Catheter‐associated venous air embolism in hospitalized horses: 32 cases

Abstract

BackgroundVenous air embolism is a potentially life‐threatening complication of IV catheter use in horses. Despite widespread anecdotal reports of their occurrence, few cases have been reported in the literature and the prognosis is currently unknown.Hypothesis/ObjectivesOur objective was to describe the surrounding circumstances, clinical signs, treatment, progression, and outcome of venous air embolism in hospitalized horses.AnimalsThirty‐two horses with acute onset of compatible clinical signs associated with IV catheter disconnection or damage.MethodsMulticenter retrospective study. Data extracted from clinical records included signalment, presenting complaint, catheter details, clinical signs, treatments, and outcome.ResultsMost cases resulted from extension set disconnection occurring within approximately 24 hours after catheter placement. In fewer horses, extension set damage was cited as a cause. Common clinical signs included tachycardia, tachypnea, recumbency, muscle fasciculations and agitation, with abnormal behavior including kicking and flank biting. Less commonly, pathological arrhythmias or more severe neurologic signs, including blindness and seizures, were noted. Progression was unpredictable, with some affected horses developing delayed‐onset neurologic signs. Mortality was 6/32 (19%), including 2 cases of sudden death and other horses euthanized because of persistent neurologic deficits. Negative outcomes were more common in horses with recorded blindness, sweating or recumbency, but blindness resolved in 5/8 affected horses.Conclusions and Clinical ImportanceThe prognosis for resolution of clinical signs after air embolism is fair, but permanent neurologic deficits or pathologic cardiac arrhythmias can arise. Unpredictable progression warrants close monitoring. Systematic clinic‐based surveillance could provide additional useful information to aid prevention.

Evaluation of the effects of medial saphenous venous pressures as an indirect method of measurement of intra‐abdominal pressures in the horse

“…Risks for venous catheterization in the distal limb should be taken into account, and can include thrombus formation, venous air embolism, localized infection, and safety of the clinician placing the catheter. 46,47 The consequences of any peripheral catheter should be considered before installation for monitoring purposes in critically ill patients, and mitigating factors, such as sterile bandaging, as well as monitoring of coagulation parameters would be recommended. While the health of the animal is an important factor in the development of thrombophlebitis, dwell time should also be restricted to a minimum to reduce the risk of injury to the vessel.…”

Highlights of recent clinically relevant papers

“…In this retrospective study, Nicholas Parkinson and colleagues in the UK and USA investigated catheter‐associated venous air embolism in hospitalised horses .…”

Central blindness following general anaesthesia due to suspected catheter‐related venous air embolism in a gelding

“…Central blindness is a rare complication reported after general anaesthesia or venous catheter‐related incidents in horses 1–4. The condition is linked to cerebral ischaemia/hypoxia either due to decreased cardiac output or embolism of the relevant areas of the brain, and in severe cases outcome can be fatal due to cerebral necrosis 2–5.…”

“…Central blindness is a rare complication reported after general anaesthesia or venous catheter‐related incidents in horses 1–4. The condition is linked to cerebral ischaemia/hypoxia either due to decreased cardiac output or embolism of the relevant areas of the brain, and in severe cases outcome can be fatal due to cerebral necrosis 2–5. If venous catheter‐associated air embolism is suspected, clinical symptoms are usually rather imminent1 3 4 while in case of generalised cerebral ischaemia, blindness seems to be related to severe neurological symptoms with a delayed onset (5 hours to 7 days) 2…”

“…Placement of the jugular catheter towards the heart predisposes to catheter‐associated air embolism 3. A recent retrospective study investigating the incidence of catheter‐associated venous air embolism found that acute clinical symptoms have been developed in 0.1%–0.2% of the horses where catheter has been placed 3.…”