Chapter 3

Techniques of Venous Catheter Placement

Philip C. Pieters

Kurt Wetzler

A detailed description of the techniques involved in the placement of central venous catheters is not possible because the techniques vary widely, depending on personal preference. No two radiologists or surgeons place catheters in the same manner, step for step; however, some basic steps are invariable, including the following:

Each basic step is discussed in detail. The techniques presented are not the only “correct” techniques, but they have been successful over many years. They may stimulate discussion with the hope that the reader may develop new methods or improve the current methods that he or she employs. Techniques are constantly evolving as new information is obtained. The goal in this chapter is to present as much information about the techniques as possible so that readers can decide which methods work best for them.

PREPARING THE PROCEDURE ROOM

Procedure Room Environment

Patients are typically anxious about these procedures; therefore, the procedure room should have a warm and comfortable feel to it. Patterns on the walls will help to minimize the sterile feel of white walls. Music should be soothing to help the patient relax; however, if the patient has a strong preference for music that cannot be classified as “soothing,” playing the music of the patient’s choice may divert the patient’s attention from the procedure and allow him or her to relax. The ceiling needs to be high enough to accommodate overhead lighting. The floor should be hard and seamless to facilitate cleaning.

The doors to the procedure room should be closed throughout the procedure. A sign should be placed on each door warning “Sterile procedure is under way: Do not enter,” or something to that effect, to prevent mistaken entry into the room. Unnecessary traffic into and out of the room should be avoided. Procedure rooms typically are equipped with a high-efficiency particulate air (HEPA) filtered-air circulatory system under positive pressure with 17 to 20 air changes per hour. The air in the procedure room has a positive pressure with respect to the air in the hallways so that unfiltered air does not enter the procedure room. Air-handling systems with filtration can reduce the number of airborne microbes by reducing the number of particles to which microbes may be attached. Appropriate design of cabinetry and placement of storage space can reduce the number of times the door to the procedure room is opened during a procedure. The number of door openings, and therefore the bioparticle count, can be reduced significantly by appropriate design of the storage space.

Rituals abound in the operating room and in interventional radiology procedure rooms because the high-intensity, life-threatening situations in these areas requires control and discipline. Rigid adherence to rules that are translated into “policies and procedures” sets limits on behavior and assists in labeling actions as “correct” or “wrong.”^1,2 Condon and Quebbeman³ state that although the efficacy of many rituals has not been established, the procedures protect the patient from environmental sources of infection and are worth following for reasons of improved and disciplined behavior of the procedure room personnel.

The following procedure room rituals as listed by Gruendemann² may create order, consistency, cleanliness, and sterility:

Preparing the Procedure Table

Most hospital personnel have worked in the operating room and should recall the consequences of touching or coming too close to the sterile field or to the sterile table. If one comes within 2 feet of the table, the wrath of the scrub nurse will ensue. This same mentality must prevail in the angiography suite. The table should be meticulously set up such that it is not contaminated, and once it is prepared for the procedure, only the sterile physician and assistants should touch the table. The table should stand in the center of the room and not rest against the wall or equipment.

Since the demonstration of bacteria in droplets in the nose and mouth by Flugge in 1897⁴ the face mask has been considered a necessity for reducing surgical wound infections. A 1926 study by Meleny and Stevens⁵ seemed to confirm this assumption by showing a reduced infection rate when attendant personnel wear masks. Meleny⁶ repudiated this finding in a subsequent 9-year prospective study, however; this study showed the infection rates to be similar with and without surgical masks. Numerous subsequent studies^7–11 also have brought into question whether masks prevent wound infections, and several of these studies suggest that face masks increase postoperative wound infection rates.^7,9 It has been suggested that the friction of the face mask against the skin of the face releases skin scales that carry bacteria, usually staphylococci.¹² The use of masks should therefore be reconsidered.

It could be argued, however, that masks do protect the operator from splashed blood products touching the mucosal surfaces of the eyes, mouth, and nose and are therefore worth wearing. Consider, however, the splash shield, which not only protects the operator from splashed blood but also eliminates friction to the skin of the face, which may release scales with pathogenic colony-forming units (CFUs). In rooms with air circulatory systems under positive pressure, which carry airborne contamination away from the center of the room toward the periphery, the splash shield should deflect a jet of air from personnel, behind his or her head, which would be carried away from the table.^13–14

The use of surgical masks was adopted a century ago, and the practice was passed along because it seemed reasonable. The ritual of wearing a face mask continues without questioning the effectiveness of the face mask in preventing wound infections. Actual scientific studies suggest that face masks could be replaced by splash shields^15–16 without compromising the quality of care to the patient, providing savings to the medical care system (face masks cost in the range of 25¢ to 50¢ apiece) and greater comfort to personnel. The question is whether the medical community and our patients are willing to accept changes in this age-old practice.

