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Featured

Hunger for Air

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“I can’t breathe,” said the woman, panic stricken and one hand clutched at her chest. Her forehead was lined with sweat and fear of death etched on her face. Breathing, after all, is essential for life.

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We take breathing or respiration for granted. It is an involuntary, autonomous and automatic reflex that is present from birth to death. We can consciously take deep or shallow breaths, but we cannot stop breathing at will. In short, you cannot commit suicide by voluntarily ceasing to breathe.

Breathing difficulty is a perception. Some people may have fairly severe lung restriction, but be able to continue their normal activities. Others may feel breathless with the slightest unaccustomed exertion. This is more likely to occur if the person is unfit, obese and unaccustomed to exercise. A sudden “panic attack” owing to an external factor can be “breath stopping”. High altitudes and high temperature can also cause similar problems.

Breathing difficulty can occur suddenly because of a foreign body like a peanut which has got lodged in the food pipe. This then becomes a medical emergency. Immediately stand behind the person, make a fist with both hands and exert a sudden forceful upward thrust in the stomach area below the chest bone (sternum). This is called a “Heimlich maneuver” and it has saved many lives.

Mucous secretions — watery in case of viral infections and allergy, and thick and viscous in case of secondary bacterial infection — can clog the nasal passages and bronchi. Some of these secretions can drip backwards into the throat, causing a post nasal drip with a sense of suffocation.

The nasal passages can be cleared with nose drops. It is important to use saline nasal drops. This is commercially manufactured by many companies. It needs to be used every two hours. Nasal drops containing chemicals may provide faster relief. But as the effect wears off, they may cause “rebound congestion” with worse blockage. Long-term frequent usage of chemical nose drops may cause habituation, wherein the body stops responding to the medication. If the nasal block is due to an allergy, prescribed locally acting steroid nasal sprays are very effective.

The bronchi can narrow in response to exposure to ingested allergens like peanuts and food colour, or inhaled ones like cigarette or wood smoke, room fresheners and mosquito repellents. This is called reactive airways disease or asthma.

Smokers may have damaged their lungs structure permanently, causing a disease called COAD (chronic obstructive airways disease). This sets in around 20-30 years after the first puff. It attacks people in their 40s and 50s. They become breathless with exertion and sometimes even at rest. Some require continuous artificial oxygen supply.

Initially — that is, before damage sets in — airway constriction is reversible. Inhalers or rotahalers deliver relief producing bronchodilating medication directly to the bronchi. The respite is immediate and sustained if the medication is “puffed” as prescribed. Direct delivery systems make medication more effective and are less likely to cause side effects.

The rate of breathing increases during pregnancy because of the oxygen demand of the baby. Moreover, pregnancy causes the uterus to enlarge which pushes the abdominal contents upwards. This may cause a feeling of inadequacy while breathing. This is self-limited and disappears with delivery.

Congenital heart disease, heart failure and myocarditis (disease of the heart muscles) can cause difficulty in breathing and a feeling of air hunger. This is because a failing heart provides inefficient circulation of blood and insufficient oxygenation to the tissues of the body. The blood carrying capacity of the body itself may be compromised because of anaemia. Specific medication for the diseases will help with the problem.

Breathlessness needs to be evaluated if:

The difficulty occurred suddenly for no apparent reason

• It was accompanied by chest discomfort, pain or pressure

• It comes with a slight exertion or at rest

• There is an inability to lie down flat and sleep

• It is accompanied by fever

• There is pressure, fullness or a squeezing pain in the chest.

Good breathing techniques require the co-ordinated use of intercostals (groups of muscles that run between the ribs, and help form and move the chest wall), diaphragm and stomach muscles. As the breath goes in, the intercostals and stomach expand and the latter moves outwards. And as we breathe out, the chest contracts, the diaphragm moves up and the stomach moves in. Breathing is a natural response and occurs normally and naturally in children. As age advances, we tend to lose the ability to breathe efficiently.

Long hours at work seated in a sloppy posture, obesity or an inactive life without the mandatory one hour of aerobic activity (running, swimming, jogging or cycling) results in inefficient and inadequate breathing, even in a normal individual.

Place a hand on your abdomen, stand in front of a mirror and breathe in and out to check if your breathing is correct. Consciously correct deficiencies and practise breathing exercises (yoga pranayam) for a healthier tomorrow.

