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 cannulation 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 accomplished 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 standards 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 between 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 location 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 process 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 running 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 approximately 1.5 cm lateral and parallel to a line drawn from the angular process of the mandible to the manubrium. The external jugular 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 the mandible and along the expected path of the external jugular vein (Fig. 2). The external jugular or a 16-gauge × 8 in. central venous catheter (Arrow, Reading, vein was typically located 2 to 3 cm beneath the skin’s surface. Pa.) was used. The catheterization was performed by first insert- Technique. Anesthetized pigs were placed in dorsal recum- ing an 18- to 20-gauge × 2.5 in. thin-wall introducer needle at bency. Hair was clipped from the insertion site and its approximately a 30°-angle through the skin directed caudally surrounding area. The clipped region was cleansed with a along the expected path of the vein and into the jugular’s lu- chlorhexidine gluconate scrub and isopropyl alcohol alternately men. The introducer needle was provided in the catheter kits, three times with a total contact time of 5 min. The site was draped to probe for the target vessel. Blood flashback indicated success- with a sterile surgical drape. An assistant placed his/her thumb ful puncture of the vessel. Aspiration via a 6-cc syringe connected tip into the space lateral to the manubrium and cranial to the to the introducer needle occasionally was used as an alternate sternocostal articulation of the first rib providing inward pres- technique to confirm successful puncture of the vessel. After the sure to occlude the external jugular vein. The ipsilateral thoracic vein was entered, a flexible wire guide (length, 60 cm) was passed limb was held slightly flexed and slightly abducted at the shoul- through the introducer needle, and a portion was advanced into der (Fig. 3). A 7-French (length, 8 in.) triple-lumen central the vessel lumen. The guidewire was left in place and the intro- venous catheter (B. Braun, Bethlehem, Pa.), a 16-gauge × 8 in. ducer needle withdrawn. The puncture site was enlarged by single-lumen central venous catheter (Burron, Bethlehem, Pa.), making a small stab incision immediately adjacent to the

Volume 41, No. 1 / January 2002 CONTEMPORARY TOPICS © 2002 by the American Association for Laboratory Animal Science 39 Figure 4. Diagram of the catheterization technique used. (A) A thinwall introducer needle is inserted caudally at an approximate 30° angle through the skin into the lumen of the jugular vein. (B) A wire guide is passed through the needle and advanced into the vessel lumen. (C) The thinwall needle is removed leaving the guidewire in place. (D) A rigid dilator is threaded over the guidewire and is advanced through the skin and subcutaneous tissue and into the vessel lumen. The dilator then is removed, leaving the guidewire in place. (E) The catheter is advanced over the guidewire and into the vessel. (F) The wire is then removed. The catheter is capped and secured in place. guidewire with a #11 scalpel blade. A rigid dilator supplied with Results the kit then was threaded over the guidewire, advanced through Outcomes. Catheters were placed by one of four veterinary tech- the skin and subcutaneous tissue, and removed. This action cre- nicians or one veterinarian. Prior to the study, none of the techni- ated a tract that facilitated insertion of the vascular catheter (21). cians had ever placed a percutaneous catheter by using the Selding- The catheter, filled with heparinized saline (10 U/ml), was ad- er technique. The median time required for catheter placement vanced over the guidewire and into the vessel (Fig. 4). Catheters was 38 min (range, 25 to 95 min), including anesthesia induction were premeasured and advanced until the tip was thought to be and recovery. Thirteen catheters were placed in the right exter- just cranial to the base of the heart. Once the catheter was in nal jugular, and four were placed in the left external jugular place, the wire was