A Minimally Invasive Percutaneous Technique for Jugular Vein Catheterization in Pigs MACK FUDGE, DVM, MPVM, DIPLOMATE, ACVECC,1 RANDALL E. COLEMAN, BS, RLAT,1* AND SHERI B. PARKER, PHD2 The objective of this study was to develop a simple, safe, reproducible, and efficient technique that used readily available commercial materials for percutaneous catheterization of an external jugular vein in the pig. Guidewire-assisted vascular cannula- tion was introduced in the early 1950s and is often called the Seldinger technique, after its inventor. With few modifications, this technique has become widely used for all types of vascular cannulation in human and veterinary patients. The technique has the advantage of minimizing damage to soft tissues and blood vessels. We adapted this procedure by using five anatomical landmarks to target and catheterize the external jugular vein in pigs. Percutaneous catheterization of the external jugular vein can be accom- plished easily in most pigs by using this technique. Novice technicians were able to quickly and easily learn the procedure. Swine are increasingly being used for research models, espe- neous wire-guided techniques for jugular catheterization; these cially in the area of cardiovascular study because of their methods used insertion points close to the manubrium typically similarities to human anatomy and comparative hemodynamics used for venous blood collection (19, 20). Each of the above and coagulation (1, 2). Established central venous access is es- minimally invasive techniques demonstrated little hormonal or sential for monitoring and treating both the clinical patient and behavioral effect in the pigs as a result of the catheterization the research subject. Access to a central vein is indicated for procedure. However, none of the studies describe in detail the numerous clinical situations including long-term infusion of anatomy associated with the technique. hypotonic, hypertonic, potassium-containing, and other irritat- The objective of this study was to develop a simple, safe, repro- ing solutions, or when there is lack of accessible peripheral ducible, and efficient technique using readily available commercial superficial veins. In addition, central venous access is necessary materials for percutaneous catheterization of an external jugular for research protocols or husbandry support applications, in- vein in the pig. We developed a minimally invasive procedure to cluding central venous pressure monitoring, long-term catheterize the external jugular vein in pigs with a novel approach intravenous access for repeated blood sampling, and venous using five distinct anatomical landmarks and a standard commer- hemodialysis, and as access for pulmonary arterial catheteriza- cial, wire-guided, central venous catheter kit. tion (3). Long-term venous catheterization for repeated blood sampling reduces or eliminates important variations of biochemi- Materials and Methods cal, hematologic, and hormonal metabolites seen when restraint is used for jugular vein puncture of swine (4-7). Similarly, re- General procedures. All procedures were performed in strict peated jugular puncture is likely to be extremely stressful for accordance with the guidelines outlined in the Guide for the Care the animal and will almost certainly affect hormone levels (8). and Use of Laboratory Animals. All animals were housed in an In the research setting, central venous catheterization in swine AAALAC-accredited facility. The swine were conventional York- often is performed by surgical cut-down. Although a successful shire farm pigs (Sus scrofa domestica) purchased through a technique, surgical jugular catheterization requires general an- USDA-approved vendor (Archer Farms, Bel Camp, Md.) and in- esthesia and potentially demanding post-operative care of the dividually housed in 1.25 m × 2.75 m stainless-steel large animal animal (9-13). The standard of care in patient management is runs with expanded metal flooring. Room temperature was main- to use less insidious methods, and as such, less invasive vascular tained at 22 ± 3°C with 50% ± 20% relative humidity and 12 to access techniques are currently being used in the clinical treat- 15 air changes hourly. Photoperiods were 12:12 h light:dark, with ment of patients. The need for similarly less invasive techniques lights on from 6 am to 6 pm. Animals were fed Lab Porcine Diet for central vascular access in research subjects and models in Grower 5084 (Lab Diet, Richmond, Ind.) twice daily, and water which they are used are important refinements for valid com- was available ad libitum by automatic waters. Recommendations parisons and investigator evaluations. In addition, minimal for the insertion of vascular catheters were followed in accor- manipulation