Asthma: Acute Exacerbations

by Jeremy Brown, PhD

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    00:01 in very selected patients. Acute exacerbations of asthma. This is a common cause of medical admissions or presentation to the action to merge and then being discharged back home again and most doctors need to know how to deal with this. The patient usually knows they have asthma. The attack itself often comes on over minutes or a few hours. But it’s usually preceded by a few days where the patient has a deteriorating control of their asthma with increased breathlessness, increased cough, increased nocturnal symptoms, and increased use of their beta2 agonist rescued medication.

    00:39 So this is important because that preceding few days with correct education of the patient and a treatment plan allows you to pre-empt the potential exacerbation in many patients.

    00:51 And if that deterioration and control is treated effectively by an increased use of the inhalers, increased corticosteroids, perhaps a quart of oral prednisolone, then many exacerbations could be prevented. And the patient may not need to end up in hospital.

    01:06 There’s often actual trigger for this. The patient had a cold or flu recently. They’ve gone through particular form of stress. And occasionally, acute attacks might occur because of smoke exposure. In the old days when people used to smoking pubs, occasionally, asthma attacks would occur because an asthmatic has gone into particularly smoky pub, for example.

    01:26 And we have these situations occur occasionally during summer when there’s been a thunderstorm and the release of fungal spores actually precipitates a large number of acute exacerbations of asthma over the next few hours. The patient presents with basically exaggerated version of the normal symptoms of asthma which is breathlessness, wheeze, and cough, with breathlessness being dominant and the main reason why they’re coming to a hospital.

    01:51 And when you listen to their chest, there will be a polyphonic expiratory wheeze throughout both lungs. And importantly, their peak flow, the measure of the airways obstruction, when you repeat it in casualty, will be lower than it should be normally.

    02:04 So, it’s very important for the patient to be able to tell you what their normal peak flow is when they are well so you can compare during an exacerbation to give you a feel for how severe the exacerbation is. In normal exacerbation, they will be more breathless.

    02:21 They’ll be wheezy, and there will be a fall in peak flow. A more severe exacerbation, then the patient starts to becoming so breathless that they can’t talk in complete sentences.

    02:31 The pulse rate will be very high above 110. The respiratory rate will be greater than 25. If you measure their blood pressure, there will be a fall in systolic blood pressure and inspiration that’s called pulsus paradoxcus. And the peak flow, when you measure it, it would be less than 50% predicted or their previous best result.

    02:51 These are indicators of severe disease which is going to require quite an intense treatment.

    02:57 Now, the signs of very severe disease, in fact, when the pulse rate starts to go down or the breathing rate starts to go down, then you should really worry because the patient is close to respiratory arrest. The same with the blood pressure that starts to fall that is clearly showing severe physiological upset. And if the patient’s conscious level is fluctuating and drowsy, then again, that’s a very bad sign indeed that the patient has a very severe disease. When you listen to chest in severe asthma, you may not hear the wheeze. There’s so little air moving on inspiration that the breath sounds will be very quiet. And the peak flow unrecordable will considerably be low than normal. They are less than 30% predicted. And when the patient develops central cyanosis due to hypoxia or a CO2 that starts to increase, then you know the patient has bad disease. Normally, carbon dioxide level, actually falls in mildest attacks of acute asthma because the hyperventilation leads to a degree of respiratory alkalosis.

    04:05 As the attack becomes more severe, the carbon dioxide actually becomes normal. So a normal PaCO2 in somebody presenting an asthma attack is actually a bad sign. It suggests they have a very severe level of asthma attack. And then when it starts to rise, then that really does show that they’ve got severe hyperventilation going on and they are in danger of a respiratory arrest. The treatment for asthma exacerbations is relatively straightforward; high flow oxygen, nebulized bronchodilators, salbutamol and ipratropium, an immediate stat dose of intravenous high-dose corticosteroids. And then if there’s no immediate response to a nebulised bronchodilators with rapid improvements in peak flow in the patient’s condition, then you may want to consider intravenous bronchodilators. The commonest being used nowadays is magnesium and/or aminophylline, a theophylline based bronchodilator.

    05:02 Once you’re doing this, you need to organize a chest X-ray, and the chest X-ray is important not because it’s going to be abnormal in somebody with asthma but to make sure that when you’re examining the patient, you haven’t missed something like a pneumothorax or a lober collapse which will contribute towards why the patient is feeling so bad. And clearly, a pneumothorax can be corrected very rapidly by insertion of a chest drain. It’s a very important thing not to miss. You’ll also measure the peak flow and get the blood gases. So you have the levels available to monitor their improvements, or you have the levels available to identify the severity of the diseases that we discussed a slide or two ago. And also, so that you can monitor if the patient is improving with the medication that you’re giving.

    05:47 And you monitor using oxygen saturations, the pulse rate, the respiratory rate, and repeating the peak flow. And if the patient is not responding and it’s doing badly with very low peak flows, low conscious level, despite all that medication, then there should be no delay in intubation and mechanical ventilation of the patient to take over the work of breathing for them, because otherwise, there is a risk of cardiac respiratory arrest, and then there’s a very high chance the patient would die. And there are over a thousand deaths each year in the U.K. due to asthma, and a lot of those have been shown to be avoidable if more effective treatment was initiated, or more importantly, the exacerbation was pre-empted by effective treatment a few days before they present to the hospital. So asthma can get

    About the Lecture

    The lecture Asthma: Acute Exacerbations by Jeremy Brown, PhD is from the course Airway Diseases.

    Author of lecture Asthma: Acute Exacerbations

     Jeremy Brown, PhD

    Jeremy Brown, PhD

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