removed. The catheter was aspirated to con- vein. Catheters remained in place and patent for at least 48 h in firm placement and then flushed with heparinized saline. each pig. Catheter placement in two pigs was confirmed radio- Injection ports filled with heparinized saline were luer-locked graphically; no abnormalities were noted (Fig. 5). onto the catheter hubs. The catheter was secured in place by Complications. Inadvertent arterial catheterization occurred using 000 silk and 1-in. non-porous tape used to create “butter- in one pig. The catheter was allowed to remain in the pig for 48 fly wings.” In addition, a small cutaneous suture was placed h. In addition, in a pilot study of six catheter placements in three around the catheter at its insertion site. After the catheter was pigs, one catheter was placed inadvertently into an artery. This secured, topical Betadine ointment (Purdue Frederick, Norwalk, catheter remained in place for 72 h. After that period, the cath- Conn.) was placed at the site of insertion with an overlying oc- eter was removed, and manual pressure was placed over the clusive bandage (Tegaderm HP, 3M Health Care, St. Paul, catheter site for 5 min. No adverse clinical signs were observed Minn.). Finally, the lumens of catheters that were not to be used subsequent to removal of the catheter. for 24 h or more were filled with 0.5 cc heparin (1000 U/ml). Prior to use, the catheter was aspirated and flushed with physiolog- Discussion ic saline solution to confirm patency. Guidewire-assisted vascular cannulation was introduced in the

40 CONTEMPORARY TOPICS © 2002 by the American Association for Laboratory Animal Science Volume 41, No. 1 / January 2002 Figure 5. Postplacement radiographs used to confirm location and placement of jugular catheter. (A) Ventral dorsal thoracic radiograph showing the tip of the jugular catheter cranial to the base of the heart. (B) Right lateral thoracic radiograph showing the tip of the jugular catheter just cranial to the base of the heart. early 1950s and is often called the Seldinger technique, after its second layer of 2” adhesive tape (Elastikon, Johnson & Johnson, inventor. In 1953, Seldinger described a simple method of in- Arlington, Tex.) wrapped once around the neck. The cranial in- troducing a catheter for use in percutaneous arteriography. The sertion site allowed the tape to be well cranial to the pig’s thoracic main principle centered on the catheter being introduced on a limbs and thus prevented any possible interference with gait or flexible leader (guidewire) through the puncture hole after with- normal day-to-day functions. The other two reports we mentioned drawal of the puncture needle (22). With few modifications, this used bandage tape as part of their catheter securing technique, technique has become widely used for all types of vascular can- covering the catheter insertion sites and going around the pig’s nulation. The guidewire technique has the presumed advantage neck and/or the ipsilateral thoracic limb. Their insertion site lo- of minimizing damage to soft tissues and blood vessels by using cations and bandaging techniques arguably could have affected a small-bore probe needle. In some cases, the use of a rigid dila- the animal’s mobility, but such complications were not reported. tor catheter to facilitate catheter advancement through tough Less invasive procedures have become the standard of human skin and subcutaneous tissue may somewhat reduce this advan- care as they decrease tissue trauma and allow faster patient recov- tage. However, postexperimental necropsy evaluations in our ery. Animal model research necessary for medical device study revealed minimal tissue damage with our use of dilators. development has increased the need to use similar techniques Even with these suggested complications, the guidewire technique during investigational device evaluation (24). Vascular access in currently is the preferred method for central venous and arterial research swine usually is obtained by surgical cut-down that ob- cannulation (21, 23). This technique is illustrated in Fig. 4. viously causes at least some disruption along the tissue tract as Other reports have demonstrated the usefulness of a guidewire well as some activation of cytokine inflammatory mediators or technique for vascular catheterization in pigs of varying sizes inflammation. Another obvious benefit of minimally