Central catheter - Installation of a central venous catheter

Description

The central catheter is a long, thin tube that is inserted into a large vein. A central catheter is used to deliver medications, nutrition, intravenous drugs, and chemotherapy into the bloodstream.

There are different types of central catheters, including:

• Peripheral central catheter - the catheter is inserted through a vein in the arm until it reaches a vein close to the heart;
• A non-tunneled central venous catheter is inserted into a large vein in the neck or leg; the end of the tube is outside the skin.
• A tunneled catheter is a catheter that is secured in place when scar tissue forms. It can be used for several weeks or months. The catheter is inserted into a large vein in the neck, which returns blood to the heart. It is then advanced along the chest wall and removed through the skin at a distance of about 12 cm from the injection site into the vein.
• Port catheter - a device inserted into a vein in the shoulder or neck. A port (titanium chamber) is placed under the skin and a catheter is inserted into a central vein. To administer medications, the port membrane is pierced with a special needle, and for the next 3-5-7 days, any solutions in any quantities can be injected through this needle.

Types of intravenous catheters by size

Depending on the material from which the catheter is made, metal (the part of the cannula remaining in the vein is made of metal alloys) and plastic catheters can be distinguished.
Metal catheters consist of a needle connected to a connector. After puncture, the needle remains in the vein, performing the function of a catheter. Connectors can be transparent plastic or metal and have wings, for example, VENOFIX® (Fig. 1), BUTTERFLY®.

Modern metal catheters VENOFIX9 (butterfly needles). The catheter is a needle made of chromium-nickel alloy with a microsiliconized cut, integrated between plastic fastened wings. On the other hand, a transparent flexible tube 30 cm long is connected to the needle through the wings, at the end of which there is a Luer lock type connection with a hydrophobic plug. Catheters come in different sizes with different needle lengths

Fig.1

This is the most optimal option for intravenous catheters with a steel needle for long-term use (approximately 24 hours). Of all the metal intravenous catheters, they are the most commonly used. Among these catheters, the following modifications are distinguished:

• catheters with reduced cut length and needle length (to reduce mechanical irritation);

• with a flexible tube between the needle and the connector (also to reduce mechanical irritation - forced manipulations of the connector are not transmitted to the sharp tip of the needle);

• with wings made of soft plastic, between which the needle is integrated, which ensures safe puncture even in difficult-to-reach veins.

In modern practice, steel catheters are used extremely rarely, since they are not suitable for long-term stay in the vein due to the high incidence of complications associated with their use. The rigidity of the needle causes mechanical irritation (with further development of phlebitis or thrombosis), trauma and necrosis of sections of the vein wall, followed by extravasal administration of the drug, the formation of infiltration and hematoma. Infusion media introduced through these catheters are poured into the vein not along the blood flow, but at an angle to it, which creates conditions for chemical irritation of the intima of the vessel. A sharp needle creates an abrasive effect on the inner surface of the vessel. To reduce the incidence of these complications when working with steel catheters, their reliable fixation is required, and achieving this condition limits the patient’s motor activity and creates additional discomfort for him. However, there are advantages to using steel catheters. When they are installed, the risk of infectious complications is reduced, since the steel prevents the penetration of microorganisms through the catheter. In addition, due to their rigidity, manipulation of the puncture of difficult-to-visualize and thin veins is facilitated. In pediatrics and neonatology they are the catheters of choice. Plastic catheters consist of an interconnected plastic cannula and a transparent connector, pushed onto a guide steel needle. The transition from a steel needle to a plastic tube in modern catheters is smooth or with a slight conical design, so that at the moment of venipuncture the needle moves without resistance (Fig. 2).

Rice. 2. Transition between the catheter and the guide needle

Unlike catheters with metal intravenous elements, plastic ones follow the route of the vein, which reduces the risk of vein trauma, infiltration and thrombotic complications, and increases the time the catheter remains in the vessel. Thanks to the flexibility of the plastic, patients can allow greater physical activity, which contributes to their comfort.

Today, various models of plastic intravenous catheters are offered. They may have an additional injection port (ported, Fig. 3) or not (non-ported, Fig. 1), and they may be equipped with fixation wings or produced models without them.

