Differential Diagnosis of Acute Asthma
| Disorder | Comment |
|---|
| Acute exacerbation of chronic obstructive pulmonary disease | A relevant smoking history will assist in differentiating between an exacerbation of asthma and an exacerbation of COPD. |
| Upper airway obstruction | These individuals may have a more chronic course; however, they may present acutely, for example inhalation of a foreign body or acute anaphylaxis. The key in determining the differences will be in the history. In a more chronic setting, flow-volume loops are very helpful. |
| Vocal cord dysfunction | Acutely VCD can present in a similar manner to acute asthma. It can be difficult to differentiate VCD from asthma as some patients with VCD may also have asthma and respond to acute treatment. Arterial blood gases will be normal in VCD and often patients with VCD find inspiration more difficult than expiration. |
| Anaphylaxis | Individuals with anaphylaxis can have wheeze and allergy is common in those with asthma. The key to determining the difference will be the history, that is, an acute trigger in those with analphylaxis and other signs such as an urticarial rash and angioedema. Treatment for both will include bronchodilators and steroids. Individuals with anaphylaxis will also require adrenaline. |
| In patients presenting with atypical histories, signs or symptoms, other important diagnoses to consider are: |
| Disorder | Comment |
|---|
| Gastro-oesophageal reflux | This often presents more chronically as a cough; however, gastro-oesophageal reflux can exacerbate symptoms of asthma. |
| Cystic fibrosis | This is an inherited disorder resulting in deficiency of the cystic fibrosis transmembrane receptor. These individuals often have bronchiectasis and can also develop cystic fibrosis related asthma and can therefore present with wheeze and cough. Often these patients will also have thick sputum that can be difficult to expectorate, this would be an unusual finding in those with asthma that is not related to CF. |
| Heart failure | Heart failure can also present with breathlessness and wheeze. The history is key, the symptoms are often progressive over a period of time, heart failure tends to occur in the older population and those with a significant history of cardiac disease. These individuals will respond well to diuresis. |
| Foreign body aspiration | There will often be a very acute history involving a feeling of ‘choking’ whilst having eaten something. If the foreign body is lodged within the upper airway and there is complete obstruction, respiratory arrest may occur. Partial obstruction of the upper airway may cause stridor. If the foreign body passes below the carina a more chronic course of symptoms will occur, such as cough, wheeze and recurrent infection. |
| Eosinophillic lung disease | Eosinophilic pneumonias are a group of disorders characterized by peripheral blood eosinophilia and evidence of eosinophilia within the airways. Causes of eosinophilic pneumonia include: helminth and tropical infections; medication such as NSAIDs and antibiotics; Churg-Strauss syndrome (eosinophilic granulomatosis with polyangitis); ABPA and idiopathic eosinophilic pneumonias. The history and searching for a trigger, for example medication or travel to endemic areas will assist in the diagnosis. These individuals tend to present with a chronic course of symptoms and blood tests, and often bronchoscopy/lung biopsy may be necessary to clinch the diagnosis. Many of these conditions will respond to steroid treatment |
| Carcinoid tumour | These are neuroendocrine tumours that can occur in the digestive tract and sometimes the lung. Carcinoid syndrome encompasses the following signs and symptoms: flushing, diarrhoea, telangiectasia, hepatomegaly, heart disease and wheeze caused by bronchospasm. These additional signs and symptoms should alert a clinician to a diagnosis other than lone asthma. Diagnosis will be made through imaging and hormone profile; a bronchoscopy may be necessary to determine if there is carcinoid tumour present in the airway. |
| Interstitial lung disease | ILD often causes cough and breathlessness; wheeze can occur although it is more unusual. Presentation of ILD is often later in life and examination will elicit other findings such as crackles and evidence of an underlying connective tissue disorder. |
| Churg-Strauss syndrome | Often now called eosinophilic granulomatosis with polyangitis, CSS is a vasculitis of small to medium-sized vessels that is characterized by asthma, peripheral eosinophilia, pulmonary infiltrates, polyneuropathy and allergic rhinitis. The ANCA (predominantly p-ANCA) will often be positive in these individuals. Churg-Strauss syndrome is a multisystem disorder and therefore the presence of other system involvement should suggest a diagnosis of CSS rather than asthma alone. |