Central Venous Catheter placement is a common procedure used for venous access and various other indications in intensive care units. The advantages over peripheral venous access include reducing phlebitis, availability of multiple ports for the administration of medications, nutrition, fluids and central venous pressure recording. The technique needs expertise and training for proper placement, reduction in complications and safe medical practice. Ultrasound-guided placement of central venous catheters (CVCs) placement should also be practised to increase success rate and decrease complications.
INDICATION OF CENTRAL VENOUS CATHETER
• Hemodynamic monitoring (CVP)
• Poor peripheral venous access
• Insertion of pulmonary artery catheter
• Infusion of vasoactive substances, chemotherapy or hyperalimentation
• Rapid resuscitation with fluids, blood and blood products
• Temporary dialysis access
• Transvenous pacing
• Aspiration of air embolism
CONTRAINDICATION OF CENTRAL VENOUS CATHETER
• Infection at site of insertion
• Anatomic variation or obstruction
• Superior vena cava (SVC) syndrome.
• Presence of coagulopathy
• Presence of pacing wires or any other indwelling catheters at insertion site
• Patient with right ventricular assist device.
ANATOMY OF CENTRAL VENOUS CATHETER
The most common sites for central venous cannulation include internal jugular vein (IJV), subclavian vein (SCV) and femoral vein (FV). Other veins like external jugular vein (EJV), brachial vein and axillary vein may also be chosen in some select patient populations. Selection of site is usually based on indication, operators experience, comfort and presence of coagulopathy.
Internal Jugular Vein
• Location of vein is in between two heads of sternocleidomastoid muscle (SCM)
• Internal jugular vein lies just lateral to the carotid artery
• Right IJV has a straight course to right atrium
• The lower pleural dome on right side makes right internal jugular less vulnerable to trauma (pneumothorax), as compared to left IJV
• Right IJV cannulation avoids injury to thoracic duct.
• It is located below the clavicle and passes over the first rib and apical pleura,
parallel to the subclavian artery.
• Located in femoral triangle just medial to femoral artery
• Higher incidences of infection are reported as compared to SCV or IJV catheterization.
TECHNIQUE AND EQUIPMENT OF CENTRAL VENOUS CATHETER
Attempts to central venous access occurred in the early 1900s. First described catheters using the cubital veins and FV. In 1956, Forssmann and others were awarded the Nobel Prize for their work in venous access techniques. Aubaniac was the first to describe his 10th-year experience with the use of subclavian catheters for the rapid resuscitation with fluids in military casualties in 1952.
Choice for insertion site and approaches:
Internal Jugular Vein
• Bleeding can be recognized
• Malpositions are rare
• Less risk of pneumothorax
• High success rate.
• Carotid artery puncture
• Not suitable for patients with tracheostomies
• Not preferred for patients with elevated intracranial pressure
• Uncomfortable for patients
• Difficult access during emergencies when airway control is also required.
Three techniques are commonly followed for IJV cannulation. These include:
1. Anterior approach
2. Central approach
3. Posterior approach
Anterior approach: The needle is inserted along the medial edge of the SCM just lateral to the carotid artery. The needle is inserted towards clavicular head of SCM at an angle of 45°.
Central approach: Known as low or apex approach. The needle is inserted caudal to the junction of sternal and clavicular heads of SCM at an angle of 30° to the skin with the direction toward clavicular head of SCM or ipsilateral nipple.
Posterior approach: Needle is inserted at the posterior lateral margin of SCM muscle about 5 cm cephalad from the sternoclavicular joint near the margin of EJV and posterior margin of SCM. The direction of needle should be toward suprasternal notch or contralateral nipple.
• Comfortable for patient
• Easier to maintain
• Less chances of infections
• Useful in patients with short neck and morbid obesity
• Unlikely to collapse in circulatory shock because of its fibrous attachment to clavicle hence it becomes the vein of choice in these clinical situations.
• High chances of pneumothorax
• Difficult to compress inadvertent subclavian artery puncture
• Not a good choice in coagulopathic patients.
