This clinical trial is for subjects undergoing right upper extremity surgery. The aim of the study is to investigate the dose-response relationship between local anesthetic volume and ipsilateral hemidiaphragmatic paresis (HDP) in patients getting ultrasound-guided supraclavicular brachial plexus blocks in a blinded, prospective trial.
With traditional landmark-based or nerve-stimulator techniques, the incidence of HDP following supraclavicular blocks is approximately 50-67%. Ultrasound-guided techniques are thought to enhance precision while reducing the volume of anesthetic used, but even then HDP incidence is nearly 60%. To date, no trials have studied the dose-response relationship between local anesthetic volume and degree of HDP. Patient Selection 30 eligible patients undergoing right upper extremity surgery and eligible for supraclavicular blocks will be recruited at NewYork-Presbyterian/Weill Cornell Medical Center. Evaluation of HDP Baseline M-mode recordings of diaphragm function will be made by an anesthesiologist. Patients will perform "voluntary sniff" (VS) tests, or forceful nasal inhales, immediately preceding the brachial plexus blockade, and again at 15 minutes and 30 minutes after the block. Diaphragmatic excursion from baseline will be measured in centimeters; three measurements will be made and averaged. Hemidiaphragmatic paresis will be defined as greater than or equal to 60% reduction in diaphragmatic excursion, no movement, or paradoxical movement in the VS test. Evaluation of Pulmonary Function A bedside negative inspiratory force (NIF) meter will be used to measure negative inspiratory force prior to the block and 30 minutes after the block. Evaluation of Supraclavicular Block At the 15- and 30-minute marks, the investigators will assess sensory blockade and motor block in the axial, musculocutaneous, radial, median, and ulnar distributions. Both will be judged on 3-point scales. The investigators will also apply a 0-10 point verbal rating scale to assess dyspnea at 30 minutes. Oxygen saturation will be measured off of supplemental oxygen before the block and 30 minutes after the block. Following the assessments, patients will have surgery using brachial plexus blockade as the primary anesthetic.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
24
M-mode tracings of right diaphragm motion will be made and recorded by a skilled anesthesiologist. Patients will be examined in the supine position and scanned from a low intercostal or subcostal approach using the liver as an acoustic window. Patients will be asked to perform a "voluntary sniff" (VS) test, for which they will be asked to forcefully inhale through the nose in a sniffing position. The above measurement will be performed immediately preceding the brachial plexus blockade, and then at 15 minute and 30 minutes after block.
The patient will be positioned supine with the head turned to the contralateral side. The ultrasound will be placed in the supraclavicular fossa, and the skin and subcutaneous tissues will be infiltrated lateral to the probe with 2% lidocaine. The anesthesiologist can redirect the needle and perform additional injections for complete coverage of the brachial plexus. The local anesthetic will be a 2:1 mix of 1.5% mepivacaine and 0.5% bupivacaine.
Weill Cornell Medical College
New York, New York, United States
Number of Subjects With Hemidiaphragmatic Paresis at Various Volumes of Local Anesthetic 15 Minutes After Supraclavicular Block
Diaphragm motion was recorded during voluntary sniffing fifteen minutes after supraclavicular block with the specified volume of local anesthetic. Blinded investigators reviewed the scans and determined whether the scans were indicative of hemidiaphragmatic paresis (HDP) or not (No HDP). This data was fit to a dose response curve.
Time frame: 15 minutes
Number of Subjects With Hemidiaphragmatic Paresis at Various Volumes of Local Anesthetic 30 Minutes After Supraclavicular Block
Diaphragm motion was recorded during voluntary sniffing 30 minutes after supraclavicular block with the specified volume of local anesthetic. Blinded investigators reviewed the scans and determined whether the scans were indicative of hemidiaphragmatic paresis (HDP) or not (No HDP). This data was fit to a dose response curve.
Time frame: 30 minutes
Change in Negative Inspiratory Force (NIF) at 30 Minutes
The change of the absolute value of NIF from the baseline measurement to that at 30 minutes after the block
Time frame: 30 minutes
Dose Response Curve for Motor and Sensory Block 15 Minutes After Block
As described in the protocol, each subject's block was assessed via motor and sensory exam at 15 minutes and given a score (0-20), with 20 being a perfect block and any score less than 10 indicating an ineffective block. A dose response curve was generated for block score with different volumes of local anesthetic administered.
Time frame: 15 minutes
Dose Response Curve for Motor and Sensory Block Score 30 Minutes After Block
As described in the protocol, each subject's block was assessed via motor and sensory exam at 30 minutes and given a score (0-20), with 20 being a perfect block and any score less than 10 indicating an ineffective block. A dose response curve was generated for block score with different volumes of local anesthetic administered.
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A bedside negative inspiratory force (NIF) meter will be used to measure negative inspiratory force prior to the block and 30 minutes after the block.
Time frame: 30 minutes
Change in Room Air Oxygen Saturation at 30 Minutes.
The change in room air oxygen saturation from baseline to 30 minutes after the block was calculated.
Time frame: 30 minutes
Subjective Dyspnea 30 Minutes After Block
30 minutes after the block, patients were asked to rate any symptoms of dyspnea on a scale of 0 (no trouble breathing) to 10 (extreme trouble breathing).
Time frame: 30 minutes