10.2 Caring for Patients with Tubes and Devices

The following five principles apply to the care of drainage tubes. Knowledge of these principles should help the nurse to provide appropriate care to clients who have these kinds of tubes.

1. Closed cavities of the body are sterile cavities. Insertion of any tube must be performed with adherence to the principles of asepsis.
2. A portal of entry that comes into contact with a non-sterile surface immediately becomes non-sterile. When disconnecting drainage tubes, such as a urinary catheter or a T-tube, the ends must be kept sterile.
3. Gravity promotes the flow of drainage from a cavity. Keep drainage tubes and collection bags at a lower level than the cavity being drained.
4. Drainage will flow out of the tubing if the lumen is not occluded. Avoid kinks and coils in the tubing and watch that the person does not lie on the tubing. Do not clamp tubes without a prescriber’s order.
5. Properly cleanse the site before accessing any tubing to reduce possible introduction of microorganisms into a cavity. Sometimes contrast media and radiopharmaceuticals are injected via the tubing. An alcohol swab may be used to clean the entry point prior to accessing the tubing.

The following four factors affect the flow of fluid through tubes.

1. Pressure difference
   • A fluid will flow through a tube only when a pressure difference occurs between the two ends. In other words fluid moves from an area of higher pressure to an area of lower pressure. The larger the pressure difference, the more flow there will be. For example an abscess that is full of fluid will have higher pressure than the drain that is inserted into it and attached to a drainage bag for passive drainage.
   • A liquid in an enclosed container produces pressure by virtue of its weight. Weight, in turn, is determined by the density of the liquid and by the height of the liquid column from its surface to its outlet. For example, a large volume IV bag will have more pressure and, thus, greater potential for flow than a small volume IV bag.
2. Diameter
   • The diameter of a tube is the width of its lumen or inside opening. This diameter has a significant effect on the resistance to fluid flow. Increasing a tube’s diameter increases the flow rate, and vice versa. For example, IV fluids can be infused more quickly through large lumen IV cannulas as compared to small lumen IV cannulas.
3. Length
   • The length of a tube affects the rate of fluid flow. Fluid is slowed down by the friction of its molecules against the walls of the tube. The longer the tube, the more surface area there is for the fluid to rub against. As well, the friction is greater in narrow tubes because the fluid is near the walls. Tubes should be as short as possible, but long enough to achieve their purpose without unduly restricting the person’s movement. For example, drains should have relatively short drainage tubing, and IV tubing for IVs run by gravity should not be excessively long.
4. Viscosity
   • Viscosity refers to the tendency of a fluid to resist flow because of the friction of its molecules rubbing against each other. This lack of slipperiness causes the fluid to flow slowly. The rate of a slowly flowing fluid can be increased by raising the height of the container to increase the pressure difference; opening the clamp more or using a larger tube so there is a wider diameter; or diluting the fluid to make it less viscous. For example, blood run by gravity may require the height of the bag to be raised.

Caring for patients with multiple tubes and attachments can be challenging. Follow the guidelines in Table 10.1 to help you care for patients with tubes and attachments.