After all, surgical rubber gloves are worn, and they act as sterile barriers that provide protection against wound contamination on the hands of team members. The fact is that a large number of sterile rubber gloves become punctured during a procedure. Studies have shown gloves with holes following procedures range from 12 to 86%.^17–22 These defective gloves are a prime source of wound contamination during procedures. Double gloving can reduce perforations and reduce the risk of wound contamination. One study showed that perforations occurred in both the inner and outer gloves in only 9% of surgical cases.²² Although the risk of a glove being perforated and the operator carrying a virulent strain of bacteria and transferring it into the wound may be small, it is not insignificant, and the operator should scrub the hands and forearms with an antiseptic before every sterile procedure. An antiseptic is a chemical agent that reduces the microbial population on the skin.

The Skin

Human skin harbors microorganisms, providing a complex environment. The stratum corneum is the outermost surface of the skin, which comprises many layers of interposed sheaths of flat, scale-like cells composed of keratin. The cells in this layer of the epidermis are rough and contain a multitude of crevices where bacteria reside. Bacteria are most numerous near the surface of the epidermis and are less numerous in the crevices of the deeper layers of the stratum corneum. Transient bacteria, including Staphylococcus aureus, Streptococcus species, Escherichia coli, Klebsiella species, Enterobacter species, Proteus species, Pseudomonas species, and others, are present on the surface of the epidermis.²³ These bacteria can be exchanged easily between individuals and are removed easily with hand washing. In fact, humans continually shed the bacterialaden cells of the stratum corneum into the environment. The bacteria in the deeper layers of the stratum corneum are called residents and can be removed only with a focused effort and then never completely because of the complex structure of the stratum corneum, which limits complete access of any chemical into the deeper niches. Resident flora includes gram-positive aerobes, such as Staphylococcus epidermis and gram-positive anaerobes. Fungi such as Candida species, S. aureus, Klebsiella species, and Enterobacter species may also be found as resident flora²³ in some individuals. Although resident florea are ubiquitous, they are more concentrated in the axilla, groin, and scalp areas. Because they seem to be anchored firmly to the epidermal elements, they are more difficult to remove with antiseptics than are transient flora. Similarly, up to 20% live in hair follicles or in other nooks and crannies on the skin surface and therefore are not accessible to surface scrubbing. The epidermis below the stratum corneum is virtually sterile.

Numerous antiseptic agents can greatly reduce the bacterial colony counts from the skin immediately after scrubbing. Especially in the moist environment of a sweaty hand in a plastic glove, however, the bacteria counts from the hand increase with time. The counts increase at a faster rate with agents that have only bactericidal activity compared with agents that have both bactericidal and bacteriostatic action.^24,25 These agents, however, do not create a totally sterile skin because, as noted earlier, the resident flora on the skin is not 100% accessible to these preparations. The ideal solution would be inexpensive, have a broad spectrum of bactericidal activity, and be nonirritating and nonallergenic.

Chlorhexidine gluconate (Hibiclens) is the most frequently used surgical scrub today, and it has bacteriostatic and bactericidal properties. Chlorhexidine creates a chemical bond with proteins in the stratum corneum of the skin, which is why its antibacterial action is persistent (i.e., it is also bacteriostatic).^24,26,27 This bacteriostatic action results in less rapid multiplication of bacteria on the gloved hand which, in turn, should decrease the risk of postoperative wound infection if glove puncture does occur. It has a wide range of activity against bacteria (being especially active against gram-positive bacteria and somewhat less active against gram-negative bacteria), yeasts, and viruses. The chemical binds to the negatively charged groups on the bacterial cell wall, producing irreversible damage and death. It may cause irritation in the eyes and middle-ear damage.

