With respect to specific activating events, conditioning is one way that stimuli become able to elicit anxiety. It is believed that these changes are controlled by the vagus nerve, which affects activity in the chest and abdomen. Accordingly, painful experiences can condition fear to blood-injury stimuli. Investigators typically classify around 60% of self-reported onsets of blood-injury phobia as beginning with conditioning experiences. However, examinations of available case-by-case verbal summaries call into question the conclusion that conditioning episodes are as prevalent as reported. For example, Thyer et al. (1985) identified a conditioning episode when a "patient received an injection at age 13 and fainted", and in another person when "at age six she heard her elementary school teacher give a talk on the circulatory system. This frightened the patient to the point of syncope." Symptoms
Physical
Rapid heart rate
Trouble breathing
Shaking or trembling
Tightness or pain in chest
Lightheadedness
Sweating
Hot or cold flashes
Violation

Emotional
Extreme feelings of anxiety or panic
Overwhelming need to escape situations involving blood
Feeling as if you will die or pass out
Concerned that you have lost control
Feeling powerless over your fear

Treatment
The standard approach to treatment is the same as with other phobias—cognitive-behavioral therapy, desensitization, and possibly medications  to help with the anxiety and discomfort. In recent years, the technique known as applied tension, applying tension to the muscles in an effort to increase blood pressure, has increasingly gained favor as an often effective treatment for blood phobia associated with drops in blood pressure and fainting.Because the fear of blood is extremely common, it is frequently exploited in popular culture.
If a lumbar puncture (spinal tap) is performed, the protein level in the cerebral spinal fluid would be normal. Screening
Initial screening for CIP/CIM may be performed using an objective scoring system for muscle strength. The Medical Research Council (MRC) score is one such tool, and sometimes used to help identify CIP/CIM patients in research studies. The MRC score involves assessing strength in 3 muscle groups in the right and left sides of both the upper and lower extremities. Each muscle tested is given a score of 0–5, giving a total possible score of 60. An MRC score less than 48 is suggestive of CIP/CIM. However, the tool requires that patients be awake and cooperative, which is often not the case. Also, the screening tool is non-specific, because it does not identify the cause a persons muscle weakness.Once weakness is detected, the evaluation of muscle strength should be repeated several times. If the weakness persists, then a muscle biopsy, a nerve conduction study (electrophysiological studies), or both should be performed. Prognosis
CIP/CIM can lead to difficulty weaning a person from a mechanical ventilator, and is associated with increased length of stay in the ICU and increased mortality (death). It can lead to impaired rehabilitation. Since CIP/CIM can lead to decreased mobility (movement), it increases the risk of pneumonia, deep vein thrombosis, and pulmonary embolism. Critically ill people that are in a coma can become completely paralyzed from CIP/CIM. Improvement usually occurs in weeks to months, as the innervation to the muscles are restored.