Factors affecting the choice of location for intravenous access include:
1 Patient preference
2 Venous anatomy
3 Short-term use (e.g., day surgery). In this case, dorsal hand veins are suitable.
4 Intravenous access is needed for several days. In this case, mid-forearm veins provide an ideal location. Forearm intravenous catheters permit freedom of movement of the patient’s arm without occlusion when the arm is flexed.
5 Rapid fluid or blood product administration is required. In this case, the cephalic and basilic veins located in the anti-cubital fossa are larger caliber veins that can be catheterized. Maintenance of an anticubital catheter is more problematic postoperatively as occlusion frequently occurs when the patient’s arm is flexed. This can trigger the intravenous infusion pump alarm and disturb the patient’s sleep and recovery.
Fig. 5.6 Distal traction is applied to immobilize the dorsal veins of the hand. Note how the operator’s thumb is used to apply distal traction on the patient’s skin. The thumb is held below the patient’s knuckles allowing the intravenous needle to be inserted in the same plane as the vein.
Fig. 5.8 Intravenous catheter sizes. The smaller the gauge number, the larger the diameter of the catheter. The most common sizes are 18, 20 and 22 gauge catheters.
Size of Intravenous Catheter:
The intravenous catheter gauge refers to the internal diameter of the catheter. A small gauge (ga.) number indicates the catheter has a larger internal diameter. The larger the diameter the greater the potential flow rate, as flow increases to the fourth power of the catheter radius. Large-bore intravenous catheters (14 ga. and 16 ga.) are used for rapid infusion of large volumes of fluids and blood. A 20-gauge catheter is the most common general purpose catheter used for adults. When venous anatomy is challenging, a smaller 22-gauge intravenous catheter may be used to induce general anesthesia. Under general anesthesia, venous vasodilation occurs as a result of the effects of the volatile anesthetic vapours and the reduction of the patient’s emotional stress. With venous vasodilation, an additional larger gauge intravenous catheter can be secured if required.
Local anesthesia may be used to decrease the discomfort associated with intravenous insertion. Either a 25 or 27-gauge needle with 1% or 2% plain lidocaine may be used to raise a skin wheal where the intravenous catheter insertion is planned. Subcutaneous local anesthesia is commonly provided for very anxious patients or in patients requiring a large bore intravenous catheter. Some clinicians prefer not to use local anesthesia, stating that it involves an additional injection that may be more painful than the intravenous catheter insertion and may obscure the patient’s vein. Alternatively, AmetopTM, a local topical anesthetic can be applied for 30 – 45 minutes on the dorsum of the patient’s hand prior to insertion of the intravenous catheter.
Intravenous Insertion Technique:
Refer to the additional resources at the end of the chapter to view a brief video demonstration of the insertion of a peripheral intravenous catheter. Below is a list of the sequential steps required to establish intravenous access.
1 Explain the procedure to the patient and answer any questions the patient may have.
2 Prepare the intravenous tubing and fluid to be used.
3 Place a tourniquet on the patient’s upper arm.
4 Clean your hands and put on disposable gloves (see Clinical Pearls #4 below).
5 Inspect the patient’s hand and forearm for the best site for venous access.
6 Gently tap the vein. This promotes dilation of the vein, increasing its diameter and the chance for success.
7 Clean the site with an alcohol swab.
8 If using local anesthesia for intravenous insertion, inject a small amount of local anesthetic at the entry point.
9 Break the seal between the intravenous cannula and needle.
10 Immobilize the vein by applying gentle distal traction on the skin.
Distal traction on the skin to is used to immobilize the vein (Fig. 5.6). Once the needle tip pierces through the skin at a 20 – 30 degree angle, decrease the angle of insertion to a shallower 5 degree angle approach to avoid advancing the needle tip beneath the vein. Note that the operator’s thumb used to apply distal traction on the veins remains below the patient’s knuckles to permit the needle to be advanced at a shallow angle (Fig. 5.6).
1 Insert the needle tip just beneath the skin at a 20 – 30 degree angle.
2 Decrease the angle of entry such that the needle is almost parallel to the skin.
3 Advance the needle towards the vein.
4 Watch for a flashback of blood in the intravenous needle chamber. Some safety needles (e.g., BD InsyteTM 24, 22, and 20 gauge catheters) have incorporated ‘InstaflashTM’ technology. These catheters have a side port in the needle at the distal end such that blood will spill through the port between the needle and catheter as soon as the needle enters the vein. A flash of blood between the needle and catheter immediately confirms that the needle has entered the vascular lumen.
5 Advance the needle another 1 – 2 mm to ensure the catheter is in the vein lumen.
6 Without moving the needle, advance the catheter off the needle and into the vein.
7 Release the tourniquet.
8 Apply pressure over the skin at the tip of the intravenous catheter to prevent back bleeding.
9 For safety needles, deploy the safety needle retraction spring.
10 Attach the intravenous tubing to the catheter.
11 Tighten the luer lock connection between the intravenous tubing and the catheter.
12 Open the intravenous roller clamp and verify that the fluid flow is unrestricted.
13 Place a transparent sterile dressing over the intravenous catheter.
14 Secure the tubing to the patient with tape.
15 Dispose of any needles in an appropriate ‘sharps’ container.
Fig. 5.9 A slight angulation of the intravenous needle and catheter. This simple but useful technique can be used to prevent the needle tip from going too deep when establishing an intravenous in the forearm.
General Anesthesia Induction:
With intravenous access secured and appropriate monitoring procedures established, a baseline set of vital signs are recorded. The ‘Preoperative Pause’ should be completed (if this has not