invasive (8, 19, 20). The technique described here represents a reli- techniques is in pain reduction. Even minor surgical procedures able alternative to the usual catheterization of the jugular vein are associated with perioperative discomfort and pain. Minimally in pigs under anesthesia. This procedure differs from those in invasive procedures arguably cause less tissue damage and are less the reports of Matte and Carroll et al. (19, 20) using similar tech- painful. These type procedures are often very amenable to short- niques for jugular catheterization in four main areas. We used term, local analgesia. three different, readily available, commercially made catheter- Some reported percutaneous vascular techniques require spe- ization kits. Matte (20) modified a blood collection device to pass cial equipment often expensive and/or not readily available in a guidewire and then used a larger gauge needle to increase the every institution. The procedure described here requires only insertion site opening. Through this opening, polyethylene tub- the catheter and its associated supplies. Central venous catheters ing was passed over the wire for a vessel cannula. Carroll et al. (19) are commercially readily available and come in a variety of styles used components of a commercial catheterization kit augmented and kits. Depending upon how elaborate the kit used, prices vary with a blood collection device similar to the one used by Matte. from a few dollars to perhaps as much as $75. Our investigators Further, unlike these other methods, our procedure was done actually preferred the less expensive, more rigid catheters for aseptically. One of the most important parts of any guidewire the purposes of their experiments. technique is controlling the wire to prevent it from touching The anesthesia protocol we used was selected for its ease, speed any non-sterile surface. Once a guidewire is contaminated, it is of induction, and depth of sedation. Auricular venous catheter- impossible to pass a catheter over that wire without contaminat- ization was well tolerated in most pigs; a few pigs required manual ing the catheter, too. restraint of their ears during catheter placements. Minimal vo- We used a more cranial insertion site, well demarcated by obvi- calization occurred during auricular venous catheter placements, ous anatomical landmarks, than the insertion sites of other meth- especially if the surrounding area was kept quiet and without ods. This more cranial location should reduce the possibility of ia- distraction during catheterization. Propofol induction was rapid trogenic pneumothorax caused by inadvertently advancing the and smooth. No cardiac or respiratory problems were encoun- insertion needle into the cranial thoracic cavity or the lung apex. tered at the doses used. Pigs were maintained at a depth of The exterior portion of our catheters was secured by locally apply- anesthesia sufficient to allow the pigs to remain comfortably in ing an adhesive occlusive bandage. In some cases, we also used a dorsal recumbency. Recovery times were short, with unassisted

Volume 41, No. 1 / January 2002 CONTEMPORARY TOPICS © 2002 by the American Association for Laboratory Animal Science 41 ambulation typically seen less than 15 min after stopping the 4. Takahashi, H. 1986. Long-term blood-sampling technique in pig- propofol infusion. Some catheter insertion sites were infused lo- lets. Lab. Anim. 20: 206-209. cally with lidocaine for patient comfort. No subjective difference 5. Baldi, A., M. Verga, M. Maffii, et al. 1989. Effects of blood sam- was noted between patients that received lidocaine and those pling procedures, grouping and adrenal stimulation on stress responses in the growing pig. Reprod. Nutr. Dev. 29:95-103. that did not. Few problems have been reported regarding per- 6. Farmer, C., P. Dubreuil, Y. Couture, et al. 1991. Hormonal changes forming similar central venous catheterization procedures in following an acute stress in control and somatostatin-immunized awake, snared animals. These problems included vocalization pigs. Domest. Anim. Endocrinol. 8:527-536. subsequent to being snared, and a propensity to assume the sit- 7. Brenner, K. V., and H. Gurtler. 