Axillary approach versus the infraclavicular approach in ultrasound-guided brachial plexus block: comparison of anesthetic time

Abstract

Background: With ultrasound guidance, the success rate of brachial plexus block (BPB) is 95-100% and the anesthetic time has become a more important factor than before. Many investigators have compared ultrasound guidance with the nerve stimulation technique, but there are few studies comparing different approaches via the same ultrasound guidance. We compared the axillary BPB with the infraclavicular BPB under ultrasound guidance.

Methods: Twenty-two ASA physical status I-II patients presenting with elective forearm surgery were prospectively randomized to receive an axillary BPB (group AX) or an infraclavicular BPB (group IC) with ultrasound guidance. Both groups received a total of 20 ml of 1.5% lidocaine with 5 µg/ml epinephrine and 0.1 mEq/ml sodium bicarbonate. Patients were then evaluated for block onset and block performance time was also recorded.

Results: Group IC demonstrated a reduction in performance time vs. group AX (622 ± 139 sec vs. 789 ± 131 sec, P < 0.05). But, the onset time was longer in group IC than in group AX (7.7 ± 8.8 min vs. 1.4 ± 2.3 min, P < 0.05). All blocks were successful in both groups.

Conclusions: Under ultrasound guidance, infraclavicular BPB was faster to perform than the axillary approach. But the block onset was slower with the infraclavicular approach.

Keywords: Brachial plexus; Nerve block; Ultrasound.

Fig. 1

Total anesthetic time, onset and procedure duration of the axillary approach (AX) and the infraclavicular approach (IC). Total anesthetic time is the sum of the onset and the procedure duration. The procedure duration was significantly shorter in the IC group. The onset is significantly shorter in AX group. As a result, the total anesthetic time was similar between two groups. NS: not significant. ^*P < 0.05.

Fig. 2

Percentage of patients with sensory block (score of 1-0) according to the time of cutaneous distribution of: (A) the radial nerve, (B) the median nerve, (C) the ulnar nerve and (D) the musculocutaneous nerve. Significantly more patients showed sensory block of the radial nerve in the AX group immediately after block procedure. AX: Axillary approach group, IC: Infraclavicular approach group. Sensory score: 0, no sensation; 1, hypoesthesia; 2, normal sensation. ^*P < 0.05 compared with IC group.

Fig. 3

Percentage of patients with motor block (score of 2-1) according to the time of cutaneous distribution of: (A) the radial nerve, (B) the median nerve, (C) the ulnar nerve and (D) the musculocutaneous nerve. Significantly more patients showed motor block of musculocutaneous nerve in the AX group 0 and 5 minutes after block procedure. AX: Axillary approach group, IC: Infraclavicular approach group. Motor score: 1, complete paralysis; 2, inability to move against gravity; 3, significant muscle strength reduction; 4, slightly reduced muscle strength; 5, normal muscle strength. ^*P < 0.05 compared with IC group.