astma

Asthma Cause, Asthma Symptoms, AsthmaTreatment

by DR.

Asthma is caused by widespread, reversible, inflammation of your lung's airways making them narrow. To grasp this asthma information we need to take a microscopic look at your lungs.

Your lungs are like an upside down tree. In fact, you can feel the trunk in the front of your neck as the Adam's apple in males. The trunk divides over and over again like branches and twigs behind your breast bone. The leaves at the branch ends are where air swirls and gases exchanges with your blood.

One important difference however, is that this 'tree' is hollow. When you breathe you suck air through the trunk, past the divisions, and ultimately to the 'leaves', or alveoli, where your blood takes up the oxygen it needs and gets rid of carbon dioxide created from burning your food for fuel.

An asthma attack is when the branches and twigs of the lungs get inflammed and narrow. That narrowing is like the difference between blowing through a pipe (1) or a straw (2). Not only is blowing through the straw noisy i.e. wheezing, but it's also more difficult i.e. you feel short of breath.

The reason your airways narrow in asthma is because of inflammation. You already know what inflammation is if you've ever been bitten by a mosquito. The bitten area reacts to the irritant mosquito saliva by swelling, itching, and reddening. A similar thing happens when you breathe in something your lungs find irritating. The lining of the airways swell, minuscule muscles in the airways contract clamping down the size of its branch, mucous making is stepped up to help wash it out, and white blood cells come to the area to destroy the substance. The end result is a narrowed, noisy airway. But unlike the mosquito bite which only affects one area of your skin, when you breathe in something it gets spread to all of your airways so your whole lung is affected. That's what makes asthma so dangerous; with all of your airways suddenly trickling air to the 'leaves' you find yourself suffocating. This is called an 'Asthma Attack'.

The irritants which cause these events can vary from colds, allergies, perfumes, and many more as we'll see.

Symptoms of an Asthma Attack:

• Wheezing. The most obvious sign of asthma is a wheezing musical sound made by narrowed air passages.
  
• Chest Tightness like a large rubber band around the chest making breathing difficult.
  
• Coughing with or without sputum.
  
• Fast Breathing. As less air reaches the lungs you breathe faster to make up the deficit.
  
• Accessory Muscle Use. As an asthma attack gets worse the airways pushing air through the narrow pipes gets difficult. Muscles of your torso pitch in to help. This is seen as tugging motion at the pit of the throat (2), and sucking in of the belly just under the breast bone (5) and between the ribs (4) with each breath.
  
• Heart palpitation. As part of your body's reaction to less air and increased work to move air, your heart starts to beat faster (3).
  
• Posture Change. Note the shoulders in our female asthmatic above. As asthma gets serious asthmatics try to sit up and support their shoulders on outstretched arms with each breath as a brace to force air into their lungs. This is a sign of a serious degree of asthma and is called a 'tripod' stance.
  
• Gasping Conversation. Another serious sign is when an asthmatic can no longer keep up a conversation with you as they gasp to finish sentences.
  
• Skin Color Change. When an asthma attack becomes severe enough that too little oxygen reaches the body, the asthmatic can faint and around their lips and fingernails looks blue - blood with too little oxygen turns from red to blue. At this point breathing may slow or stop all together and no wheeze may be heard. This is an emergency.
  

Symptoms of an Asthma Attack in young children

In young children/ babies, breathing fast, nostril flaring, and sucking in beneath the chest are easy to spot and very good signs that your child is in trouble and to be taken immediately to a medical center for care. 'Wheezing is more difficult to tell and often gurgling throat noises are mistaken for it.

The picture to your left shows an example of flaring of the nostrils in an asthma attack and is an especially good sign of breathing difficulty in young children.

Types of Asthma:

Though the end result of asthma is the same - irritated airways narrowing - the causes of this irritation that trigger off an ASTHMA ATTACK vary from person to person i.e. one person might start wheezing when in a dusty room while another only wheezes when s/he has a cold. The following are the most common types of asthma:

• Childhood Asthma. As its name suggests, this form of asthma happens as a child, and most kids 'outgrow it'. The reason why is like acne which doesn't bother you as a child but starts in your teen years - your body goes through a number of changes at this transition period making you not only look different but function differently too. Predicting if this will happen to your asthma is reasonably done by asking if your parents suffered from asthma too. If they did, and outgrew it, chances are you will too. The treatment of childhood asthma is no different to adult asthma as the causes are the same. What varies is the doses of medicines which are adjusted to body weight.
  
