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. 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,...
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