Supraclavicular Block vs Retroclavicular Block: Incidence of Phrenic Nerve Paralysis

To date, there has not been a study that has compared clinically the retroclavicular
brachial plexus block to the supraclavicular brachial plexus block or other brachial plexus
blocks. The aim of this study is to evaluate differences between ultrasound guided
supraclavicular versus retroclavicular brachial plexus blocks, with primary focus on the
incidence of diminished ipsilateral hemidiaphramatic excursion (ipsilateral phrenic nerve
blockade). We will also evaluate differences between the two techniques in the success of
producing surgical anesthesia, procedural time to perform the block (including imaging time
and needling time), block onset time, ease of quality ultrasound needle visualization, and
incidence of paresthesias, vascular puncture and pneumothorax. Lastly, we will observe and
compare the distribution of motor and sensory blockade of the two techniques

Inclusion Criteria:

1. patients scheduled for lower arm surgery

2. patients aged 18 years or older

3. patients ASA class I-III

Exclusion Criteria:

1. Patients unable to cooperate or consent to the study

2. pre-existing neuropathy

3. significant pulmonary disease

4. contralateral phrenic nerve or diaphragmatic dysfunction

5. allergy to local anesthetics

6. infection at needle insertion site

7. history of coagulopathy

8. BMI > 40 kg/m2