Iodine solutions (Betadine) are excellent antiseptics for skin preparation because they are broad spectrum and fast acting. The formulation most commonly used for surgical scrub is iodophor, which contains 1 to 3% elemental iodine. Iodophors are a water-soluble complex of iodine conjugated with organic compounds. They have a good spectrum of activity against both grampositive and gram-negative organisms and possess some activity against spores and fungi. The povidine-iodine preparations are similar in bactericidal effect to Chlorhexidine gluconate initially; however, they lack residual activity²⁸ (i.e., they are bactericidal but not bacteriostatic). For short procedures (less than 1 hour), either Chlorhexidine or iodophor solutions are effective and can be used.²⁹ For longer procedures, Chlorhexidine is clearly superior and should be considered the agent of choice.²⁴

Other antiseptic agents available for surgical scrub are hexachlorophene and alcohol. Hexachlorophene has a narrow spectrum of activity. It does not kill gramnegative organisms that have emerged as significant nosocomial pathogens. Alcohol has a rapid onset but no sustained action. The spectrum of activity of alcohols includes most gram-positive and gram-negative bacteria, tubercle bacillus, many fungi and viruses, including human immunodeficiency virus (HIV). Isopropyl alcohol is an excellent antiseptic and is preferred in many hospitals, although it tends to dry the skin. It is not commonly used as a hand antiseptic because it is not a detergent; therefore, it should be used on skin that is grossly clean (following hand washing with soap and water).

Length of Scrub

The concept of a good surgical scrub has undergone much refinement over the years. With the use of more effective detergents, there is an increasing tendency to shorten the scrub time. Several studies have shown no advantage of a 10-minute scrub over a 5-minute scrub^30–32 in terms of the number of bacteria remaining on the hands. The advantages of a shorter scrub time include a reduction in skin trauma and dermatitis, a saving in water consumption (it is estimated that 50 gallons of water are used in a single 10-minute scrub, and a saving in procedure time.³² O’Shaughnessy et al.³³ recommend a 4-minute scrub for the first surgery of the day, followed by a 2-minute scrub for subsequent surgery. Interventional radiologists do not perform one sterile procedure after another, however, with nonsterile cases usually interposed. Therefore, we recommend a 4-or 5-minute scrub before each sterile procedure.^30,34

Hand-Scrubbing Techniques

The purpose of a surgical scrub is the removal of dirt and grease as well as transient and resident flora. This is best achieved by use of a sponge brush soaked with a detergent preparation. All physicians have performed the 5-minute scrub in medical school; however, medical school may have been a few years in the past. Therefore, we will review the surgical scrub in detail. Masks, hats, glasses, thyroid shields, and lead aprons should already be in place when hand washing commences.

Putting on the Sterile Gloves and Gowns Surgical gowns must be made of waterproofed, impermeable materials. At least the sleeves and front of the gown should be reinforced with such materials.³⁵

The following is a safe way to put on sterile gloves without assistance:

PREPARATION OF THE PATIENT

Sedation

Sedation is an important aspect of any invasive procedure. The use of conscious sedation by nonanesthesiologists has helped to allow the increase in the number of minor procedures (e.g., tunneled catheters) performed out of the operating room. Appropriate conscious sedation increases patient comfort and may increase the safety and speed of a procedure by decreasing patient movement. Many patients will require several catheter-related procedures over the course of their treatment, thus making comfort an important aspect of their care.

It is important to establish a formal program for conscious sedation at every institution in which it is used. The program should be set up and run in collaboration with the anesthesia department at the institution. The Joint Commission of Accredited Healthcare Organizations (JCAHO) expects patients to receive the same quality of anesthesia throughout the hospital regardless of where it is administered and by whom. Patients can check with that institution to determine whether a program exists.

Basic elements of a conscious sedation policy should include the following:

Flumazenil (Romazicon) is a BDZ antagonist. It may require as much as 30 minutes to take effect. If both an opiate and a BDZ have been given, treat with naloxone first. Opiates have a greater effect on respiratory drive, and naloxone takes effect more quickly than flumazenil. Flumazenil also has a shorter half-life than many BDZs. If it is used for reversal, the patient should be closely monitored because he or she may become more sedated as the effects of the flumazenil wear off. It is given in 0.1- to 0.2-mg increments IV up to 3 to 5 mg or in 0.5-mg increments if the patient is apneic.

In procedures in which indigenous contamination is not expected (such as venous catheter placement), extrinsic bacteria that contaminate the open wound cause most postoperative wound infections. Possible sources of extrinsic contamination include the skin overlying the operative site,^36,37 members of the procedure team, surgical equipment, and other items in the environment. Methods to prevent contamination from other sources, such as surgical hand scrub, wearing sterile gowns and hats, and disinfecting and sterilizing equipment have been discussed. We now discuss the preparation of the patient’s skin to prevent this source of extrinsic bacteria.

