Peripheral catheters
Percutaneous peripheral catheters
Peripheral venous catheters are the most commonly used catheters in most hospital settings. They are relatively safe and easy to insert. Improvements in technology have produced catheters with small calibers, resistance to bacterial colonization, and lowered rates of thrombotic complications. They can be used for a variety of indications and are safe with a variety of commonly administered medications.
The dorsal veins of the hands are excellent choices for catheterization, and they should be the first choices in the placement of peripheral catheters. The dorsal veins of the foot are excellent first choices in neonates and infants but should be avoided in older children [eg, toddlers] if possible because catheters placed here are painful and difficult to maintain without becoming easily dislodged.
Superficial scalp veins [frontal, superficial temporal, posterior auricular, and occipital veins] are also convenient access points in neonates, but shaving of the surrounding hair is required, and the catheters can be difficult to maintain. Care must also be taken when scalp veins are used to avoid inadvertent cannulation of the temporal artery or one of its branches.
Although other veins, such as the median antecubital, basilic and median cephalic veins are relatively large and easy to cannulate, these sites should be reserved as second choices in case a percutaneously inserted central catheter [PICC] or venous cutdown is required.
The great saphenous vein [GSV] is another excellent choice in the pediatric population because of its large size and consistent anatomy. This vein can often be cannulated with ease without direct visualization or palpation.
With a sound knowledge of the anatomy, the femoral vein is another potential site for vascular access. However, because of concerns with infection and thrombotic complications, this site is generally used only in emergency situations. Extreme care must be taken when femoral lines are inserted to avoid damage to the femoral nerve or artery. These lines are best used for short-term access because of their proximity to the groin. Ater insertion, care should be taken to keep the insertion site as clean as possible to minimize the risk of line infection.
Finally, the external jugular vein [EJV] may be used to gain vascular access [see the image below]. The EJVs can be difficult to cannulate because the infant must often be restrained and placed in a dependent position to allow the veins to be visualized. In addition, catheters are difficult to stabilize here and frequently become dislodged; these disadvantages preclude their routine use in this site.
When placing peripheral catheters, the physician may use tourniquets, transillumination, or heat lamps to facilitate insertion. Infants and small children may also benefit from the application of local anesthetic agents [eg, lidocaine and prilocaine [EMLA] cream] to the insertion site to minimize pain and discomfort during catheter placement. When using topical anesthetic creams, one must plan in advance to allow at least 1 hour for the cream to provide the desired effect. Care should also be taken in selecting an anesthetic agent; some may cause vasoconstriction of the vessel, making insertion more difficult.
When placing a peripheral catheter, the physician should always anticipate the need for adequate restraint. Parents and nursing staff can help minimize movement of the child during catheter placement. After the peripheral catheter is placed, adequate stabilization should be used to prevent its dislodgement. Tape and an arm board might be applied to the extremity.
A "flashback" of blood into the catheter tubing may not occur in infants, leading the physician to assume that the catheter is improperly placed. In such a case, the catheter should be flushed with sterile normal sodium chloride solution. Infiltration of surrounding tissues with this solution indicates improper placement.
Peripheral venous cutdown catheters
Peripheral access can be gained by using a surgical venous cutdown. In the past, this method was frequently used in children in whom access was difficult or in emergency situations. However, this technique has fallen out of favor because of its related morbidity, relatively short patency, and technical difficulty.
This technique still has a limited role in emergency situations when other peripheral and intraosseous attempts fail. The cutdown approach poses virtually no risk of pneumothorax or hemothorax and allows direct visualization of the vein. The exposed veins are often of small caliber, and this limits the size of the catheter that can be used. In addition, the distal end of the vein is typically ligated; therefore, the vein is precluded from use as future vascular access.
Although the GSV is usually the primary choice for surgical venous access, the antecubital and femoral vessels can also be used. The course of the GSV anterior to the medial malleolus of the tibia makes it a popular choice for cutdown access [see the image below].
