Abstract
Aims and Objectives:
To study and compare the “standard” and “lower” approach interscalene block in terms of- Time required performing the block, success rate, onset and duration of sensory and motor block and Complications if any.
Results:
We observed that, success rate of “lower” approach was 90% versus “standard” approach which has success rate of only 74%. “Lower” approach required lesser time (6.78 ± 2.64 mins. (Mean ± S.D.)) to perform the block compared to “standard” approach which required 10.06 ± 2.44 mins. (mean ±S.D). When we compared the two approaches in terms of onset of sensory block for axillary, musculocutaneous, radial, median, and ulnar nerves, we found no significant difference except ulnar nerve which showed significant difference (p<0.05). Ulnar sparing was more (17.8%) in “standard” approach as compared to (2.1%) of “lower” approach. There was no significant difference (p>0.05) for onset and duration of motor block as well as duration of sensory block. Rate of occurrence of complications was more for “standard” approach (Horner syndrome-50%, Recurrent Laryngeal nerve palsy-22%, Hemidiphragmatic palsy-30%) as compared to “lower” approach in which only 2% patients developed Horner’s syndrome.
Conclusion:
Lower approach interscalene brachial plexus block can be safely used for surgeries of upper extremity with advantages like lesser time required to perform the block, with higher success rate, lesser sparing of ulnar nerve and negligible complications. Thus lower approach interscalene brachial plexus block is superior to standard approaches of interscalene block as well as general anesthesia.

Introduction
Background:
Inter-scalene brachial plexus block was first described by Winnie in 1970 (1) known as “standard approach” (Winnie’s approach) given at inter-scalene groove at the level of cricoid cartilage (C6 level) for surgery on shoulder and arm. Providing adequate analgesia is a major challenge for anaesthesiologist in patient undergoing surgeries like-shoulder manipulation, surgery on shoulder, proximal 1/3 arm surgery. It was common observation that these procedures are still being performed under general anaesthesia due to one or other reason like-Technical difficulties and significant complications. To take over the drawbacks of proximal Winnie’s approach which is difficult to master, and significant side effects, alternative technique is lower approach inter-scalene brachial plexus block. In this prospective observational study, we evaluated the time required to perform the block, differences in onset and duration of the sensory-motor blocks, success rate and complication rate between standard and lower approach interscalene brachial plexus block.

Methods
Source of Data
The present study was designed as a hospital based prospective study carried out in the Department of Anaesthesiology at Government Medical College and Hospital during period from August 2010 to September 2012. 100 patients aged between 18-70 yrs admitted to S.R.T.R.G.Medical College, Ambajogai, undergoing surgeries on upper 1/3^rd humerus were included in the study. The elective surgical interventions were shoulder dislocation, fixation of neck humerus with k-wire, interlocking and plating for # shaft humerus. The patients were randomly divided into two groups of 50 patients each.

Group S (Standard approach) – block given, using standard approach interscalene brachial plexus block.
Group L (Lower approach) – block given, using lower approach interscalene brachial plexus block.

Patients with ASA I and II physical status, within the age group of 18 to 70 years, of both sexes, patients undergoing elective surgeries on upper 1/3rd humerus and shoulder dislocation were included in the study. Patient’s refusal, local skin infection, patients with coagulopathy or on anticoagulants, patients with peripheral neuropathy, ASA grade III and IV patients, patients with allergy to local anesthetics were excluded from study.

Preparation
After obtaining the approval of the study protocol by the hospital ethical committee, all the patients underwent thorough preanaesthetic evaluation on the day prior to surgery. Thorough general and systemic examination was done including airway and the surface anatomy where the block was to be given.

Investigations
The following investigations were done.
• Blood investigations: Hb%, TLC, DLC, BT, CT, serum urea, serum creatinine, serum bilirubin, blood sugar and blood group.
• Urine: routine and microscopy.
• ECG and Chest x-ray PA view.

Local anaesthetic used
Injection Lignocaine Hydrochloride 2% 10 ml, diluted up to 15 ml. Injection Bupivacaine 0.5% 10 ml, diluted up to 15 ml. Both were diluted using sterile water, making total volume up to 30 ml.

1. Clavicle
2. Posterior border of the clavicular head of the sternocleidomastoid muscle
3. External jugular vein

Technique for standard (Winnie’s) approach ISB
Standard ISB is given at the level of cricoids cartilage (C6 level). A line extended laterally from the cricoid cartilage and intersecting the interscalene groove indicates the level of the transverse process of C6. Middle and index fingers were placed at this level at posterior border of clavicular head of sternocleidomastoid muscle and interscalene groove is palpated. Just creating space between middle and index finger needle was inserted perpendicular to skin at 45 degree caudad and slightly posterior angle. Nerve stimulator set to deliver 1 mA, 1 Hz and at pulse 0.1 second. Needle advanced slowly until stimulation of brachial plexus was obtained. Once any motor response of brachial plexus was elicited current reduced from 1 mA and accepted at 0.4-0.6 mA. Local anaesthetic agent i.e.10 ml 2% inj. Lignocaine hydrochloride + 10 ml 0.5 % inj. Bupivacaine hydrochloride diluted to 30ml, injected slowly with intermittent aspiration to rule out intravascular injection. If the twitch disappeared on decreasing the current strength, needle position was adjusted by one to two millimetres in such a way as to elicit the twitch response and again the procedure was repeated.

Technique for lower approach ISB
Procedure for the lower ISB is same as the standard approach ISB except block is given more caudad than standard approach ISB. Middle and index fingers placed at posterior border of clavicular head of sternocleidomastoid muscle so as middle or index fingers should touch to clavicle depending on left or right side to be blocked. After palpating interscalene groove, needle was advanced perpendicular to skin plane and in slight caudal direction. The needle is advanced till stimulation of brachial plexus was obtained.

Successful block
we considered our block was successful when analgesia was present in all areas supplied by the five major nerves with complete motor blockade.

Partial block
we considered our block was partial when there was blunted sensation in one or more neural distribution after 20 mins of the block.

Failure of the block
was defined as the absence of sensory block in at least one neural distribution and / or absence of motor block after 20 mins of the block and/or the need of another anaesthetic technique to allow surgery.

Results

Nerve

S Group (mins)
(mean ± SD)

L Group (mins)
(mean ± SD)

P Value

Radial

11.51 ±1.49

11.49±2.33

0.9608

Median

12.20 ±2.16

12.09±2.47

0.8223

Ulnar

14.65±2.37

12.35±2.58

0.0000

Axillary

11±1.60

11.30±2.24

0.4620

Musculocutaneous

12.07±2.13

11.26±2.15

0.0728

Discussion
Mean time to perform the block with lower ISB approach (6.78 ± 2.64 mins) was significantly shorter when compared to standard ISB group (10.06 ± 2.44 mins). Janet L. Dewees et al (2006) found the mean performance time for standard ISB to be 9.62 ± 5.31 minutes. The shorter time for the block performance found in group of lower ISB can be explained by more superficial location of brachial plexus at this level. Mean duration of sensory onset for ulnar nerve in standard ISB was 14.65±2.37 min whereas it was 12.35±2.58 min in lower ISB and the difference was statistically significant & it was not significant in remaining nerve distribution. The significant difference can be explained as local anesthetic preferentially reaches the superior and middle trunks of the brachial plexus and arrives later and in lower concentrations at the inferior trunk.

Conclusions
From our study it was concluded that lower ISB-

References