Provocative tests with allergens: conjunctival, nasal, inhalation

August 22, 2017 23:00 | Methods Of Diagnosis

For the treatment of an allergic disease, it is necessary to accurately determine the agent that initiates a negative reaction of the body.In the human environment of such substances that can fall under suspicion of an allergist, a huge amount.It is required to find confirmation that some allergen is the cause of the aggravation.

What is provocative test

The study is to determine the allergen through the creation of a provocation by introducing it into a body that has an allergic disease as part of a special fluid. The appearance of allergy signs suggests that the sample received a positive reaction.

What are provocative samples, this video will tell:

To whom they are assigned

Provocative tests relate to ways of diagnosing allergies.When the patient is examined, an anamnesis of the disease is collected.The specialist is trying to get a complete picture of everything that can provoke an aggravation.

To determine from the list of allergens that are suspected as initiators of the disease, to

determine the actual provocateurs of the allergy, make samples.Assign a procedure for more accurate diagnosis with such allergic manifestations:

  • bronchial asthma,
  • conjunctivitis,
  • rhinitis,
  • chronic pollinosis.

Why do they do

Provocative tests are done in cases where other methods do not bring complete clarity in diagnosing the allergen. The procedure is designed to determine which agents cause allergies, which will allow you to choose the right treatment.

Accurate diagnosis will help the patient make conscious efforts to avoid contact with the allergen.This factor will significantly contribute to improving his state of health.In a day you can do one provocative test.

Types of procedure

Provocation probes are of the following types:

  • inhalation,
  • nasal,
  • conjunctival.

Indications for

Provocative tests help in clarifying the allergen for the patient in cases:

  • if the history and skin test data indicate a negative result for certain allergens, and the underlying disease becomes more aggravated;
  • results of skin tests, other studies on the allergen, as well as personal sensations and patient's observations regarding the initiator of the allergy do not match;
  • when testing new drugs against allergy to efficacy;
  • is not indicated for the patient to do skin testing( skin disease).

About whether the provocative tests are performed in case of bronchial asthma and other ailments, we will tell below.

Contraindications for

Provocative tests are not performed if the patient has such circumstances:

  • the underlying disease is in a difficult stage, it is possible that complications have occurred;
  • Concomitant diseases undergo an exacerbation stage,
  • is a major disease in the period of exacerbation,
  • diseases that are not related to the underlying disease are in development in the acute phase;
  • the patient has an acute period of chronic infectious disease,
  • if the patient at the time of the study:
    • pulmonary cardiac insufficiency 2 and 3 degrees,
    • active phase of rheumatism,
    • severe liver disease,
    • kidney dysfunction,
    • Acute inflammatory process,
    • active tuberculosis,
    • heart disease during decompensation,
    • bronchial asthma of complex shape,
    • hyperthyroidism,
    • third degree hypertonic
    • pregnancy;
  • the patient's sensitivity to the action of the allergen is so high that it poses a risk of severe consequences.

Safety method

The procedure is not completely secure. The body can respond to provocation, so experts should have performed tests that have experience in restoring normal conditions, if necessary.

The room should be equipped with the necessary devices for carrying out restorative actions, if there was a reaction of the body to the allergen.The most dangerous is an inhalation test, so it is performed only in a hospital.

The worst possible response of the body is anaphylactic shock.Such cases are rare, but should be prepared to help the patient in intensive care.

Preparation for procedure

In the case of carrying out a nasal test, the following preliminary actions are performed:

  • Prepare the liquid for carrying out the test sample: the allergen is combined with a special liquid so that a tenfold dilution is obtained.
  • The examiner examines the patient's readiness for the sample.The nasal passages are examined by the rhinoscopy method.The doctor fixes such data:
    • character of breathing through the nose,
    • degree of secretion in the nasal passages,
    • color of the mucosa.

