A 6-year-old male neutered German Shepherd dog, named Chief, presented on emergency for acute onset of vomiting and restlessness. Initial diagnostics were consistent with gastric dilation and volvulus and he was taken to surgery as soon as medically stable. Surgery revealed a 540 degree clockwise volvulus which was returned to normal position and a routine incisional gastropexy performed. Other than intermittent ventricular premature contractions, mild persistent hypercalcemia and an anxious nature, Chief’s recovery from surgery and GDV were unremarkable. On the morning of his discharge, while removing the original cephalic intravenous catheter (18g), the device was severed at the skin surface, removing only the hub and initial 1mm of catheter. A standard small bandage of vetwrap and gauze was applied over the catheter site to encourage clotting. As the dog was resisting restraint at the time, it was not certain the catheter segment was still within the dog. A thorough search of the kennel and bedding provided no clues to the location of the remainder of the catheter. A quick release (rubber) tourniquet was placed at the level of the elbow and the dog encouraged to remain quiet. Gentle palpation of the forearm from carpus to elbow did not reveal any foreign material. An ultrasound exam using a linear 12 MHz probe similarly did not reveal any obvious echogenic material from the catheter site proximal to the elbow joint. The tourniquet was removed (in place for approximately 5 minutes).
The dog was moved to radiology and a single AP view taken of the affected forearm showing a distinct linear foreign body over the craniomedial radius. He was sedated with dexmedetomidine and fentanyl, and provided with flow-by oxygen during the brief procedure. The left forearm was gently prepped with chlorhexidine scrub and solution and draped to allow access from the carpus to the elbow. Lidocaine (0.3 ml of 2%) was infused subcutaneously proximal to the catheter puncture site. An #11 blade was used starting at the catheter puncture extending proximally for 10mm through skin only. Mosquito forceps were used to bluntly dissect soft tissues from the cephalic vein to allow better visualization. A 5mm venotomy was performed starting at the catheter puncture extending proximally. The proximal tip of the catheter was visible within the cephalic vein just distal to the venotomy. A 22g needle was used to capture and retract the catheter fragment into the venotomy (Figure 1) where the mosquito forceps could grasp it (Figure 2). Figure 3 demonstrates the size of the cateter. Venous bleeding from the foot resumed normal flow once the catheter fragment was removed. The venotomy was closed with small gauge absorbable suture followed by subcuticular closure and skin staples. The site was protected by a light bandage. Chief recovered from sedation routinely and was discharged later the same day.
Catheter fragmentation and embolization is a recognized, but thankfully uncommon complication of intravenous catheter use in veterinary medicine. Most reported cases are either associated with iatrogenic laceration during catheter removal (such as in Chief’s case), transection during placement (with the stylette) or with catheters of long term duration. In the latter scenario, it is believed that repeated micro-motion at the junction of the catheter and hub creates fragility, ripe for breakage and subsequent migration of the catheter fragment within the vascular system. There is anecdotal evidence that catheters which break on their own (i.e. cycle to breakage) are less likely to move downstream due to fibrosis around the catheter site. Catheters which have been severed (as by bandage scissors) may not have as much fibrosis nor the burr at the hub end to hold the fragment in place.
The central question surrounding catheter fragments is how aggressively to attempt removal. In human patients, the standard of care is immediate removal, generally through minimally invasive means. There is considerable data available to our MD colleagues to help guide decisions about fragment retrieval. As with many topics in the veterinary field however, there is little hard data to help direct therapy. There is no argument against attempting a cut-down to retrieve a fragment still sitting at the original site. However, if the fragment migrates into larger vasculature, the heart or the lungs, there is debate about the importance of removal. Complications (both fatal and non-fatal) reported in humans include cardiac perforation, pulmonary thrombosis, endocarditis, sepsis, arrhythmias, renal and adrenal gland infarction and caval syndrome. The relative risk in our veterinary patients is unknown, but the potential seriousness should be considered on a patient-by-patient basis. Collateral circulation is generally sufficient in our patients to deal with a migrated catheter fragment induced thrombosis. Several of the reported cases show radiographic evidence of catheter fragments ultimately residing in the lungs, presumably fibrosed in place and walled off from general circulation. In this scenario, the risk of abscess formation or showering of thromboemboli is possibly minimal compared to the risks associated with retrieval. However, a collection of canine cases presented in JAVMA documented the location of fragments within the main pulmonary artery or a branch of the pulmonary artery.3 The fragments were removal via minimally invasive techniques the day of fragmentation out to two weeks after catheter fragmentation. Patients where the catheter fragment migrates into a large vessel and/or the heart are likely the best candidates to benefit from retrieval efforts. Similar to removal of adult heartworms, catheter fragments can be recovered using fluoroscopic guidance and endovascular instruments such as the loop snare.1,2 In human patients, success during minimally invasive procedures to recovery catheter fragments is reported 90-100%.4
The decision surrounding the use of a tourniquet in the acute situation of a lost catheter fragment is also not straightforward. A well placed tourniquet may indeed prevent a loose fragment from migrating proximally within a vein to a point where simple retrieval is no longer an option. However, a tourniquet may increase the likelihood of a catheter fragment moving by dilating the vein and mechanically separating the fragment from the wall of the vessel. In Chief’s case, the catheter was of short duration (<36 hours) and had been sharply transected thus was amenable to migration. The tourniquet placed shortly after discovery of the complication may have created enough backpressure to move the catheter segment distal beyond the original site or this may have been the result of direct manipulation during diagnostics combined with changes in vascular pressure from sedation. In any event, the fragment was distal to the area of highest suspicion and had moved again following radiography.
Performing a cut down should only be undertaken if there is substantial evidence that the catheter fragment is still present. Palpation, visualization (seeing the burr of plastic at the catheter site), sonographic or radiographic evidence are valid reasons to pursue cut-down. The patient should be kept as quiet as possible and the skin over the site should be disturbed as little as possible prior to cut down to decrease the chance of fragment migration. The surgeon should be prepared to extend a venotomy and to close it or simply ligate the vein and rely on collateral circulation for healing. In Chief’s case, the 22g needle tip was used to control the catheter fragment to reduce manipulation (and thus trauma) of the cephalic vein walls. Surgical loupes can be of assistance in meticulous creation and closure of a venotomy. Fine ophthalmic or other precision instruments (neurologic, vascular) could also have been used.
As with any iatrogenic complication, immediate and clear communication with clients is paramount. In the event the fragment cannot be found using in-clinic diagnostics, referral to a specialty hospital is recommended to establish the current location and determine a plan (e.g. retrieval vs. monitoring).
- Gentile JM et al: Endovascular retrieval of embolized jugular catheter fragments in three dogs using a nitinol gooseneck snare, J Vet Cariol 10(1):81-85. 2008.
- Little D et al: Percutaneous retrieval of a jugular catheter fragment from the pulmonary artery of a foal, J Am Vet Med Assoc, 220(2):212-214, 2002.
- Culp WTN et al: Percutaneous endovascular retrieval of an intravascular foreign body in five dogs, a goat and a horse, J Am Vet Med Assoc 232:1850-1856, 2008.
- Schechter MA, O’Brien PJ and Cox MW: Retrieval of iatrogenic intravascular foreign bodies, J of Vascular Surgery, 57:276-281, 2013. (meta-analysis)