• Nocturnal Asthma. Nocturnal just means 'at night'. Some people wheeze mostly at night. The reason is that blood levels of epinephrine and cortisol drop at night to allow you to sleep. But these chemicals also keep your airways open. This type of asthma typically happens in the wee hours of the morning. A useful treatment for this is taking a steroid inhaler before going to bed or a long acting bronchodilator inhaler. This reduces the tendency of the airways to narrow as you sleep.. Another measure is to wash your bed sheets and pillow regularly and cover your bed with a zipped allergen guard as dust mites live on dead skin and produce an irritating stool that irritates your lungs as you sleep.
  
• Allergy Asthma. An allergy is where your body overreacts to some substance around you. This type of asthma is associated with a runny nose, itchy eyes, sneezing, and dry or productive cough. Steroid inhalers are useful in this condition by 'calming' your air passages. Antihistamine type drugs also play a role. But the best method of control is to get allergy tested and then avoiding the offending substances. If you can't, allergy desensitization treatment may be beneficial. This works by exposing your body to minute amounts of the substance and working back up to normal amounts without a reaction.
  
• Sports Asthma / Exercise Induced Asthma. After exercise some people wheeze. This is believed to be a reaction to changes in temperature of air in the lung. It can be avoided by using a bronchodilator inhaler just prior to basketball, football e.t.c. and breathing through your nose until your body feels warmed up.
  
• Cardiac Asthma. This type of asthma is unlike the other types of asthma discussed so far. It is caused by a heart that is failing to push blood around the body at a satisfactory rate. This leads to congestion of small blood vessels and they leak. In the lung this fluid irritates the airways causing them to narrow and makes a bubbling noise called 'crackles' or 'creps'. There's a tendency to cough up pink frothy sputum. While standard inhalers will help to bring the wheeze under control you'll also need diuretics like Lasix and careful blood pressure control.
  
• Cold and Flu Asthma. Some persons wheeze when they have a sore throat/ flu. This is because the offensive flu virus irritates your lung's airways which then narrow. This will respond to your inhalers and typically the virus lasts only about a week. Bacterial bronchitis infections can also lead to wheezing and in this case addition of an antibiotic is beneficial - antibiotics kill bacteria but not viruses so do not help in a viral infection.
  
• Occupational Asthma. This is a form of allergy asthma to something at your work place like smoke, dust, mold, or fumes. Sometimes it can be controlled by steroid inhalers and bronchodilators. If not, ventilating the area by opening windows or wearing a dust mask helps. If severe, you may be left with no option but to seek transfer to another area or job.
  
• COPD / Emphysema Asthma. Common in smokers, this type of asthma is caused by permanent loss of 'elastic-ness' of airways causing the floppy airways to narrow. It responds to asthma medications but symptoms tend to be daily and residual shortness of breath is common.
  

Asthma Test / Asthma Diagnosis:

A past history of other family members with asthma, sinusitis, eczema, or hay fever, and repeated wheezing which goes away after inhaling a bronchodilator is a good indicator of asthma. Occasionally when a diagnosis is unclear asthma can be showed by 'challenging' you with a special vapor such as methacholine or histamine which reproduces wheezing in an asthmatic but not a normal person.
In very young children/ babies, doctors are reluctant to label asthma on a first episode of wheezing (as there are other causes of wheezing besides asthma) especially if the child is suffering a flu at the time. The term 'reactive airway disease' is preferred until more episodes of wheezing are demonstrated related to allergens.
In an adult or child with new wheezing a chest xray may be done to rule out some of the many other non-asthmatic causes of wheezing like a child who has breathed in a peanut, pebble etc. or emphysema in an adult.

Asthma Treatment:

Home

• Asthma Prevention. This means avoiding things which make you wheeze, and using your preventative steroid inhaler everyday. If you haven't wheezed in six months then a trial off of inhalers can be made.
  
