The differential indications will be found in the materia medica for each of the remedies. A generalizationcan be made based upon Inula having stimulating expectorant effects whilst Verbascum is more of a relaxing expectorant. Tussilago is the best of the three for children.

Maintenance of Respiratory Health
Much of the disease commonly associated with both upper and lower respiratory systems is preventable. Air quality is the key. By avoiding particulate air pollution and chemical irritants such as sulphur dioxide, many of the disabling conditions of the lungs would not develop. Thus smoking, both active and passive, as well as urban and industrial pollution are important issues for the therapist and the patient. This need not be developed here, but anyone concerned about the health of their lungs should become active in Friends of the Earth!

Patterns of Disease
There are five primary symptoms in this system, and whilst each may be treated effectively with herbs, they must be seen as signposts to the underlying pathology. These symptoms are

• Cough, defined as a sudden explosive expiatory maneuver that tends to clear material from the airways. This will be caused by irritation somewhere within the respiratory tract, and is discussed below.
  
• Dyspnoea, or breathlessness of some degree, is discussed under asthma. It is defined as an unpleasant sensation of difficulty in breathing, and has a range of clinical manifestations

1. Physiological Dyspnoea: This is the commonest type of breathlessness and is associated with physical exertion. Ventilation is increased and maintained through an augmented respiratory stimulus provided by metabolic and other factors. Dyspnoea is common during acute hypoxia (oxygen lack), such as at high altitudes, where the increased respiratory stimulus is in part the effect of arterial hypoxia on the carotid bodies. These are receptor sites in the carotid arteries that monitor the concentration of gases in the blood.
   
2. Pulmonary: The two major causes here are a restrictive defect which lessens the lungs or chest wall from efficient movement (e.g. pulmonary fibrosis), or an obstructive defect which increases resistance of flow in the airways (e.g. asthma)
   
3. Cardiac: In the early stages of heart failure the availability of oxygen to the tissues of the body via the blood fails to keep pace with increased metabolic need during exercise. As a result respiration is increased because of tissue and cerebral acidosis, causing hyper-ventilation. In later stages the lungs are congested are congested and edematous, the capacity of the stiff lungs is reduced and the effort needed to breath is increased. Cardiac asthma is a state of acute respiratory insufficiency often very similar to other types of asthma but it originates from left ventricular failure. Orthopnea, or breathing discomfort that occurs while laying flat, is usually symptomatic of a cardiovascular basis to dyspnoea.
   
4. Circulatory (air hunger): is often a medical emergency due to lack of oxygen following blood hemorrhage. It may occasionally be associated with anemia.
   
5. Chemical: related to uremia or diabetic acidosis.
   
6. Central: connected to cerebral lesions.
   
7. Psychogenic: Know as `hysterical over breathing'.

• Chest pain, is a common presenting symptom and calls for skilled differential diagnosis. Cardiovascular causes must be distinguished from the range of pulmonary problems that might be implicated.
  
• Wheeze, describes an awareness of noises associated with breathing.
  
• Hemoptysis, or the coughing up of blood, is a sign that skilled diagnosis is called for.