Source: The Telegraph (Kolkata, India)

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Ailmemts & Remedies

Emphysema

Definition:-

Emphysema is a type of chronic obstructive pulmonary disease (COPD) involving damage to the air sacs (alveoli) in the lungs. As a result, your body does not get the oxygen it needs. Emphysema makes it hard to catch your breath. You may also have a chronic cough and have trouble breathing during exercise.

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The most common cause is cigarette smoking. If you smoke, quitting can help prevent you from getting the disease. If you already have emphysema, not smoking might keep it from getting worse.

It is  characterized by an abnormal, permanent enlargement of air spaces distal to the terminal bronchioles. The disease is coupled with the destruction of walls, but without obvious fibrosis.  It is often caused by exposure to toxic chemicals, including long-term exposure to tobacco smoke.

As it worsens, emphysema turns the spherical air sacs — clustered like bunches of grapes — into large, irregular pockets with gaping holes in their inner walls. This reduces the number of air sacs and keeps some of the oxygen entering your lungs from reaching your bloodstream. In addition, the elastic fibers that hold open the small airways leading to the air sacs are slowly destroyed, so that they collapse when you breathe out, not letting the air in your lungs escape.

Airway obstruction, another feature of COPD, contributes to emphysema. The combination of emphysema and obstructed airways makes breathing increasingly difficult. Treatment often slows, but doesn’t reverse, the process.

Emphysema is characterized by loss of elasticity (increased pulmonary compliance) of the lung tissue caused by destruction of structures feeding the alveoli, in some cases owing to the action of alpha 1-antitrypsin deficiency.

Classification:-
Emphysema can be classified into primary and secondary. However, it is more commonly classified by location.

Emphysema can be subdivided into panacinary and centroacinary (or panacinar and centriacinar, or centrilobular and panlobular).

Panacinary (or panlobular) emphysema is related to the destruction of alveoli, because of an inflammation or deficiency of alpha 1-antitrypsin. It is found more in young adults who do not have chronic bronchitis.

Centroacinary (or centrilobular) emphysema is due to destruction of terminal bronchioli muchosis, due to chronic bronchitis. This is found mostly in elderly people with a long history of smoking or extreme cases of passive smoking.
Other types include distal acinar and irregular.

A special type is congenital lobar emphysema (CLE).

Congenital lobar emphysema:-
CLE is results in overexpansion of a pulmonary lobe and resultant compression of the remaining lobes of the ipsilateral lung, and possibly also the contralateral lung. There is bronchial narrowing because of weakened or absent bronchial cartilage.

There may be congenital extrinsic compression, commonly by an abnormally large pulmonary artery. This causes malformation of bronchial cartilage, making them soft and collapsible.

CLE is potentially reversible, yet possibly life-threatening, causing respiratory distress in the neonate

Symptoms:
Emphysema symptoms are mild to begin with but steadily get worse as the disease progresses. The main emphysema symptoms are:

*Shortness of breath
*Wheezing
*Chest tightness
*Reduced capacity for physical activity
*Chronic coughing, which could also indicate chronic bronchitis
*Loss of appetite and weight
*Fatigue
When to see a doctor

*You tire quickly, or you can’t easily do the things you used to do
*You can’t breathe well enough to tolerate even moderate exercise
*Your breathing difficulty worsens when you have a cold
*Your lips or fingernails are blue or gray, indicating low oxygen in your blood
*You frequently cough up yellow or greenish sputum
*You note that bending over to tie your shoes makes you short of breath
*You are losing weight.

These signs and symptoms don’t necessarily mean you have emphysema, but they do indicate that your lungs aren’t working properly and should be evaluated by your doctor as soon as possible.

Causes:
The causes of emphysema include:

1.Smoking. Cigarette smoke is by far the most common cause of emphysema. There are more than 4,000 chemicals in tobacco smoke, including secondhand smoke. These chemical irritants slowly destroy the small peripheral airways, the elastic air sacs and their supporting elastic fibers.

2.Protein deficiency. Approximately 1 to 2 percent of people with emphysema have an inherited deficiency of a protein called AAt, which protects the elastic structures in the lungs. Without this protein, enzymes can cause progressive lung damage, eventually resulting in emphysema. If you’re a smoker with a lack of AAt, emphysema can begin in your 30s and 40s. The progression and severity of the disease are greatly accelerated by smoking.

