Pathophysiology of Asthma – Essay
Exam Case Scenario Pathophysiology of Asthma Asthma is a chronic lung disease characterized by episodes in which the bronchioles constrict due to oversensitivity. In asthma, the airways (bronchioles) constrict making it difficult to get air in or out of the lungs. Breathlessness is the main symptom. The bronchi and bronchioles become inflamed and constricted. Asthmatics usually react to triggers. Triggers are substances and situations that would not normally trouble an asthma free person. Asthma is either extrinsic or intrinsic.
Extrinsic is when the inflammation in the airway is a result of hypersensitivity reactions associated with allergy (food or pollen). Intrinsic asthma is linked to hyper responsive reactions to other forms of stimuli like infection. Or they can have a combination of both. The bronchi and bronchioles contain smooth muscle and are lined with mucus-secreting glands (goblet cells) and ciliated cells (push the mucus towards the throat). Next to the airways blood supply there are lots of mast cells.
Once they become stimulated the mast cells release a number of cytokines (chemical messengers), which cause physiological changes to the lining of the bronchi and bronchioles. Three such protein cytokines are histamine, kinins and prostaglandins (leukotrienes) which cause smooth muscle contraction, increased mucus production and capillary permeability. The airways soon narrow and become flooded with mucus and fluid leaking from the blood vessels. Airflow becomes obstructed resulting in a wheeze.
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As the airways become obstructed the patient will become fatigue and their respiratory effort becomes weak and inadequate causing hypoxaemia and hypercapnia. Airway – Assess the airway. If the patient is talking this means they have a patent (clear) airway therefore they are breathing and have brain perfusion. Look and listen for signs of airway obstruction. A partial obstruction is often noisy, and in complete airway obstruction there are no breath sounds. Maintain and monitor the airway and report any changes. If the airway does become compromised suction or sit the patient up.
If the patient’s level of conscious has altered carry out the head tilt and chin lift. If you have had airway management training insert an oropharyngeal or nasopharyngeal airway. Breathing – Count the respiratory rate over 1 minute. The normal range is between 14 – 20 resps per min. A high respiratory rate (tachypnoea) indicates that the patient is unwell and that the patient is struggling to breath. Evaluate the rate, rhythm and depth of the breathing. Make sure the patient’s chest is moving equally on both sides (symmetrical), if not this could indicate a pneumothorax.
Observe to see if the patient is using his or hers accessory muscle to breath (if the patient feels they are having difficulty getting enough oxygen, their body begins to clench these muscles every time they breath in an attempt to acquire more air) as this could be a sign of respiratory distress. Monitor the peripheral oxygen saturation (SpO2) using a pulse oximeter. A low SpO2 reading can indicate that the patient is in respiratory distress. Give oxygen as prescribed using a venturi mask. Check the colour of the patient’s lips and tongue, central cyanosis indicates lack of oxygen to the skin.
Listen to the patients breathing, breath sounds are normally quite. Any abnormal sounds such as wheezing suggest that there could be a fluid build up in the lungs. Circulation – Palpate the radial pulse, assessing for the rate, quality and rhythm. The normal range for this is between 60-100 beats per min. An elevated pulse rate can be due to the patient being in pain, anxiety or a sign of an infection. Take the patient’s blood pressure and insure that this is within the normal range (100/60 – 140/90 mmHg). Look at the patient’s colour in their hands and fingers, and check if the patient feels warm or cool.
Measure the capillary refill time (CRT). Apply pressure to a fingertip, held at a level of the heart, for 5 seconds so that the skin becomes blanched and then release. Measure how long it takes for the colour to return. The normal capillary refill time is less than 2 seconds, anything over indicates reduced skin perfusion. Ask the patient if they have any chest pain, if so begin a ECG monitoring. Take the patients temperature. The normal range for this is 36-37. 5 degrees Celsius. A high temperature can be a sign of infection.
The doctor may also like to re-take the patient’s Arterial Blood Gas (ABG) because previous results showed respiratory acidosis. Disability – Assessment of disability involves evaluating the patient’s central nervous system function. Assess the patient’s level of consciousness using the AVPU scale. Talk to the patient if they are alert and talking they are classified as A. If the patient is not fully awake establish whether they respond to the sound of your voice (opening their eyes, making any sounds) if they do they are classified as V.
If the patient does not respond to voice administer a painful stimulus (gently rubbing the sternum bone). If they respond they are a P on the AVPU scale. And finally if they do not respond to any of the above they are a U, you should then move onto the more detailed Glasgow Coma Scale (GCS). You will assess the patient’s pupils (eyes) and motor responses (arms and legs) among other things to give the patient a score out of 15 (15 being the highest). A GCS of fewer than 8 is a medical emergency and you would then have to go back to assessing the patient’s airway.
Exposure – It may be necessary to undress the patient, taking care to maintain their dignity at all time, in order to undertake a thorough head to toe check, looking out for any signs of DVT, sores or rashes. Always gain consent before any procedure so always keep the patient informed of what it is you are doing. Reassure the patient to reduce anxiety and try to make them as comfortable as possible. Ask the patient if they are in any pain and get the doctor to prescribe an appropriate analgesia.
