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IV THERAPY
 

Indications

 Establish or maintain a fluid or electrolyte balance

 Administer continuous or intermittent medication

 Administer bolus medication

 Administer fluid to keep vein open (KVO)

 Administer blood or blood components

 Administer intravenous anesthetics

 Maintain or correct a patient's nutritional state

 Administer diagnostic reagents

 Monitor hemodynamic functions 

IV Devices

Steel Needles 
Example: Butterfly catheter. They are named after the wing-like plastic tabs at the base of the needle. They are used to deliver small quantities of medicines, to deliver fluids via the scalp veins in infants, and sometimes to draw blood samples (although not routinely, since the small diameter may damage blood cells). These are small gauge needles (i.e. 23 gauge).

 

Over the Needle Catheters  

Example: peripheral IV catheter. This is the kind of catheter you will primarily be using.

   

 

 

 
 

A Word About Gauges

 

And now, a word about gauges: Catheters (and needles) are sized by their diameter, which is called the gauge. The smaller the diameter, the larger the gauge. Therefore, a 22-gauge catheter is smaller than a 14-gauge catheter. Obviously, the greater the diameter, the more fluid can be delivered. To deliver large amounts of fluid, you should select a large vein and use a 14 or 16-gauge catheter. To administer medications, an 18 or 20-gauge catheter in a smaller vein will do.

IV Fluid

There are three main types of fluids:

 

Isotonic fluids 

Close to the same osmolarity as serum. They stay inside the intravascular compartment, thus expanding it. Can be helpful in hypotensive or hypovolemic patients. Can be harmful. There is a risk of fluid overloading, especially in patients with CHF and hypertension. Isotonic fluids contain an approximately equal number of molecules (blue dots) as serum so the fluid stays within the intravascular space. Remember that fluid flows from an area of lower concentration of molecules to an area of high concentration of molecules (osmosis) to achieve equilibrium (fluid balance). In this example, there is no fluid flow into or out of the intravascular space.

Examples: Lactated Ringer's (LR), NS (normal saline, or 0.9% saline in water).

Hypotonic fluids 

Have less osmolarity than serum (i.e., it has less sodium ion concentration than serum). It dilutes the serum, which decreases serum osmolarity. Water is then pulled from the vascular compartment into the interstitial fluid compartment. Then, as the interstitial fluid is diluted, its osmolarity decreases which draws water into the adjacent cells.  Can be helpful when cells are dehydrated such as a dialysis patient on diuretic therapy. May also be used for hyperglycemic conditions like diabetic ketoacidosis, in which high serum glucose levels draw fluid out of the cells and into the vascular and interstitial compartments. Can be dangerous to use because of the sudden fluid shift from the intravascular space to the cells. This can cause cardiovascular collapse and increased intracranial pressure (ICP) in some patients.

Example: D5NS.45 (5% dextrose in 1/2 normal saline).

Hypotonic fluids
Contain a lower number of molecules than serum so the fluid shifts from the intravascular space to the interstitial space (represented by the green arrows). This decreases the interstitial space osmolarity (because of the increase of fluid and constant number of molecules within it) which then causes fluid to move into the cells. Note that the green arrows represent fluid movement, not molecule movement.

Hypertonic fluids 

Have a higher osmolarity than serum. Pulls fluid and electrolytes from the intracellular and interstitial compartments into the intravascular compartment. Can help stabilize blood pressure, increase urine output, and reduce edema.  Rarely used in the prehospital setting. Care must be taken with their use. Dangerous in the setting of cell dehydration.

Examples: 9.0% NS, blood products, and albumin.

Hypertonic fluids
Contain a higher number of molecules than serum so the fluid shifts from the interstitial space to the intravascular space (represented by the green arrows). This increases the interstitial space osmolarity (because of the loss of fluid and constant number of molecules within it) that then causes fluid to leak out of the cells.

There Are Two Main Groups Of Fluids

Crystalloid Are isotonic and remain isotonic and are therefore, effective volume expanders for a short period of time. However, both the water and the electrolytes in the solution can freely cross the semipermeable membranes of the vessel walls (but not the cell membranes) into the interstitial space, and will achieve equilibrium in two to three hours. They are ideal for patients who need fluid replacement. 

When using an isotonic crystalloid for fluid replacement to support blood pressure from blood loss, remember that 3 mL of isotonic crystalloid solution are needed to replace 1 mL of patient blood. This is because approximately two thirds of the infused crystalloid solution will leave the vascular spaces by about one hour.