Risk Factors:

Risk factors for emphysema include:

*Smoking. Emphysema is most likely to develop in cigarette smokers, but cigar and pipe smokers also are susceptible, and the risk for all types of smokers increases with the number of years and amount of tobacco smoked.

*Age. Although the lung damage that occurs in emphysema develops gradually, most people with tobacco-related emphysema begin to experience symptoms of the disease between the ages of 40 and 60.

*Exposure to secondhand smoke. Secondhand smoke, also known as passive or environmental tobacco smoke, is smoke that you inadvertently inhale from someone else’s cigarette, pipe or cigar. Being around secondhand smoke increases your risk of emphysema.

*Occupational exposure to fumes or dust. If you breathe fumes from certain chemicals or dust from grain, cotton, wood or mining products, you’re more likely to develop emphysema. This risk is even greater if you smoke.

*Exposure to indoor and outdoor pollution. Breathing indoor pollutants, such as fumes from heating fuel, as well as outdoor pollutants — car exhaust, for instance — increases your risk of emphysema.

*HIV infection. Smokers living with HIV are at greater risk of emphysema than are smokers who don’t have HIV infection.

*Connective tissue disorders. Some conditions that affect connective tissue — the fibers that provide the framework and support for your body — are associated with emphysema. These conditions include cutis laxa, a rare disease that causes premature aging, and Marfan syndrome, a disorder that affects many different organs, especially the heart, eyes, skeleton and lungs.

Complications:-
Emphysema can increase the severity of other chronic conditions, such as diabetes and heart failure. If you have emphysema, air pollution or a respiratory infection can lead to an acute COPD exacerbation, with extreme shortness of breath and dangerously low oxygen levels. You may need admission to an intensive care unit and temporary support from an artificial breathing machine (ventilator) until the infection clears.

Pathophysiology:-
In normal breathing, air is drawn in through the bronchi and into the alveoli, which are tiny sacs surrounded by capillaries. Alveoli absorb oxygen and then transfer it into the blood. When toxicants, such as cigarette smoke, are breathed into the lungs, the harmful particles become trapped in the alveoli, causing a localized inflammatory response. Chemicals released during the inflammatory response (e.g., elastase) can eventually cause the alveolar septum to disintegrate. This condition, known as septal rupture, leads to significant deformation of the lung architecture. These deformations result in a large decrease of alveoli surface area used for gas exchange. This results in a decreased Transfer Factor of the Lung for Carbon Monoxide (TLCO). To accommodate the decreased surface area, thoracic cage expansion (barrel chest) and diaphragm contraction (flattening) take place. Expiration increasingly depends on the thoracic cage and abdominal muscle action, particularly in the end expiratory phase. Due to decreased ventilation, the ability to exude carbon dioxide is significantly impaired. In the more serious cases, oxygen uptake is also impaired.

As the alveoli continue to break down, hyperventilation is unable to compensate for the progressively shrinking surface area, and the body is not able to maintain high enough oxygen levels in the blood. The body’s last resort is vasoconstricting appropriate vessels. This leads to pulmonary hypertension, which places increased strain on the right side of the heart, the side responsible for pumping deoxygenated blood to the lungs. The heart muscle thickens in order to pump more blood. This condition is often accompanied by the appearance of jugular venous distension. Eventually, as the heart continues to fail, it becomes larger and blood backs up in the liver.

Patients with alpha 1-antitrypsin deficiency (A1AD) are more likely to suffer from emphysema. A1AD allows inflammatory enzymes (such as elastase) to destroy the alveolar tissue. Most A1AD patients do not develop clinically significant emphysema, but smoking and severely decreased A1AT levels (10-15%) can cause emphysema at a young age. The type of emphysema caused by A1AD is known as panacinar emphysema (involving the entire acinus) as opposed to centrilobular emphysema, which is caused by smoking. Panacinar emphysema typically affects the lower lungs, while centrilobular emphysema affects the upper lungs. A1AD causes about 2% of all emphysema. Smokers with A1AD are at the greatest risk for emphysema. Mild emphysema can often develop into a severe case over a short period of time (1–2 weeks).

