Alternating Pressure Overlay on Weight Bearing Tissue Tolerance in People With Spinal Cord Injury
Condition: Spinal Cord Injuries; Pressure Ulcer
MeSH terms: Spinal Cord Injuries; Pressure Ulcer; Wounds and Injuries
Study type: Interventional

Summary: 
      The purpose of this study is to test if the newly-developed Dabir alternating pressure (AP)
      overlay could be beneficial to preventing skin damage during daily activities, such as lying
      in bed. Specifically, the study is being done to test if the Dabir AP overlay could be used
      to increase skin tolerance when lying in bed for an extended period of time (40 minutes),
      including reducing pressure and increasing skin blood flow (amount of blood supply to oxygen
      and nutrients to skin) as compared to regular operation room (OR) overlay.

      A total of 20 participants with spinal cord injury will be recruited. Subjects will undergo
      study procedures including: AP and Control protocols. Skin blood flow and interface pressure
      will be collected non-invasively (from outside the body) during both protocols. During AP
      protocols, subject will be asked to lie on side (10 min), on back on AP overlay (40 min), on
      side (30 min), on back on OR overlay (40 min), and on side (10 min). During Control protocol,
      subject will be asked to lie on side (10 min), on back on OR overlay (40 min), and on side
      (10 min). Subject will then proceed to vascular control measures, including: non-invasive
      skin blood flow and tissue oxygen measurements with mild heating and electrical stimulation.
      Findings from this study will help us understand the effectiveness of the AP overlay on skin
      blood flow response during prolonged lying in bed.
    

Detailed description: 
      Tissue ischemia is one of the main etiologies of pressure injury. It is inevitable during
      bed-ridden and wheelchair bound conditions, such as spinal cord injury (SCI), or prolonged
      surgery procedure in the operating room. Active alternating pressure (AP) mattresses are
      covered by Medicare policy for patients with multiple/large stage 2/ stage 3 pressure
      injuries to relief interface pressure and prevent recurrence of pressure injuries. Previous
      studies demonstrated that the protective mechanisms of AP on pressure injury include
      redistribution of surface pressure, and allowing more blood supplies while lying on the
      support surface. The Dabir AP overlay is low profile yet possesses similar characteristics as
      other AP mattresses on the market; it is intended for clinical use, such as operation room
      (OR) where AP mattresses may not be an option. We expect Dabir AP overlay will be beneficial
      to people at risk of pressure injury by maintaining the blood supply during weight bearing
      condition.

      The objective of this study is to evaluate the protective mechanisms of Dabir AP overlay on
      weight bearing tissue of people with chronic spinal cord injury (SCI). Our central hypothesis
      is that the Dabir AP overlay will cause lower amount of interface pressure and allow more
      skin blood flow during weight bearing as compared to regular OR overlay.

      Each subject will undergo two study protocols: AP and control, and the order of the protocols
      will be randomized by drawing one envelope from the envelope pool. We will start with a pool
      of total 20 envelopes (10 envelopes indicating AP protocol first, and 10 envelopes indicating
      control protocol first). A 30-minute washout period will be provided in between the two
      protocols. Two Laser Doppler flowmetry (LDF) flat probes (moor instrument, Wilmington, DE)
      will be taped to the sacrum and one heel to collect the skin blood flow response throughout
      both AP and control protocols. A whole body pressure mapping system will be used between the
      subject and the overlay to collect the inter pressure data. For the AP cycle, we will use
      four 10-minute cycles (5 minutes of high pressure and 5 minutes of low pressure).

      AP protocol: The subject will first lie on his/her side quietly for 10 minutes to collect the
      baseline skin blood flow, followed by lying supine on the Dabir AP overlay for 40 minutes,
      and then side lying for 30 minutes to collect the first reactive hyperemic response. To test
      the effect of preconditioning, the subject will then lie supine on the OR overlay for 40
      minutes followed by side lying for 30 minutes for the second reactive hyperemic response.

      Control protocol: The subject will first lie on his/her side quietly for 10 minutes to
      collect the baseline skin blood flow, followed by lying supine on the OR overlay for 40
      minutes, and then side lying for 30 minutes to collect the reactive hyperemic response for
      control protocol.

      The PI, or key personnel will then collect the vascular control measures, including the heat
      hyperemic (HH) blood flow response, and the skin vasomotor response. A non-invasive combined
      laser Doppler and white light reflectance spectroscopy (LDF-WLRS) probe (CP2T-1000, Moor
      Instrument, Wilmington, DE) will be used for both measures.

      HH blood flow response will be measured at the sacrum and one heel while the subject is in
      side-lying position. HH will be induced with the heater at the tip of the probe head (41°C
      for 5 minutes). This HH measure will take approximately 7 minutes (2 min-baseline, 5
      min-heating) per location. In total, the HH measures will take up to 15 minutes to complete.

      The skin vasomotor response will be induced using cutaneous electrical stimulation (3-10 mA,
      0.2-1.0 ms pulses at 20 Hz, 1 s trains) delivered via 1 cm Ag-AgCl surface electrodes applied
      bilaterally (4 cm apart) to the forehead (above lesion) and the abdominal wall (below lesion)
      while the subject is in a semi-reclined position.12 For each site, 5-8 stimuli will be
      delivered randomly. CP2T-1000 probe will be used to collect SBF and tissue oxygenation data
      at pulp of the second finger and toe. Subject will be in a semi-reclined position (about 30°
      from horizontal plane) during this protocol, and it will take up to 15 minutes to complete
      this protocol.

      Pressure mapping of wheelchair: (approximately 10 minutes) The subject will be asked to
      transfer back to his/her wheelchair with the pressure mapping system placed between the
      wheelchair and the subject to collect the interface pressure data. The pressure mapping
      system is the same as that used between the subject and overlay to collect the interface
      pressure data.
    

Intervention name(s): Dabir Air overlay
Intervention type(s): Device
Intervention description(s): The Dabir Air overlay is a low profile alternating pressure overlay that is designed to place on top of mattress and operation room table.
Intervention model: Single Group Assignment
Intervention model description: Repeated measures design. Subject serves as his or her own control.
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: spinal cord injury; pressure ulcer; laser Doppler flowmetry