in performance horses [1].
Diagnosis
Perivascular hematoma formation is recognized by swelling that occurs at the injection site during or immediately after needle or catheter placement. Visibly progressing hematoma formation associated with jugular venipuncture or catheterization is indicative of carotid artery injury. Perivascular inflammatory reactions may be differentiated from hematomas because they are more delayed in onset, occurring minutes to hours after the injection. The swellings may be more diffuse and the vein may be thickened when palpated. Knowledge of recent administration of an irritating substance will be an important historical detail in differentiating this type of reaction.
Perivascular injections may be recognized by the accumulation of injection fluid at the injection site. There may be increased resistance of flow to the intravascular injection; however, if the injection is given through a catheter that is cracked and leaking at the insertion site, there may be no change in resistance. Horner’s syndrome (ipsilateral ptosis, miosis, enophthalmos, protrusion of nictitating membrane, and localized sweating) may develop if the vagosympathetic trunk is injured [7]. Signs of Horner’s syndrome are typically a transient reaction (self‐resolving within 12–24 hours), but it may be permanent. Injury to the left recurrent laryngeal nerve will result in left laryngeal hemiplegia [1]. This neurological deficit is typically not recognized at the time of venipuncture, because the signs are exercise intolerance and inspiratory stridor. Signs of perivascular swelling may or may not be evident.
Treatment
Small hematomas will either self‐resolve or resolve with digital pressure. Large, progressing hematomas, especially those associated with carotid injury, require a padded pressure wrap being placed over the area for at least 20–30 minutes and selection of an alternate site for venipuncture or catheterization. Perivascular inflammatory reactions are best treated by avoiding further injection or catheterization of that vessel until the swelling has completely resolved [8]. Local application of warm compresses and topical anti‐inflammatory agents (diclofenac, dimethylsulfoxide) are typically used to hasten resolution and prevent progression. If perivascular nerve injury is noticed at the time of injection, treatment can include local and systemic anti‐inflammatory medication. Oral administration of Vitamin E (10 iu/kg po q24hr) is thought to aid in neurologic healing. Knowledge that a highly irritating substance has been injected perivascularly will guide more aggressive treatment. At the very least, the subcutaneous tissues in the area should be injected with saline or balanced electrolyte solution to help dilute the irritant and the intravascular catheter should be removed from the associated vein [6]. Skin fenestration to allow drainage or tissue debridement may be necessary if necrosis is evident.
Expected outcome
Perivascular hematomas and mild inflammatory reactions will resolve without further treatment, although local application of warm compresses and topical anti‐inflammatory medications may speed resolution. Severe inflammatory reactions may result in temporary or permanent loss of patency of the vein and associated nerve function. Injury or inflammation of the vagosympathetic trunk or left recurrent laryngeal nerve is usually temporary, assuming there are no other clinical signs, but may be permanent, especially if there is severe associated, perivascular inflammation.
Intra‐Arterial Injection or Catheterization
Definition
Accidental arterial penetration during venipuncture or catheterization will result in a significant hematoma formation but no other consequences if quickly recognized. Administration of medications into the arterial circulation is associated with severe and violent reactions when it involves the cerebral circulation or may be associated with arteriospasm and tissue necrosis if it involves a peripheral artery.
Risk factors
Anatomical location: The common carotid
Poor lighting
Fractious or insufficiently restrained patient
Inability or inexperience to recognize anatomic landmarks, and accessing the vein in the lower part of the neck [2]
Use of smaller gauge needles
Pathogenesis
The needle is advanced and placed into the arterial lumen inadvertently and the solution injected. The common carotid artery is the most common artery to be accidentally punctured, especially in the caudal two‐thirds of the neck, because of the close proximity of the carotid artery to the jugular vein and common use of the jugular vein for venous access [1, 2]. Risk of inadvertent arterial injection or catheterization is less with the cephalic vein, lateral thoracic vein, and saphenous veins, because there are no adjacent arteries. Smaller gauge needles prevent recognition of inadvertent arteriopuncture.
Prevention
Adequate knowledge of anatomy is required; inject into the cranial aspect of the jugular vein whenever possible. Adequately restrain the patient and perform injection in areas with adequate lighting. Use needles not smaller than 18–20 gauge, although these calibers also show weak or absent pulsations [9].
Diagnosis
Accidental penetration of the artery is typically associated with pulsatile and projectile ejection of bright red blood from the catheter or needle; however, projectile arterial blood is not always apparent [9, 10]. Smaller gauge (18–20 gage and smaller) needles are associated with weak or absent pulsations [9]. Placement of the bevel against the arterial wall or incomplete seating of the needle in the vessel may also prevent forceful ejection of blood. The most serious consequence of arterial catheterization is injection of medications into the arterial system. Intracarotid injections are the most severe and serious of these accidental injections because of the typically immediate and violent reactions by the patient. Clinical signs can range from disorientation to hyperexcitability to seizures and death.
Treatment
If arterial puncture is recognized, the needle or catheter should be removed and firm direct pressure applied to the site immediately. Reactions to accidental intracarotid injections can be immediate and violent. Personnel and patient safety should be prioritized. Immediate treatment of accidental intracarotid injection includes sedation and/or anticonvulsive medications (alpha‐2 agonists, benzodiazepines, and phenobarbital) and provision of neuroprotective treatments (dimethylsulfoxide, corticosteroids, and mannitol) [10].
Expected outcome
The severity of intracarotid injections depends on the amount and type of medication administered. Oil‐based formulations, such as phenylbutazone, are associated with fatal reactions [10]. Outcome may also be affected by injuries incurred subsequent to the injection (e.g. head trauma, etc.). Although systemic reactions are not pronounced with accidental injection of other arteries, ischemia and necrosis of the tissues supplied by the artery may occur if the artery thromboses.
Catheter‐Related: Difficult or Incorrect Placement, Dislodgement and Loss of Patency
Definition
Inability to advance catheter or guidewire is a technical complication that can occur during placement of either an over‐the‐needle