Removing Hair

Multiple studies have demonstrated that shaving the skin prior to surgery increases the risk of postoperative wound infection.^38–40 The old routine of shaving the surgical site the night before surgery has been shown to be risky. Hamilton et al.⁴¹ found the reason for the increased risk of infection. Using electron microscopy, they showed that razors cut not only hair but also the skin, leaving superficial wounds in which bacteria may multiply. If the field is shaved 24 hours in advance, the resulting exudate from abrasions becomes a breeding ground for bacteria, increasing the risk of postoperative infection. If shaving is necessary (e.g., dense hair growth makes suturing or attaching a dressing difficult), it should be performed immediately before the procedure.

Better options than shaving are the use of clippers, which do not cause trauma to the skin, and depilatory creams. Depilatory cream does not increase the risk of infection, ³⁹ but its use has not become widespread because of skin sensitivity to creams. The best action concerning hair removal is not to do it unless it absolutely must be done. If hair must be removed, the use of clippers is the best option.

Antiseptic Solutions

The skin is colonized by resident skin flora. These commensal organisms form part of the body’s defense system and, when confined, are harmless. They are capable of multiplying, gaining nourishment from skin lubricants, burrowing into hair follicles and sweat glands, and becoming inaccessible to usual skin-cleaning methods. Some organisms, including S. aureus, Micrococcus species, Corybacterium species, and some gram-negative bacteria also can take residence on the skin.²³ These can cause infection when transposed to deeper tissue planes as a result of an invasive procedure. They can assume a pathogenic role and are of particular concern when foreign bodies such as catheters and ports are present. The aim of the antiseptic skin preparation is to remove transient and pathogenic organisms on the skin surface and to reduce the resident flora to a low level.^24,42,43 About 20% of the resident flora are beyond the reach of surgical scrubs and antiseptics, and therefore the skin cannot be “sterilized”⁴⁴ Bacteria harbored in the hair follicles invariably rise to the surface and contaminate the previously prepared area.

As previously discussed, several antiseptic topical agents are now available for preparation of skin. Without definitive comparative scientific studies, the consensus favors the use of an iodophor or Chlorhexidine as an antibacterial agent.

Application of Antiseptic Solutions

With the patient in the proper position, preparing the field begins. The operative field must be free from contamination from hair or clothing falling onto the field. The patient should wear a surgical cap so that hair does not fall onto the field. Oxygen tubing for nasal cannula should be wrapped around the head, instead of looped around the ears, and taped to the face. The patient’s gown should be pulled far away from the operative field.

To apply antiseptic solutions, 4 × 4 gauzes on a long clamp or disposable “lollipop” sponges can be used. The gloved hand must not be used to hold the gauzes alone because the hand most certainly will become contaminated. With the first antiseptic-soaked sponge or 4 × 4 gauzes, the antiseptic is rubbed onto the skin, starting at the center of the operative field, which would be the site of venous puncture and the skin exit site (or subcutaneous pocket site). From this central point, the antiseptic solution should be applied in a circular or outwardly spiraling manner (Fig. 3–3).

The edges of the field are painted last so that the contaminants from the edges are not carried to the center of the field, where the incisions will be made. This process should be repeated using two or three more sponges, starting in the center with each 4 × 4 or sponge and spiraling outward. It is critical that a wide area of skin be cleansed with the antiseptic solution. This wide field of preparation is necessary to prevent contamination of the central field from the edges of the operative field. For instance, surgical drapes should not be moved once they are put in place, but occasionally the drapes unavoidably shift because of patient or other motion. If a wide field of skin has been prepared, the drape that has shifted onto the central field is more likely to have migrated from an area of skin that was also cleansed with an antiseptic and will be less likely to contaminate the field. Additionally, despite well-laid plans, procedures do not always go exactly as planned. For example, a subcutaneous tunnel may need to be relocated, and it is good if the new site of the tunnel is already prepared.

A typical operative field for a jugular puncture, for example, should extend from the mastoid process to the nipple and from the axilla to the contralateral edge of the sternum (Fig. 3–3).

Applying the Drapes

Contamination of the catheter by skin organisms at the time of insertion is one of the causes of development of subsequent catheter-related infection. Antiseptic solutions and other methods that decrease bacteria burden at the insertion site prevent catheter colonization and infection. Protective isolation using sterile barriers reduces nosocomial infection during catheter placement.^45–47

Drapes come in a wide variety of shapes and sizes, with central openings that also vary in shape and size. The choice of drapes is based on personal preference and costs. For internal jugular vein punctures and subclavian vein punctures, we prefer brachial drapes, which are large enough to cover a large area, but small enough to be removed easily from the patient’s face. The drape may be cut away from over the patient’s face by an assistant. Another technique to remove the drape from the patient’s face is to have an assistant fold the drape, exposing the face on the side contralateral from the procedure (Fig. 3–4A), with the drape still tented over the face on the side of the procedure.