• Asthma Allergy Testing. Learning what your asthma triggers are helps you avoid them. If you come into contact with them or expect to, you can take both your preventative and bronchodilator inhaler before the wheeze has a chance to start. This can completely abort or reduce the severity of an upcoming asthma attack. Common triggers are things like dust, smoke, colds, etc. For example, if you know that cat dander makes you wheeze and you were planning to visit Aunt Mary with fifty cats,before going over you should take two puffs of both your preventative and bronchodilator inhalers.
  
• Remove Asthma Triggers at home. This means keeping pets outside if allergic to furs, removing dusty carpets and drapes or regular vacuuming if allergic to dust, asking smokers to smoke outside, keeping an eye out for mold in your bathroom and around sinks.
  

Hospital

Most hospitals have a section specialized for asthma treatment. When you get there you typically are first assessed by an attendant listening to your chest, taking your vitals and by asking you to blow into a peak flow meter (PFM).

After taking a deep breath you place your mouth over (1) a card cylinder and blow out as hard as you can which forces an arrow along a scale (2). How far you pushed it is compared to how far you should be able to for your age and height and helps to determine how bad your attack is, and when repeated after treatment, how well you have responded.

If you are a mild to moderate wheezer, you are placed on a nebulizer with oxygen to help your breathing, and a bronchodilator to open your airways. Periodically you are then reassessed by listening to your chest with a stethoscope and repeating the peak flow meter. After repeated nebulizations with unsatisfactory improvement, a chest xray is done to rule out other causes of wheezing from asthma and admission to the hospital for overnight nebulization and observation considered.
Severe asthma cases are immediately obvious. These persons come in unable to carry on a conversation, their whole body shakes as they try to breathe, they can't pause to blow on the peak flow meter or score poorly and their chest sounds are very noisy. These patients are treated much more aggressively.

If the person has exhausted to the point that they are no longer able to breathe, an endotracheal tube attached to an artificial lung is inserted through their mouth into their windpipe and the machine continues to breathe for them. In other cases nebulizations and supplemental oxygen are carried out as before (1), blood tests are done (2) one of these being from an artery in the forearm to measure the levels of gases such as oxygen (3). An IV is also set up and injectable bronchodilators such as aminophylline given (4). Oxygenation of the blood can also be determined with a finger probe (5). Periodic review is done as before, and if poorly responding admission to hospital done.

Asthma Medications

• Beta 2 Agonists/ Bronchodilators. Ventolin, Berotec, Airomir, Bronchomat, Bricanyl are examples of this class of asthma drug. They work by signaling muscles of your airways to relax and open easing air flow. They are the most powerful of the asthma drugs in an acute asthma attack. A major disadvantage with daily use is that airways can become tolerant and begin to ignore them so that you have to take more and more for the same effect. Some of the most complained of side effects from these drugs are hand tremors and racing heart - more common in the tablet and syrup forms as more reaches the rest of your body. These medicines are usually given as two inhalations three times a day as needed. In young children who cannot use inhalers, syrups are used varying from a quarter teaspoon in babies to two teaspoons in children.
  
• Anti-inflammatory Steroids. The steroids used in asthma are not the same ones bodybuilders use. These preparations work by 'sedating' your airways, making them less likely to react violently to irritants. They work slowly so are best at preventing an attack but not good at stopping a wheeze already present. And in order to work, you need to take them once every 12 hours. A big mistake many asthmatics make is waiting until they wheeze, trying them, then saying they don't work. It won't work at that point, but if you took it before you wheezed you may not have wheezed at all. Taken as an inhaler you can expect no major side effects as the doses reaching the rest of your body are miniscule. But the back of your throat may become sore and your voice hoarse. This can be prevented by sipping a little water after each inhaler use to wash the medicine off these areas. Taken as tablets or syrups for many weeks continuously can lead to a host of problems such as weight gain (bloat rather than muscle), susceptibility to infection, and slowed bone growth in children. For this reason, tablet or syrup forms of steroids are not typically used for longer than a week or two during which time very little side effects can be expected, even in children. Steroids inhalers are given usually as two puffs twice a day every day. As tablets they are given as 1 milligram per kilogram of bodyweight (including children) up to a maximum of 60 mg in adults for a week. Used for less than 10 days there is little risk of complications.
  
