Neil Goldsack,
Respiratory specialist registrar,
Chest Clinic,
North Middlesex Hospital,
London
David Howell,
Medical Research Council fellow,
Richard Marshall,
Wellcome fellow
Hugh Montgomery,
Cardiology specialist registrar,
University College and Middlesex Hospital,
London

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In the third part of our emergency series, Neil Goldsack, Hugh Montgomery, Richard Marshall, and David Howell tell you how to deal with young breathless patients

Being called to the emergency department to see a breathless young patient is a common experience as a medical house officer, and quite often there may be little wrong. The problem, however, is that there are several causes of breathlessness which may prove rapidly fatal, and these can be really very tricky to spot, especially for inexperienced doctors. Often, the only sign is the breathlessness itself, with little obvious clue as to the cause. Taking a history may be the answer, but in an emergency situation (especially as the patient may be finding it hard enough to breathe let alone talk) this is often inappropriate. There are few other cases in which you have to be so vigilant and thorough.

Common causes of breathlessness in a young patient
You are called to the emergency department to see "breathless patients," not "asthma patients." So what is your differential diagnosis of a young breathless patient? It is clearly not the same as for an older breathless patient (about which we will talk at a later date).

 

Box 1: General symptoms and signs of asthma Dypsnoea Cough Wheeze

(i) Asthma is probably the commonest diagnosis. It should never be underestimated as it still kills several hundred people a year in the United Kingdom. The signs of asthma are shown in box 1. Remember that severity of wheeze is a poor guide. Both mild asthma (with minimal airway narrowing) and severe asthma (with hardly any air flow) are accompanied by little wheeze.

Asthma is the commonest diagnosis for breathlessness in a young patient . . .
Photo: CONOR CAFREY/SCIENCE PHOTO LIBRARY

In these patients bronchoconstriction narrows the airways and makes breathing out very hard. This may be compounded by thick, viscid sputum and swelling of the bronchial endothelium, all of which makes breathing very hard work and leads to a spiral of panic (asthmatic patients are often very frightened). Try to allow yourself to exhale only through a drinking straw. You won't like the experience. After a minute, you will be gasping for air. You probably won't last much longer than that. This approximates to the feeling that a person with severe asthma has.

. . . but management is straightforward in a known asthma patient.
Photo: DAMIEN LOVEGROVE/SCIENCE PHOTO LIBRARY

You will note that the problem here is with the airways and not with the lung tissue. Gas exchange really ought not to be a problem, particularly in the early stages. Because of dypsnoea, asthmatic patients breathe faster. Thus, those with asthma usually have normal concentrations of arterial oxygen unless they are very seriously ill. A very low concentration of oxygen in a patients with asthma suggests lung disease (has an infection precipitated the asthma?) or a patient who may soon die.

As asthma patients respond to dypsnoea by overbreathing, this should thus lead them to "blowing off" their CO₂. People with asthma therefore have a low concentration of CO₂ (<4.5 kPa). A normal or high concentration of CO₂ (>4.5 kPa) should be taken very seriously, as it may mean hypoventilation: the patient is tiring and may suddenly decline and die in minutes. This failure to get air in and out of the lungs is the first cause of death in patients with asthma. As the patient tires and his or her respiratory muscles fatigue, less and less air is drawn in and out. This leads to retention of CO₂, mounting acidosis, and mounting CO₂ narcosis. Typically, this downward spiral happens precipitously, much like those graphs of battery power you see in the adverts: a slow and slight decline leads to a sudden rapid and fatal failure.

 

Box 2: Reasons why people with asthma die Failure of patients to recognise the severity of their condition Failure of the doctor to recognise the severity of the patient's condition Missed secondary diagnosis (for example, pneumothorax)

The second cause of death in asthma patients is the "missed diagnosis." Asthma patients may have pneumothoraces, which you may not remember to look for. After all, you have one diagnosis, and who seeks a second? You should!

