Taylor, A.H., Mair, T.S., Smith, L.J. et al. (2010). Bacterial culture of septic synovial structures of horses: does a positive bacterial culture influence prognosis? Equine Vet. J. 42: 213–218.25 25 Moore, R.M., Schneider, R.K., Kowalski, J. et al. (1992). Antimicrobial susceptibility of bacterial isolates from 233 horses with musculoskeletal infection during 1979–1989. Equine Vet. J. 24: 450–456.
26 26 Divers, T.J. (2014). Appendix 4 – Adverse drug reactions, air emboli, and lightning strike. In: Equine Emergencies: Procedures and Treatments, 4e (J.A. Orsini and T.J. Divers), 812–816. St. Louis: Elsevier Saunders.
27 27 Alcott, C.J. and Wong, D.M. (2010). Anaphylaxis and systemic inflammatory response syndrome induced by inadvertent intravenous administration of mare’s milk in a neonatal foal. J. Vet. Emerg. Crit. Care. 20: 616–622.
28 28 Nielsen, I.L., Jacobs, K.A., Huntington, P.J. et al. (1988). Adverse reaction to procaine penicillin G in horses. Aust. Vet. J. 65: 181–185.
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3 Complications of Intravascular Injection and Catheterization
Julie E. Dechant DVM, MS, DACVS, DACVECC
School of Veterinary Medicine, University of California–Davis, Davis, California
Overview
Intravascular injection is commonly used to intermittently administer small volumes of medication to horses. Intravascular catheterization is employed to administer large volumes or frequent administrations of medications, provide continuous administration of intravenous fluids, or secure vascular access during situations when immediate access is needed (i.e. anesthesia) or maintaining access is problematic [1, 2]. Types of catheters most commonly used in equine practice are over‐the‐needle stylet catheters and over‐the‐wire catheters. With the exception of intra‐arterial stem cell injections [3] or direct blood pressure monitoring, intravascular catheterization and injection nearly always involves the venous circulation. Complications may occur during catheter placement and venipuncture or while the catheter is indwelling within the vessel.
List of Complications Associated with Intravascular Injection and Catheterization
Anatomic considerations
Perivascular swelling and inflammation
Intra‐arterial injection or catheterization
Catheter placement/dislodgement/patency
Thrombophlebitis
Intravascular foreign bodies
Vascular air embolism/bleeding
Anatomic Considerations
The most commonly used site for intravenous injection and catheterization in the horse is the external jugular vein due to large vessel size and ease and convenience of access. The left and right jugular veins are located in the jugular furrows on either side of the neck. The jugular vein is in close association with the trachea on the ventromedial surface and the common carotid artery and vagosympathetic trunk on the dorsomedial surface [1]. The left jugular vein is also closely associated with the esophagus and the left recurrent laryngeal nerve, which are located dorsomedially to the vein [1]. Although venipuncture or catheterization may occur at any site where the vein is visible, the carotid artery is closer to the jugular vein in the lower part of the neck.
The recommended site for jugular venipuncture and catheterization is the proximal third of the neck, because the omohyoideus muscle traverses between the jugular vein and the carotid artery, placing the jugular vein more superficially and increasing the separation between the two vascular structures [1, 2]. Alternate sites for venous access if the jugular vein is not patent or accessible include the cephalic vein, the lateral thoracic vein, and the saphenous vein [1, 2]. These sites are less preferred because of reduced patient compliance during venipuncture or catheterization (cephalic and saphenous), difficulty in visualizing the vein (lateral thoracic), and increased chance for occlusion or dislodgement of catheters (all sites) compared to the jugular veins [1, 4].
Perivascular Swelling and Inflammation
Definition
Perivascular swelling is localized swelling that occurs at the site of intravascular injection, which may be a minor blemish that does not obscure visualization of the vascular structure or it may be severe swelling that prevents further use of the site or causes associated tissue injury.
Risk factors
Un‐cooperativeness of the patient
Inexperience of the person performing the procedure
Underlying coagulopathies
Injection of irritating substances, such as phenylbutazone, guaifenesin, tetracyclines, etc.
Pathogenesis
Perivascular swelling may be caused by hematoma formation, inflammation of the tissues, or both. Perivascular swelling during intravascular injection or catheterization results from hematoma formation due to trauma to the target vessel or adjacent vessels. The size and rate of hematoma formation will depend on the origin of the bleeding (venous or arterial) and the size of the needle or catheter being used. The second reason for perivascular swelling in the acute setting is a localized inflammatory response to the injection [1, 5, 6]. Perivascular inflammation is most commonly due to perivascular leakage of even miniscule amounts of an irritating medication, but rarely may be caused by individual horses having a hypersensitivity to the silicone coating on most commercial hypodermic needles. If a highly irritating substance is inadvertently given perivascularly, the local reaction may be so severe as to cause necrosis and sloughing of tissues [6]. Irritation or inflammation of the vagosympathetic trunk or the left recurrent laryngeal nerve is an uncommon sequella to jugular venipuncture or catheterization, but is likely related to the causes of perivascular inflammation and swelling.
Prevention
Hematoma formation may be minimized by excellent restraint of the patient, good lighting, clear identification of associated anatomy, and sufficient experience with the procedure. Use of smaller gauge needles or catheters will reduce the vascular trauma but may inhibit recognition of inadvertent arteriopuncture. Perivascular administration of a highly irritating substance may be minimized or avoided by placing an intravenous catheter whenever an irritating substance will be injected. A long (5.25”) catheter should be used preferably over a short (3.5”) catheter to reduce risk of the catheter being dislodged from the vein. The intravascular positioning of the catheter should be confirmed by aspirating blood or passively allowing blood to egress through an unclamped extension set prior to injection of the medication. Although injury to the vagosympathetic trunk may occur on either the left or right side, some veterinarians endorse preference for the right jugular vein to avoid risking