If the doctor has prescribed the patient antibiotics ensure that blood cultures are done prior to giving the patient their antibiotics, this will give an accurate result from the lab. Give the patient any other due medication making sure to ask if they have any known allergies. Regular peak flows should be done on the patient pre and post medication, this will tell us if the medication being given to the patient is working or not. Spirometry test will show how well the patient breathes in and out and it is also used to monitor the severity of some lung conditions, and their response to treatment.
Take a mid stream urine sample from the patient and dip stick, depending on the results send down to the lab. The doctor might also want a chest x ray from the patient. Complete all the relevant risk assessment such as the Waterlow score (patients are classified according to their risk of developing a pressure sore), the MUST score (screening tool to identify adults who are malnourished or at risk of malnutrition), falls risk assessment (what the chances are of the patient falling) and Moving and Handling (if the nurses are required to use any equipment on the patient).
And the patient’s hygiene needs must be assessed and if necessary an appropriate nursing plan must be put into place. Start the patient on a fluid chart, making sure to write down any IV fluids that they have. The cannula site must be checked and the patient must have a VIP score to make sure there are no signs of phlebitis. A sputum sample must also be collected and sent to the lab. Carry out a blood glucose test to ensure that the patient’s blood glucose levels are within normal ranges (4-7 mmol/l). A referral should be made to the respiratory nurse who will provide support to patients who suffer from chronic respiratory diseases.
Give patient advice to avoid any triggers that they are aware of, advice on medication and if relevant give advice on smoking cessation. Symbicort combination inhaler containing budesonide and formoterol Inhalers are used to deliver drugs to relieve or prevent the symptoms of asthma. Budesonide – Corticosteroid drug used in an inhaler to prevent attacks of asthma but will not stop an existing attack. Budesonide is used by patients whose asthma is not controlled by bronchodilators alone. Budesonide controls symptoms by reducing inflammation in the swollen inner layers of the airways.
By suppressing airway inflammation they reduce the swelling (oedema) inside the bronchioles. There are fewer side effects to the drug when inhaled because it is absorbed by the body in much smaller quantities than when it is taken orally. Budesonide is usually taken twice a day and normally lasts between 12 to 24 hours. Asthma prevention is the condition for which prolonged use may be required. There may be a small risk of glaucoma, cataracts, and effects on bone with high doses inhaled for a prolonged period.
Side effects include a cough, sore throat Formoterol – Bronchodilator’s are prescribed to widen the bronchioles and improve breathing. Bronchodilator drugs act by relaxing the muscles surrounding the bronchioles. Formoterol is from the sympathomimetic group which is mainly used for the rapid relief of breathlessness. Sympathomimetic drugs interfere with nerve signals passed to the muscle through the autonomic nervous system. Because sympathomimetic drugs stimulate a branch of the autonomic nervous system that controls the heart rate, the patient may sometimes feel palpitations or trembling.
People with heart problems, high blood pressure or an overactive thyroid gland will have to be extra cautious. Salbutamol inhaler/nebuliser Salbutamol is a sympathomimetic bronchodilator that relaxes the muscle surrounding the bronchioles. It is used to relieve symptoms of asthma. Inhalation is considered more effective because the drug is delivered directly to the bronchioles, thus giving rapid relief, allowing smaller doses and causing fewer side effects. Compared to some similar drugs it has little stimulant effect on the heart rate and blood pressure, making it safer for people with heart problems.
Salbutamol is usually taken 1-2 inhalations 3-4 times a day, usually starts working within 5-15 min and can last up to 6 hours. The most common side effect of salbutamol is fine tremor of the hands also anxiety, tension and restlessness may occur. Prednisolone A powerful corticosteroid used to reduce inflammation and suppress allergic reactions and immune system activity. Corticosteroid drugs reduce inflammation by blocking the action of chemicals called prostaglandins that are responsible for triggering the inflammatory response.
These drugs also temporarily depress the immune system by reducing the activity of certain types of white blood cell. Because corticosteroids suppress the immune system, they increase susceptibility to infection. They also suppress symptoms of infectious disease. IV Hydrocortisone Hydrocortisone is a corticosteroid used in the treatment of a variety of allergic and inflammatory conditions. Hydrocortisone is chemically identical to the hormone cortisol, which is produced by the adrenal glands. Prolonged high dosage may cause diabetes, glaucoma, fragile bones and thin skin.
Aminophylline Aminophylline is a bronchodilator used to treat bronchospasm (constriction of the air passages) in patients suffering from asthma. It can be used to treat acute attacks. Slow-release formulations of the drugs produce beneficial effects lasting for up to 12 hours, they are also useful taken at night to prevent night-time asthma and early morning wheezing. Side effects are headaches and nausea. Smoking and alcohol increase excretion of xanthines from the body, reducing their effects.
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