The principal period groups were digitalis preparations, squill, broom, juniper oil, buchu, nitrous ether spirit, and several soluble potassium salts. They were grouped by observed promotion of urine flow, rather than by one common mechanism. The following are historical adult quantities per administration, expressed in the contemporary units; they are not present-day prescriptions.
Other recognised period agents included dandelion and copaiba. The dandelion decoction was given in quantities of 1–2 fluid ounces, its soft extract in quantities of 10–30 grains, and its preserved juice in quantities of ½–2 fluid drachms. Copaiba was given in quantities of 15–30 minims, and copaiba oil in quantities of 5–20 minims. Their historical inclusion does not establish that they are suitable substitutes for current diuretic therapy. [ref]
The distinction between preparations matters more than a single “dose of the plant”: an infusion, tincture, juice and powder have different concentrations. Likewise, a salt's small historical diuretic dose is not its larger purgative dose. A modern explanation also separates a direct effect on renal tubules from improved cardiac output in appropriate heart failure: digitalis preparations cannot be understood simply as agents that make every kidney excrete more water. Modern digoxin is used for selected cardiac indications, rather than as a general treatment for low urine output. [ref]
The chief physiological routes are abrupt failure of blood circulation, failure of pulmonary ventilation or gas exchange, or catastrophic failure of the central control of those functions. Historical clinical accounts used labels such as syncope, asphyxia and medical coma in explaining deaths; these terms describe broad physiological failures rather than identifying the underlying diseases.[ref] A brief faint or ordinary medical coma is not itself necessarily fatal.
In primary circulatory failure, effective delivery of blood to the brain stops. Modern examples include ventricular fibrillation, pulseless ventricular tachycardia, severe bradyarrhythmia and asystole. They may arise in coronary artery disease, after myocardial infarction, in cardiomyopathy, or from inherited cardiac ion channel disorders. An electrical cause may leave little distinctive gross evidence at autopsy. These modern mechanisms refine the broad historical description of cardiac syncope.[ref]
Mechanical interruption of blood circulation gives another group: massive haemorrhage, rupture of an aortic aneurysm, cardiac tamponade, and large pulmonary embolism. The immediate deficit differs in each. Haemorrhage removes circulating volume; cardiac tamponade prevents adequate filling; pulmonary embolism obstructs flow through the pulmonary circulation. All can end with critically low cardiac output even if some electrical activity persists.[ref]
Respiratory failure includes obstruction of the airway by a foreign body, laryngeal oedema or aspiration; drowning; and depression of breathing by drugs or major brainstem injury. Oxygen delivery then fails and secondary cardiac arrest follows. Carbon monoxide poisoning and cyanide poisoning illustrate related failure of oxygen transport or use: not every hypoxic death is caused by physical obstruction of an airway.[ref][ref][ref]
A major intracranial haemorrhage or rapidly developing brain herniation can destroy or compress the pathways maintaining consciousness and breathing. A severe disturbance of electrolytes, especially potassium, may instead act directly on the heart's electrical function. A fatal seizure can involve respiratory and circulatory mechanisms; sudden unexpected death in epilepsy remains a diagnosis requiring exclusion of other causes, not merely recognition of a history of epilepsy.[ref]
The practical distinction is between mode, immediate mechanism and underlying cause. For example, rupture of an aneurysm can cause haemorrhage, then circulatory failure, then irreversible hypoxic-ischaemic brain injury. A complete explanation identifies that chain. Inspection, histology, examination of the airway and heart, and appropriately interpreted toxicology may establish it; an unexplained sudden death cannot be assigned a precise cause from its suddenness alone.