In many cases there is an upset in the normal body fluid quantities and the constituents of these body solutions. This is particularly common in surgical cases after an operation and in conditions where the patient cannot eat; these formerly constituted a serious problem. However, there are now many means of combating these situations which are effective, yet quite simple. The fluids, nutriments, and various salts the body is deficient in are replaced by infusions of the desired elements. These may be given into the veins, the subcutaneous tissues, the rectum, or by stomach tube. They run in by gravity through a tube from the exterior to the patient.
The most common route is by intravenous (I.V.) infusion. For this a needle is inserted into the vein and the solution allowed to run in through a tube from its bottle to the needle at a slow rate. The vein puncture is no more painful than injection for any cause, and once it is in place there is no further discomfort. The only difficult part of the procedure is that the patient must hold the arm perfectly still during the procedure. The arm may be bound in position if the patient so desires, so that he may read or visit without having to concentrate on holding his arm still. Intravenous infusions may be administered into the veins of the arms, the feet, or the legs. If several infusions are likely and there is difficulty in inserting the needle, it is often anchored in place and left for subsequent infusions rather than inserting a needle each time. The length of time the I.V. infusion takes depends on the quantity your doctor ordered and the rate at which he ordered it to flow. The flow is measured in drips per minute and regulated by the clamp on the tubing and the height of the bottle. Some patients will require one infusion, others will need several.
Infusions given into the fatty layer beneath the skin (subcutaneous infusion) may be given to almost any area, but they are most often given into the thighs. Often a substance is added to hasten the absorption from the site into the blood stream, but otherwise the same principles apply as with intravenous infusion. Of paramount importance with both of these procedures is the use of sterile techniques, of course. Infusions given through rectal tube or stomach tube are entirely painless. The fluids are absorbed from these sites into the blood stream. Frequently specific medications are also added to infusions.
Blood is about half cells and half fluid by volume (actually 45 per cent and 55 per cent). The fluid portion is called plasma. In many conditions the patient is deficient in the plasma portion but not the cellular elements. There are valuable protein fractions in the plasma which cannot be supplied artificially from any other source but human plasma. The various salts and nutrients can be supplied by intravenous infusions, but when the proteins are needed, plasma or whole blood is the only means of supplying them; and, if the cells are present in normal amount, plasma is the fluid of choice.
In sudden hemorrhage whole blood, of course, is the best means of replacing the blood volume, but in slow continual bleeding, the body may be capable of producing enough cells to replace those lost, but unable to keep up with the protein losses. Therefore, in some cases of whole blood loss, plasma is the agent of choice for replacement. In cases of shock there is an escape of the plasma out of the blood vessels into the tissue, while the cells remain in the vessels. In mild shock, intravenous infusions suffice to replace the plasma, but in severe cases plasma must be used. In cases of weeping wounds, such as large burns, plasma is indicated to replace the proteins lost in the wound drainage. Plasma is also necessary when there are low blood proteins, as in kidney disease where there is loss through the urine, or in liver disease or malnutrition.
Plasma is administered just like an intravenous infusion and no typing or crossmatch is needed as with blood transfusions.