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.
[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.