Tag: Respiratory Disorders

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Diagnonistic Test

Ventilation-Perfusion Scan or “V-Q Scan”

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Definition

A pulmonary ventilation/perfusion scan is a pair of nuclear scan tests that use inhaled and injected material to measur breathing (ventilation) and circulation (perfusion) in all areas of the lungs.

.click tom see the pictures

The ventilation-perfusion scan is a nuclear scan so named because it studies both airflow (ventilation) and blood flow  (perfusion) in the lungs. The initials V-Q are used in mathematical equations that calculate airflow and blood flow. The  purpose of this test is to look for evidence of a blood clot in the lungs, called a pulmonary embolus, that lowers oxygen  levels, causes shortness of breath, and sometimes is fatal.

Why is the Test Performed?
*The ventilation scan is used to evaluate the ability of air to reach all portions of the lungs.

*The perfusion scan measures the supply of blood through the lungs.

*A ventilation and perfusion scan is most often performed to detect a pulmonary embolus. It is also used to evaluate lung  function in people with advanced pulmonary disease such as COPD, and to detect the presence of shunts (abnormal circulation)  in the pulmonary blood vessels.

How is the Test Performed?
*A Pulmonary ventilation/perfusion scan is actually two tests that may be performed separately or together.

*The perfusion scan is performed by injecting albumin into a vein. The patient is immediately placed on a movable table that  is positioned under the arm of a scanner. The lungs are scanned to detect the location of the radioactive particles as blood  flows through the lungs.

*The ventilation scan is performed by scanning the lungs while having the person inhale gas. A mask is placed over the nose  and mouth, and the patient is asked to breathe the gas while sitting or lying on the table beneath the arm of the scanner.

How to Prepare for the Test?
*No special diet, medications, or fasting are necessary before the test.

*A chest x-ray is usually performed prior to or following a ventilation and perfusion scan.

*The patient usually signs a consent form and is asked to wear a hospital gown or comfortable clothing without metal  fasteners.

About one hour before the test, a technician places an IV in your arm. A slightly radioactive version of the mineral technetium mixed with liquid protein is injected through the IV to identify areas of the lung that have reduced blood flow.

What happens when the test is performed?

The test is performed in the radiology department of a hospital or in an outpatient facility. You are asked to put on a  hospital gown. Once you are ready, multiple pictures of your chest are taken from different angles, using a special camera  that detects the radionuclide. For half of these pictures, you are asked to breathe from a tube that has a mixture of air,  oxygen, and a slightly radioactive version of a gas called xenon, which can be detected by the camera, and which measures  airflow in different parts of the lung. For the other half of the pictures, the camera tracks the injected radionuclide to  determine blood flow in different parts of the lung. A blood clot is suspected in areas of the lung that have good airflow but poor blood flow. Except for the minor discomfort of having the IV placed, the test is painless. It usually takes less  than one hour.

How Will the Test Feel?
The table may feel hard and/or cold. There may be a sharp prick during injection of material into the vein for the perfusion portion of the scan. The mask used during the ventilation scan may give you a claustrophobic feeling. You must lie still during scanning. The injection usually does not cause discomfort.

Risks Factors:

Many people worry when they hear that the liquid and gas used in this test are slightly radioactive. In truth, the radioactivity you are exposed to in this test is so small that there are no side effects or complications, unless you are pregnant.

*Risks are essentially the same as for x-rays (radiation) and needle pricks.

*There is a small exposure to radiation from the radioisotope. The radioisotopes used during scans are short lived, with almost all radiation gone in a few days. However, as with any radiation exposure, caution is advised during pregnancy or if a woman is breastfeeding. No radiation is emitted from the scanner; it detects radiation and converts it to a visible image.

*There is a slight risk for infection or bleeding at the site of the needle insertion. The risk with perfusion scan is no different than for placement of an intravenous needle for any other purpose.

*It is extremely rare, but a person may develop an allergy to the radioisotope, which may include serious anaphylactic reaction.

Must you do anything special after the test is over?
Nothing

How long is it before the result of the test is known?

The results are usually available within a few hours, because the test is done only when you are suspected of having a potentially life-threatening condition (pulmonary embolus). Your doctor can interpret the pictures to determine whether your probability of having a blood clot in your lungs is high, low, or intermediate. If the probability is high, usually yourdoctor will order bloodthinning medicine. If it is low, he or she may not give immediate treatment, but will want to examine you again in a short time. If you face an intermediate risk, or if the V-Q scan cannot be clearly interpreted, your doctor may order a pulmonary angiogram (see page 8) to help determine whether you have a blood clot. This test is more definitive than a V-Q scan, but because it is more difficult and risky, the V-Q scan usually is done first.

