What is a peripherally Inserted Central Venous Catheters (PICC) – A safe alternative to traditional intravenous vascular access
Traditional intravenous access commonly referred to as an IV is a small catheter placed into a vein peripherally (usually on the arm but also in the hand or foot) with the tip of the catheter also terminating peripherally. An IV is traditionally placed by a nurse at bedside and is very common.
A PICC line on the other hand is a class of catheter that enters a vein in the arm much like a traditional IV but has a tip terminating in the larger veins near the heart. PICCs are used for intravenous access that is more stable and allow for longer term access and outpatient care (patients can and are commonly discharged from the hospital with this kind of catheter as opposed to simple IVs which cannot be left in place when you are discharged). PICCs allow medications to be administered closer to the heart because of the location of the tip of the catheter. This allows for administration of medication where the vessels are larger and allows for dilution of the medication being administered. This method also makes it possible to intravenously administer more caustic medications which could irritate the vein walls if administered through a traditional IV which terminates in the smaller veins of the hand or forearm.
An additionally peripherally inserted catheter commonly confused with a PICC is called a midline catheter whose tip terminates somewhere between the location of the entry site and the large central veins near the heart. A Midline catheter is essentially a PICC that is cut short and whose tip is positioned somewhere in the arm prior to reaching the central veins near the heart. Midline catheters are generally not recommended because of the greater risk of thrombosis and DVT which we will discuss later.
PICC line Vs Midline catheter – what are the differences?
PICC stands for Peripherally Inserted Central Catheter = “peripherally inserted central venous catheter”. It is a central venous access that is introduced into the upper arm via a peripheral vein and the tip of the catheter is positioned in the superior vena cava ( superior vena cava)/Right atrium or at the cavoatrial junction . PICCs are mainly used in medium-term intravenous therapy (1 to 6 months). This makes them an excellent alternative to other central venous catheter systems, e.g. Portacath or Broviac catheter.
The midline catheter is a vascular access that is also introduced on the upper arm – but has a maximum length of approximately 25 cm. The tip of the catheter lies in a peripheral vein before getting to the level of the chest. A midline catheter is a safe alternative to IV and can remain in place longer than conventional IV (recommended for treatments 5-28 days) but are generally reserved for patients who cannot get a conventional PICC or in whom treatment requires IV access for greater than 5 days where non-caustic medication is administered. When more caustic medication such as some antibiotics and chemotherapy is to be administered a PICC is preferred because the central position of the catheter tip allows for mixing of the medication with the high blood flow near the catheter tip.
Advantages of a PICC:
PICCs are a safe and easy alternative to other central venous catheters such as Ports and broviac catheters (small bore central venous catheters), since they can also be placed on an outpatient basis by an experienced interventional specialist (e.g. doctor who has experience with image guided central venous access placement). The benefits of this type of catheter is the relative ease of placement which can be performed at bedside as compared with a port which needs to be placed in the operating room given that a skin incision and pocket has to be made to allow for the port to be implanted under the skin. Additionally infusion through a PICC is simple as is subsequent removal of the catheter which can also be done at bedside.
- Catheter can be placed at bedside for Inpatients or outpatients
- Patients can go home with PICC lines in place and have the option for outpatient infusion therapy.
- PICCs are especially favored in patients who have previously suffered a port infection
- Catheter can be left in place for medium to long terms
- New devices can confirm catheter tip position as appropriate even when the PICC is placed at bedside (port and many other catheters require xrays to confirm tip location)
- Easy removal of the catheter, which is also possible on an outpatient basis
Advantages of a midline:
For patients requiring infusion therapy of more than six days, a midline catheter is a safe alternative to an indwelling tunneled small bore central venous catheter. Midline catheters do not have to be changed regularly, and can be left on the patient for several weeks unlike peripheral IVs. This eliminates the need to repeatedly puncture the patient’s arm for IVs. Additionally, the infusion therapy can be carried out at home. Having said the benefits we generally prefer PICC lines be placed especially for those patients receiving medication which can irritate/be caustic to venous walls. The reason for this is that PICCs unlike Midline catheters have tips that terminate near the heart and allow medication to be mixed in with the high blood flow near the heart. In contrast to PICCs midline catheters tip terminates in the axilla (arm pit region) where infusion of some medications can irritate vein walls.
- Much like PICCs midline catheters can be placed at bedside for Inpatients or outpatients
- Midlines are generally reserved for those patients whom infusion duration exceeds six days.
- Outpatient infusion therapy and thus shortened hospital stay
- No x-ray is needed during placement of the midline (much like the PICC) however catheter tip does generally need to be confirmed with a post procedural xray given that devices to localize catheter tip without x ray are not widely available as they are with PICCs.
- No repeated puncture of the patient as you may need with IVs
Complications of PICC Lines
Because of the simplicity of placing central venous catheters through peripheral veins of the upper extremities, peripherally inserted central catheter (PICC) placement for various indications has become increasingly popular. Because of the way they are placed PICCs avoids complications of pneumothorax or injury to the vessels of the neck and chest, which can occur with placement of other central lines. PICCs are however associated with other important complications. The most common and concerning of which is an increased risk of deep vein thrombosis (DVT). There is some literature that suggests that PICCs are responsible for a large portion 1/3 of all upper extremity DVTs.