Rice. 3. Plastic intravenous catheter with an injection port and a protective clip on the guide needle

To protect against needle sticks and the risk of infection, cannulas with a self-activating protective clip mounted on the needle have been developed. To reduce the risk of contamination, catheters are produced with removable injection elements. To better monitor the catheter, which is in the vein, X-ray contrast strips are integrated into the transparent cannula tube. The puncture is also facilitated by sharpening the piercing cut of the guide needle - it can be lanceolate or angular. Leading PVC manufacturers are developing a special position of the injection port above the fixation wings of the connector, which reduces the risk of cannula displacement when performing additional injections. In addition, some catheters have special holes in them to ventilate areas of the skin located under the fixing wings.

Thus, the following types of cannulas should be distinguished:

1. A cannula without an additional port for bolus injections is a catheter mounted on a stylet needle. After entering the vein, the cannula is moved from the stylet into the vein. 2. A cannula with an additional port expands the possibilities of its use, facilitates maintenance, and therefore extends the period of its installation.

There are two modifications of this cannula. The first modification is the most common configuration. Convenience during placement and fixation, the presence of an upper port for short-term insertions and heparinization of the cannula during infusion breaks have earned the love of doctors.

A wide variety of brands from different manufacturers is distinguished only by the quality of the product. But despite the apparent simplicity of the design, not everyone manages to combine the triad of qualities:

1) needle sharpness and optimal sharpening angle;

2) atraumatic transition from needle to cannula;

3) low resistance to insertion of the catheter through the tissue.

Manufacturers of such cannulas include BOS Ohmeda (part of the BD concern).

In the process of peripheral vein cannulation, sometimes the first attempt may fail for one reason or another. “Scuffs” on the cannula that are invisible to the eye, as a rule, do not allow it to be reused or shorten the period of use to one day. released a traditional cannula from a new material, which potentially allows it to be used if the first attempt at cannulation is unsuccessful without reducing the installation time, and gives the cannula greater resistance to sticking when kinked. This cannula is registered under the brand name "Cathy". The second modification of the cannula with an additional port was developed by Wallace Ltd (a subsidiary of SIMS Portex Ltd) together with a Cambridge doctor, J. Farman. The presence of a silicone insert in the cannula body and a silicone injection port on a flexible lead makes the cannula absolutely safe with respect to contact with the patient’s blood containing hepatitis or AIDS viruses. Retaining all the advantages of its predecessors, it is “bloodless” and, having a flexible outlet, allows you to manipulate infusion access without the risk of developing “mechanical” phlebitis. Since the development of plastic catheters, the composition of the polymer used for their production has also changed. Previously, polyethylene and polypropylene were the most commonly used materials for the manufacture of intravenous catheters. The first is a flexible, non-looping, inert material, the easiest to process, but the catheter tube is relatively thick-walled, has increased thrombogenicity, causes irritation of the inner lining of blood vessels, and, due to its rigidity, is capable of perforating the vascular wall. The second is suitable for the manufacture of thin-walled catheters, but is a very rigid material, used mainly for arterial access or insertion of other catheters. Today, these materials are used only for the insertion of other catheters (“guide catheters”). Currently, three plastic compositions are commonly used: polytetrafluorethylene (PTFE), fluoroethylenepropylene-copolymer (FEP), polyurethane (PUR).

PTFE is one of the embedding materials with a very high level of organic tolerance. Catheters made from PTFE glide well and pose minimal risk of blood clots. Thin-walled models may form loops and become compressed.

FEP (Teflon): In addition to the positive characteristics of PTFE, copo polymer also increases the stability and controllability of the catheter. A radiopaque contrast medium can be integrated into the material, which helps localize the catheter in the blood vessel.

The hardness of PUR depends on temperature (thermoelastic). When cooled, PUR becomes rigid and allows easy insertion of the catheter. When heated by body temperature, PUR becomes soft, resulting in increased tolerance. Experience with the use of PUR for the production of central venous catheters demonstrates the tolerance of this material to venous tissue, as well as low rates of thrombus formation. Therefore, there is a growing trend towards using PUR for the manufacture of intravenous catheters. In recent years, active measures have been taken to prevent the risk of transmission (to the user, medical personnel) of dangerous diseases (viral hepatitis, AIDS) through contact with blood. Particularly in the USA, in order to avoid needle damage, protective fasteners are used that are attached to needles* and catheters, and active and passive protection systems are used. In passive protection systems, when the steel needle is removed, an automatic system surrounding the tip of the needle is activated, thus protecting the user from injury. Thus, the protective clip on some peripheral venous catheters self-activates when the guide needle is removed from the cannula (Fig. 3). In addition to the fact that this type of protection protects medical personnel from injury from a used needle, the opened clip in no way returns to its original “inactive” state, which makes it impossible to re-insert the guide needle into the catheter.