Resources:
https://www.health.harvard.edu/fhg/diagnostics/ventilation-perfusion-scan.shtml
http://www.mmpc.com/specialties/pulm/patient/vqscan

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Diagnonistic Test

Sputum Evaluation (and Sputum Induction)

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Introduction:
If your doctor thinks you have pneumonia, he or she might examine a sample of your sputum, the phlegm that you cough out of your lungs, to try to determine what type of bacteria or other infectious agent might be the cause.

Sputum induction is also  a new support tool for the diagnosis and evaluation of occupational asthma.
In order to evaluate a new test for helping in the diagnosis and evaluation of occupational asthma, 24 workers with occupational asthma were recruited. Besides assessing their respiratory function, their bronchial inflammation was evaluated by sputum induction, a simple method that evaluates bronchial cellularity non-invasively. The results show that the functional and inflammatory parameters of subjects with occupational asthma improve mainly in the 6 months following removal from exposure. Furthermore, it appears that the workers with eosinophilic bronchial inflammation at the time of diagnosis evolve more favourably after removal from exposure than those without this inflammation.

CLICK & SEE

How do you prepare for the test?
Drink plenty of fluids the night before the test; this may help to produce a sample.

What happens when the test is performed?
You need to cough up a sample of sputum. To be useful for testing, the stuff you cough up has to be from deep within the lungs. If your cough is too shallow or dry, the doctor might ask you to breathe in a saltwater mist through a tube or mask. This mist makes you cough deeply, usually producing an excellent phlegm sample.

You may click to see:->

Method and apparatus for inducing sputum samples for diagnostic evaluation

Lung Tests in Asthma

Risk Factor: No risk is involved.

Must you do anything special after the test is over? : Nothing

How long is it before the result of the test is known?
The technician stains the sputum sample and views it under a microscope. Some of the sample is incubated to grow the bacteria or other germs in it for further testing. This step is called a sputum culture.While some stain results might be available on the day of your test, the culture usually requires several days.

Resources:
https://www.health.harvard.edu/diagnostic-tests/sputum-evaluation.htm
http://www.irsst.qc.ca/en/_projet_3045.html

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Cold Virus Decoded, Cure Now Possible

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Curing the common cold, one of medicine’s most elusive goals, may now be in the realm of the possible. Researchers said on Thursday that they had decoded the genomes of the 99 strains of common cold virus and developed a catalog of its vulnerabilities
“We are now quite certain that we see the Achilles’ heel, and that a very effective treatment for the common cold is at hand,” said Stephen Liggett, an asthma expert at the University of Maryland and co-author of the finding.
Besides alleviating the achy, sniffly misery familiar to everyone, a true cold-fighting drug could be a godsend for the 20 million people who suffer from asthma and the millions of others with chronic obstructive pulmonary disease. The common cold virus, a rhinovirus, is thought to set off half of all asthma attacks.

Even so, it might be difficult to kindle the interest of pharmaceutical companies. While the new findings are “an interesting piece of science”, said Glenn Tillotson, an expert on antiviral drugs at Viropharma in Exton, Pennsylvania, he noted that the typical cost of developing a new drug was now $700 million, “with interminable fights with financiers and regulators”. Because colds are mostly a minor nuisance, drug developers say, people would not be likely to pay for expensive drugs. And it would be hard to get the Food and Drug Administration to approve a drug with any serious downside for so mild a disease.
Perhaps the biggest reason the common cold has long defied treatment is that the rhinovirus has so many strains and presents a moving target for any drug or vaccine. This scientific link in this chain of problems may now have been broken by a research team headed by Liggett and Ann Palmenberg, a cold virologist at the University of Wisconsin.

Fernando Martinez, an asthma expert at the University of Arizona, said the new rhinovirus family tree should make it possible for the first time to identify which particular branch of the tree held the viruses most provocative to asthma patients. The rhinovirus has a genome of about 7,000 chemical units, which encode the information to make the 10 proteins that do everything the virus needs to infect cells and make more viruses. By comparing the 99 genomes with one another, the researchers were able to arrange them in a family tree based on similarities in their genomes.

That family tree shows that some regions of the rhinovirus genome are changing all the time but that others never change. The fact that the unchanging regions are so conserved over the course of evolutionary time means that they perform vital roles and that the virus cannot let them change without perishing. They are therefore ideal targets for drugs because, in principle, any of the 99 strains would succumb to the same drug.

