Thresholds
In pain science, thresholds are measured by gradually increasing the intensity of a stimulus in a procedure called quantitative sensory testing which involves such stimuli as electric current, thermal (heat or cold), mechanical (pressure, touch, vibration), ischemic, or chemical stimuli applied to the subject to evoke a response. The "pain perception threshold" is the point at which the subject begins to feel pain, and the "pain threshold intensity" is the stimulus intensity at which the stimulus begins to hurt. The "pain tolerance threshold" is reached when the subject acts to stop the pain. Assessment
A persons self-report is the most reliable measure of pain. Some health care professionals may underestimate pain severity. A definition of pain widely employed in nursing, emphasizing its subjective nature and the importance of believing patient reports, was introduced by Margo McCaffery in 1968: "Pain is whatever the experiencing person says it is, existing whenever he says it does". To assess intensity, the patient may be asked to locate their pain on a scale of 0 to 10, with 0 being no pain at all, and 10 the worst pain they have ever felt. Quality can be established by having the patient complete the McGill Pain Questionnaire indicating which words best describe their pain. Visual analogue scale
The visual analogue scale is a common, reproducible tool in the assessment of pain and pain relief. The scale is a continuous line anchored by verbal descriptors, one for each extreme of pain where a higher score indicates greater pain intensity.
Reactions that begin sooner are typically more severe. Epidemiology
Acute hemolytic transfusion reaction is estimated to occur in 1 in 38,000 to 1 in 70,000 transfusions. An estimated 41% of ABO-incompatible transfusions result in AHTR. == References ==