A Device to Determine Return of Sensation From Spinal Block
Condition: Sensation Diminished, Pinprick
MeSH terms: Somatosensory Disorders
Study type: Interventional

Summary: 
      Participation in this study will involve having a pad wrapped onto the subject's non-surgical
      leg to detect when sensation returns after spinal anesthetic and while in recovery room. The
      pad is part of an approved medical device, but which has been modified and will be used in an
      experimental way. The device will run cold water through the pad wrapped to the subject's
      leg. The subject will be asked to press a stop button when they feel the pad gets cold.
      Nurses in the recovery area will also be testing return of sensation using a standard
      technique and this will be compared to when the subject begins to feel the cold.
    

Detailed description: 
      Regional anesthesia investigators have always shown interest in measuring the specific
      duration of neuraxial or peripheral nerve blocks, and how variations in block technique or
      medications affect that duration. Although ostensibly a simple concept, there are many
      sensory modalities available for block testing (light touch, cold or hot temperature, pain,
      pressure, etc.) and there is no consensus in the anesthesia literature on how best to measure
      the duration of nerve block (. Sensory testing is repetitive, and must be practical and
      consistent. Pinprick and cold sensation are commonly employed, and these modalities share the
      same afferent fibers (C-delta) so there is close overlap in the sensory loss mapping after
      regional block. With respect to pinprick sensation there can be variability in the sharpness,
      pressure, and reproducibility of a pinprick test. Testing for cold sensation may be more
      consistent, using a controlled stimulus temperature and duration, and there are different
      methods of testing such as a cooled glass vial (5℃) or Rolltemp (25℃).

      Testing for long-acting blocks overnight adds an additional challenge since it requires
      repetitive subject awakening for assessment, and the interval for testing is a compromise
      between test specificity and sleep disruption. Again, there is no consensus on the proper
      interval for testing recovery from regional block.

      Cold therapy is a commonly applied modality following strenuous exercise or during recovery
      from extremity surgery, and is expected to reduce tissue damage and relieve pain. There is
      some evidence of benefit but little consensus on the optimum interval and duration of
      therapy, and there are many approved medical devices available for use.

      This investigation proposes an adaptation of an approved cold therapy device to administer
      automated, periodic cold stimulus at a location made insensate by regional block. When the
      subject perceives cold at that site, they will press a stop switch to discontinue cooling
      which will also stop a timer and give an accurate duration of the time to recovery of
      sensation at that site.

      The concept will be tested by comparing the duration measured to the standard measurement of
      recovery from nerve block (spinal) employed by post-anesthesia care unit (PACU) nurses who
      will use pinprick (toothpick) testing of lumbar dermatomes every thirty minutes. If the
      device shows acceptable agreement with standard block recovery testing, a follow-up study
      would be its evaluation for long-duration block testing as an alternative to research
      assistant repeated testing overnight.
    

Intervention name(s): cooling device
Intervention type(s): Device
Intervention description(s): device placed on patient in recovery on non surgical side to determine resolution of spinal anesthetics.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: All participants will have the device placed in the recovery room to determine resolution of regional anesthetics.
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: nerve block; spinal block; local anesthetic; regional anesthesia