume dependent, and the overall incidence is higher at greater volumes. Hence, caution is required against compromised perioperative lung function in patients with preexisting cardiorespiratory dysfunction.

Reduced Hemidiaphragmatic Paresis With a "Corner Pocket" Technique for Supraclavicular Brachial Plexus Block: Single-Center, Observer-Blinded, Randomized Controlled Trial

BACKGROUND AND OBJECTIVE

Hemidiaphragmatic paresis is common after supraclavicular brachial plexus block (SCBPB). In this randomized trial, we compared the incidence of hemidiaphragmatic paresis in patients who had local anesthetic injected primarily in the corner pocket (defined as the intersection of the first rib and subclavian artery) during SCBPB with that of patients who underwent injection primarily inside the neural cluster.

METHODS

Thirty-six patients scheduled for right elbow, forearm, wrist, or hand surgery under SCBPB (using 12.5 mL of 0.75% ropivacaine and 12.5 mL of 2% lidocaine with 1:200,000 epinephrine) were randomly assigned to 1 of 2 groups. In group CP, local anesthetic was injected primarily in the corner pocket (20 mL) and secondarily inside the neural cluster (5 mL). In group NC, local anesthetic was deposited primarily inside the neural cluster (20 mL) and secondarily in the corner pocket (5 mL). The primary outcome was the incidence of hemidiaphragmatic paresis, as measured by M-mode ultrasonography 30 minutes after SCBPB.

RESULTS

The incidence of hemidiaphragmatic paresis was significantly lower in group CP than in group NC (27.8% vs 66.7%, P = 0.019). The median decreases in forced expiratory volume at 1 second (7.5% [interquartile range, 3.3%-17.1%] vs 24.4% [interquartile range, 10.2%-31.2%]; P = 0.010) and forced vital capacity (6.4% [interquartile range, 3.3%-11.1%] vs 19.3% [interquartile range, 13.7%-33.2%]; P = 0.001) were also lower in group CP than in group NC.

CONCLUSIONS

The incidence of hemidiaphragmatic paresis was effectively reduced when local anesthetic was injected primarily in the corner pocket during right-sided SCBPB. However, the 28% incidence of hemidiaphragmatic paresis associated with the corner pocket technique may still represent a prohibitive risk for patients with preexisting pulmonary compromise.

CLINICAL TRIAL REGISTRATION

This study was registered at Clinical Trial Registry of Korea, identifier KCT0001769.