Sources: The Times Of India

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Asthma Medicines Don’t Work and Can Be Dangerous

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An overview of recent studies finds that there are no clear benefits to using long-acting beta2-agonists (LABAs) for the treatment of asthma in children. Researchers report that there is currently insufficient evidence to suggest that the drugs offer any additional benefit when used in conjunction with conventional preventative medications.

asthma,asthma medicine,vitamin DAn overview of recent studies finds that there are no clear benefits to using long-acting beta2-agonists (LABAs) for the treatment of asthma in children. Researchers report that there is currently insufficient evidence to suggest that the drugs offer any additional benefit when used in conjunction with conventional preventative medications.

LABAs, such as salmeterol and formoterol, can reduce the symptoms of asthma for periods of up to 12 hours. They are commonly given to relax the airways overnight or after exercise, and are recommended as add-on therapies to inhaled corticosteroids. But since LABAs have previously been shown to increase the risk of life-threatening adverse effects in adults when used as the only drug, they are not recommended as the main treatment agent in asthma in any age groups.

Now researchers say that their use does not generally provide any further benefit over regular ICS therapy for children. The overview included four previous reviews of trials in children above the age of four. They showed that LABAs did not reduce severity of asthma symptoms as measured by hospital admissions, or the need for steroid medication.

If you want something that really works for asthma, you might want to look into vitamin D. One study has shown that poor diets and the lack of vitamin D among mothers were the two strongest determining factors in whether their children suffered from asthma — more so even than whether or not the mothers smoked.

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Eating Nuts During Pregnancy Might Increase Asthma Risk

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Children born to mothers who ate nuts or nut products daily were 50% more likely to have asthma than those whose moms avoided the foods, a Dutch study shows.

NO SURE THING: Asthma and asthma symptoms did occur in some children whose mothers, in a study, rarely or never ate nuts while pregnant.

What’s new: A pregnant woman who eats nuts or nut products every day during pregnancy may increase her child’s risk of developing asthma.

The finding: A large study by the Dutch government has found that children born to women who ate nuts or peanuts, or items made from them, such as peanut butter, daily while pregnant were 50% more likely to wheeze, have difficulty breathing or have asthma diagnosed by a doctor compared with children whose mothers rarely or never ate nuts or nut products while pregnant. The study, published in the American Journal of Respiratory and Critical Care Medicine this month, is part of a larger, ongoing research initiative, the Prevention and Incidence of Asthma and Mite Allergy study, which is investigating how allergies develop in children and how they can be prevented.

Another finding: The odds of developing one particular asthma symptom — wheezing –were reduced in children whose mothers ate fruit daily during pregnancy, but the design of the study made it difficult for the researchers to conclusively link the two in a cause-effect relationship.

How the study was done: Nearly 4,000 expectant mothers, recruited into the study more than a decade ago, completed a dietary questionnaire on how often they ate fish, eggs, milk and milk products, nuts and nut products, fresh fruit and vegetables. Researchers followed up on the women’s offspring at 3 months old and then once a year until the children were 8, gathering information about the children’s diets, allergies and asthma symptoms.

Aside from nuts, none of the other dietary components appeared to affect the children’s likelihood of developing asthma or asthma-related symptoms. The food the children ate also appeared to have no bearing on their risk of asthma. Only the children whose mothers ate nuts or nut products every day while pregnant were more likely to experience wheezing, shortness of breath or other asthma symptoms.

Why it matters: A scientifically validated link between what a woman eats and her child’s risk of a health problem would, of course, affect the advice doctors give to expectant mothers — and, it is hoped, reduce the incidence of that problem.

Numerous studies have tried to clarify the relationship between a woman’s diet during pregnancy and the development of asthma or allergies in her child. Researchers have found that some vitamins and minerals (such as vitamin D and iron), as well as some foods (such as fish and apples), may protect against asthma and allergies. Others have shown that exposure to peanuts while in utero may increase a child’s risk of developing an allergy to them. But the current study, its authors say, is the first of its kind to follow up with its participants repeatedly over a long period, and thus is expected to be more reliable.

This study is also significant for what it didn’t show. Unlike those earlier studies that found that eating more fish during pregnancy can reduce the risk of asthma or allergies in offspring, the Dutch researchers produced no evidence to support those findings. (They were unable to draw conclusions about apples or specific vitamins or minerals, however, because they didn’t ask mothers for such dietary details.)

What we still don’t know: How could fetal exposure to nuts trigger asthma? Scientists have proposed a number of ideas, but the precise mechanisms are still unknown. Though the study suggests a link between nut consumption and asthma, it doesn’t show that a woman who avoids nuts during pregnancy has found a surefire way to prevent asthma in her offspring: Asthma and asthma symptoms did occur in some children whose mothers rarely or never ate nuts while pregnant. The study may be large and well designed, but its findings will need to be replicated before its results can join the legions of advice given to pregnant women across the globe.

Sources: Los Angles Times

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