Access Of Permanent Central Venous Lines
To understand permanent central venous access, the concept of a central venous catheter must be introduced. These are intravascular probes that can be inserted into the large venous vessels of the chest and abdomen. The most commonly used are the internal jugular, subclavian and femoral veins.
Professionals select the most suitable vein to create the access. They do so after first assessing the rates of complications that may develop in each case.
These complications can be classified as mechanical, thrombotic, and infectious. However, most of the contraindications can normally be corrected or treated.
Both in surgical wards and in critical patient units, the installation of a central venous catheter is a frequent situation. This is because in both places the administration of multiple solutions, drugs, even parenteral feeding is required.
Due to the importance of these techniques, the insertion of these catheters must be carried out by the anesthesiologist, internist or surgeon.
Characteristics of the permanent central venous lines
First, it is important to define and be clear about the concept of a central catheter. Catheters are devices that place their distal end in the superior or inferior vena cava. That is, just before entry into the right atrium.
These catheters are called permanent when they can be implanted in the patient for a long time. It is important to mention that in these cases there will be a lower incidence of complications. The chances of injury to the vascular wall are also reduced.
The main requirements for permanent central venous lines are that they be soft and flexible. Likewise, a white radio is very necessary, focused on its radiological control.
Thus, there are a number of materials most commonly used for making catheters. These are as follows:
- Silicone.
- Polyethylene.
- Thin hydrophilic polyurethanes.
- Polyvinyl Chloride. It is known to professionals as PVC.
- Polytetrafluoroethylene Teflon. Professionally referred to as PTFE.
Types of permanent central venous lines
The different accesses can be classified into two types. On one side are the tunnelled ones. On the other, those with a subcutaneous implant. We develop both types below.
Tunneled central venous catheter
This is the access that is usually used in patients who require treatment for long periods. Either continuously or intermittently. Its composition usually includes silicone and thin hydrophilic polyurethanes.
The installation process of these accesses is carried out by creating a subcutaneous tunnel between the clavicle and the nipple. The distal end of the venous line reaches the right atrium through the external or internal jugular vein.
On the other hand, there is a classification of tunnelled catheters. The following stand out:
- The Hickman-Broviack permanent central venous line. It is characterized because it does not have an antireflux valve.
- The Groshong permanent central venous line. Unlike the previous one, this one does have an anti-reflux valve.
Indwelling catheters travel a subcutaneous path between the skin entry site and the punctured vein.
There is a small Dacron cuff attached to the catheter that induces an inflammatory reaction in the tunnel with subsequent fibrosis. Its function is to fix the catheter to the subcutaneous cellular tissue. In this way the risk of infection is significantly reduced.
Permanent central venous lines with subcutaneous implant
In a generic way, these types of pathways consist of boxes or reservoirs of single or double lumen that work together with a catheter. The aforementioned access is tunnelled until it enters the access vein.
These routes are commonly used in patients who require treatment for prolonged periods and continuously or intermittently. One of the most common examples is chemotherapy treatment.
These accesses are installed by connecting the catheter at its proximal end to the subclavian vein and right atrium. In addition, on their distal side they are attached to a titanium deposit or reservoir. This is located between the muscle and the subcutaneous tissue of the infraclavicular fossa.
Among all the classifications of central catheters, this type is the one with the fewest infections. This is because the device is located under the surface of the skin.
