_Of the Operation of Bleeding._
Bleeding is thought in general to be a very simple performance; but in
fact, there is not an operation in all surgery, requires more care, or
is liable to more dangerous consequences, if ill performed.
It is not only the opening a vein, but it is to open it properly,
(taking care not to prick an artery or tendon) to take away a sufficient
quantity of blood, and to heal up the orifice again.
In the bend of the arm are three distinct veins, the _head_, _median_,
and _basilican_. The ancients, before the discovery of the circulation
of the blood, fancied the _head_, or upper vein, carried the blood from
the head; the _median_, or middle, from the breast; and the _basilican_,
from the liver, &c. but this idle conjecture is laid aside, as being
highly absurd. When it is remembered what was said in the first Lecture,
in Sect. V. of the circulation of the blood, it will then plainly
appear, that all these veins become one before they enter the body; so
that there can be no difference as to their quality in being opened:
either therefore, which lays most conspicuously easy, is the vein that
should be chosen; for the arms of people differ in this respect, as much
as their features.
In order to chuse therefore properly, examine with the finger how the
veins lie; if upon a flat hard substance, it is a tendon; if a pulsation
is perceived, there is an artery; both which ought to be avoided if
there is a vein that lays more free and conspicuous to the sight and
touch. If however it cannot be avoided, the vein ought to be opened with
the greatest caution, for the pricking of a tendon would not only be
exquisitely painful, but endanger the arm by inflammation, and even life
itself; and the pricking of the artery would endanger the patient’s
bleeding to death, or else form an _anauresma_, (which is a bag of blood
protruding from the artery) equally dangerous to the life of the
patient. In general the middle vein is the safest and most convenient,
provided it does not cross the tendon: for the upper vein lies
frequently very deep, and is but small, and the lower frequently crosses
a tendon, or lies immediately over an artery.
However, one or the other will frequently suit, and, with caution, the
operation may be performed with ease.
As to the choice of the arm, it can make no difference in regard to the
effect, whether it is the right or left, for the veins of both arms end
at last in the great trunk of the _vena cava_, before they enter the
heart. To the operator, however, the right is the handiest, and to the
patient, the left is most convenient. In that arm however where the best
vein offers, that should be chosen.
When the arm is fixed on, then tie it up. The place should be on the
upper arm, about two inches from the bend, and the vein fixed on to be
bled, first drawing up the skin a little, and laving on the ligature
twice round the arm, drawn together with a draw knot; the reason of
laying on the ligature above the intended orifice of the vein, is plain,
as it stops the reflux of the blood, which is transfused from the heart
by the arteries towards the fingers, from thence taken up by the veins,
and by the ligature prevented from flowing back again, and consequently
distends the veins, and swells them up.
When the ligature is laid on, (which may be a garter, or a piece of
tape, about four or five feet long) and the veins are swelled up, then
open the vein. Bend the lancet so that the blade and handle may make an
acute angle; take the blade between the thumb and fore finger in the
right hand, if the right arm is bled, but if the left arm, the lancet
ought to be held in the left hand,[9] and open the vein obliquely, so
that the lancet cuts all the while, stretching the vein a little
downwards with the opposite thumb. The lancet should cut a little
slantingly, for if perpendicular, it would not only cause much pain, but
be apt to slip through the vein, prick a tendon or artery, and occasion
dangerous mischief.
Footnote 9:
This is the proper method of bleeding; for a bleeder ought to be
equally dexterous with the left hand as with the right, which custom
soon makes familiar; but those who are awkward with the left hand,
must stand behind the left arm to bleed, which method may be adapted
rather than to risk danger.
The orifice should be somewhat obliquely in the vein, neither directly
length-ways, as the veins would be apt to slip, and the orifice not
sufficiently opened to let the blood pass freely; neither should the
opening be right across, as thereby the vein might be divided, and the
blood not be easily stopt, or the orifice heal up. When now the vein is
well opened, let the blood run, (the arm a little bent) till it changes
to a higher colour, the surest sign of being enough, and this will be in
about four, six, or eight ounces, according to the constitution of the
patient. This simple rule I would advise to be attended to, for whatever
may be pretended about presaging the quantity of blood beforehand,
certain it is, it cannot be ascertained but in the time of bleeding.
When it is time to leave off, slacken the ligature, and gradually untie
it, when generally the blood ceases to run; draw close the orifice, and
wipe it clean all round. Let the patient bend the arm a little, and
close the orifice very close, then lay a four-folded dry compress, the
bigness of a crown, of clean tolerable fine linen rag, and tie the arm
up: lay the ligature (a garter or a piece of tape about four feet long)
at the middle of the compress, the one half round the upper arm, the
other on the lower arm, alternately, so that they always cross each
other in the bend of the arm on the compress, till at last it is either
tied or pinned; care being taken that it neither be too tight or too
slack, so that the arm may be bent or extended with tolerable ease. Let
the ligature remain on twenty-four hours, when all will be closed up.
What is to be done if unfortunately a tendon or an artery should be
pricked, I shall mention hereafter.
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