Subclavian vein is cannulated by two common approaches:
1. Supraclavicular approach
2. Infraclavicular approach
Supraclavicular approach: Insert the Pilot needle at 45°, bisecting the approximately 90° angle formed by the superior aspect of the clavicle and the lateral border of the SCM. The needle should be introduced parallel to the chest wall.
• Turn patients head away from the side which is to be cannulated and position his arms at the side
• Locate the midpoint of the clavicle and insert the pilot needle 1 cm lateral and inferior to the clavicle.
• Using an angle of 10–15° beneath the clavicle, aim medially in the direction of the suprasternal notch, and “walk” the needle below the clavicle.
• Once the clavicle is passed, further advancement should be almost parallel to the skin for approximately another 2–3 cm until you aspirate free-flowing venous blood.
• Easy access
• Does not interfere with cardiopulmonary resuscitation (CPR)
• Does not interfere with airway access.
• Deep vein thrombosis
• Retroperitoneal bleed
• Difficult in ambulatory patients
• Delayed delivery of drugs during CPR.
The FV is cannulated 1–1.5 cm medial to the femoral arterial pulsations and 2–3 cm inferior to the inguinal ligament.If femoral arterial pulsations are feeble or weak then the FV is cannulated as follows: Divide the space between the anterior superior iliac spine and the pubic tubercle into three segments. The femoral artery lies where the medial segment meets the other two segments and the FV lies 1–1.5 cm medial to this point. The needle is inserted 2–3 cm below the inguinal ligament directed cephalic at 45–60° angle.
Less Preferred Sites for Central Venous Cannulation
External Jugular Vein
• Location variable in neck and left side is easier to access for right-handed person
• Usually difficult in hypotensive patient due to poor filling
• Difficult to pass guidewire to the SCV due to the presence of valve.
• Can be localized with arm in extended position
• Lies in axillary fossa just medial to axillary artery
• Localization is better with the use of ultrasound-guide
• There is limited data on infection rate associated with its cannulation.
Central Venous Catheter
Material and Properties
Central venous catheters are polyurethane (commonly used for catheter body) catheters with characteristics like:
• Tensile strength, which allows for thinner-wall construction and smaller external diameter
• High degree of biocompatibility, kink and thrombus resistance
• Ability to soften within the body.
Types of Catheter
• Based on lumen of catheter: Single or multiple lumen catheter
• Drugs coated catheter: Catheter coatings may include the bonding of the catheter surface with antimicrobial and/or antiseptic agents to decrease catheter-related infection and thrombotic complications. Heparin-bonding process is one example. Other agents reported in the literature include antibiotics such as minocycline,rifampin, antiseptic agents like chlorhexidine and silver sulfadiazine.
• Choice of catheters: It is based on the clinical assessment and needs of the patient. Usually depends on the basis of lumens, length, approach and the specialized coated catheters.
• Flow rate of catheter: It is important to remember that the flow in central lines is determined by the diameter of the catheter and the length of the line (Poiseuille’s law). Thus a 16 gauge peripheral intravenous (IV) will have far greater flow rates (up to 220 mL/min) than a double or triple lumen CVC.
Length of Catheter to be Inserted
Incorrect positioning of catheters can manifest with serious complications. Ideally, the correct position of the tip of CVC should be in the SVC above the level of pericardial reflection along the long axis of SCV. Site chosen for insertion, patient’s height and body habitus should decide the catheter length insertion. Length of insertion based on above factors may not be practical and hence catheter length insertion calculated for different sites may be used. McGee et al. suggested that an insertion depth of 16 cm is safe for IJV and SCV route while Russel et al. suggested a length of 13 cm for the CVCs to be appropriate. It has also been recommended that when using central approach for cannulating the right-sided IJV the catheters can be fixed at a length of 12–13 cm in males and 11–12 cm in females. Catheters can be fixed at a length of 13–14 cm in males and 12–13 cm in females in the left IJV for correct positioning of the tip of the catheter. Chest X-ray (CXR) is the gold standard to confirm the correct position of CVC. Ideally the tip of the catheter should lie at the level of carina in CXR.