To perform a saphenous cutdown procedure, a sterile field is prepared with the lower extremity immobilized and the foot turned laterally. After 1% lidocaine is subcutaneously injected over the vein, an incision is made perpendicular to the vein. Careful blunt dissection of the subcutaneous tissue with a hemostat is used to isolate the vein. Silk sutures are then looped around the vein, one proximally and one distally. The distal loop may be used to ligate the vein. Gentle tension is then applied to the proximal vessel loop, and a venotomy is made with a No. 11 blade in a parallel fashion to avoid transection of the vessel [see the image below].
The cannula is then inserted into the vein and secured in place by tying the proximal loop. Care must be taken to avoid occluding the cannula [see the image below]. The wound is closed with sutures and dressed. In infants and newborns, the saphenous vein can be accessed at the level of the femoral junction in the proximal thigh.
Although peripheral catheters are commonly used, they are all limited to short-term usage, small-to-moderate infusion volumes, and low-osmolarity solutions. The most common complication of peripheral catheter placement is dislodgment or occlusion, which leads to extravasation of fluids into the extravascular tissues. If this occurs, the catheter should be removed. Extravasation of infusates, especially those of a hypertonic or irritative nature, can have dire consequences, such as tissue necrosis and compartment syndrome.
Intraosseous catheters
Intraosseous catheters were commonly used in the past, but with advances in IV catheters and alternative access techniques, their use has declined. However, the intraosseous catheter still has a major role in life-threatening emergency situations when other access methods fail and when time is of the utmost importance.
Pediatric resuscitation guidelines from the ninth edition of the American College of Surgeons Advanced Trauma Life Support [ATLS] manual recommended the use of intraosseous access when "venous access is impossible due to circulatory collapse or for whom percutaneous peripheral venous cannulation has failed on two attempts" in children aged 6 years or younger. In addition, the guidelines recommended that intraosseous access should be established in the newborn if umbilical venous access cannot be rapidly achieved. [6, 7]
Intraosseous vascular access is based on the anatomic presence of noncollapsible veins in the medullary sinuses in the bone marrow [see the image below]. This venous network drains directly into the central venous circulation by means of emissary veins, resulting in rapid and almost immediate absorption. A variety of drugs [including resuscitation drugs], crystalloid solutions, and even blood products may be given rapidly via the intraosseous route. The large bore of these catheters enables the administration of blood without lysis of red blood cells [RBCs].
Achievement of intraosseous vascular access is simple, rapid, and consistent when known anatomic landmarks are used. [7] In infants and small children, the proximal tibia is the primary choice for insertion. In older children and adolescents, the sternum can be accessed. Other sites for insertion include the distal tibia, the distal femur, the distal radius, and the os calcis. Like all other catheters, intraosseous catheters should not be placed in an already injured limb.
For placement in the proximal tibia, the anatomic landmarks must first be recognized. With a large-bore [16- or 18-gauge] bone-aspiration needle, the insertion is made 1-3 cm below and just medial to the tibial tuberosity by advancing through bone into the marrow space [see the image below]. Correct placement is confirmed with the aspiration of marrow and with the easy infusion of fluid.
Complications are rare with intraosseous vascular access, but they have been reported. The most common reported complication is osteomyelitis, but this is rare [< 1%]. Other complications include fracture, compartment syndrome, leakage at the insertion site, and failure of infusion due to bending of the needle or occlusion of the needle with bone marrow. Intraosseous catheters are not recommended for long-term use and should be removed within 12-24 hours after their insertion.
Peripherally inserted central catheters
PICC lines have become increasingly popular in patients who require intermediate- to long-term venous access. They have become the most popular form of vascular access in the neonatal intensive care unit [NICU]. PICC lines share attributes of both peripheral and central venous access and are readily inserted at the bedside under strictly sterile conditions [as for all centrally placed vascular catheters]. PICC lines are composed of biocompatible materials and come in a variety of sizes. Large PICCs can have multiple lumina.
Careful attention must be paid to choosing a suitable vein. The GSV and the veins of the antecubital fossa [basilic, brachial, cephalic vein] are those most commonly used in clinical practice. After a suitable vein is located [with the help of ultrasonographic [US] guidance if necessary], [8] the PICC line is inserted into the peripheral vein by using a peel-away introducer needle. When the vein is successfully cannulated, the catheter is the advanced to a desired length into a large central vein. Correct positioning of the PICC line is then confirmed with a chest radiograph.