Pathogenesis
Severe emphysemaWhile A1AD provides some insight into the pathogenesis of the disease, hereditary A1AT deficiency only accounts for a small proportion of the disease. Studies for the better part of the past century have focused mainly upon the putative role of leukocyte elastase (also neutrophil elastase), a serine protease found in neutrophils, as a primary contributor to the connective tissue damage seen in the disease. This hypothesis, a result of the observation that neutrophil elastase is the primary substrate for A1AT, and A1AT is the primary inhibitor of neutrophil elastase, together have been known as the “protease-antiprotease” theory, implicating neutrophils as an important mediator of the disease. However, more recent studies have brought into light the possibility that one of the many other numerous proteases, especially matrix metalloproteases might be equally or more relevant than neutrophil elastase in the development of non-hereditary emphysema.

The better part of the past few decades of research into the pathogenesis of emphysema involved animal experiments where various proteases were instilled into the trachea of various species of animals. These animals developed connective tissue damage, which was taken as support for the protease-antiprotease theory. However, just because these substances can destroy connective tissue in the lung, as anyone would be able to predict, doesn’t establish causality. More recent experiments have focused on more technologically advanced approaches, such as ones involving genetic manipulation. One particular development with respect to our understanding of the disease involves the production of protease “knock-out” animals, which are genetically deficient in one or more proteases, and the assessment of whether they would be less susceptible to the development of the disease. Often individuals who are unfortunate enough to contract this disease have a very short life expectancy, often 0–3 years at most.

Prognosis and treatment

Emphysema is an irreversible degenerative condition. The most important measure to slow its progression is for the patient to stop smoking and avoid all exposure to cigarette smoke and lung irritants. Pulmonary rehabilitation can be very helpful to optimize the patient’s quality of life and teach the patient how to actively manage his or her care. Patients with emphysema and chronic bronchitis can do more for themselves than patients with any other disabling disease.

Emphysema is also treated by supporting the breathing with anticholinergics, bronchodilators, steroid medication (inhaled or oral), and supplemental oxygen as required. Treating the patient’s other conditions including gastric reflux and allergies may improve lung function. Supplemental oxygen used as prescribed (usually more than 20 hours per day) is the only non-surgical treatment which has been shown to prolong life in emphysema patients. There are lightweight portable oxygen systems which allow patients increased mobility. Patients can fly, cruise, and work while using supplemental oxygen. Other medications are being researched, and herbal organic remedies are being offered by companies.

Lung volume reduction surgery (LVRS) can improve the quality of life for certain carefully selected patients. It can be done by different methods, some of which are minimally invasive. In July 2006 a new treatment, placing tiny valves in passages leading to diseased lung areas, was announced to have good results, but 7% of patients suffered partial lung collapse. The only known “cure” for emphysema is lung transplant, but few patients are strong enough physically to survive the surgery. The combination of a patient’s age, oxygen deprivation and the side-effects of the medications used to treat emphysema cause damage to the kidneys, heart and other organs. Transplants also require the patient to take an anti-rejection drug regimen which suppresses the immune system, and so can lead to microbial infection of the patient. Patients who think they may have contracted the disease are recommended to seek medical attention as soon as possible.

A study published by the European Respiratory Journal suggests that tretinoin (an anti-acne drug commercially available as Retin-A) derived from vitamin A can reverse the effects of emphysema in mice by returning elasticity (and regenerating lung tissue through gene mediation) to the alveoli.

While vitamin A consumption is not known to be an effective treatment or prevention for the disease, this research could in the future lead to a cure. A follow-up study done in 2006 found inconclusive results (“no definitive clinical benefits”) using Vitamin A (retinoic acid) in treatment of emphysema in humans and stated that further research is needed to reach conclusions on this treatment…..click & see

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Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://en.wikipedia.org/wiki/Emphysema
http://www.mayoclinic.com/health/emphysema/DS00296

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News on Health & Science

If Tea is Hot, Wait Four Minutes

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Drinking very hot tea appears to increase the risk of oesophageal cancer, a new study has shown, prompting suggestions for a four-minute wait before swallows of freshly boiled tea.

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The study from northern Iran, the largest so far to explore tea-drinking habits and oesophageal cancer, has corroborated earlier research from India, Singapore and South America that linked this cancer to hot beverages.