Ultrasound-guided Central Venous Cannulation
Bedside ultrasound not only displays us an image of patient’s vascular anatomy but also gives us real-time visualization of the needle as it enters the vein.
• Real-time visualization and guidance for venous cannulation
• Success of cannulation with minimal attempts
• Decreased procedure-related complications.
It is important to understand the sonographic difference between veins and arteries. Veins appear as thin-walled, non-pulsatile, and easily compressible structures. This principle applies to both the central and peripheral veins. Also, it is essential to keep in mind that superficial vessels stand-alone while deeper vessels are paired (vein and arteries together). It is always safe to spend adequate time in vein scanning prior to needle puncture. The depth, direction and patency of the vein should be examined using ultrasound prior to needle insertion.
The choice of central vein for ultrasound-guided procedure is usually the IJV or SCV. The FV should only be considered if the above veins are not accessible.Since the SCV runs for a significant distance under the clavicle its ultrasound visualization is difficult due to high acoustic impedance from the clavicle. Only In a lateral or supraclavicular approach good imaging of SCV can be obtained. Hence it is a difficult choice for ultrasound-guided cannulation. On the contrary, the IJV does not have any bony interference, making it an ideal vessel to cannulate.
Probe selection: Transducer frequency ranging from 7.5 MHz to 10 MHz, and flat surface (linear array) is recommended for ultrasound-guided vascular access. Care must be taken to cover the probe with a sterile sheath prior to starting the procedure.
PREPARATION OF CENTRAL VENOUS CATHETER
• Obtain consent from patient or next of kin when possible except in emergent conditions, explaining the risks and benefits of the procedure.
• Institute monitoring to the patient [pulse oximeter, blood pressure cuff, electrocardiogram (ECG)], if not previously attached.
• Review investigations like platelet count, international normalized ratio (INR) and activated partial thromboplastin time (aPTT). Coagulopathy may decide the site of cannulation or need for transfusion of blood products during or after cannulation and also the choice of ultrasound-guided cannulation.
• Obtain peripheral IV access whenever possible before attempting central venous cannulation.
• Give oxygen therapy, if procedural sedation is required for a conscious patient.
• Optimize patient position according to site and comfort of operator.
• Perform full asepsis for the procedure.
• Equipment required: Central venous catheter insertion tray, sterile gloves, an antiseptic solution with skin swab, sterile drapes, sterile towels, sterile gown, sterile saline flush,(approximately 30–50 mL), lidocaine 1% (obtain additional vial of lidocaine 1%, if needed), gauze pieces, dressing and scalpel blade no. 11.
PROCEDURE OF CENTRAL VENOUS CATHETER
• Site selection: The procedure begins with the identification of the optimal site, identifying relevant landmarks and patient positioning for site access and operator comfort.
• Maximal sterile barrier precautions Maximum sterile barrier constitutes use of a surgical cap, surgical mask, sterile gown and gloves, protective eye shield, and a large sterile drape that covers the patient’s entire body from head to toe. This technique has shown a significant reduction in the incidence of catheter-related bloodstream infections (CRBSI). Any deviation from these standard precautions, except in emergent life-threatening situations, should result in an immediate cessation of cannulation until the deviation is corrected.
• Site preparation: Chlorhexidine gluconate sterile preparation should be used for at least 30 seconds (e.g. if internal jugular cannulation is planned then prepare from external auditory meatus to clavicle and to the trachea). For Children less than 2 months old, povidone-iodine may be used.
• Allow chlorhexidine site to dry (2 min).
• Prepare your procedure kit with the help of a nurse assistant who should be wearing a sterile gown, sterile gloves, cap and mask. It is important to keep in mind that the central venous line set should be opened only after site preparation and when you are ready to introduce the pilot needle to decrease the exposure time of central venous line to atmosphere.
