1860: Dr. Salter's asthma causes and triggers

Dr. Henry Hyde Salter must have spent many sleepless nights thinking about what might have caused the disease that often took his breath away, and also inspired his professional expertise, and likewise inspired him to write a book.

Based on his own experience, and by questioning his patients, he concluded that the following are the general causes of the affection called asthma.

1.  Intrinsic Causes: Affecting the air tubes primarily and directly, or applied to the air tubes themselves.  Things that affect the lungs primarily. (1, page 71-74)

• Things Inhaled:
• Particular kinds of air: , i.e. country air, city air, thundery weather, fog, cold air, change of weather, change of wind, close air (crowded room, enclosed room, church, railway, carriage)
• Chemical and mechanical irritants:   These are things that naturally offend the air passages and produce irritation of the bronchial mucus membrane as secures their immediate expulsion by cough   These tend to throw the air passages into a violent motion and vibration, thus causing a spasm.  Examples include coughing and sneezing.  Irritants that may cause this are dust, smoke, pungent fumes, mephitic (foul smelling) vapors, cold air, hay season, grass season, bright hot dusty sunshine.  The most likely to cause a spasm is smoke and dust. Cats and rabbits seem to trigger asthma in many, so they'll have to avoid cats and rabbits.  
• Animal and vegetable emanations: Irritants here would include hay, ipecacuan, grass, certain animals, etc. The best remedy for this type is removal of the asthmatic from the exciting cause, or removing the exciting cause from the asthmatic.  For example, a hay fever sufferer may benefit from a sea voyage, or a person with ipececuan asthma not opening a can of ipecacuan powder.  Do not pet cats, or sleep with a feathered pillow. 
• Inflammation of air passages (morbidly irritable condition of the bronchial mucous membrane):
• Chronic Bronchitis:  Caused by permanent organic change of lung 
• Acute Bronchitis:  Cold air can cause bronchitis if it causes first a cold
• Offending Condition of Blood (presence of a blood in the pulmonary system and acts as a source of irritation, such as the blood after a meal.) This is not necessarily morbid, although can be. Often called peptic, or peptic asthma, and is caused by digestion or improper digestion. 
• Alimentary (nourishment) irritants:
• Being of the wrong quality:  Unwholesome and indigestible food (see chapter XII: Dietetic treatment of asthma)
• Being excessive in quality:  Bloated stomach after eating too much
• Being taken too late in the day:  May cause nocturnal asthma due to dyspepsia 
• After all food (full meal*, any particular food, undigested meal)
• After certain ingesta: wine, beer, peanuts, cheese (especially if old), 
• Preserved food (due to ingredients require, such as antiseptics because they prevent "putrefaction" out of the body, and opposes digestion): sausage, potted meats, dried tongue, stuffing and seasoning, 
• Preserved fruits: (due to ingredients required) ginger, candied orange peel, dried figs, raisins)
• Meat pies, Beef stake, Kidney pudding, Coffee (if taken strong and with sugar can be very indigestible and trigger asthma), Heavy Malt Liquors
• Drinks containing carbolic acid (Bottled Scout, Scotch ale, etc.)
• From dyspepsia (upset stomach, indigestion)

2.  Extrinsic Causes: Applied to some remote part. Things that affect the lungs secondarily, and reach the bronchial tubes by the nervous circuit -- ganglionic or cerebral spinal.

• Reflex nervous irritation:
• Through the organic nervous system:
• Organic disease of the brain
• Hysterical Asthma: uterine or full rectum effect organic nervous system
• Through the cerebral spinal nervous system:
• Cold air (it acts as a stimulant)
• Cold feet
• Central Nervous System
• Irritant psychical (involving the mind):
• Smells
• Stress
• Mental excitement
• Smells (like smell of lucifer match)
• Irritant physical (involving the body): 
• Laughter (Anything that excites that nervous system can cause congestion of the face and chest by excito-motory action)
• Physical Excitement: Excitement, fear, violent emotions
• Over exertion (taxing respiratory organs, pulmonary congestion and producing nervous excitement and exhaustion)

Dr. Salter wanted to make certain that he made an adequate definition of cause, which he divided into two categories: (1, page 70)

1. Things that cause the disease: The original and essential cause of the asthmatic tendency
2. Things that cause the paroxysm: The immediate provocative of the attack. These are called your immediate and exciting causes of an asthma attack or paroxysm. 

He said that "sometimes the cause of the two are the same -- that which has laid the foundation of the disease will produce the subsequent attacks. Thus asthma often takes its origin in bronchitis, and whenever bronchitis subsequently occurs it brings an attack of asthma with it."

