How to Manage difficult Cannulation

What is ‘Difficult’ Cannulation?

Difficult intravenous access (DIVA), or difficult peripheral intravenous cannulation (DPIVC), describes a situation wherein a practitioner is having difficulty gaining peripheral vascular access, often because the patient’s veins cannot easily be seen or felt. It is generally defined as:

• Two or more failed cannulations, and/or
• Needing to use advanced or rescue techniques to gain peripheral vascular access.

Difficult or anchor veins are veins that are challenging to access or cannulate due to various factors, such as:

1. Depth
2. Location
3. Size
4. Tortuosity
5. Scar tissue

Which Patients are ‘Difficult’ to Cannulate?

Patients who might be difficult to cannulate include:

• Patients who have undergone frequent recent cannulations (e.g. patients with renal impairment or a history of intravenous drug abuse), as they may have fewer suitable veins left to access
• Obese patients or patients who have recently undergone chemotherapy, as intimal damage or altered subcutaneous fat distribution may make their veins more difficult to locate
• Underweight or premature infants who have extremely small veins
• Infants and children due to smaller veins, lower pain tolerance and susceptibility to emotional distress
• Patients with darker skin, due to decreased visibility of the veins
• Patients with fragile skin
• Dehydrated patients
• Patients in shock
• Patients living with chronic illness
• Patients who have edema, which may cause poor vein visibility or palpability.

Techniques for Managing Difficult/Anchor Veins:

Pre-Cannulation Techniques:

1. Warm compresses
2. Topical anaesthetics (e.g., lidocaine)
3. Ultrasound guidance
4. Vein illumination devices

Cannulation Techniques:

1. Use of smaller gauge needles
2. Adjustable needle bevels
3. Over-the-needle catheters
4. Ultrasound-guided cannulation

Anchor Vein Techniques:

1. Anchor vein technique (using a longer catheter)
2. Central venous access devices (CVADs)
3. Peripherally inserted central catheters (PICCs)
4. Midline catheters

Alternative Access Methods:

1. Midline catheters
2. Peripheral IVs
3. Central venous access devices (CVADs)
4. Arterial lines

Method of Cannulation

Deep veins of the upper arm are generally larger and are the best targets, especially the basilic and cephalic veins.

Ideal in these situations: Peripheral IV candidates complicated by obesity, IV drug use, or inability to lie flat for procedures

Not ideal in these situations: Central access needed, cardiac arrest

Optimal positioning: Ideally, position patient with shoulder slightly abducted, elbow completely extended, forearm completely supinated. The ultrasound machine should be placed next to the patient’s head or on the opposite side of the bed, so that you turn your neck as little as possible if needed.

Troubleshooting Difficult Cannulation

Note that the use of the following strategies will depend on the urgency of the situation and the patient’s condition.

• Apply the tourniquet early.
• Gently tap the vein to make it bigger.
• Try releasing the tourniquet and reapplying it. This will cause blood flow through the tissue that has been made ischemic, and a release of histamine that will help make the vein more prominent.

1.The Patient is an Infant

Cannulation can be distressing for infants. The following tips may help the patient feel more comfortable:

• Swaddling the patient.
• If possible, ensure the thermal environment is neutral and prevent cold stress.
• Shield the patient’s eyes from bright lights.
• Allow non-nutritive sucking from a pacifier.
• Administer pain relief.

2.The Patient is Overweight

It may be worth assessing whether it is possible to delay cannulation until IV access can be established using ultrasound guidance in the hospital, as this will be easier. You may also consider:

• Intraosseous insertion (with the proximal humerus providing most likely the best option in the presence of massive fatty tissue).
• Alternative routes such as intramuscular and intranasal (e.g. Fentanyl IN).

3.Difficulty Dilating the Patient’s Vein

Vasomotor changes due to the patient being cold, hypotensive, or nervous may mean the veins require more time to dilate. Try:

• Positioning the patient’s arm below heart level or letting it hang down.
• Warming the skin by gently rubbing or stroking.
• Covering the patient’s arm with a warm towel.
• Applying heat to the arm.
• Encouraging the patient to open and close their hand.

4.Difficulty Puncturing the Vein

You may accidentally pass the cannula through the opposite wall, which will cause blood backflow to cease when you remove the stylet. Try:

• Slightly retracting the cannula until flashback appears again.
• Levelling off the angle, advancing the cannula into the vein, and removing the tourniquet.

Never attempt to reinsert the stylet.