(ii) Pulmonary emboli. A huge pulmonary embolus may cause sudden breathlessness, a fall in blood pressure (the blood cannot get out of the right heart so easily), and a rise in jugular venous pressure. In these respects the signs may be similar to pericardial tamponade. The patient may or may not suffer haemoptysis or pleuritic pain. However, multiple small pulmonary emboli may cause no symptoms other than dyspnoea. If you ever see a breathless patient in whom clinical examination is normal and the chest x ray film unremarkable, think pulmonary emboli. Analysis of arterial blood may show a slight hypoxaemia on air and little more. These patients should be admitted to hospital and anticoagulated before further tests are done. A close relative of mine died of pulmonary emboli misdiagnosed as "asthma." She had not had her peak flow checked, and oximetry or blood gas analysis was not done until it was too late. Further, we all know of cases where a woman comes to casualty slightly breathless, the chest x ray film and examination are normal, and she is sent home, only to return and die the next day.

(iii) Pneumothorax. This can occur spontaneously. It is said to be more common in thin, athletic young men. A simple pneumothorax causes the lung to collapse, and the trachea may be pulled over to the side of the collapse. A tension pneumothorax may also occur in which air builds up outside the collapsed lung. Pressure on the other lung and around the heart thus rises, and the heart and trachea are pushed away from the collapsed lung. In both cases, the side with the collapse sounds as hollow as a drum.

(iv) Inhaled foreign body. Never forget this. You may remember this more readily in children. I remember seeing an elderly man with sudden breathlessness and stridor, however, in whom the cause turned out to be inhalation of his dental plate. Remember the sudden collapse over dinner, too - the so called "café coronary." I once saw a middle aged man in casualty, a colleague, whose wife had cooked him steak for his birthday. Over dinner, he suddenly became distressed and unable to breathe. He pointed repeatedly to his throat before going deep blue and passing out. The ambulance was there in minutes, and we removed the lump of steak from his vocal cords between which it was wedged. Cardiopulmonary resuscitation briefly restored a spontaneous heart beat, but he died not long afterwards.

These are the main causes. There are, of course, other causes of rapidly progressive breathlessness rather than sudden breathlessness. In this category, in addition to (v) chest infections, one should especially remember (vi) metabolic acidosis. This leads to respiratory compensation and a feeling of breathlessness. This is another good reason why every breathless patient (and in fact every poorly patient) should have their arterial gases checked. In this situation the arterial concentrations of CO₂ and bicarbonate will be low; pH may be low or normal if the respiratory compensation has been successful (the patient will overbreathe to correct the metabolic acidosis, this blows off CO₂ and pH returns to normal)

 

Box 3: Common causes of breathlessness in a young patient Asthma Pulmonary emboli Pneumothorax   Inhaled foreign body   Chest infections (for example, pneumonia)   Metabolic acidosis (for example, diabetic ketoacidosis)

Management and exam approach to the breathless patient
(1) Breathlessness is a medical emergency which may prove rapidly fatal. Go immediately to the accident and emergency department. On arrival, maintain a deliberately forced calm and confident approach. Many breathless patients feel as if they are about to die. It takes five seconds to rest a hand on their shoulder and tell them that you are going to make them better. If necessary, say, "I know that you may be feeling as if you are about to die, but you are not. I have done this lots of times. I will make you better." Especially to patients with asthma, this approach may relieve a great deal of anxiety which is making matters worse.

(2) Assess the need for immediate resuscitation (A, B, C).

(3) Call for help if necessary. In the case of an asthma patient, don't scream for the crash team. Rather, turn to the sister or staff nurse and calmly say, "I wonder whether you would mind fast-bleeping/dialling * * * for my anaesthetist colleague, and waiting outside for him to arrive?" You do want the anaesthetist there fast, but you don't want him crashing through the curtain, engendering mass hysteria. This will not improve the respiratory function of the patient.

