Makindo Medical Notes.com

Possible precipitants of an acute asthma attack

• Indoor allergens (house dust mites in bedding, carpets and stuffed furniture, pollution and pet dander)
• Outdoor allergens (such as pollens and moulds);
• Tobacco smoke and chemical irritants in the workplace.
• Cold air, extreme emotional arousal such as anger or fear
• Physical exercise.
• Medications: aspirin, NSAIDS, beta-blockers
• Urbanization has also been associated with an increase in asthma, however the exact nature of this relationship is unclear.
• Viral and other infections

Acute asthma is the progressive worsening of asthma symptoms, including breathlessness, wheeze, cough, and chest tightness. An acute exacerbation is marked by a reduction in baseline objective measures of pulmonary function, such as peak expiratory flow rate and FEV1. Most asthma attacks severe enough to require hospitalisation develop relatively slowly over a period of six hours or more.

220 divided by 560 x 100 = 37.5% and so he has Acute Severe Asthma

Moderate asthma PEFR 50-75%

Acute Severe PEFR 33-50%

Life threatening PEFR < 33%

He should initially receive 15L/min and so high flow oxygen through a non-rebreather mask to achieve saturations 94-98%. You should not delay starting oxygen whilst you assess saturations in a young asthmatic patient with what seems to be a severe attack.

You assess him and he is not cyanosed and making good efforts. His BP is 120/80 mmHg. He is not confused. The Oxygen level can be reduced downwards to the level that keeps his SaO₂ 94-98%. A cardiac monitor and ongoing saturation monitor are attached. A venous cannula is inserted. He refuses an ABG.

The aim of treatment is to relieve airflow obstruction and prevent future relapses. Early treatment is most advantageous.

It would be wise to commence the beta-agonist Salbutamol via nebulisers which can be given back-to-back initially.

In this situation this is often given with the anticholinergic Ipratropium Bromide.

• 2.5-5mg Salbutamol at 15-30 min intervals
• 0.5mg Ipratropium bromide stat and then 4-6 hourly
  

Absolutely not, his nebulisers should be connected to and driven by high flow oxygen to maintain saturations of 94-98%.

The exception is the patient with advanced COPD which is very different picture nebulisers often connected to room air.

He should be commenced on Systemic steroids. This is a key medication. In this situation, this is most easily done by giving Hydrocortisone 200 mg slow IV. Give it slowly as it can cause some quite extreme tingling!

The patient may also be given Oral Steroids e.g. Prednisolone 30-40 mg stat and a course initiated. The patient may be too tired or distracted to drink and some IV fluids can be helpful.

The porters come to take the patient on oxygen and drip to the Radiology department next door. It is vitally important that asthmatic patients with moderate or severe asthma are accompanied at all times. Asthmatics can suddenly get better and suddenly get worse and sustain a cardiac/respiratory arrest.

A CXR rarely alters management in acute severe asthma. A portable CXR in resus is enough and is only needed where there are concerns of failure to respond to treatment, clinical deterioration and need for ITU, suspected pneumothorax, surgical emphysema, suspected consolidation or other lung pathology. In practice, almost all admitted patients will get a CXR.

It is hard work for the asthmatic patient with tight airways and airflow obstruction to maintain that effort. The patient can become fatigued with tiring respiratory muscles.

It would be reasonable to give IV Magnesium get senior EM help and to talk to the Critical care outreach team and ITU Registrar or Consultant.

You prescribe Magnesium sulphate 2g IV infusion over 20 minutes

Others may prefer then giving either IV Aminophylline and if the patient is not taking it orally then a loading dose is given.

Other choices are IV Salbutamol infusions. This can cause a lactic acidosis. All of these agents can cause arrhythmias.

It is at this point one should be considering HDU and need for intubation and ventilation if deteriorates.

• Deteriorating PEFR but often difficult to do as too breathless
• Persisting or worsening hypoxia: You titrated down the FI)2 and now you need to increase it again to get sats 94-98%
• Hypercapnia - suggests hypoventilating and tiring
• Fall in pH in ABG
• Exhaustion
• Reduced GCS

In asthma with a breathless patient the PCO₂ should in fact be low. This suggests tiring and impending respiratory difficulties. Get ITU help. Ensure high flow oxygen and Sats 94-98%.

Consider an additional agent such as IV Salbutamol whilst help arrives. A MET call would be appropriate to get help.

Patients may have an infection such as pneumonia or develop a Hospital or Ventilator-associated pneumonia if he goes to ITU

Lobar collapse may be due to mucus plugging. May require Bronchoscopy

Pneumothorax may be seen and if present on CXR will need chest drain insertion

Respiratory failure - Oxygen < 8KPA may be seen and these patients need high flow oxygen and bronchodilators, steroids, magnesium and urgent ITU review for Intubation

Cardiac arrest due to hypoxia, arrhythmias, fatigue

Side effects from treatment: hypokalaemia, arrhythmias

Any of these make the diagnosis of acute severe asthma

• PEFR 33–50% best or predicted
• Respiratory rate of at least 25/min
• Pulse rate of at least 110/min
• Inability to complete sentences in one breath
• Oxygen saturation of at least 92%.
• Exhaustion
• Arrhythmias
• Cyanosis
• Silent chest
• Poor respiratory effort
• PAO₂ < 8KPA
• Normal PCO₂ 4.6-6 Kpa

• PEFR < 33% best or predicted
• PaCO₂ > 6 Kpa