Styptics are substances which arrest the flow of blood from broken or wounded surfaces or vessels. They may do this either by aiding the rapid formation of a coagulum which will plug up the wounded vessels, or by causing the vessels themselves to contract so much as to check the flow of blood out of them. They are closely connected with astringents, which, as we have already mentioned, nearly all coagulate albuminous substances.

Acids.

Actual cautery.

Alum.

Ferric chloride.

Tannin.

Lead acetate.

Collodion,

Matico,

Spider's-web, acting mechanically.

Substances acting on the blood-vessels :Cold (Ice).

Digitalis.

Ergot.

Action

Matico and cobwebs act mechanically in aiding the formation of a clot around the fibres. Collodion also acts mechanically by exerting pressure over the surface, and thus preventing the blood from issuing.

Alum, lead acetate, and ferric chloride cause coagulation of the blood.

Pressure to the surface, cold sponges or ice, cause the vessels to contract, and thus prevent the blood from running out of them in superficial haemorrhage.

Lead acetate and gallic acid, when absorbed into the blood, not only tend to lessen secretion from the mucous membranes, but arrest haemorrhage from internal organs. This is probably partly due to their effect in increasing the coagulability of the blood, and possibly partly also to their power of causing contraction of the arterioles. Ergot and digitalis also lessen or arrest haemorrhage, although they have little or no action on coagulation, and their action probably depends on their power to cause contraction of the arterioles.

A dependent position increases the pressure of blood locally in the part, and thus tends to increase haemorrhage. It is therefore advisable to keep the bleeding part as much raised as possible.

Powerful action of the heart tends to increase the blood-pressure generally. In cases of severe haemorrhage it is therefore of the greatest importance that the patient should keep absolutely quiet, and that all the food should be taken cold.

Cold to the surface is a powerful agent in checking internal as well as superficial haemorrhage. It probably acts by causing reflex contraction of the vessels (compare Rossbach's experiments, p. 252). A cold key to the back of the neck and cold water to the nose are frequently useful in epistaxis, and ice-bags to the chest or epigastrium are useful in haemoptysis and haema-temesis. It is probable that other stimuli to the surface act on the vessels in a similar way, and probably this is the explanation of the fact that menorrhagia and metrorrhagia are sometimes successfully treated by placing a plug of cotton wool soaked in a mixture of vinegar and brandy in the vagina, or applying the same mixture either on cotton wool or on a napkin to the vulva.

The powerful action of hot water injected into the vagina and uterus in arresting post partum haemorrhage (p. 455) is probably due partly to its causing a reflex contraction of the vessels and of the uterus itself, and probably also to its direct stimulating action on the muscular walls of the uterus.