"But," he continued, "more often the cause of the disease and the cause of the paroxysm have nothing to do with one another -- are quite distinct; that which produces the disease not producing the paroxysms, and that which produces the paroxysms not producing the disease.  Thus measles may have laid the foundation for the disease; but it never occurs again to produce the paroxysms; on the other hand, the presence of ipacacuanha powder in the inspired air may produce the paroxysm, but it could not produce the asthmatic tendency."

While the cause of the disease may forever go unknown, most asthmatics will eventually learn what the exciting causes are that trigger their disease.  They will learn to avoid them, and learn the remedies that will allay the symptoms of being exposed to them, or at least give some relief as to take the edge off until the symptoms pass, or the exciting cause goes away.

So, the immediate causes, or exciting causes, or provocative causes of the asthma attack are as follow:

• Monthly period (1, chapter IV)
• Laughter (causes extreme expiration witch excites the asthma)
• Prolonged expiration (forcing air out of your lungs, as in laughing, or forced wheeze)
• Excitability
• Headache
• Bodily exertion (1, page 43)
• Yielding to sleep
• Cardiac Asthma (organic lesion is cause of spasm)
• Chronic Bronchitis (organic lesion is cause of spasm)  
• Particular kinds of air I (i.e. country air, city air)
• Chemical and mechanical irritants
• Animal emanations
• Hay season
• Grass season
• Bright, hot, dusty sunshine
• Dust (1, page 44)
• Smoke
• Certain food
• Certain drinks (wine, beer)
• Full meal
• Undigested meal
• Dyspepsia (upset stomach)
• Mental excitement
• Peanuts
• Fog
• Thundery weather
• Heat (heat and thundery weather make nervous system more irritable or sensitive)
• The smell of Lucifer match
• Coughing
• Sneezing (same as coughing)
• Cold air
• Change of weather
• Change of wind
• Type of wind (east wind, west wind, north wind, south wind)
• Close air (stuffy room, closed room, carriage, crowded room, church, railway)
• Pungent fumes
• Rabbits
• Cats (Cat-Asthma)
• Horses
• Beasts
• Guinea pigs 
• Dogs
• Cattle (1, page 76)
• Sheep
• Manageries 
• Eating too late in day
• Eating the wrong foods
• Eating too much (undigestible)
• Cheese (especially if old), 
• Preserved food (sausage, potted meats, dried tongue, stuffing and seasoning, 
• Preserved fruits (ginger, candied orange peel, dried figs, raisins)
• Meat pies
• Beef stake
• Kidney pudding
• Coffee (if taken strong and with sugar can be very indigestible and trigger asthma)
• Heavy Malt Liquors
• Bottled Scout (has carbolic acid)
• Scotch ale (has carbolic acid)
• Other drinks containing carbolic acid)

These exciting causes are things that may cause irritation of the bronchial mucus membrane. Many of these belong in more than one of the above categories.

It's also interesting to note that a single patient may have more than one exciting cause, and may even have more than one exciting cause from various categories: such as thundery weather, beer and wine, smell of Lucifer (one mental, one bronchial, one peptic)

The following are the theories as to why people develop asthma:

• Organic injury of the lung:  It results from some disease that caused organic damage to the lungs. This is probably the cause of about 80 percent of youth asthma.  In this case, one will show no signs of asthma until one of the following diseases takes place (be it close to birth or at the age of ten or later).  These are conditions that cause damage to the bronchial mucous membrane, and then some changes occur in the air passages making them sensitive to asthma when exposed to exciting causes.  Examples would include:
• Whooping cough
• Bronchitis
• Measles
• Etc. 
• Non-organic injury to the lung:  The asthma occurs even when there is no history of any disease to form organic lung changes.  In these cases the asthma is congenital, heriditary, and acquired.  Examples include: (1, page 80-81)
• Ipecacuan Asthma:  The asthma is caused and aggravated by Ipecacuan
• Hay Asthma: The asthma is caused and aggravated by Hay or Grass

So these are the things that Dr. Salter suspected were the causes of asthma, the things that might cause one to develop asthma, and the exciting causes, or what we would refer to as asthma triggers.

*Salter said that many physicians believe a full meal causes asthma because a full stomach presses up against the diaphragm, thus creating less room for the lungs. He said this was a fallacy, that the reason a full stomach caused asthma was because the food inside it is indigestible, thus irritating the nerves..

References:

1. Salter, Henry Hyde, "On Asthma: It's Pathology and Treatment," 1882, New York, William Wood and Company, pages 70-81 (or as otherwise stated)

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