Generally, a good rule of thumb is that initial crystalloid replacement should not exceed three liters before whole blood is instituted. Continued use of crystalloids runs the very real risk that the fluid that has leaked into the interstitial space will result in edema, primarily in the lungs (pulmonary edema).

            Examples: Lactated Ringer's (LR), NS (normal saline).

Colloid These contain molecules (usually proteins) that are too large to pass out of the capillary membranes and therefore remain in the vascular compartment. The large protein molecules give colloid solutions a very high osmolarity. As a result, they draw fluid from the interstitial and intracellular compartments into the vascular compartment. They work well in reducing edema (as in pulmonary or cerebral edema) while expanding the vascular compartment. 

Colloids can produce dramatic fluid shifts and place the patient in considerable danger if they are not administered in a controlled settings.

             Examples: albumin and steroids

 

Vein Selection

 Veins of the Hand

1. Digital Dorsal veins
2. Dorsal Metacarpal veins
3. Dorsal venous network
4. Cephalic vein
5. Basilic vein


 Veins of the Forearm

1. Cephalic vein
2. Median Cubital vein
3. Accessory Cephalic vein
4. Basilic vein
5. Cephalic vein
6. Median antebrachial vein

Generally speaking, it is better to try to cannulate the most distal veins first. If for example, the antecubital veins are ruined as a result of failed cannulation attempts this can cause problems in the event of a successful cannulation further down. Any drugs or fluids put through the cannula may extravasate at the failed cannula site.

The cepahlic vein is one of the best veins available. It tends to be large, and the forearm provides a natural splint (Weinstein, 1997). If you place the cannula too far distally along the vein, you can run into problems with the wrist joint, and are getting close to the radial nerve. Also the tendons that control the thumb can obscure the vein (Hadaway, 1995). These problems can usually be avoided by moving a little further proximally along the vein.

The basilic vein is often overlooked, hiding as it does along the ulnar border of the hand and forearm. On the plus side, it's often fairly large - on the minus side it can roll like a tanker in a rough sea and can have more valves than a submarine.

The dorsal veins are often quite handy (excuse the pun) as the metacarpals splint cannulae well (Weinstein, 1997), but they can be quite small. If the patient is elderly, look elsewhere. The lack of turgor in the skin and loss of subcutaneous tissue make it quite difficult to cannulate these veins in the chronologically gifted (Whitson, 1996).

Cannulation of the antecubital veins can also cause problems as the cannula may occlude as the patient bends their arm. Avoid, if you can, areas where cannulation or venipuncture has previously taken place. Repeated puncture of the vein wall can result and is painful (Ahrens et al., 1991)

In general, locate the vein section with the straightest appearance. Choose a vein that has a firm, round appearance or feel when palpated. Avoid areas where the vein crosses over joints.

If the IV treatment is for a life-threatening illness or injury, your choice may be limited to an area that remains open during hypoperfusion. Otherwise, limit IV access to the more distal areas of the extremities.

Technique

 It is important to point out that starting an IV is an art-form which is learned with experience accumulated after performing many IVs. Some patients are easy but many
are difficult.

 

Preparation It is important to gather all the necessary supplies before you begin. You will need:

Prepare the IV fluid administration set

Perform the venipuncture

If not successful If you are unsuccessful in entering the vein and there is no flashback, then slowly withdraw the catheter, without pulling all the way out, and carefully watch for the flashback to occur. If you are still not within the vein, then advance it again in a 2nd attempt to enter the vein. While withdrawing always stop before pulling all the way out to avoid repeating the painful initial skin puncture. If after several manipulations the vein is not entered, then release the tourniquet, place gauze over the skin puncture site, withdraw the catheter and tape down the gauze. Try again in the other arm.

Otherwise, After entering the vein, advance the plastic catheter (which is over the needle) on into the vein while leaving the needle stationary. The hub of the catheter should be all the way to the skin puncture site. The plastic catheter should slide forward easily. Do not force it!!

Occasionally, you may inadvertently enter an artery. You'll recognize this because bright red blood is quickly seen in the IV tubing and the IV bag because of the high pressure that exists. If this occurs, stop the fluid flow, remove the catheter, and put pressure on the site for at least 5 minutes.

It is sometimes helpful to draw blood after you have entered the vein and before you have connected the IV tubing and bag. You can easily withdraw blood into a 15 or 20 mL syringe and then inject it into blood vials. Be sure to fill the vials to at least three quarters full. To recall the order of the blood tubes, remember the pneumonic Red Blood Gives Life for red, blue, green, lavender top tubes. Gently rock the tubes back and forth a few times to mix the blood with the additives. There is no need to rock the red top tube, however, the blood in this tube will clot quickly because it contains no additives. It should not be shaken because this will destroy the sample.