HELPFUL HINT

A sterile plastic barrier with adhesive along one border can be used to drape across the forehead, taping the brachial drape into position so that it does not move or fall across the patient’s face (Fig. 3–4B). This is especially useful when performing a jugular puncture while standing at the head of the table. Without the plastic barrier in place, the nonsterile top of the head and the face are too close to the sterile puncture site. In this circumstance, it would be easy for the end of the catheter or suture material to accidentally drag across the forehead or for a sterile glove accidentally to touch the top of the patient’s head, thus contaminating the hand. The sterile plastic barrier also allows the physician to brush against the table without contaminating the front of the gown, which then could easily contaminate the gloves.

It is important to keep the patient’s face uncovered by using one of the preceding techniques or by creating a tent under the drape. Most patients are claustrophobic to some degree, and having their face covered raises their level of anxiety. With the face uncovered, the patient is able to see the nurse nearby, who can provide moral support and comfort to the patient.

Larger drapes, such as pediatric drapes and femoral drapes (placing one of the openings at the venous access site), also can be used but may be difficult, because of the large size of these drapes, to fold away from the patient’s face. Alternatively, these larger drapes can be used, and a portion of the drape cut away from the face or a tent can be created over the patient’s face such that the patient can see daylight.

A large sterile barrier or femoral drape should be placed over the lower half of the body from approximately the level of the nipples to the feet. This drape allows a large working area from which to rest the end of guidewires and instruments. This drape also covers the table controls, allowing for sterile use.

After cleansing the skin, applying the drape, and obtaining venous access, gently lift the adhesive portion of the drape in the direction that you wish to create the subcutaneous tunnel (and pocket if needed). Cut a section of drape large and long enough to create the tunnel/pocket. This skin underlying the drape is still clean because the overlying drape is sterile. Ensure that the drape does not move such that a contaminated portion of the drape moves over a sterile area of the skin. Therefore, when originally placing the drape, the opening must be placed precisely at the puncture site and the drape adhesive adhered to the skin immediately. The drape should not be moved from this point onward. Care must be taken when pulling up on the adhesive to cut the drape, not to allow the drape to slide. The drape should be cut with scissors to avoid cutting the patient with a scalpel blade. We cut the drape in the shape of a keyhole (Fig. 3–4A), with the upper round portion of the keyhole being the round opening of the drape where the venous puncture was performed and the lower flared end at the skin exit site or the site where the pocket for a port will be placed. The alternative to cutting away a portion of the drape is to use a drape with a larger opening; however, it may be difficult to center the opening over the sterile area without including a nonsterile portion of the body within the drape opening. Some interventionalists place an iodophor-impregnated occlusive covering (3M) over the operative site. Incisions can be made through the covering.

After preparing the skin and draping the patient, the skin overlying the vein to be punctured should be anesthetized. First, identify the skin site that will be punctured by palpating landmarks, by performing a preliminary localizing ultrasound, or with a venogram. Inject the lidocaine and allow the anesthetic to diffuse in the tissues for at least 30 seconds before performing the venous puncture, at which time there should be onset of anesthesia.⁴⁸ A burning pain is commonly experienced on injection of lidocaine and can make injection of a large amount of local anesthetic unpleasant to the patient. The burning pain is attributed to several factors, including an intradermal instead of subcutaneous injection, injection of anesthetic at room temperature rather than at body temperature,^49–51 pressure effect from rapid injection, the use of large needles, and the acidity of the solution.^52–54 Several precautions can be taken to make injection of lidocaine less painful: (1) always use a 25- or 27-gauge needle; (2) inject slowly to allow the anesthetic time to diffuse in the tissues and decrease the pressure effect; (3) keep lidocaine in a warmer; (4) do not start by making a large “wheal,” which is very painful to the patient, instead push the needle quickly through the dermis and inject into the subcutaneous tissue; (5) buffer the lidocaine solution (see later discussion). Other helpful steps include the following:

