Overview The Tensilon test uses the drug Tensilon (edrophonium) to help your doctor diagnose myasthenia gravis. Tensilon prevents the breakdown of the chemical acetylcholine, a neurotransmitter that nerve cells release to stimulate your muscles. People with the chronic disease myasthenia gravis don’t have normal reactions to acetylcholine. Antibodies attack their acetylcholine receptors. This prevents muscles from being stimulated and makes muscles easy to
tire. A person tests positive for myasthenia gravis if their muscles get stronger after being injected with Tensilon. Read more: Myasthenia gravis » Your doctor might order the Tensilon test if they suspect that you have myasthenia gravis. If you’ve already been diagnosed, they may also perform the test to monitor your dosage of Tensilon or another drug of a similar type, called an anticholinesterase. Anticholinesterase drugs work by preventing the breakdown of
acetylcholine in people with myasthenia gravis. Labored breathing and extremely weak muscles are symptoms that your myasthenia gravis has worsened or that you’ve overdosed on the medication. The Tensilon test helps your doctor determine the right treatment. Before the test, your doctor might set dietary restrictions or tell you to discontinue your use of certain medications or supplements. Let your doctor know all of the medications you’re taking, including herbs. Some
substances can interfere with your test results. The test will start with an intravenous (IV) needle placed in your arm or the back of your hand. A small amount of Tensilon will then be injected. Your stomach might feel upset or your heart rate might increase from the drug. Depending on why the test is being administered, the rest of the procedure will continue in different ways. If your doctor suspects that you have myasthenia gravis, they’ll
tell you to perform a repetitive movement to test your muscles. This movement may be:
Each time you get tired, they’ll give you another dose of Tensilon. You might get 3 or 4 doses of the drug. Your doctor will observe whether the dose revives your strength each time. If it does, you may be diagnosed with myasthenia gravis. Your doctor may also administer another anticholinesterase drug, called neostigmine (Prostigmin), to confirm the diagnosis. For checking Tensilon overdose and disease progressionIf your doctor is trying to determine whether you’ve overdosed on Tensilon or if your disease is getting worse, they’ll inject a small amount of Tensilon and see what happens. Depending on the results, you’ll be given an additional drug, either neostigmine or atropine (Atreza), to stabilize you. Each of these procedures should take about 15 to 30 minutes. Your doctor should be able to tell you the test results right away. You’ll likely be put on long-term anticholinesterase drug therapy if you’re diagnosed with myasthenia gravis. Your doctor might want you to undergo additional testing to confirm the diagnosis. For determining whether you overdosed on medication or your condition has worsened, this test provides and immediate answer. If an injection of Tensilon temporarily boosts your strength, the myasthenia gravis has gotten worse and you’ll need further treatment. If the Tensilon injection makes you even weaker, then you might have too much anticholinesterase medication in your system. Anticholinesterase medication is taken when necessary. There’s no fixed dosage. This is because the symptoms of myasthenia gravis can vary each day due to factors such as stress and weather. The varying dosage makes an unintentional overdose more likely. Reducing your dosage should solve the problem if you have minimal side effects. Contact your doctor immediately if you have:
The Tensilon test has a number of common side effects. These usually last for less than a minute. Side effects include: If you continue to feel unwell, the doctor may give you an injection of atropine. This drug reverses the effects of Tensilon. In rare cases, the Tensilon test can have dangerous outcomes. These may include breathing failure or abnormal heart rhythms. That’s why the test is performed in places where emergency resuscitation equipment is available. You might not be a good candidate for the test if you have: If you have sleep apnea, your doctor might not recommend the Tensilon test. This is a condition in which you temporarily stop breathing while sleeping. Let your doctor know if you have any of these conditions. They’ll be able to determine the right treatment options for you. Myasthenia gravis can be difficult to diagnose and you may need several tests. First a GP will ask about your medical history and symptoms. Alternatively, an optician may have noticed problems such as double vision or eyelid droop. If they think you could have a problem with your brain or nerves, they may refer you to a specialist for tests in hospital to help diagnose myasthenia gravis and rule out other conditions with similar symptoms. The main test for myasthenia gravis is a blood test to look for a type of antibody (produced by the immune system) that stops signals being sent between the nerves and muscles. A high level of these antibodies usually means you have myasthenia gravis. But not everyone with the condition will have a high level of antibodies, particularly if it's only affecting the eye muscles (ocular myasthenia). The blood test may be repeated at a later date if the result is normal but your symptoms continue or get worse. If your blood test result is normal but the doctor still thinks you could have myasthenia gravis, they may suggest an electrical test of your nerves and muscles. These tests, known as electromyography, involve inserting very small needles into your muscles to measure the electrical activity in them. The needles are typically inserted around the eyes, in the forehead or possibly in the arms. The electrical recordings can show whether the signals sent from the nerves to the muscles are