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Patients experience significant postoperative pain following shoulder surgery, Single shot interscalene block is used in ambulatory shoulder surgery for its advantages that include significant reduction in acute pain and analgesic requirements, prolonged time to first analgesic request, decreased incidence of nausea, as well as earlier hospital discharge.The process of nerve block requires several needle passes, with each of them being at risk of causing nerve injury either by direct trauma or intraneural injection even with the use of the ultrasound. These facts raised concerns and several authors stated that maybe the anesthesiologists should be more careful, keep a safe distance from the nerve, and inject the local anesthetics into fascial planes containing the nerve and not attempt to place the needle in close proximity to the nerve. This study is designed to determine the maximal effective distance away from the nerve for the injection to be effective.
Success of the inter-scalene block at 20 minutes after injection at a specific distance of the needle tip from the outer sheeth of the nerve [ Time Frame: 20 mins ]
Secondary Outcome Measures :
The onset time of sensory and motor block [ Time Frame: the block success will be assessed for each patient every 5 min for 20 mins in the block room beginning when the needle exits the skin ]
The proportion of inadequate and failed blocks. [ Time Frame: the block success will be assessed for each patient every 5 min for 20 mins in the block room beginning when the needle exits the skin ]
The duration of block, defined as the time from the completion of block performance to the time of the request for the first postoperative analgesic. [ Time Frame: during the first 24 hours post operative ]
The amount of pain and level of satisfaction, [ Time Frame: every 30 minutes starting at post anesthesia care unit admission till 120 minutes ]
The presence of a Claude-Bernard-Horner Syndrome [ Time Frame: up to 24 hours post operative ]
The presence of hoarseness. [ Time Frame: up to 24 hours post operative ]
The presence of other complications such as hematoma, infection, pneumothorax. [ Time Frame: up to 24 hours post operative and 7 days post op ]
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Ages Eligible for Study:
18 Years to 85 Years (Adult, Older Adult)
Sexes Eligible for Study:
Accepts Healthy Volunteers:
Patients undergoing shoulder surgery (shoulder arthroscopy or open shoulder surgery)
ASA physical status I-III
18-85 years of age, inclusive
surgery less than 3 hours
contraindications to brachial plexus block (e.g., allergy to local anesthetics, coagulopathy, malignancy or infection in the area)
existing neurological deficit in the area to be blocked
history of neck surgery or radiotherapy
severe respiratory disease
inability to understand the informed consent and demands of the study