Dose-Response Relationships for Hemidiaphragmatic Paresis Following Ultrasound-Guided Supraclavicular Block
Condition: Surgery of Right Upper Extremity
MeSH terms: Paresis
Study type: Interventional
Phase: Phase 4

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Ultrasound Imaging; Supraclavicular Block; Bedside Negative Inspiratory Force Meter
Intervention type(s): Diagnostic Test; Drug; Other
Intervention description(s): 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.; 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.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: A modified "3+3" dose escalation design, modeled after Phase I dose-finding trials, was used to define the dose response curve for local anesthetic volume in the supraclavicular block and resulting hemidiaphragmatic paresis in patients undergoing right upper extremity surgery with supraclavicular block as the primary anesthetic. Possible dosing levels of 5, 10, 15, 20, 25, 30, 35 and 40 mL of local anesthetic were pre-specified with a cohort of three subjects per dose. Diaphragm function was determined by a blinded assessor with M-mode tracings of the right diaphragm before and after supraclavicular block. Secondary objectives included the assessment of respiratory function via negative inspiratory force, oxygen saturation and subjective dyspnea, as well as the extent of sensory and motor blockade.
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment