Successful cannulation of a peripheral vein requires proper site selection, as well as knowledge of the gross anatomy of a vein.

Anatomy of a Vein

 

Potential IV Sites

Anatomy of a Vein

Veins are thin walled-structures that lack the thick, circumferential smooth muscular layer that is present in arteries. As such, peripheral veins may collapse and may be difficult to cannulate (or even locate) in patients with hypovolemia, low blood pressure, etc.

Venous return to the heart is dependent upon contraction of regional skeletal muscle (e.g. the gastrocnemius and soleus in the lower leg.) Additionally, many veins contain valves that prevent retrograde flow of blood. ( Moore, KL) If the intravenous catheter abuts one of these valves, flow of intravenous solution may be occluded. (Similiarly, valves can interfere with phlebotomy.)
 
Potenital IV Sites

General Concepts | Upper Extremity | Lower Extremity | External Jugular

 

General Concepts

The identification of the optimal site involves both visual and tactile exploration. The vein may be visible as a blue-green subcutaneous structure. It may “pop out” as it engorges with blood or merely be palpable as a springy canal coursing between the soft tissues. Given the wide variation in anatomic location of superificial veins, purely "blind" attempts, without visual or palpable landmarks, are highly unlikely to be successful and should be discouraged except in emergent situations.

Ideally target a good sized vein with a straight segment at least the length of the catheter. For elective placement, site consideration should include:

  • Ease of access
  • Use of the non-dominant extremity
  • Avoiding joint areas
  • Avoiding use of the lower extremities
  • See the Contraindications section for other sites to avoid.

  

Upper Extremity

In most situations, intravenous catheters are inserted in the antecubital fossa, the forearm, the wrist, or the dorsum of the hand.

The three main veins of the antecubital fossa (the cephalic, basilic, and median cubital) are frequently used. These veins are usually large, easy to find, and accomodating of larger IV catheters. Thus, they are ideal sites when large amounts of fluids must be administered. However, their location in a flexor region is a drawback, as bending of the elbow can be uncomfortable to the patient and may occlude the flow of the intravenous solution. Cannulation of the cephalic, basilic, or other unnamed veins of the forearm is preferrable.

 

The veins in the dorsal hand may be utilized if large bore access (18 gauge or larger) is not required. Care must be taken to find a vein that is straight and will accept the entire length of the catheter.

 

The portion of the cephalic vein in the region of the radial styloid is commonly known as the "student's" or "intern's" vein, as it is often a large, straight vein that is easy to cannulate

 

Lower Extremity

 

Cannulation of the veins of the feet is not ideal. ***ADD REFERENCES*** Insertion can be quite painful, and the catheter may cause more discomfort than if it were started in the hand or forearm. Additionally, IV catheters placed in the feet are more likely to become infected, to not flow properly, and are more likely to produce phlebitis.

 

The great saphenous vein runs anteriorly to the medial malleolus, and may be accessed via a peripheral venous cutdown in emergent situations. The lesser saphenous vein runs along the lateral aspect of the foot. These two veins converge medially to form the dorsal venous arch. There are numerous unnamed vessels that are branches of these veins. (Clemente) Any vein in the foot large enough to accept the IV catheter may be used if necessary.

 
External Jugular

 

The external jugular ("EJ") vein can be cannulated if necessary. It orginates near the angle of the mandible, and courses over the sternocleidomastiod muscle. Proximal to the clavicle, the EJ dives into the subcutaneous tissue, eventually emptying into the subclavian vein. (Moore)

The EJ is a large vein that can accomodate a large bore IV catheter (18 gauge or larger), in most patients. It is especially useful in patients with poor access in the arms who require a large volume of fluid. Additionally, the EJ is often engorged in patients with heart failure and provides an alternative in these patients if other venous access sites are not available. Please refer to the Alternatives section for further discussion on utilizing the external jugular vein.

 

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