Electrical Skin Conductance Monitoring as an Assessment of Post Operative Pain Scores
Condition: Postoperative Pain
MeSH terms: Pain, Postoperative
Study type: Observational

Summary: 
      Pain has been defined as a subjective experience. Various pain assessment tools, (such as
      NRS) have been developed and validated to objectively monitor and treat pain. There are
      certain patient populations, in whom, the current pain assessment tools cannot be used
      effectively due to communication problems such as cognitively impaired patients. In the US,
      the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has made it
      mandatory to monitor and treat pain. In the absence of reliable pain assessment tools that
      would objectively measure pain, there is also risk of under treatment and overtreatment of
      pain that may lead to negative outcomes. Therefore, a monitor that is able to predict pain
      levels objectively, will help to achieve above goals. The investigators are using Skin
      Conductance Algesimeter (SCA) to measure pain by analyzing changes in skin conductance.
    

Detailed description: 
      Pain was defined as the fifth vital sign, and assessment and treatment of pain were
      introduced as a mandatory standard. This directive has improved pain management and patient
      satisfaction, but it has also increased the incidence of opioid-related side effects
      including respiratory depression with fatal outcomes. The most accepted pain assessment is
      the patients' self-report of their pain. Various pain assessment tools, such as the numeric
      rating scale (NRS), have been developed and validated. The self-report of pain is defined as
      the gold standard even though it may be influenced by anxiety, level of education, employment
      status, age and sex. The NRS is reported to be more clinically applicable than the visual
      analogue scale (0-100mm) specifically in elderly and in patients on opioids.The current
      self-report assessment tools cannot be used effectively in certain patient populations who
      are unable to report their pain such as cognitively impaired patients, sedated patients and
      children. In this group of patients, there is a risk of inadequate or overtreatment of pain
      which in turn may lead to negative outcomes. When patients cannot report their pain,
      observational and physiological parameters are used. Therefore, a monitor to objectively
      assess the pain would be clinically valuable. An ideal monitor would be non-invasive,
      fast-reacting, continuous (real-time), sensitive and specific to assess pain.

      The Skin Conductance Algesimeter (SCA) measures skin sympathetic nerve activity mirrored by
      variations in skin conductance responses (SCR) on the palmar side of the hand. Each time the
      skin sympathetic nervous system is activated, the palmar and plantar sweat glands fill up
      with sweat. Due to electrolytes present in sweat, the skin resistance decreases and the skin
      conductance increases. The reabsorption of the sweat in the sweat glands reverses this
      process, and leads to a decrease in skin conductance. SCR can be monitored by SCA and this
      response is directly linked to skin sympathetic nerve activity. The number of SCR is a
      measure of how often the skin sympathetic nerves fire. The numbers of SCR increase during
      emotionally stressful stimuli like moderate-severe pain, and this is different than the
      painless or mild pain conditions.

      To examine how the SCR is influenced by stimuli other than pain postoperatively, it is
      important that SCR is studied in the absence of moderate-severe pain.The goal of this study
      is to evaluate the correlation of SCR with emotional stressors other than pain such as:
      anxiety, nausea, and intellectual task performance. We hypothesized that SCR would not show a
      significant positive correlation with emotional stressors other than pain, thereby will
      increase the specificity of SCR as a viable physiological monitor for the assessment of
      moderate-severe pain postoperatively.
    

Intervention name(s): Total Hip Replacement (THR) and Total Knee Replacement (TKR)
Intervention type(s): Procedure
Intervention description(s): Total Hip Replacement is a surgical procedure where the cartilage and bone of the hip joint is replaced with artificial materials. Total Knee Replacement involves replacement of all three compartments of the knee the medial, the lateral and patellofemoral compartment.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients undergoing surgery for unilateral Total Hip Replacement and Total Knee
        Replacement.