of research subjects reduces the number of ani- dance with the Centers for Disease Control’s universal mals required and minimizes needs for sham-treated controls. precautions. Prior to inserting catheters, technicians washed their Percutaneous access to vessels in swine often is considered hands with an antimicrobial scrub, chlorhexidine gluconate. difficult because of the relatively deep location of the large ves- Technicians assisting with catheter insertion wore sterile gloves, sels and a perception that these vessels have a tendency to spasm caps, masks, and surgical attire. after minimal mechanical stimulation (13, 14). Three percuta- Anesthesia. Eighteen castrated male Yorkshire pigs weighing neous methods have been described in which the authors used 19.4 ± 1.57 kg were administered atropine (0.04 mg/kg) intra- a “through the needle” catheterization technique of introduc- muscularly as a preanesthetic. After being gently restrained in a ing various types of small-bore tubing modified in their Panepinto sling, a peripheral intravenous catheter was placed laboratories (15-17). Another nonsurgical technique was de- percutaneously into an auricular vein. Anesthesia was induced scribed in which a catheter was placed into the jugular vein via via an intravenous injection of propofol (3 mg/kg) and main- an auricular vein. However, these catheters remained in place tained by a continuous-rate intravenous infusion of propofol (20 for less than 4 h (8, 18). Two other reports illustrated percuta- mg/kg hourly). Anesthesia was monitored in accordance with American Society of Anesthesiologists’ standards. These stan- dards were written for human patients and are the standard Department of Veterinary Surgery, Walter Reed Army Institute of Research1 and Department of Environmental Physiology, Naval Medical Research Center,2 Silver Spring, Maryland operating procedures at our facility. 20910 Anatomy. The maxillary and linguofacial veins form the ex- 38 CONTEMPORARY TOPICS © 2002 by the American Association for Laboratory Animal Science Volume 41, No. 1 / January 2002 Figure 2. Photograph of a pig in dorsal recumbency showing landmarks used to locate the external jugular vein in the pig. One solid line is drawn between the angular processes of the mandible, and the other connects the right angular process of the mandible and the manubrium. The dashed line lies approximately 2 cm lateral and parallel to the line be- tween the angular process and the manubrium. This dashed line marks the expected path of the right external jugular vein. The arrow points to the location of the ventral spinous process of C6. The external jugular vein crosses the lateral aspect of this process. The circle marks the loca- tion where the restrainer applies inward pressure to occlude the external Figure 1. Photograph of a pig in dorsal recumbency highlighting the loca- jugular vein to assist with cannulation. The X marks the insertion site, a tions of the right sternocephalicus and cleidocephalicus muscles in relation point midway between the manubrium and the line between the angu- to the manubrium. These muscles were used as the medial and lateral lar processes crossing the expected path of the external jugular vein. landmarks, respectively, for targeting the pig’s external jugular vein. ternal jugular vein, which extends caudally until it converges with the subclavian vein to form the brachiocephalic vein. The external jugular vein runs roughly from near the angular pro- cess of the mandible ventrolaterally and caudally toward a point just lateral to the thoracic inlet. Through post-mortem dissec- tions, five easy-to-identify anatomical landmarks were defined and used to target the external jugular vein. The mastoid part of the cleidocephalicus muscle, a prominent strap-like muscle run- ning from the cranial humerus to the mastoid process, and the mastoid part of the sternocephalicus muscle, a similar strap-like muscle running from the sternum to the mastoid process, were used as the lateral and medial limits, respectively (Fig. 1). The external jugular vein tended to lie just lateral to the sternocephalicus muscle. The external jugular vein was approxi- mately 1.5 cm lateral and parallel to a line drawn from the angular process of the mandible to the manubrium. The external jugu- lar vein also ran along the lateral aspect of the C6 ventral spinous Figure 3. Photograph of a pig in dorsal recumbency demonstrating the process as palpated through the skin on the ventrum of the neck. positioning of the pig and the assistant’s hand placement prior to drap- The insertion point for the catheter was chosen by finding a point ing for jugular vein catheterization. midway between the manubrium and a line drawn between the two angular processes of