• Mast Cell Stabilizers. In allergies, one of the main chemical culprits for making you feel bleary eyed and stuffy is Histamine. Medicines like Intal, Cromolyn, and Singulair stop the cells that release this chemical inappropriately from being able to do so.
  
• Antihistamines. These drugs are your cold and flu relievers. They work by blocking the histamine signal that causes sneezing, runny nose, cough and itching. As many asthma attacks are closely related to allergies to dust etc. these medicines are commonly used with steroids and bronchodilators to bring an attack under control. They are usually given as syrups in hospitals but as tablets in the community. Examples are Actifed, Reactine, Histal, Claritine, Aerius and Claritine. The main complaint with these drugs is daytime sleepiness.
  
• Coffee and Tea for Asthma. The active ingredient which makes you feel good in tea is called 'Theophylline' and it's chemically related to the Caffeine in coffee. Both chemicals have a positive effect on dilating air passages in asthma. In severe asthmatics theophylline can be prescribed as a tablet preparation e.g. Theodur or given by IV in hospital. They are effective but bundled with many side effects: anxiety, tremor, difficulty sleeping, and loss of appetite. They are used sparingly in persons not given enough relief with traditional inhalers and as evening doses in persons who wake at night from asthma.
  

Asthma Puffer Metered Dose Inhalers

This section will familiarize you with asthma inhalers.
The purpose of inhalers is to send a chemical message to narrowed airways to reopen. They can be packaged as a liquid or powder. Liquid inhalers use compressed gas to blow them as an aerosol into your lungs. Dry powder inhalers use your breath to pull them into your lungs as a medicated dust cloud.

	The design to your left is a gas propelled asthma inhaler. The gas and medicine are stored in the canister (1) which is held in your hand by the housing (2). After removing the dust cap, and shaking the canister, it is pressed down opening a valve at its base and releasing a jet of air and medicine (3) as you inhale.
	This is a dry powder asthma inhaler. It does not need to be shaken. Its base is twisted (1) to load your next dose, the shaft is placed into your mouth (2) and the medicine sucked up as you breathe in.

One bad thing about the dry powder inhaler is that it's difficult to tell if you've actually breathed in anything - there's nothing to taste, feel, or smell while you can immediately tell if a gas inhaler is empty: it feels light, if you spray it in the air you see no spray, and if you put the older canisters in a bowl of water it will float like a log and sink when full.

Conversely, gas inhalers need to be used with special care to effectively get the medicine into your lungs or it ends up at the back of your throat. The inhaler should not be placed into the mouth.
It is to be placed a few finger breaths away from your open mouth and triggered after shaking while breathing deeply in. Then hold your breath 3 s . Repeat.
Using Asthma Spacers Children can't coordinate the above. Asthma spacers (1) work by blowing asthma medication into a confined space over the child's face. As your child breathes, it sucks in the medicated vapor. This can't be done with the dry powder inhaler. Spacers can also be used for adults.

There are three other methods of getting asthma medication to your lungs: tablets; syrups; and injections. The first two make use of your digestion passing the active ingredients into the blood through the stomach, which then carries it to the lungs i.e. it's slower than an inhaler but the drug will linger around the lung for a longer time. Injections are used in severe asthma at hospitals to deliver high medication concentrations quickly to the lungs. The big disadvantage of all these methods is that instead of medication reaching only the lungs as with inhalers, the entire body is exposed making side effects more likely. Syrups have a special place in very young children - when inhalers are difficult to use - and in adults who don't like, or can't swallow tablets but need more than an inhaler to control their asthma.

Asthma Nebulizers

One final note is the asthma nebulizer. This device uses an air pump attached to a mask filled with liquid bronchodilator and/or steroid and held over your face while you breathe. It delivers a continuous medicated vapor to your lungs and is very effective at home for moderate to severe asthmatics in which inhalers alone are not enough. Owning a machine is costly but a worthwhile investment and many pharmacies rent them cheaply.