A 65 year old woman with chronic airways disease presents with acute respiratory failure.
Outline how you would establish the precipitating cause of her acute respiratory failure.
• Duration of respiratory failure – is it acute deterioration on a normal functional background or acute on chronic?;
• setting (in community or hospital); any trauma/surgery/anaesthesia/procedure related;
• respiratory depressant drug use;
• fever/sweats/cough/sputum production;
• history of others developing respiratory infection or epidemics;
• recent travel especially overseas;
• history of DVT/PE, malignancy, cigarette smoking,
• recent chest pain or symptoms of heart failure;
• medication use related to potential anaphylaxis or upper airway oedema;
• is there a septic or SIRS process generating a metabolic acidosis that this patient’s respiratory system cannot deal with?
• Level of consciousness
• presence of stridor or wheeze
• cyanosis indicative of oxygenation failure
• barrel chested / pursed lips / nasal flaring indicating hyperinflation
• tracheal deviation indicating severe collapse or PTX;
• subcutaneous emphysema;
• flap indicative of hypercapnia;
• ?new heart murmur or other signs indicative of heart failure;
• signs of non-respiratory sepsis (eg abdomen) or SIRS generating a severe metabolic acidosis;
• focal limb oedema. Investigation: consider
• ABG – assess oxygenation/ventilation/acid-base status (metabolic and respiratory)
• Spirometry – obstructive or restrictive airflow pattern
• Hb – is there polycythaemia due to chronic severe disease or severe anaemia contributing decreased O2 delivery?
• ECG – is there RHF or myocardial ischaemia?
• CXR – collapse / PTX / pneumonia / heart size / pulmonary oedema / hyperinflation /effusion / trauma / malignancy / airway compression.
• Sophisticated investigations like thoracic CT are not necessarily appropriate in the acute setting unless suspecting a PE.
• Possible use of V/Q scanning.
This question is painfully broad. It requires the candidate to think carefully about the diagnostic pathway in respiratory failure. A structured response is always better. This one has been derived from the excellent UpToDate topic, "Evaluation of the adult with dyspnea in the emergency department".
|Endocrine and metabolic||
|Haematological and oncological||
|Infectious and immunological||
|Potentially relevant investigations||