PICC lines are suitable for a number of indications, including TPN, blood sampling, and administration of nearly all medications. They can be used in both the hospital and home setting, a feature that makes them a popular choice for outpatient therapy. PICC lines offer many advantages in the pediatric population, including lowered overall cost and risks compared with surgical vascular-access methods. In addition, they have a solid record of efficacy.
Although no evidence suggests that PICC lines decrease the risks of infection or thrombotic complications, they virtually eliminate the problems of pneumothorax, air embolization, and cardiac arrhythmias. PICC lines are less likely than traditional peripheral vascular access methods to become dislodged, and they can be easily removed when treatment is stopped or when complications [eg, infection or phlebitis] occur.
Because of their often small lumen, one disadvantage of using PICC lines is an increased occlusion rate. Another concern is overusage that potentially exhausts upper-extremity venous access sites. This may have serious implications in chronically ill patients, especially those with renal failure who may eventually require arteriovenous fistulas for dialysis access.
Central venous catheters
Central venous catheters [CVCs] offer many advantages over peripheral lines. They offer a reliable method of infusing large volumes of fluid; they can be maintained over the long term; and they allow the administration of blood products, TPN, antibiotics, and chemotherapy drugs. In addition, they are frequently used for critical care monitoring [eg, monitoring of central venous pressure]. [9]
Percutaneous polyethylene catheters
Various veins are suitable for polyethylene catheters, including the subclavian veins, the internal jugular veins [IJVs], and the femoral veins. Like PICC lines, polyethylene catheters can be readily placed on an elective basis or in an emergency situation. They can usually be placed with only local anesthesia, depending on the child's age and cooperativeness, by using the Seldinger technique. A number of CVCs are available with either a single lumen or multiple lumina.
After a suitable vein is located, a sterile field is prepared. For the Seldinger technique, the patient is positioned appropriately in the Trendelenburg position to access the subclavian veins and IJVs or in a flat-to-reverse Trendelenburg position to access the femoral veins. Local anesthetic [1% lidocaine] is injected locally. Young children may require light, monitored sedation. The syringe and needle are then passed subcutaneously in the direction of the vessel with constant negative pressure applied to the syringe; this point cannot be stressed strongly enough.
When venous blood returns to the syringe, needle advancement is stopped. Should no blood return, the needle is completely withdrawn, and another attempt is made. Attempts to adjust the needle in the tissue pose a risk of damaging the surrounding tissues, including the vein, artery, and nerve.
When blood is aspirated, the syringe is removed, and the guide wire is advanced through the needle into the vein. The guide wire should pass easily. If resistance is met, no attempt should be made to advance the wire further. In this case, the wire should be carefully withdrawn; the syringe should be reattached to the needle, and a further attempt is made to aspirate blood. If no blood is aspirated, the needle is withdrawn, and a further attempt is undertaken. If blood is aspirated, the needle can be carefully rotated 90°, and a second attempt at passing the wire is made.
Difficulty in passing the guide wire should alert the physician to obtain additional help, including radiographic guidance if necessary. Care must also be taken to maintain control of the guide wire at all times. If the guide wire meets no resistance, it is inserted a few centimeters into the vein. Careful attention should be paid to the electrocardiography [ECG] monitor, if available, in order to detect and avoid cardiac arrhythmias.
After the guide wire is in place, the needle is carefully removed to avoid dislodging the wire. A small incision is made in the skin at the insertion site. This incision should be no bigger than the width of the catheter to be inserted.
Many CVC kits contain dilators, which can be used with extreme caution. Again, these should pass without resistance. The catheter is then threaded over the wire and into the vessel. This is a critical point where strict control of the wire must be maintained to avoid losing it in the vein.
After the catheter is in place, each lumen should be aspirated to prevent an air embolism. Blood should be easily withdrawn from all lumina. The lumina are then flushed with heparinized sodium chloride solution; the catheter is secured to the skin with more than one suture. The insertion site is covered with a sterile dressing.