being disrupted, which may be a sign of myasthenia gravis. You may also have a CT scan or MRI scan of your chest to check if your thymus gland is bigger than usual or has grown abnormally (a thymoma). The thymus gland is a small gland in the chest that forms part of the immune system. Problems with the gland are closely associated with myasthenia gravis. Sometimes an MRI brain scan may also be carried out to check that your symptoms are not being caused by a problem in your brain. If it's still not clear what's causing your symptoms, the doctor may recommend a test called an edrophonium test. It involves having an injection of a medicine called edrophonium chloride. If you have a sudden but temporary improvement in muscle strength after the injection, it's likely you have myasthenia gravis. But this test is rarely done these days because there's a risk it could cause potentially serious side effects, such as a slow heartbeat and breathing problems. It's only done if absolutely necessary and in a hospital setting where treatment for any side effects is readily available. Page last reviewed: 17
January 2020 Patients with myasthenia gravis who are in respiratory distress may be experiencing a myasthenic crisis or a cholinergic crisis. Before these possibilities can be differentiated, ensuring adequate ventilation and oxygenation is important. [14] Patients with myasthenic crisis can develop apnea very suddenly, and they must be observed closely. Evidence of respiratory failure may be noted through ABG determination, pulmonary function tests, or pulse oximetry. Open the airway by suctioning secretions after positioning the jaw and tongue. Administer high-flow oxygen, and measure oxygen saturation by pulse oximetry. If respirations remain inadequate, ventilate by bag-valve mask while preparing to intubate. In the patient without an intact gag reflex, an oral airway may be placed. Rapid sequence intubation should be modified, because depolarizing paralytic agents (eg, succinylcholine) have less predictable results in patients with myasthenia gravis. The relative lack of ACh receptors makes these patients relatively resistant to succinylcholine; therefore, higher doses must be used to induce paralysis. Once paralysis is achieved, it may be prolonged. [9] A rapid-onset, nondepolarizing agent (ie, rocuronium, vecuronium) is the preferred paralytic agent for these patients. Although nondepolarizing agents delay the onset of paralysis, compared with succinylcholine, these medications do not result in unwanted prolonged paralysis. Following paralysis, intubation is accomplished as usual. ABG sampling guides ventilator settings. Preliminary studies suggest that bilevel positive airway pressure (BiPAP) can prevent intubation in patients with myasthenic crisis without overt hypercapnia and should be considered in the patient who can be closely monitored. [9, 15] Hypercapnia present at the time of BiPAP initiation can predict failure and the need to proceed to endotracheal intubation. [16, 6] Once the airway is secured, investigation into the cause of the exacerbation of myasthenia gravis may proceed, with the most common reason for an exacerbation being infection, followed by inadequate treatment with cholinesterase inhibitors. However, up to 30% of patients will not have an identified cause of their exacerbation. [5] Differentiation from cholinergic crisis can proceed as described above. In less severely ill patients, oral pyridostigmine can be administered until clinical improvement is seen. The patient should be closely observed and monitored during this trial. Other reasons for the exacerbation can then be investigated. Although patients with myasthenia gravis can develop any common infection that can result in decompensation, the most likely source of infection is pulmonary. Cultures of blood, sputum, and urine may be indicated on an individual basis. Chest radiography is important in detecting pneumonia. Appropriate broad-spectrum antibiotics are indicated for sepsis and pneumonia. It is important to consider that fluoroquinolones and antibiotics may adversely affect cholinergic transmission in patients with myasthenia gravis, and these antibiotics should be avoided if possible. Patients with myasthenia gravis are sensitive to high temperatures (core or ambient), and their muscle strength can improve when temperature is lowered with cooling measures or antipyretics. Which clinical manifestations with a nurse expect for a client who has myasthenia gravis?People with myasthenia gravis may experience the following symptoms:. weakness of the eye muscles (called ocular myasthenia). drooping of one or both eyelids (ptosis). blurred or double vision (diplopia). a change in facial expression.. difficulty swallowing.. shortness of breath.. impaired speech (dysarthria). What are the most common early symptoms of myasthenia gravis?Common symptoms of myasthenia gravis include:. droopy eyelids.. double vision.. difficulty making facial expressions.. problems chewing and difficulty swallowing.. slurred speech.. weak arms, legs or neck.. shortness of breath and occasionally serious breathing difficulties.. What happens in myasthenia gravis?In myasthenia gravis, your immune system produces antibodies that block or destroy many of your muscles' receptor sites for a neurotransmitter called acetylcholine (as-uh-teel-KOH-leen). With fewer receptor sites available, your muscles receive fewer nerve signals, resulting in weakness.
What causes myasthenia gravis symptoms?Myasthenia gravis is caused by an abnormal immune reaction (antibody-mediated autoimmune response) in which the body's immune defenses (i.e., antibodies) inappropriately attack certain proteins in muscles that receive nerve impulses.
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Which clinical manifestations would the nurse expect for a client who has myasthenia gravis Quizlet
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