The site of cannulation should be based on the patient’s position during surgery, the site of surgery, and the gauge (size) of the cannula being placed. PIV placement should be avoided in areas where there are signs of infection, burns, trauma, previous or present arteriovenous fistulas, radiation exposure, or recent IV infiltration. Along with choosing a site for PIV placement, the size of cannula should also be considered. A decrease in the gauge of the catheter corresponds with an increasing catheter diameter (e.g. a 14G catheter is larger than a 24G). Poiseuille’s equation should be considered when the catheter gauge is chosen, as it states that flow through a tube is directly proportional to the pressure difference at the beginning and end of the tube and to the radius to the fourth power, and flow is inversely proportional to the length of the tube and viscosity of the fluid. For all practical purposes when selecting the size of an IV, it is the radius and length that matters, as long as blood products are not being given (i.e. higher viscosity). Additionally, it is difficult to give exact flow rates through any given catheter, but in general larger catheters and higher inflow pressures result in exponentially higher flow rates.

The upper extremities are usually the preferred site of placement as this location allows for easier access to the IV during the surgical procedure and a greater ability to reassess the site during a procedure to check for infiltration. Common sites of cannulation in the upper extremities include the veins of the hand and forearm, which include the cephalic and basilica vein systems. The median antecubital vein can usually accommodate a larger bore PIV, however flow may be limited if the arms are positioned with even a slight bend. Furthermore, a PIV in this position can be frustrating to the patient and care team after surgery as it will consistently cause an infusion pump to alarm if the arm is bent, thus causing the catheter to be kinked within the vessel. The dorsal veins of the foot can also be accessed. However, this is associated with a higher risk of thrombophlebitis, along with patient discomfort. If a lower extremity PIV is needed, the saphenous vein can often be easily palpated just anterior to the medial malleolus and it can typically accommodate a larger gauge catheter if the upper extremities are not accessible.

The external jugular vein is another peripheral intravenous site frequently used by the anesthesiologist because of its reliable anatomical position. It is typically located close to the surface of the skin superficial to the sternocleidomastoid muscle. Placement of this line requires a shallow angle when attempting cannulation. Caution should be taken when placing an external jugular cannula due to the risk of inadvertent puncture of the deeper structures of the neck, including the carotid artery, internal jugular vein, and pleural space. External jugular intravenous catheters also frequently require turning of the head to the contralateral side to run effectively.

As with any procedure, an explanation of what the patient can expect (mild, temporary discomfort during placement) and the risks, including infection and bleeding, should be discussed with the patient. Gloves should be worn during the placement of any PIV and the area should be thoroughly cleaned with alcohol or chlorhexidine. A tourniquet should be tied tightly proximal to the site of cannulation to promote engorgement of the vein.

The gauge of the intravenous cannula needed for each patient is dependent upon their surgical procedure, likelihood of blood loss or need for vasoactive drugs, their specific comorbidities and the size of the vein being accessed. Once the gauge has been determined, inspect the metal needle and plastic cannula noting the distance between the tip of the needle and the tip of cannula. The amount of exposed needle increases with increasing size of the catheter, thus requiring deeper entry into the vein before the catheter can be advanced off of the needle.

The decision to use local anesthetic at the site for pain depends on the size of the needle being inserted. Although local anesthetic creates a sympathectomy that can prevent venoconstriction, it may also obscure the view of the vein. Lidocaine 1 % is typically used and a volume of 0.5–1 mL at the insertion site is adequate to reduce or eliminate pain.

To stabilize the vein, use your non-dominant hand to pull the skin taught distal to the site of insertion. Use your dominant hand to insert the cannula and needle together at a 5–30° angle to the skin. The idea is simply to put a tibe (catheter) inside another tube (vein). Thus, lining up the axis and angle of the two is the most important step. Once the vein as been entered a “flash” of blood will appear in the reservoir of the catheter. Lower the angle of the catheter so that it is parallel to the axis of the vein and continue to advance the needle and cannula simultaneously an additional 2–3 mm. This ensures that the tip of the cannula has also entered the vein. Next, thread the cannula off of the needle into the vein. Once the cannula has been threaded to its hub, remove the tourniquet and apply pressure proximal to the cannula to occlude the vein in order to prevent back bleeding when the needle is removed. Remove the needle, placing your sharp in a safe location, and attach the intravenous tubing. The intravenous fluid should flow freely into the catheter if the fluids are above the level of the heart. Finally, apply a sterile dressing to secure the intravenous catheter in place.