The user must activate the protective mechanism of active systems manually. These are expensive systems and are currently only used in high-risk situations. Thus, WHO supports and promotes the use of this type of product in some African countries. The flexulle design has also changed over the years. The absolute leader in sales of intravenous catheters, the company B. Braun Melsungen AG, received the European Design Award “Columbus Egg” in 2004.

Catheters with injection ports are the absolute standard in Western Europe, where 90% of all peripheral venous access catheters used are Braunulen. This type of catheter has a valve that prevents the infused solution from flowing back into the injection port (Figure 4).

Rice. 4. Scheme of the movement of the drug when administered through the injection port

A syringe without a needle can be directly attached to the injection port. This allows an additional injection to be performed at any time during the infusion, which is why such catheters are most widely used in anesthesiology and intensive care. The scope of application of non-ported (Fig. 5) catheters is much wider. They are applicable in almost all branches of medicine and account for 90% of the total number of catheters used in the world.

Rice. 5. Modern plastic inner catalyzer without injection port

These cannulas have their advantages over ported catheters. They are more economical, more compact, and pose less of a contamination risk because the IV access system's detachable injection unit is changed daily. However, an additional injection is not possible when using catheters of this type, and a separate puncture is required for each injection.

TRANSFUSION SYSTEMS

Transfusion systems

Infusion systems with plastic and metal needles:

Infusion systems are designed for infusion of liquid drugs and solutions. The materials from which the device parts are made are approved by the Ministry of Health.

Infusion systems consist of:

— cap piercing devices with built-in air valve;

— transparent dropper with filter (retains microclots larger than >30 microns)

— transparent camera;

- a long flexible tube with a precise clamp-regulator for the flow of a latex section, allowing additional injections during infusion;

The systems are internally sterile and pyrogen-free for single use; Each system is packaged in a sterile plastic bag.

Transparent tubes. The tubes and droppers are made of polymer material, which allows you to see air bubbles, the liquid level and the drop sequence with the naked eye.

The clamp-regulator provides regulation of the fluid flow from complete shutdown to a jet flow.

The connection of the device parts can withstand an excess pressure of 40 kPa.

The injection unit ensures self-tightening when pierced six times with a needle with a diameter of 0.8 mm in different places.

An injection needle with a triangular sharpening, the needle has a silicone coating, thanks to which piercing any area of ​​the skin makes the injection as painless and safe for the patient as possible, and the treatment as effective as possible.

Certificate of conformity

Reasons for performing the procedure

A central catheter is inserted when the patient needs:

• Administer medications or fluids long-term;
• During chemotherapy;
• For nutrition, if food intake through the digestive system is impossible;
• Periodic blood sampling;
• Blood transfusion;
• For intravenous administration of drugs when the veins in the arm are difficult to access;
• For dialysis.

The central catheter is usually inserted by an interventional radiologist or vascular surgeon. Once inserted, the catheter can be used for several weeks to months.

Principle of catheter design

First of all, the medical staff should know how to administer intravenous infusion of medications. But if patients know information about the procedure, they may be less afraid.

A catheter for intravenous drug administration is a thin, hollow tube. It is inserted into the bloodstream.

This can be done in the arms, neck or head. But inserting catheters into the vessels of the legs is not recommended.

These devices are installed so that there is no need to constantly pierce the veins. After all, this can cause them to become injured and inflamed. Constant damage to their walls leads to thrombus formation.

Possible complications after insertion of a central catheter

Complications are rare, but no procedure is guaranteed to be risk-free. Before you install a central catheter, you need to be aware of possible complications, which may include:

• Bloodstream infections, when bacteria enter the bloodstream through or around the central line;
• Bleeding;
• Lung collapse;
• Arrhythmia (unstable heartbeat);
• Nerve damage;
• An air bubble or part of the catheter may block blood vessels, causing chest pain, shortness of breath, dizziness, and rapid heartbeat;
• Blood clots in a vein or catheter can block blood flow.

Factors that may increase the risk of complications include:

• Smoking;
• Difficult access to veins;
• Blood clots;
• Obesity;
• Broken bones;
• Infection;
• Poor blood circulation;
• Bleeding tendencies.

How is a central catheter inserted?