To discontinue an IV

 Remember to observe universal precautions. Start by clamping off the flow of fluids. Then gently peel the tape back toward the IV site. As you get closer to the site and the catheter, stabilize the catheter and remove the rest of the tape from the patient's skin. Then place a 4 x 4 gauze over the site and gently slide the plastic catheter out of the patient's arm. Use direct pressure for a few minutes to control any bleeding. Finally, place a band aide over the site.

Some of this text was modified and the pictures borrowed from an unknown nursing website.

How to correctly apply a warm, moist compress Put a bath towel under hot water and wring it out.  Then fold it in half (by width not length) and enclose the arm from fingertips to elbow in the towel.  Now place the towel-wrapped arm into a plastic bag and seal the open end of the bag near the elbow.  While the pack is working (using heat to cause venous dilation), you can be setting up your supplies and be ready to perform the venipuncture as soon as you remove the pack.  It works wonders!  Many professional, experienced IV Therapy nurses would not even consider performing a venipuncture on patient with limited venous access without using a pack first

 

The Five Rights

Remember the five rights: The minimum standard of practice for medication administration is checking the “five rights” (right drug, right patient, right dose, right time and right route) to provide patient safety.

Do I have the right drug?

Do I have the right patient?

Do I have the right dose?

Do I have the right time?

Do I have the right route?

Now add to this:

Do I have the right solution?

Flow Rates

You will often need to calculate IV flow rates. The administration sets come in two basic sizes: 

 

Microdrip sets   Allow 60 drops (gtts) / mL through a small needle into the drip chamber. Good for medication administration or pediatric fluid delivery

Macrodrip sets   Allow 10 to 15 drops / mL into the drip chamber. Great for rapid fluid delivery. Also used for routine fluid delivery and KVO

Fluid may be ordered at a KVO rate. This means to Keep the Vein Open, or run in fluids very slowly, enough to keep the vein open, but not really deliver much volume. At times, you may desire a faster flow rate. This is usually expressed in mLs / hour. In other words, how much fluid do you want your patient to receive each hour? A common "maintenance" amount, for instance, would be "run it in at 125 an hour". Your patient would receive 125 mL of fluid every hour. Unless you are using an electronic pump to deliver the fluid at precise amounts, you will need to learn how to set a flow rate yourself. This is usually done by counting the number of drops that fall into the clear drip chamber on the IV administration set in one minute. To do this, you must know what size administration set you are using (micro or macrodrip). Plug the numbers into the following formula and you've got it!

(Volume in mL) x (drip set) 

 

gtts

------------------------------------

=

------

(Time in minutes) 

 

min

Let's say you want your patient to receive 250 mL of normal saline (NS) over a 90 minute time period. You decide to use a macrodrip (10gtt / mL) administration set. The formula will now look like this:

(250 mL) x (10 gtts/min) 

 

gtts

------------------------------------

=

------

(90 min) 

 

1 min

Which becomes: 

2500 

 

gtts

------------------------------------

=

------

90 

 

1

Then solving for gtts:

 

 

gtts

27.7

=

------

 

 

1

Or, gtts = 28

 

Sometimes you will need to know how many milligrams of a medication to give a patient based on their weight. Let's say you need to give the patient some D50. You look up the medication and see that it should be given in a concentration of 0.5 mg / kg. The patient weighs 220 pounds. The first thing to do is convert the weight to kilograms. Then we can express all of this as simple ratios. We now have:

0.5 mg 

 

? mg

---------

=

------

1 kg 

 

100 kg

Solving for? Give us 50 mg     ((0.5 mg x 100) kg / 1 kg) Fortunately for you; 50 mg is exactly what is in one amp of D50.

Want to try this yourself? Let's say you want your patient to have 500 mL of NS given over a two-hour period using a microdrip administration set. Use the first formula above.

 

Here's how it's done. First, the formula...

(Volume in mL) x (drip set)

 

gtts

------------------------------------

=

------

(Time in minutes)

 

min

Plug the numbers in...

(500 mL) x (60 gtts/min)

 

gtts

------------------------------------

=

------

(120 min)

 

1 min

Which becomes:

30000

 

gtts

------------------------------------

=

------

120

 

1

Which becomes:

 

 

gtts

250

=

------

 

 

min