Researchers from the Tehran University of Medical Sciences studied tea-drinking habits and patterns of oesophageal cancer in Golestan province where black tea is popular. They found that people who consumed very hot tea (defined as 70°C or higher) had an eight-fold higher risk of oesophageal cancer than people who drank tepid tea (65°C or lower).

They found that drinking tea at temperatures between 65°C and 69°C — defined as simply hot — was associated with twice the risk of cancer of the oesophagus. Their research will appear in the British Medical Journal on Friday.

“It’s clear hot beverages are contributing to high levels of oesophageal cancer in this population, Paul Brennan, a research team member from the International Agency for Research in Cancer in Lyons, France, told The Telegraph.

“But other factors may be associated with oesophageal cancer in other populations,” said Brennan, head of genetic epidemiology unit at the IARC. “We need to investigate different factors in different regions or populations.”

The Iranian study also showed that waiting for tea to cool lowered the risk of the cancer. People who typically drank their tea within two minutes after it was poured had a five-fold higher risk than those who waited for four minutes or longer.

Although previous studies have pointed to the potential danger of hot beverages, Iranian digestive disorder specialist Reza Malekzadeh and his colleagues are among the first to investigate the link through rigorous temperature measurements.

Malekzadeh said the significance of the new research was in the use of statistical techniques to eliminate the effects of other risk factors that could also contribute to oesophageal cancer.

But doctors assert that there is no cause for alarm. “The public health message here is that people should wait four minutes before they begin sipping from a cup of hot tea,” Malekzadeh told The Telegraph.

Eight years ago, Rup Kumar Phukan and his colleagues at the Regional Medical Research Centre, Dibrugarh, Assam, had examined dietary habits in parts of northeastern India and shown that hot beverages and spicy food were linked to oesophageal cancer.

They had suggested that the long-term consumption of exceptionally hot food or beverages could cause chronic irritation and harm the lining of the oesophagus. “But chewing tobacco and smoking are also likely to be among the contributing factors in this region,” said a scientist at the Dibrugarh centre.

The Iranian study measured tea temperatures consumed by more than 48,500 people and studied tea-drinking habits of 300 patients with oesophageal cancer and 571 healthy people, emerging as the largest study on the topic.

Speculating on mechanisms to explain the link, the researchers have pointed out that chronic inflammation by high temperatures may stimulate the release of nitric oxide and reactive oxygen species — potentially harmful biomolecules.

Doctors caution that cancer is almost always a multi-factorial disease. The risk may be lowered or increased by several factors. Low consumption of fruits and vegetables, for instance, may increase the risk of cancer.

You may click to see:->Steaming hot tea linked to cancer

Sources: The Telegraph (Kolkata, India)

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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

Pulmonary Function Tests

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Alternative Names: PFTs; Spirometry; Spirogram; Lung function tests
Definition:Pulmonary function tests are a group of tests that measure how well the lungs take in and release air and how well they move oxygen into the blood. These tests can tell your doctor what quantity of air you breathe with each breath, how efficiently you move air in and out of your lungs.
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Pulmonary Function Testing has been a major step forward in assessing the functional status of the lungs as it relates to :

1.How much air volume can be moved in and out of the lungs
2.How fast the air in the lungs can be moved in and out
3.How stiff are the lungs and chest wall – a question about compliance
4.The diffusion characteristics of the membrane through which the gas moves (determined by special tests)
5.How the lungs respond to chest physical therapy procedures

Pulmonary Function Tests are used for the following reasons :

1.Screening for the presence of obstructive and restrictive diseases

2.Evaluating the patient prior to surgery – this is especially true of patients who :
a. are older than 60-65 years of age
b. are known to have pulmonary disease
c. are obese (as in pathologically obese)
d. have a history of smoking, cough or wheezing
e. will be under anesthesia for a lengthy period of time
f. are undergoing an abdominal or a thoracic operation

Note
: A vital capacity is an important preoperative assessment tool. Significant reductions in vital capacity (less than 20 cc/Kg of ideal body weight) indicates that the patient is at a higher risk for postoperative respiratory complications. This is because vital capacity reflects the patient’s ability to take a deep breath, to cough, and to clear the airways of excess secretions.