1981. Further studies of swine reac- ting position during cannulation (16, 17, 20). Due to the simplicity tion to fixation with a maxillary sling based on metabolic and of administration, propofol’s rapid induction and recovery, and hematologic parameters. Arch. Exp. Vet. Med. 35:401-407. ease in controlling the depth of anesthesia/sedation, we saw no 8. Zanella, A. J., and M. T. Mendl. 1992. A fast and simple technique benefit in attempting our procedure on an awake animal. for jugular catheterization in adult sows. Lab. Anim. 26:211-213. 9. Christison, G. I., and T. M. Curtin. 1969. A simple venous catheter Routine thoracic radiographs allow confirmation of catheter for sequential blood sampling from unrestrained pigs. Lab. Anim. placement. Parsa and Shoemaker (25) reported a 99.3% clini- Care 19:259-262. cal accuracy in detecting the position of jugular catheters in 10. Takken, A., and K. C. Williams. 1981. A simplified procedure for humans as corroborated by routine radiographs. Considering other long-term catheterisation of the anterior vena cava in adult pigs. indications for radiographic study for the detection of pneumotho- Aust. Vet. J. 57: 14, 17-18, 20. rax, phrenic nerve injury, catheter tip erosion, and all otherwise 11. Pijpers, A., E. N. Noordhuizen-Stassen, S. A. Goedegebuure, et al. questionable situations, they estimated 80% of catheters do not 1989. Intravenous catheterisation of conventional pigs without ap- require routine radiographs postplacement. plication of antimicrobial agents. Vet. Quart. 11:216-221. 12. Bain, S. A., J. Ting, C. J. Simeonovic, et al. 1991. Technique of Inadvertent arterial catheterization is one of the most commonly venous catheterization for sequential blood sampling from the pig. reported complications in humans and occurs in about 5% of cases. Lab. Anim. 4:103-107. All arteries adjacent to the veins are at risk for inadvertent punc- 13. Gaymes, C. H., M. M. Swindle, P. C. Gillette, et al. 1995. Percuta- ture (3). No clinically significant complications were observed in neous serial catheterization in swine: a practical approach. J. Invest. pigs in our study in which an artery was inadvertently catheter- Surg. 8:123-128. ized. Inadvertent arterial catheterization can be avoided by 14. Smith, A. C., F. G. Spinale, B. A. Carabello, et al. 1989. Technical attempting to enter the lumen of the jugular vein relatively closer aspects of cardiac catheterization of swine. J. Invest. Surg. 2:187-194. to the insertion site and further from the thoracic inlet. 15. Ford, J. J., and R. R. Maurer. 1978. Simple technique for chronic venous catheterization of swine. Lab. Anim. Sci. 28:615-618. Percutaneous catheterization of the external jugular vein can 16. Smith, C. A., and M. D. Ficken. 1991. Non-surgical cannulation of easily be accomplished in most medium to large sized pigs under the vena cava for chronic blood collection in mature swine. Lab. mild-to-moderate general anesthesia by using the Seldinger tech- Anim. Sci. 41:274-278. nique. Novice technicians easily learned the methodology and were 17. Damm, B. I., L. J. Pedersen, J. Ladewig, et al. 2000. A simplified able to perform the procedure “uncoached” by the third attempt. technique for non-surgical catheterization of the vena cava cranialis in pigs and an evaluation of the method. Lab. Anim. 34:182-188. 18. Shearer, I. J., and G. D. Neal. 1972. The establishment and mainte- Acknowledgments nance of indwelling venous catheters in adult female pigs. N. Z. We thank Lisa Verzosa, Jennifer Hill, and Vicki Brennan for their Vet. J. 20:73-75. efforts in performing the described procedures. In addition, we thank 19. Carroll, J. A., J. A. Daniel, D. H. Keisler, et al. 1999. Non-surgical Linda Davis for her photographic support. This work was supported by catheterization of the jugular vein in young pigs. Lab. Anim. 33:129-134. the Naval Sea Systems Command No. 63713N.84FC.PQR17.A0022. The 20. Matte, J. J. 1999. A rapid and non-surgical procedure for jugular opinions and assertions contained herein are the private ones of the catheterization of pigs. Lab Anim. 33:258-264. authors and are not to be construed as official policy or to reflect the 21. Marino, P. L. 1998. Vascular access, p. 53-75. In S. R. Zinner (ed.), views of the Department of the Army, Navy Department, Department of The ICU book. Williams & Wilkins, Baltimore, Md. Defense, or the U.S. Government. 22. Seldinger, S. I. 1953. Catheter replacement of the needle in percutaneous arteriography: a new technique. Acta Radiol. 39:368-376. 23. Shively, M. 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