Buffering Lidocaine As discussed, the burning pain associated with injecting local anesthetic can be attributed to several factors, but the most important of these is the acidity of the solution being injected. Lidocaine has a pH of 5.0 to 7.0, which makes it more soluble and stable and extends its shelf life to 3 or 4 years. At the labeled pH, however, there are more charged particles, which are believed to produce the burning pain associated with injecting the solution.^55–57 Buffering the lidocaine to a pH of 7.1 to 7.4 has been demonstrated in many studies to reduce the pain of injection.^55–62 The studies have encompassed various fields of medicine, including interventional radiology,⁵⁹ foot surgery, ⁶¹ obstetrics and gynecology (Norplant System implantation)⁶⁰ and plastic surgery (liposuction).⁶² The optimal concentration of buffered lidocaine as calculated by Stewart⁶³ can be obtained by injecting 3 mL of 8.4% sodium bicarbonate into a 30 mL vial of 1% lidocaine. That is, the mixture should be approximately 10 parts 1% lidocaine and 1 part 8.4% sodium bicarbonate. With alkalization, the shelf half-life of lidocaine is shortened, and for this reason, the mixture is prepared immediately prior to use. The rapidity of onset of anesthesia has been shown to be slightly faster with the buffered solution⁴⁸ and the duration of action is the same as the acidic solution, at least 1.5 hours.^52,58

Lidocaine with Epinephrine Vasoconstrictors This is added to local anesthetics to decrease the amount of bleeding during an invasive procedure.^64–71 Other possible benefits of epinephrine in lidocaine are prolonged duration of anesthesia^72–75 and reduction of systemic toxicity of the anesthetic by reducing systemic absorption.

Epinephrine, however, is systemically absorbed after local injection and produces dose-dependent cardiovascular effects due to stimulation of alpha- and beta-adrenergic receptors. Stimulation of the beta-receptors occurs at lower levels of systemic epinephrine, causing increased heart rate, cardiac output, and myocardial oxygen consumption, which ultimately can lead to cardiac arrhythmias. At higher levels, alpha-receptor stimulation causes increased vascular resistance and can lead to systemic hypertension. Local toxicities also can occur with subcutaneous injection of epinephrine, including delayed healing of the wound⁷⁶ and skin necrosis.^77,78 These complications are dose related; therefore, use of the minimal concentration and minimal dose of epinephrine sufficient to provide adequate vasoconstriction to decrease bleeding should reduce the risk of toxicity. Dilute solutions of 1 to 100,000, 1 to 200,000, and 1 to 400,000 provide vasoconstriction with little difference in blood flow reduction between these concentrations.^64,66,67,72

VENOUS PUNCTURES

General Principles

The use of small needles and wires with coaxial dilators (micropuncture sets) that allow conversion to standard guidewires is preferred for jugular and subclavian vein punctures. Using venographic or ultrasonographic guidance, traversing the pleura is unlikely, but is possible. Data comparing the rate of pneumothorax using large needles (16 to 18 gauge) and using fine needles (20 to 22 gauge) shows lower rates for the latter^79,80 during percutaneous lung biopsies. These data can be extrapolated for venous access. Also, the risk of pneumothorax increases with the number of times the pleura is transgressed. Therefore, good image guidance is very important. Smaller needles also decrease the risk of bleeding or injury to adjacent arteries if inadvertently punctured.

Also, a dermatotomy need not be made prior to skin puncture. An improperly placed dermatotomy can limit the approach and result in distortion of the skin at completion of the procedure. Therefore, it is better to make the skin puncture at the exact desired position rather than using a dermatotomy, which already has been made. Multiple dermatotomies can lead to wound and possible tunnel infections.

For making the puncture, the syringe should be held with one hand only, holding the syringe within the palm of the hand and applying back pressure on the plunger of the syringe (Fig. 3–5). The other hand is used to palpate the carotid artery or hold an ultrasound probe, depending on the method employed for access. A small syringe (5 or 10 mL) with the attached needle fits nicely into the palm of the hand, and the plunger can be pulled back with the fingers at the same time.

Regardless of the technique used, always double check to ensure that the puncture is not being made through the sternocleidomastoid muscle because dilatation of a tract through the muscle can be difficult as well as painful, and a tunneled catheter through the muscle can result in kinking of the catheter and be constant source of pain and “a stiff neck.” When advancing the needle tip through the skin, resistance to puncture is felt, and care must be taken not to insert the needle too far after the “give” of the needle going through this skin. Likewise, it is common to reflexively pull back when the resistance of the skin gives way, often resulting in pulling the needle back out of the skin. This can result in unnecessary skin punctures.