• Position the patient according to the site of cannulation and comfort of operator. Trendelenburg position for IJV cannulation (15–30°) increases the venous return, increases intrathoracic pressure and decreases the chances of air embolization. The American Society of Anesthesiologists (ASA) task force recommends that when clinically appropriate use Trendelenburg position for IJV cannulation. Wedge support for SCV is not recommended and even turning of head for subclavian can decrease the diameter of SCV and pose difficulty in cannulation.
• Seldinger technique for cannulation, which is the guidewire dilatation technique has made the procedure safe and easy and should be always practised.
• Give adequate local anaesthesia (1%)
• The pilot puncture should be performed using an 18–20 gauge needle and syringe
• Free blood should be aspirated into the syringe
• Confirm that puncture is not arterial
– If any doubt for arterial puncture then connect the high-pressure tubing to the needle and look for the blood flow. Blood should not flow higher than the centimetre of CVP expected.
– In certain conditions like tricuspid regurgitation, and atrial fibrillation, even with venous cannulation the blood may appear to be pulsatile.
• If doubts still persist than blood gas analysis can also be done.
• After confirmation for vein with pilot puncture, puncture with CVP needle, and confirm free flow.
• The direction of bevel of the needle should be outward during IJV site and caudal during SCV cannulation.
• Direction of “J” tip of the guidewire during insertion in IJV and SCV should always be caudally directed.
• Pass the guidewire through the needle keeping an eye on ECG for any arrhythmias.
• If the patient develops arrhythmia immediately withdraw the wire.
• There are a couple of important safety points regarding guidewire insertion, enumerated below:
– The guide wire should not offer any resistance during its movement
– Never force a wire
– If you require force,the wire is in the wrong spot and can result in laceration of the vessel.
– If you cannot advance the guidewire recheck your introducer needle and syringe aspirate for free flow of blood.
• If all of this fails, remove your needle, apply pressure to the site and consider placing your central line elsewhere or take an expert’s help.
• Remove the pilot needle and leave the guidewire in situ
• Using a scalpel, make a stab incision at the junction of the wire with the skin.
• Now with the help of dilator provided in the kit widen the tract over the guidewire. Be cautious not to dilate the vessel.
• Remove the dilator and leave the guidewire in place
• Railroad the CVC over the wire
• Remove the wire and after confirming free flow of blood from each port clamp the ports.
• Suture the catheter to the skin
• Avoid antibiotic ointment for skin dressing. Ultrasound-guided Internal Jugular Vein Cannulation
• Preparation for the procedure in terms of equipment, sterility and assistance is similar to the nonultrasound-guided cannulation.
• The patient’s head can be placed in slightly rotated position or in a neutral head position (the benefit of a neutral head position is that the IJV acquires a more lateral position to the carotid artery. It would rotate anterior and can even override the artery with head movement to the opposite side especially if too much rotation is done).
• Keeping the two vessels in a parallel alignment can minimize the risk of arterial puncture. This is especially important in patients with low venous filling pressures and vein collapse.
• Ultrasoundshouldalsobeusedto locate the SCMwhile choosing the puncture site.
• Needle insertion through the muscle should be avoided to prevent muscle hematoma.
• The indicator on the transducer should be oriented in the same direction as the indicator on the screen and located in the upper left-hand side of the display. It is used as a reference point when directing the needle toward the vein.
• The transducer is placed in transverse orientation over the triangle formed by the two heads of the SCM.
• Gradually slide the probe distally, until you find, two dark and oval or round appearing vessels. Use the transducer to compress the vein to confirm it.
• Position the vein in the center of image on the screen and place the needle in the midline of the transducer. Estimate or measure the depth of the IJV from the skin surface. You can use the same distance when determining how far from the transducer the needle should enter the skin when the angle of insertion is close to 45°. In this scenario it is also important to remember that the length of the needle should be at least 1.4 times as long as the measured depth of the vein. Align the needle with the longitudinal axis of the vein while advancing it.