To perform a conjunctival test, the specialist performs the following actions:

  • determines the patient's willingness to test, his general condition and examines the conjunctiva of the eyes;
  • prepares a solution from a special liquid with the addition of an allergen in three different consistencies for the sample.

In order to conduct the inhalation test:

  • , when examining the patient, measurements of the vital capacity of the lungs are made and the pneumotachometry parameters are determined.
  • prepares a solution for test inhalation in different consistencies, with an increase in the allergen concentration in each dose.

General recommendations for preparation for the procedure:

  • It is desirable to carry out the tests in seasons when there are fewer allergens in the environment( in autumn, in winter).
  • On the eve of the sample it is recommended to undergo a general examination.
  • You should stop taking antiallergic drugs for the day before the procedure.

Sampling

It is recommended to perform the procedure during a period of stable remission of an allergic disease.The type of provocative test is determined by the fact that the disorder causes an allergy.

Nasal

In the case of allergic rhinitis, a nasal test is performed.Determine which nasal passage will be subjected to research, and which will remain unchanged to compare the result obtained during the sample. Usually, if there is a curvature of the nasal septum, then for the tests choose a nasal passage with a large lumen.Next, the prepared solution is added to the test nostril.The first time use a test solution.

The procedure is performed by an experienced specialist, the drops must fall into the septum zone. They observe the occurring reactions of the body to provocation and if nothing is noticed, then after 10 minutes they test for the allergen, instill a solution of another necessary consistency.

  • If a positive reaction to an allergen is detected, the test procedure is terminated.
  • If the reaction is not noticed, the test continues.In the nasal passage, a second solution of a stronger consistency is instilled.For the complete procedure, only three instillations are performed into the nostril of a special solution( each dose is more concentrated) after 30 minutes.

Conjunctival

If the allergen causes an eye disease, a conjunctival test is performed.The specialist chooses one eye for research, and the second remains unchanged to compare the result.A solution containing an allergen in a certain proportion drips onto the conjunctiva of the eye( the first time is a test solution).

  • If signs of an allergy do not appear during the test, then apply the solution three times in the eye area with interruptions of 30 minutes.Each subsequent batch of test solution contains a higher concentration of allergen.
  • At the first signs of redness, the conjunctival edema of the product is stopped and rehabilitated.The eye is washed with an isotonic solution of sodium chloride.

Inhalation

The inhalation test is intended to determine which allergen causes bronchial asthma.During the procedure, the patient first inhales the test solution, if a change in the human condition is not observed, the planned tests are carried out.The patient then inhales the control sample and, if there are still no signs of allergy, then under the supervision of specialists the following inhalations with increased concentrations of the allergen are carried out.

With the slightest signs of nasal congestion, coughing, discomfort in the throat area, the tests are terminated. In case of attack of asthma, it is stopped.Before the test, the lung capacity is measured by spirography.This indicator is observed during the tests.

How to find out what you are allergic by provocative samples and in another way will tell the video below:

Decoding results

Observations are conducted to summarize the results of the study for the patient during provocative samples.The results are recorded in special observation sheets.

  • In the nasal sample , the nasal respiratory rate, the abundance of secretion and the color of the mucosa before the test and then every ten minutes are recorded in the observation sheet.It turns out three records for nine records.
  • With a conjunctival sample of , a specialist inserts information on the condition of the conjunctiva prior to testing and during the test every 10 minutes.If the tests did not provoke a positive reaction to the allergen, then it does not cause an allergy in the patient.If a positive reaction is detected, the allergist analyzes the findings and designates rehabilitation measures( this point applies to all cases).
  • When the inhalation test is performed, the result is considered positive( i.e., the allergen has an effect on health) when the change in the vital capacity of the lungs towards the decrease occurred by 15%.

It( degree of influence) is expressed by categories - research response:

  • questionable,
  • weakly positive,
  • negative,
  • positive.

Average price

The price of conducting provocative samples depends on the type of suspected allergen and in different clinics has a marked difference.