In the after-treatment it is of great importance that the wound and the dressing should be kept free from bacteria by keeping everything surgically clean.

364.  Where and how to Apply Pressure.  The principal places in which to apply pressure when arteries are injured and bleeding should always be kept in mind.

Experiment 192. How to tie a square knot.  If the student would render efficient help in accidents and emergencies, to say nothing of service on scores of other occasions, he must learn how to tie a square or “reef” knot.  This knot is secure and does not slip as does the “granny” knot.  The square knot is the one used by surgeons in ligating vessels and securing bandages.  Unless one knew the difference, the insecure “granny” knot might be substituted.

  [Illustration:  Fig. 158.—­Showing how a Square Knot may be tied with a
  Cord and a Handkerchief.]

A square knot is tied by holding an end of a bandage or cord in each hand, and then passing the end in the right hand over the one in the left and tying; the end now in the left hand is passed over the one in the right and again tied.

If in the finger, grasp it with the thumb and forefinger, and pinch it firmly on each side; if in the hand, press on the bleeding spot, or press with the thumb just above and in front of the wrist.

For injuries below the elbow, grasp the upper part of the arm with the hands, and squeeze hard.  The main artery runs in the middle line of the bend of the elbow.  Tie the knotted cord here, and bend the forearm so as to press hard against the knot.

For the upper arm, press with the fingers against the bone on the inner side, and just on the edge of the swell of the biceps muscle.  Now we are ready for the knotted cord.  Take a stout stick of wood, about a foot long, and twist the cord hard with it, bringing the knot firmly over the artery.

For the foot or leg, pressure as before, in the hollow behind the knee, just above the calf of the leg.  Bend the thigh towards the abdomen and bring the leg up against the thigh, with the knot in the bend of the knee.

365.  Bleeding from the Stomach and Lungs.  Blood that comes from the lungs is bright red, frothy, or “soapy.”  There is rarely much; it usually follows coughing, feels warm, and has a salty taste.  This is a grave symptom.  Perfect rest on the back in bed and quiet must be insisted upon.  Bits of ice should be eaten freely.  Loosen the clothing, keep the shoulders well raised, and the body in a reclining position and absolutely at rest.  Do not give alcoholic drinks.

Blood from the stomach is not frothy, has a sour taste, and is usually dark colored, looking somewhat like coffee grounds.  It is more in quantity than from the lungs, and is apt to be mixed with food.  Employ the same treatment, except that the person should be kept flat on the back.