Norm of Tensilon Test
Unequivocal improvement in a single weakened muscle.
Equivocal or no improvement in a weakened muscle. False-negative tests are fairly common, and repeated tests are helpful.
Usage of Tensilon Test
Diagnosis of myasthenia gravis.
Description of Tensilon Test
Myasthenia gravis is an autoimmune neuromuscular disease characterized by fatigue of the limb, facial, bulbar, and ocular muscles with repetitive activity and by improvement with rest. Respiratory muscle fatigue can also occur. It is caused by circulating antibodies directed toward the skeletal muscle acetylcholine receptor. The factors that trigger the autoimmune response are unknown. In the Tensilon (edrophonium chloride) test, a short-acting anticholinesterase is administered intravenously, and muscle response is observed. The test is most useful if improvement in ptosis or the strength of an extraocular muscle is demonstrated because of the objective nature of this response. After intravenous administration of Tensilon, muscle strength will improve quickly in clients with myasthenia gravis.
Professional Considerations of Tensilon Test
Consent form NOT required.
- Assess for use of medications that affect muscle function, allergies, and respiratory disease.
- Establish intravenous access with a butterfly needle or an infusion of 5% dextrose in water or 0.9% saline.
- Obtain baseline vital signs.
- Have emergency respiratory support equipment and atropine available for use in the event of complications.
- Determine the muscle to observe for response.
- An initial test dose is administered because some people may be sensitive to Tensilon and may experience bradycardia or bronchospasm. These individuals should not receive additional Tensilon.
- Administer an initial dose of Tensilon intravenously as follows:
- a. Adults: 2 mg.
- b. Children weighing >75 pounds: 2 mg.
- c. Children weighing <75 pounds: 1 mg.
- d. Infants: 0.5 mg.
- Muscle strength may improve within 45 seconds. If no improvement is noted, additional Tensilon should be infused as follows:
- a. Adults: up to 8 mg over 30 seconds.
- b. Children weighing >75 pounds: up to 8 mg at a rate of 1 mg/30–45 seconds.
- c. Children weighing <75 pounds: up to 5 mg at a rate of 1 mg/30–45 seconds.
- d. Infants: Do not administer further Tensilon.
- Flush the IV access line between doses to ensure that the medication has infused.
- Be prepared for possible respiratory distress because Tensilon may stimulate a cholinergic crisis that causes extreme muscle weakness. If this occurs, up to 1 mg of intravenous atropine should be administered promptly.
- Atropine may be administered during the test to clients with respiratory diseases, such as asthma, to minimize the side effects of Tensilon.
- Once an unequivocal response is noted, the test is complete, and Tensilon administration should be stopped.
- Monitor vital signs every 5 minutes × 4.
Client and Family Teaching
- Instruct the client about the procedure and the potential side effects of Tensilon.
Factors That Affect Results
- Prednisone delays the effect of Tensilon.
- Quinidine and anticholinergics inhibit the action of Tensilon.
- Skeletal muscle relaxants may mask the effect of Tensilon.
- The side effects of Tensilon include abdominal cramps, bradycardia, diaphoresis, diarrhea, hypotension, incontinence, pupillary constriction, respiratory distress, and salivation.