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"Assessing Sensory Block: The Key to Effective Pain Management"

The term "dermatome" refers to the specific area of skin that is innervated by a single spinal nerve.

Local anesthetics function by obstructing nerve impulses on a variety of nerve fibers including sensory, motor, and autonomic fibers. Smaller diameter fibers are more susceptible to the effects of local anesthetics, with autonomic fibers being blocked first, followed by sensory fibers, and then motor fibers.

Sensory fibers are responsible for transmitting signals related to touch, pressure, pain, and temperature. Since local anesthetic medications affect both pain and temperature nerve fibers, changes in temperature perception can indicate the extent of the epidural's effect.

To determine the range of the sensory block, cold sensation (such as ice) should be used to assess which dermatome levels are covered. It is important to evaluate both the left and right sides of the body.

Evaluating the sensory block is crucial for two reasons:

1. Firstly, it helps confirm that the spinal, epidural, or caudal is adequately addressing the patient's pain.

2. Secondly, it helps verify that the block is not overly extensive, which could heighten the likelihood of complications.


To ensure the patient are comfortable and safe during the spinal, epidural or caudal procedure, we need to assess how much the patient body is affected by the anesthetic. We do this by using an ice cube wrapped in tissue to test the level of cold sensation in different areas of the patient's body.

1. First, we will apply the ice cube to a non-sensitive area of the patient's body, such as the forearm or face, and ask the patient to tell us how cold it feels.

2. Then, we will apply it to areas on the same side of the patient's body that are likely to be affected by the anesthetic, and ask if the cold sensation feels the same, warmer or colder.

3. We will repeat this process on the opposite side of the patient's body since the block may not be the same on both sides.

By doing this, we can determine which areas of the patient's body are numb and where the top and bottom of the numbness is located. We will record this information on a chart called the Flow sheet, so we can monitor patient's progress and ensure patient's safety throughout the procedure.

Assessment in infants or non-verbal patients:

1. Dermatome levels can be evaluated in infants and non-verbal patients by closely observing their facial expressions and flinching in response to ice application on presumed blocked and unblocked dermatomes.

2. Another technique to determine the effectiveness of regional anesthesia is by monitoring the patient's response to movement and gentle palpation of the surgical area.

Perform assessment 4 hourly and at the following times:

1. While in the recovery room after surgery

2. Upon returning to the ward/unit from the operating suite

3. At the start of each nursing shift

4. If the patient reports pain

5. One hour after administering a bolus or increasing the infusion rate.

Notify the physician if:

1. Epidural block higher than T3

2. No evidence of block

3. Block insufficient to relieve pain

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