5.Cannula Insertion Failure

Try adjusting the angle of entry. Remove and reassess if this still proves unsuccessful. Remember not to make more than two attempts at cannulation

6.Difficulty Advancing the Cannula

Attaching a saline-filled syringe to the catheter and gently flushing may help. If you feel no resistance, you can advance the cannula while continuing to flush. If this is unsuccessful, remove the cannula and try a different site

7.Patient has Fragile Skin

This increases the likelihood of tissue trauma and cannulation failure. Try:

• Using the smallest cannula available.
• Warming the skin to encourage vein dilation.
• Using minimal tourniquet pressure.
• Decreasing the angle of entry.

8.Venous Spasm

During cannulation, the vein may involuntarily contract, causing sharp pain and skin blanching. This may result in trauma. Try:

• Applying a warm compress to the affected site.
• Choosing a different site if unresolved.

Complications

Insertion complications

1.Nerve injury:

This can occur through poor vein choice and often results in shooting or burning pain, or sharp tingling. If this occurs, the needle and tourniquet must be removed

2.Haematoma:

Infiltration of blood into the surrounding tissues is often caused by poor insertion technique, inappropriate vein selection, inadequate pressure upon removal, incorrect use of the tourniquet or of a cannula size that is too large for the chosen vein. The risk of this occurring is increased in a patient who is receiving anticoagulant therapy

3.Arterial puncture

The inadvertent puncture of an artery rather than a vein can occur if there has been an inadequate assessment of the site and the vein chosen is very close to an artery. This can result in the formation of a haematoma and other symptoms such as numbness, pain, paleness and coldness of the limb or hand. If an arterial puncture occurs, remove the cannula, apply pressure and raise the patient’s arm.

Post-insertion complications

1.Phlebitis:

This is defined as irritation or inflammation of the vein, caused by chemical, mechanical or biological means. Patients can display a range of symptoms, which can include localised pain, oedema and erythema. If this occurs and depending on the VIP score, the cannula may need to be removed and resited. To aid with the discomfort and swelling that can be experienced, a warm or cold compress can be applied

2.Thrombus:

In some cases, a thrombus may develop within the vein that has been used for cannulation. A thrombus can also occur secondary to phlebitis (thrombophlebitis), and it may be necessary to remove and resite as per the VIP protocol

3.Infiltration:

This relates to the administration of non-vesicant medication and fluids into the adjacent tissue rather than the vein. The severity of the complication is usually graded using an infiltration scale, and close monitoring of the patient, cannula site and surrounding tissue will be needed, to assess deterioration or improvement. The VIP score will also need to be recorded

4.Extravasation:

This complication is defined as the administration of vesicant intravenous fluids or medications into adjacent tissues rather than the vein, which subsequently leads to blistering and possible tissue necrosis. Immediate signs include a slowed infusion rate, pain, oedema, and skin blanching.

If extravasation occurs, the infusion of fluid or medication must be stopped immediately and advice sought in relation to whether the fluid or medication needs to be aspirated. In some cases, the cannula will, therefore, need to remain in situ for aspiration and antidote administration to occur. As in the case of phlebitis, warm or cold compresses might be beneficial, and limb elevation may be required due to oedema

5.Air embolism:

This occurs when air or gas is admitted, iatrogenically, into the vascular or arterial system and, although rare, it can be fatal. In the case of cannulation, it can be avoided by the correct priming of the fluid administration set so that no air enters the bloodstream. Signs and symptoms include tachypnoea, reduced oxygen saturations, hypotension, tachycardia and chest pain.

REFERENCES:

1. Sou, V., McManus, C., Mifflin, N. et al. A clinical pathway for the management of difficult venous access. BMC Nurs 16, 64 (2017). https://doi.org/10.1186/s12912-017-0261-z
2. Handan Eren, Difficult Intravenous Access and Its Management, IntechOpen Publishers, https://doi.org/10.5772/intechopen.96613
3. Costantino TG, Parikh AK, Satz WA, Fojtik JP. Ultrasonography-guided peripheral intravenous access versus traditional approaches in patients with difficult intravenous access. Ann Emerg Med. 2005 Nov;46(5):456-61. PMID 16271677
4. Keyes LE, Frazee BW, Snoey ER, Simon BC, Christy D. Ultrasound-guided brachial and basilic vein cannulation in emergency department patients with difficult intravenous access. Ann Emerg Med. 1999 Dec;34(6):711-4. PMID 10577399
5. Shah, Kaushal, and Chilembwe Mason, eds. Essential emergency procedures. Lippincott Williams & Wilkins, 2007.

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