3.Evaluating the patient’s condition for weaning from a ventilator. If the patient on a ventilator can demonstrate a vital capacity (VC) of 10 – 15 ml/Kg of body weight, it is generally thought that there is enough ventilatory reserve to permit (try) weaning and extubation.

4.Documenting the progression of pulmonary disease – restrictive or obstructive

5.Documenting the effectiveness of therapeutic intervention

How do you prepare for the test?
Do not eat a heavy meal before the test. Do not smoke for 4 – 6 hours before the test. You’ll get specific instructions if you need to stop using bronchodilators or inhaler medications. You may have to breathe in medication before the test.

No other preparation is necessary.

How the Test Will Feel ?
Since the test involves some forced breathing and rapid breathing, you may have some temporary shortness of breath or light-headedness. You breathe through a tight-fitting mouthpiece, and you’ll have nose clips.

What happens when the test is performed?
This testing is done in a special laboratory. During the test, you are instructed to breathe in and out through a tube that is connected to various machines.

A test called spirometry measures how forcefully you are able to inhale and exhale when you are trying to take as large a breath as possible. The lab technicians encourage you to give this test your best effort, because you can make the test result abnormal just by not trying hard.

A separate test to measure your lung volume (size) is done in one of two ways. One way is to have you inhale a small carefully measured amount of a specific gas (such as helium) that is not absorbed into your bloodstream. This gas mixes with the air in your lungs before you breathe it out again. The air and helium that you breathe out is tested to see how much the helium was diluted by the air in your lungs, and a calculation can reveal how much air your lungs were holding in the first place.

The other way to measure lung volume is with a test called plethysmography. In this test, you sit inside an airtight cubicle that looks like a phone booth, and you breathe in and out through a pipe in the wall. The air pressure inside the box changes with your breathing because your chest expands and contracts while you breathe. This pressure change can be measured and used to calculate the amount of air you are breathing.

Your lungs’ efficiency at delivering oxygen and other gases to your bloodstream is known as your diffusion capacity. To measure this, you breathe in a small quantity of carbon monoxide (too small a quantity to do you any harm), and the amount you breathe out is measured. Your ability to absorb carbon monoxide into the blood is representative of your ability to absorb other gases, such as oxygen.

Some patients have variations of these tests-for example, with inhaler medicines given partway through a test to see if the results improve, or with a test being done during exercise. Some patients also have their oxygen level measured in the pulmonary function lab (see “Oxygen saturation test,” page 29).

Why the Test is Performed  ?

Pulmonary function tests are done to:
*Diagnose certain types of lung disease (especially asthma, bronchitis, and emphysema)
*Find the cause of shortness of breath
*Measure whether exposure to contaminants at work affects lung function
It also can be done to:

*Assess the effect of medication
*Measure progress in disease treatment
*Spirometry measures airflow. By measuring how much air you exhale, and how quickly, spirometry can evaluate a broad range of lung diseases.

Lung volume measures the amount of air in the lungs without forcibly blowing out. Some lung diseases (such as emphysema and chronic bronchitis) can make the lungs contain too much air. Other lung diseases (such as fibrosis of the lungs and asbestosis) make the lungs scarred and smaller so that they contain too little air.

Testing the diffusion capacity (also called the DLCO) allows the doctor to estimate how well the lungs move oxygen from the air into the bloodstream.

Risk Factors:
The risk is minimal for most people. There is a small risk of collapsed lung in people with a certain type of lung disease. The test should not be given to a person who has experienced a recent heart attack, or who has certain other types of heart disease.

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

Normal Results:
Normal values are based upon your age, height, ethnicity, and sex. Normal results are expressed as a percentage. A value is usually considered abnormal if it is less than 80% of your predicted value.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean:
Abnormal results usually mean that you may have some chest or lung disease.

Considerations:
Your cooperation while performing the test is crucial in order to get accurate results. A poor seal around the mouthpiece of the spirometer can give poor results that can’t be interpreted. Do not smoke before the test.

How long is it before the result of the test is known?
Your doctor will receive a copy of your test results within a few days and can review them with you then.

Resources:
https://www.health.harvard.edu/diagnostic-tests/pulmonary-function-testing.htm
http://www2.nau.edu/~daa/lecture/pft.htm
http://www.nlm.nih.gov/medlineplus/ency/article/003853.htm

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