Incidence and Risk factors for PICC related DVT
The Michigan Risk Score can be used to assess risk of developing DVT in PICC line placement. https://www.mdcalc.com/michigan-risk-score-picc-related-thrombosis
Even when used for short-term (days) or medium-term (weeks) treatment, PICCs have a higher risk of venous thrombosis compared with centrally inserted catheters. This is especially a concern in patients who are critically ill or who have a malignancy. The incidence of deep vein thrombosis (DVT) for PICCs is between 5 and 15 percent for hospitalized patients and 2 and 5 percent for outpatients. Some studies that were set up to simply screen for even asymptomatic DVTs in patients with PICCs found as high a rate as 33%. When compared with central venous catheters PICC lines have a 2.5 fold greater risk of thrombosis among several studies reviewed.
One particular study, the Medical Inpatients and Thrombosis (MITH) Study was a case-cohort study which looked at all venous thromboembolism at a single institution from 2000 to 2009. They found that central venous catheters had a 14fold increased risk of upper extremity DVT but without significantly increased pulmonary embolism risk. Other studies have shown that repeat access into the same area further increased risk of DVT.
Risk factors for forming DVTs from PICC lines include, prior history of DVT, obesity, hematological malignancies, critical illness, and comorbidities such as diabetes and obstructive lung disease have been linked to PICC-related DVT . Additionally catheters with more lumens which are invariably larger tend to have a higher risk of DVT along with catheters placed on the left side or catheters that have been exchanged multiple times.
The catheter to the vein diameter ratio affects the risk for thrombosis. When the catheter is less than 45% the diameter of the vessel it traverses the risk of DVT decreases. PICCs that are larger than 45% the diameter of the vessel they cross have a significantly (13X) increased risk of DVT formation. The brachial and basilic veins provide a large cross-sectional area for placing a PICC. 1 study found that triple lumen PICCs were associated with a greater than 58% risk of DVT.
Other considerations include the importance of proper technique for catheter placement preferably by an interventional radiologist or someone who is well trained in placement of PICC lines. Ultrasound guidance is important in obtaining access and limiting complications. Additionally positioning of the tip of the PICC line is important in limiting complications. PICC tips should be at the cavoatrial junction or in the right atrium where blood flow is rapid and DVT risk is lessened. PICCs malpositioned with the tip in the proximal SVC have a seven fold increased risk of DVT.
Newer technique for placement of PICCs including using electrocardiographic technology (a device that localizes the PICC tip to the sinoatrial node that resides close to the cavo atrial junction/right atrium) helps position the tip of the catheter in the right spot even for bedside PICC line placement.
Clinical features and diagnosis of DVT
Most DVTs occur within the first week or two of placing the PICC line. Most of the DVTs that occur are asymptomatic. These DVTs generally occur at the junction of the axillary and subclavian veins. Symptoms often include arm or forearm pain and or swelling.
Older catheters made from silicone had higher incidence of access site issues and superficial thrombosis. These risks have decreased with the advent of polyurethane devices placed using ultrasound guidance.
Although some studies have linked DVTs in the lower extremities with placement of PICCs placed in the upper extremities the relationship is not clear. Pulmonary embolism (PE) is a rare complication with PICCs.
Diagnosis of PICC related DVT
As with most DVT, diagnosis of PICC-related DVT is made by compression ultrasonography or duplex- or Doppler-enhanced ultrasound for upper extremity . abscess of flow in the vein or non-compressibility on ultrasound helps make the diagnosis. With compression the sensitivity and specificity of ultrasound for diagnosing DVTs is above 95%. Ofcourse DVTs that are more central ie. closer to the heart cannot be seen with ultrasound and can be missed so if the ultrasound is negative but the clinical suspicion is high a ct venogram or conventional venogram can be performed.
Treating DVT related to a PICC line
Treatment includes symptomatic care, anticoagulation, and possibly thrombolysis. Symptomatic care includes extremity elevation, warm or cold compresses, and oral nonsteroidal anti-inflammatory agents (NSAIDs). Whether to remove the catheter depends on necessity for access and overall clinical picture. Replacing the PICC at a different site can run the risk of causing a second DVT at the new site.
Guidelines for the treatment of venous thromboembolism disease recommend at least three months of uninterrupted systemic anticoagulation for catheter-related upper extremity DVT (including PICC-related DVT) involving deep veins of the upper extremity (brachial, axillary, subclavian) . The type and intensity of anticoagulant therapy with catheter-related upper extremity DVT is similar to that given to prevent embolization from lower extremity DVT. While both warfarin and low-molecular-weight heparin (LMWH) may be used, LMWH is preferred in patients with catheter-related DVT who are pregnant or those with cancer.
Interventional procedures for mechanical and pharmacologic thrombolysis are well established but are reserved for large burden of thrombosis or if there is concern for phlegmasia. Indications for thrombolysis include severe symptoms that do not improve with anticoagulation, thrombosis spanning both the subclavian and axillary veins, symptoms <14 days, life expectancy >1 year, and low risk for bleeding. Catheter directed thrombolysis is usually performed with tissue plasminogen activator (tPA) over a 24 to 48 hours period. Patients are brought back after 24 hours for a check and continued for an additional 24 hours (total of 48 hours) if significant residual clot burden remains after the initial 24hrs. Angioplasty and stenting can be performed if there is significant venous outflow stenosis.
Phlebitis and venous stenosis can occur in patients with long standing PICCs. Patients who are dialysis dependent or may become so are better served by placing other types of centrally inserted catheters such as broviac tunneled central venous catheters. The reason for this is to save the veins in the arms which may become stenotic post PICC placement given that these veins may be used for arteriovenous fistula formation(AVF)