or along the catheter [1, 2, 4, 8]. Clinical signs of thrombophlebitis can occur within 24 hours and include thickening at the insertion sites, local swelling, heat, cord‐like thickening of the vein, suppurative exudate (Figure 3.1), pain on palpation, and if septic, may progress to fever, obtundation, and systemic signs associated with septic embolization to distant sites [1, 2, 4, 11]. Thrombophlebitis may also result in perivascular nerve injury, such as Horner’s syndrome and left laryngeal hemiplegia. If thrombophlebitis results in occlusion of venous drainage, associated veins may become dilated and tissues may become edematous (i.e. facial and nasal edema associated with jugular venous thrombosis) [1, 4, 16].
Monitoring
Ultrasound examination of the catheter site and associated vein is most sensitive to detect early signs of thrombophlebitis, such as thickening of the vein and development of a thrombus on the catheter (Figure 3.2) [1, 2, 4, 15]. The entire length of the catheter should be ultrasounded, because thrombi are often initiated at the distal tip. Ultrasonographic evidence of thickening of the vein is evident in at least 27% of catheterized veins maintained for at least 24 hours [15], although external clinical changes are seen in approximately 8–18% of colic patients [17, 18].
Figure 3.1 Photograph of a left jugular catheter insertion site associated with nodular thickening and suppurative exudate.
Source: Courtesy of Pablo Espinosa.
Figure 3.2 Transverse ultrasound image of the jugular vein shown in Figure 3.1. Hyperechoic material was identified superficial to the jugular vein (arrowhead). There was localized thickening (arrows) of the jugular vein wall (perivasculitis). The jugular vein remained patent.
Source: Courtesy of Pablo Espinosa.
Treatment
If there are any signs of thrombophlebitis, the catheter should be removed immediately and the catheter should be cultured or saved for culture if any concerns. Treatment should be instituted if there is local swelling, pain, or inflammation, and includes warm compresses and topical anti‐inflammatory treatment (dimethylsulfoxide or diclofenac). If signs of fever, suppurative discharge, or cellulitis are present, then systemic antimicrobial treatment is indicated and should be guided by culture and sensitivity results. If re‐catheterization is necessary, the affected vein must not be used and it is recommended to use another anatomic site (i.e. do not use contralateral jugular vein, if possible, because thrombophlebitis of both jugular veins can impede venous drainage from the head). If thrombophlebitis results in abscess formation or complete occlusion of the vein (Figure 3.3), it may be necessary to surgically drain, resect, or reconstruct the vein [16, 19].
Expected outcome
Most cases of thrombophlebitis will resolve uneventfully, but may require prolonged antimicrobial therapy. Sequellae may include cosmetic blemish, permanent occlusion of the affected vein, residual edema or varicosities in the area drained by the affected vein, and laryngeal hemiplegia. Septic embolization and dissemination of infection to internal locations may occur and may be associated with additional morbidity and mortality.
Intravascular Foreign Bodies
Definition
Needle emboli, catheter fragmentation, and loss of the guidewire are causes of intravascular foreign bodies during catheter placement and/or management of indwelling catheters [1, 5, 8, 20].
Risk factors
Use of small gauge (20 gauge or smaller) needles, inadequate restraint of a fractious patient, or manufacturer defect. Risk factors for loss of guidewires identified in human medicine and relevant to veterinary medicine are inexperience in the technique or equipment, lack of adequate supervision, distractions during catheter placement, and high workload [21]. Patient restraint and resistant during the procedure would be important in equine settings.
Catheter kinking and breakage should be considered for any catheter type, especially as duration of catheterization increases, and clinicians should be most alert to failure in catheters made of stiffer materials (polytetrafluoroethylene, polyethylene, polypropylene) and over‐the‐needle stylet catheters, because they have to be stiffer to allow insertion.
Figure 3.3 Local abscessation of a jugular thrombophlebitis with complete thrombosis of the right jugular vein at the level of the abscess and 10 cm caudally.
Source: Courtesy of Pablo Espinosa.
Pathogenesis
Catheter fragmentation may occur during placement of over‐the needle stylet catheters if the catheter is advanced and then retracted back over the stylet and the stylet pierces the side of the catheter [1]. Loss of the guidewire during placement of an over‐the‐wire catheter using a Seldinger technique is not uncommon in human or veterinary medicine [21, 22]. The most common reason for loss of the guidewire is not holding onto the guidewire at all times that the wire is in the vein [22]. Catheters may be accidentally transected when the sutures are being cut during catheter removal. Indwelling catheters may bend and break (Figure 3.4), particularly if they are made of more rigid material [1, 2, 20, 23]. In an experimental study evaluating long‐term jugular vein catheterization, 67% of polytetrafluoroethylene catheters kinked, cracked or broke within 14 days, and 100% of polytetrafluoroethylene catheters kinked and broke within 30 days [12]. In the same study, none of the silicone rubber or polyurethane catheters broke, even after 30 days of catheterization [12]. Re‐use of needles is a risk factor in breaking and causing needle emboli in human intravenous drug abuse [24], but re‐use of hypodermic needles is ill‐advised in veterinary practice.
Figure 3.4 Polyurethane catheter removed from a jugular vein 48 hours after being placed. The catheter is seen to have multiple areas of bending and kinking.
Source: Julie E. Dechant.