Difficulty locating a vein can be one of the most challenging aspects of PIV insertion. Having the patient open and close their first, letting the arm hang below the level of the heart to encourage venous filling, and tapping the vein can all help increase its size. If no extremity veins are visible or palpable, or if multiple attempts have been unsuccessful, ultrasound can be used to locate the deeper veins in the arm. The basilic vein and deep brachial vein are reliable choices in this setting. A landmark-based approach to these deep veins has been shown to lead to frequent complications, such as arterial puncture and nerve injury. As such, these veins should be located and cannulated with ultrasound guidance. A longer cannula (>2 in.) may be needed to access these veins.

Valves inside a vein can sometimes prevent complete advancement of the cannula. Removing the needle and advancing the cannula further into the vein while flushing it with saline solution creates positive pressure which may help open the valve and allow passage of the cannula past the obstruction.

If a cannula is advanced outside of the vein, there is usually swelling at the site of cannulation when fluid is administered as it infiltrates the extravascular tissue. The cannula should be removed immediately and a new cannula inserted at a different site. Repeated attempts at flushing the catheter or readjusting the position should be avoided.

The most common site of arterial cannulation is the radial artery. However, the femoral, brachial, axillary, and dorsalis pedis are alternative sites based on the patient’s anatomy or surgical site. Contraindications to placement include infection at the site, arterial thrombus, trauma or burn proximal to the vessel, and concern for collateral flow. Arterial cannulas are typically 20 gauge catheters, but smaller sizes may be required for pediatric patients. Their length depends on the site being accessed with longer catheters required for femoral arteries as compared to radial arteries, particularly in the obese patient.

The Allen’s Test has been traditionally used to assess the collateral flow to the hand via the ulnar artery. To perform the test, the hand is held in a fist above the level of the heart for 30 s. The radial and ulnar arteries are occluded and the hand is opened and then the ulnar artery is released. The palm is observed to see if the pallor resolves within 10 s. Although some experts still recommend using the Allen’s Test, a recent study comparing the Allen’s Test to Doppler flow found that it was not reliable in predicting collateral flow.

Prior to performing the procedure, the patient should be appropriately consented and the procedure explained. Only the technique for cannulation of the radial artery will be discussed in this chapter. Although the incidence of arterial line infection is minimal, it is recommended that a hat, mask, and sterile gloves be worn during the procedure. A small gauze roll is placed under the wrist to slightly extend it and the hand is taped to a table or arm board for immobilization. The radial artery should be located by palpation of the pulse at the wrist between the radius and the flexor carpi radialis tendon. The area should be prepped with chlorhexidine and draped with sterile towels. A small amount of local anesthetic (0.5–1 mL of 1 % lidocaine without epinephrine) can be injected at the entry site to prevent pain during needle insertion if the cannula is placed in an awake patient. This also creates a sympathectomy that reduces vasospasm when accessing the vessel. The needle is held in the dominant hand like a pencil and should enter the skin at a 30–40° angle. Once a flash is seen in the catheter chamber, the needle is advanced 1 mm further and the angle is decreased to 10–15° as the guidewire is advanced into the artery. The cannula can then be passed over the guidewire in a Seldinger technique and the guidewire and needle can be removed. Prior to removing the guidewire, pressure should be applied proximal to the site of cannulation to prevent bleeding through the catheter. The cannula should then be attached to high pressure, low compliance arterial pressure tubing, and sutured or securely taped into place with a sterile, transparent dressing being applied.

Frequently there is only a small “flash” of blood into the arterial cannula chamber and the chamber does not fill completely or the chamber fills but the guidewire does not pass easily. In these situations, the artery can be transfixed, meaning the needle and cannula are purposely passed through the artery. The needle is then removed and the cannula is slowly pulled out of the skin until spontaneous arterial flow is identified. The guidewire can then be inserted into the cannula and the cannula advanced further into the artery.