• Advance the needle under direct vision (dynamic technique). The needle tip on the screen appears as a hyperechoic structure that casts a narrow shadow called “ring-down” artifact. Following cannulation of the vein standard Seldinger technique should be used to place the catheter during which ultrasound is usually not needed.
• The technique for central venous access of the FV is similar to the above described IJV approach.
• Preparation for the ultrasound-guided procedure in terms of equipment, sterility and assistance is similar to the nonultrasound-guided cannulation.
Key Points during Ultrasound-guided Procedure
• If we miss to identify the needle in the tissue then look at “ring-down” effect.
• Always look for the compressibility of vessel. Doppler flow can be used, if doubt still exists.
• If you angle the transducer toward the entry site of the needle on the skin you can visualize the needle earlier.
• Do not advance the needle if the needle tip is not visualized.
• Supine and Trendelenburg is the most preferred position.
• Excessive head rotation should always be avoided.
• Carotid artery and IJV should be in the same window during cannulation. Use
caution if using a long-axis approach for central venous cannulation due to
the inability to maintain visualization of the carotid artery at all times.
POST-PROCEDURE CARE OF CENTRAL VENOUS CATHETER
• Enough evidence does not exist to evaluate whether catheter fixation with sutures, staples or tape is better. It should be determined by local or institutional policies. Suture the central line through the holes on the flanges and also take suture around the body of the catheter so that it should not slip out.
• Transparent or gauze dressing may be used for site dressing depending upon the patient’s profile and unit policy. However, transparent dressings are to be preferred unless contraindicated.
• According to Centers for Disease Control and Prevention (CDC) guidelines 2011 transparent dressings can be changed every 7 days and gauze dressing can be changed every 2 days depending on clinical presentation of the patient.
• Asepsis should be maintained during handling of the hubs. For all stat medications, hub should be cleaned with alcohol swabs.
• Always order CXR to confirm tip of catheter and detection of complications.
• If position of catheter needs to be readjusted, then use full sterile technique as described for insertion of new central line.
• If IV therapy is urgent and catheterization was uncomplicated, catheter can be used prior to CXR confirmation.
• Documentation and notes of cannulation should be put in the patients file for medico-legal purposes and record.
• Examine the catheter insertion site daily for redness, induration and inflammation.
• Review the catheter daily for its need and remove if not necessary.
COMPLICATION OF CENTRAL VENOUS CATHETER
• Air embolus
• Artery puncture
• Pericardial tamponade
• Local hematoma
• Catheter embolus
– Local cellulitis
– Bloodstream infection.
• Neck hematoma with tracheal obstruction.
• Catheter malpositioning
• Catheter knotting
• Nerve injuries.
Catheter-related Bloodstream Infection
Catheter-related bloodstream infection is a clinical definition for diagnosing and treating patients which requires laboratory confirmation to identify the catheter as the source of the bloodstream infection. According to CDC guidelines (2011) diagnosing CRBSI requires fulfillment of one of the following criteria:
• A positive semi quantitative [> 15 colony-forming units (CFU) or catheter segment] or quantitative (> 103 CFU or catheter segment) cultures whereby the same organism (species and antibiogram) is isolated from the catheter segment and peripheral blood.
• Differential period of CVC culture versus peripheral blood culture positivity of more than 2 hours.
An estimate has been made and shown in various studies that in United States approximately $25,000–$56,000 increase in excess healthcare cost or infection episode. The reduction in central line related infections can be easily made by prevention techniques emphasized by CDC guidelines. Training and education of healthcare providers, who place and care catheters and utilization of maximum sterile precautions are some practices which reduce the burden of CRBSI. Use of checklist which includes central line bundle and nurse empowerment has shown to reduce incidence of CRBSI.
Central-line bundle: It includes the following elements:
• Adherence to hand hygiene
• Practice of maximal barrier precautions during central-line insertion
• Use of chlorhexidine (2%) for skin antisepsis
• Optimal-site selection depending upon patient profile for catheter insertion
• Daily review of central line with prompt removal of unnecessary lines.