The subclavian vein is the preferred route for central venous access [see the image below]. However, careful attention must be paid when CVCs are inserted in this position, and the physician must have thorough knowledge of the central venous anatomy so as to minimize potential complications. The subclavian vein site is well tolerated by children, it is easy to dress and monitor, and it has good patency.
The subclavian vein is accessed by means of the infraclavicular approach at a point inferior and lateral to the midclavicular bend. The needle is inserted toward the suprasternal notch by guiding the needle posteriorly at an angle of approximately 30° to the chest wall. In children younger than 1 year, the subclavian vein arches superiorly. This variation must be taken into account when vascular access is obtained in this population.
When the IJVs are accessed, the right IJV is preferred because of its straight descent into the right atrium and because of the decreased risk of injury to the thoracic duct, which is near the left IJV. Likewise, thorough understanding of the anatomy is required to minimize complications when the jugular vein is accessed [see the image below]. Care must be taken to avoid injury and cannulation of the carotid vessels when this approach is chosen. Numerous complications can occur when a CVC is placed [see Complications]. [10]
US-guided cannulation of the brachiocephalic vein and the superior vena cava [SVC] has been described. [11, 12, 13] The use of intracavitary ECG has been described as a means of verifying catheter tip positioning without exposing pediatric patients to ionizing radiation. [14]
Silicone catheters
Like polyethylene central catheters, silicone catheters [eg, Broviac or Hickman catheters] are percutaneously placed into a central vein, but they are tunneled a distance from the insertion site. For this reason, they are the preferred percutaneous catheter for long-term treatment needs, such as TPN or chemotherapy.
Silicone catheters are more pliable and less traumatic to veins than polyethylene catheters are. In addition, they have an attached cuff near the proximal end, which is often impregnated with antibiotics. Taken together, the tunneled feature and the cuff improve the stability of the catheter and decrease the risk of infection. Evidence suggests a lowered rate of thrombotic complications with silicone catheters because of their increased pliability, but this assertion has not been conclusively demonstrated in clinical trials. Various silicone catheters are available in both single-lumen and double-lumen formats.
Because of the tunneled feature, silicone catheters require surgical insertion. The subclavian veins, IJVs, and femoral veins can be used. [15] In neonates, the EJV and the GSV can also be selected. The catheter is advanced under fluoroscopic guidance to ensure correct placement. The extravascular portion of the catheter is then tunneled under the skin to an exit site, which is usually on the anterior chest wall. Once inserted, they are sutured in place, flushed with heparinized sodium chloride solution, and covered with an appropriate dressing.
Implantable vascular access devices
Implantable vascular access devices, or ports, have become the device of choice for patients who require long-term or even permanent access. Ports eliminate many of the problems associated with CVCs, such as infection, restriction of daily activities, altered body image, and the need for frequent dressing changes.
Central venous lines with implantable subcutaneous ports [or reservoirs] are an excellent and often preferred means of vascular access in pediatric patients with cancer. These catheters have excellent durability, as they can often be accessed more than 100 times, and the overlying skin acts as a protective barrier for infection. These types of catheters improve the cosmetic appearance, they allow for regular activities, and they do not require frequent dressing changes or special handling.
A number of devices are commercially available [eg, Port-A-Cath, Mediport] with either single- or double-lumen injection ports. Such devices consist of an injection port made from a durable, hard protective shell [eg, titanium] with an overlying silicone diaphragm, which is surgically implanted in the subcutaneous tissue [commonly the anterior chest wall]. The injection port is connected to a silicone catheter, which is placed into the vein by means of the Seldinger technique or direct cutdown. Like silicone venous catheters, ports are tunneled a distance from the access point. Because of the size of the port, children must usually weigh more than 10 kg to be good candidates for port placement.
To access the port, a Huber needle [a special side-holed needle] is used to puncture the diaphragm. The needle does not damage the diaphragm and allows the device to be used repeatedly for long-term access. After the surgical site heals, the port requires no local care or dressings. The major advantage of ports is a substantially lowered rate of infection in comparison with other access devices. One disadvantage is that ports require surgical insertion and removal when treatment ceases or complications arise.