Preparation for the procedure

• A blood test may be done to check blood clotting;
• The doctor may ask about allergies;
• You need to arrange a trip home after the procedure;
• The patient may be asked to stop taking certain medications a week before the procedure: Aspirin or other anti-inflammatory drugs;
• blood thinners such as clopidogrel or warfarin;

Anesthesia

The area where the catheter will be inserted is numbed with local anesthesia. Depending on where the central catheter will be inserted, a sedative may be given intravenously.

Description of the procedure for inserting a central catheter

This procedure can be done either in a hospital as part of treatment or on an outpatient basis.

Having a catheter increases the risk of bloodstream infection. Hospital staff should perform the procedure while taking the following steps to reduce this risk:

• Care must be taken to select a safe place to insert the catheter;
• Wash your hands thoroughly or use hand sanitizer;
• You must wear surgical gowns, masks, gloves, and cover your hair;
• Cleanse the skin with an antiseptic;
• Use a sterile drape.

The next steps may vary depending on the type of catheter and where it is inserted. In general, staff will do the following:

• Anesthesia is administered;
• A small incision is made;
• X-rays or ultrasound are used to guide the catheter into the vein;
• Before installing the catheter, you need to cut it to the desired length. The catheter is flushed with saline (salt water);
• The catheter is guided using a catheter guide. The conductor is then removed;
• The catheter is secured to the skin (usually with adhesive tape). A cap is placed on the end of the catheter;
• A bandage is applied to the catheter insertion site. The date of insertion is marked on or near the bandage.

If a port catheter is inserted, a small cavity is made under the skin to accommodate it. The incision will be closed, usually with absorbable suture.

Immediately after the procedure

The insertion site will be checked for bleeding, fluid leakage, and swelling.

Contraindications for catheter installation and special instructions

It is recommended to avoid the use of intravenous catheters:

• into the veins of the lower extremities;
• on areas of veins near joints and arteries;
• into nodular veins;
• into the median ulnar vein;
• veins located under damaged skin.

In addition, there are a number of rules related to difficulties in catheter installation that occur in patients with weak, thin and fragile veins:

• if the healthcare worker was unable to enter the vein and install the catheter after three attempts, the specialist should be changed;
• the higher the number of attempts to insert a catheter, the higher the risk of developing mechanical complications;
• mandatory treatment with antiseptic agents reduces the risk of colonization of the catheter cavity by pathogenic microorganisms.

If the catheter and insertion area are not properly treated, the risk of developing nosocomial infection increases. To reduce the risk of infection, it is allowed to leave the catheter in the patient’s vein for 72 hours. And if there is no need to administer any drugs in the future, you must immediately remove the catheter from the vein.

Caring for the patient after the central catheter insertion procedure

Hospital care

After the procedure, staff may provide the following assistance to aid recovery:

• An x-ray is taken to ensure that the catheter is in the correct position;
• The catheter insertion site is periodically checked for bleeding;
• Medicines, fluids, or nutritional solution are given through the catheter;
• The port catheter is flushed to prevent blood clots;
• Steps are taken to reduce the risk of infection: Wash your hands and gloves thoroughly before touching the catheter or changing the dressing;
• An antiseptic is used to clean the exposed parts of the catheter;
• Precautions are taken when handling medications, fluids, or foods that will be administered through the catheter;
• The patient is monitored for signs of infection, which include fever, chills, and problems at the insertion site (eg, redness, swelling, drainage);
• Visitors should not be in the hospital room when the dressing is changed;
• The catheter remains at the insertion site as long as necessary.

There are also steps you can take to reduce your risk of infection:

• Employees should be asked to take all precautions to prevent infection;
• Personnel should immediately alert the physician if there is redness or pain at the catheter insertion site;
• You must wash your hands before entering the room. Visitors should not be allowed to touch the catheter.

Home care

When you return home, you should do the following to ensure a normal recovery:

• The insertion site should be kept clean, dry and bandaged. When changing the dressing, follow the doctor's instructions;
• You should wash your hands or use hand sanitizer before touching the catheter;
• You should ask your doctor about when it is safe to shower, swim, or expose the surgical site to water;
• Do not swim or bathe with a central catheter inserted;
• Any activity that could weaken the central catheter should be avoided;
• No one should touch the catheter;
• The injection site should be checked every day for signs of infection (eg, redness, pain);
• The catheter should be flushed with saline or heparin as directed by your doctor.