(4) Sit the patient bolt upright and apply oxygen at the maximum concentration and at high flow rate. If you immediately recognise asthma, ask the nursing staff to set up a salbutamol nebuliser at once (5 mg should do for a start). Ensure that the nebuliser is being driven by oxygen and not air. Air will not improve the oxygenation status of the patient! Remember that struggling patients may feel as if they are suffocating, and may try repeatedly to rip the mask off. You should not allow this to happen. Position a nurse at the head of the patient to reassure the patient constantly and keep the mask on. Note, however, that this level of distress or confusion should worry you as much as the patient as it is often the mark of significant hypoxia or CO₂ retention.

(5) Establish venous access, while drawing your routine blood specimens. If there is a saturation probe in the department, ask a nurse to get it for you and apply it.

(6) Now rapidly assess the patient for the life threatening causes of breathlessness. The signs of a severe and life threatening asthma attack are shown in box 5. Equally, assess for massive pulmonary embolus and pneumothorax. You will need a chest x ray film, but never move patients for this test while they remain critically unwell. Call for a portable film to be done in the crash room. You should remain with the patient at all times.

(7) Initiate treatment at once for the appropriate cause. The treatment algorithms are well known and are found in any number of texts. The treatment of asthma is covered below.

(8) Now do a blood gas analysis. There is never an excuse for missing out this vital test. Remember, if you see a CO₂ concentration which is even at the upper end of the normal range in a patient with asthma, then the patient is in terrible trouble. Call the anaesthetist. Even if the patient isn't intubated, you must in general treat him or her in the intensive care unit.

 

Box 5: Features of a severe asthma attack   Inability to complete sentences in one breath   A respiratory rate >25 breaths/min   Peak flow <50% of best (or predicted normal)   Heart rate >110 beats/min   Low saturations (<93% on air) Features of a life threatening attack:   A peak flow <33% of best (or predicted normal)   Bradycardia, hypotension   A silent chest   Confusion, coma, exhaustion

Conclusion
If you remember this approach to a breathless patient then you can save lives very easily. We will now show how this works with asthma patients.

Management of asthma
If a patient is known to have asthma and presents with classic features then the following approach is appropriate.

(1) Go to casualty immediately.

(2) Assess the need for immediate resuscitation.

(3) Call for help if necessary.

(4) Sit the patient up and give high flow oxygen.

(5) Establish venous access.

(6) Perform a rapid assessment checking for the features in box 5.

(7) Initiate emergency treatment as below (box 6).

 

Box 6: Treatment of acute severe asthma Oxygen - see text (high flow) High doses of inhaled ß2 agonists (salbutamol 5 mg). Use oxygen as the driving gas High doses of steroids--200 mg hydrocortisone iv ± 30 mg oral prednisolone (remember that this takes up to 4 hours to be effective) If life threatening features are present: Call for help immediately Add 500 µg of ipratropium bromide (Atrovent) Repeat nebulised salbutamol every 10 minutes.   Your registrar will give intravenous aminophylline 5 mg/kg over 30 minutes with cardiac monitoring, unless the patient is already taking oral theophyllines, followed by an infusion of 0.5 mg/kg/hour. If they are already taking theophylline then they should just receive the maintenance infusion

Things you should be aware of
Avoid sedation of any type. Asthma patients will be anxious but a calm approach will alleviate some of this.

Antibiotics are only indicated in real infectious exacerbations. Erythromycin will elevate aminophylline concentrations and make the patient feel nauseous. Most infections are viral in origin. Furthermore, green sputum is usually as a result of eosinophil degranulation and not bacterial infection.

Acute physiotherapy with percussion can contribute to worsening bronchospasm.

Never consider a normal pCO₂ (4.5 kPa-5.8 kPa) as being normal in an acute asthma attack. This may mean that the patient is tiring and could rapidly deteriorate. Asthma patients should acutely have low arterial pCO₂ (<4.5kPa) because of the hyperventilation.

Conclusion
Although asthma can be a scary experience for all concerned, most patients do well with oxygen, nebulised ß₂ agonists and a calm, thoughtful approach by the junior doctor (often this is enough). It is important to be aware of your limitations as a house officer, you cannot be expected to handle everything. It is therefore important that if you are concerned in any way you seek help. This can help to prevent a sleepless night for both you and the patient.

Next month - the management of anaphylaxis.