Suspected fatal venous air embolism during anaesthesia in a Pomeranian dog with pulmonary calcification

CASE HISTORY: Death occurred in a 1.25 kg, 9-month-old female Pomeranian dog undergoing anaesthesia for surgical repair of partially healed fractures of the radius and ulna.

CLINICAL FINDINGS: Following sedation, anaesthesia was induced using thiopentone and maintained with halothane in oxygen. An acute decrease in the dog's end-tidal carbon dioxide (EtCO₂) measurements was noted approximately 50 min after induction, immediately following delivery of a 5-ml bolus of lactated Ringer's solution (LRS) administered to flush a small (0.06 ml) volume of fentanyl via a pre-placed intravenous (I/V) catheter. Venous air embolism (VAE) was suspected and the dog died despite interventive therapy. On post-mortem examination, several air bubbles were noted when the right ventricle was opened under water. Histologically, the kidneys appeared abnormal with immature glomeruli, and the lungs appeared diffusely mineralised. The origin of the air was probably small bubbles and microbubbles that may have been present in the extension set and 20 ml syringe used for the administration of fentanyl and I/V fluids to the dog.

DIAGNOSIS: Renal dysplasia and diffuse pulmonary calcification, with VAE as the probable cause of death.

CLINICAL RELEVANCE: In this case of VAE-associated anaesthetic death, it is further speculated that underlying pulmonary disease, in the form of pulmonary calcification, may have contributed to an increased sensitivity to the adverse effects of VAE.     

Suspected venous air embolism in a horse

A horse which had had a caecal impaction for 10 days was treated by means of an ileocolostomy [corrected] but failed to respond satisfactorily. Before a second laparotomy was performed it was observed to have dislodged the extension set from a jugular catheter and air was heard being sucked into the vein. It became very agitated but was anaesthetised again and the impaction was removed through an incision in the apex of the colon [corrected] After recovering from the anaesthesia it developed severe signs of pruritus which subsided only after 12 hours. These signs were considered most likely to have resulted from a venous air embolism.     

Suspected venous air embolism in a Finnhorse

Vascular air embolism (VAE) is the entrainment of air from the operative field or other communication with the environment into the venous or arterial vasculature, producing systemic effects. The horse described in this report, after having been discovered to have dislodged the extension set from the jugular vein catheter, demonstrated clinical signs considered most likely to have resulted from a VAE, and represents a case of primarily neurological signs resolving spontaneously. Emphasis is given to the prevention and prompt recognition of this event and to the use of all available tools in the management of cardiovascular complications.     

Suspected venous air embolism during urinary tract endoscopy in a standing horse

During cystoscopy, performed with air insufflation in a standing Argentinian gelding, the horse showed ataxia and fell to the ground with generalised muscular twitching and horizontal nystagmus, tachypnoea and tachyarrhythmia. General anaesthesia was induced. Arterial blood gas‐analysis before induction of anaesthesia revealed an increased pH, decreased partial pressure of carbon dioxide and decreased partial pressure of oxygen. Venous air embolism was suspected.     

Suspected venous air embolism in three horses

Venous air embolism was suspected in 3 hospitalised horses on the basis of an inadvertently open jugular venous line. Subsequently the 3 horses developed clinical signs including cardiovascular collapse, cardiac dysrhythmia, pulmonary oedema, behavioural abnormalities and neurological signs consistent with central nervous system injury. Treatment included intranasal oxygen therapy, i.v. fluid administration and anti‐inflammatory therapy. Specific therapy aimed at treating air embolism in man is reviewed, with pertinent therapy potentially applicable to horses emphasised.     

Suspected air embolism associated with post-anesthetic pulmonary edema and neurologic sequelae in a horse

A 523 kg Quarter Horse was anesthetized for unilateral eye enucleation. The anesthetic period was unremarkable. During anesthetic recovery the cap on the jugular venous catheter became dislodged. Clinical signs of pulmonary edema associated with moderate arterial hypoxemia subsequently developed. Although pulmonary edema resolved with medical therapy, the day following anesthetic recovery, clinical signs of vestibular disease and blindness developed. Treatment included nasal oxygen insufflation, flunixin meglumine, furosemide, dexamethasone, thiamine, dimethylsulfoxide, antimicrobials, and phenylbutazone. The horse recovered and was discharged from the hospital after 7 days of treatment and was neurologically normal at 6 weeks. While venous air embolism was not confirmed in this case, the catheter cap complication followed by signs of pulmonary edema and neurologic sequelae support the presumptive pathogenesis of this horse's complications. Diagnostic confirmation of air embolism in horses with compatible acute clinical signs should be documented with echocardiography.     

Suspected air embolism through the thoracic ventral internal vertebral venous plexus during hemilaminectomy in dogs

Venous air embolism entering via the ventral internal vertebral venous plexus was suspected during thoracic spinal surgery in two dogs. In both cases, air was seen bubbling from a pool of blood on the floor of the vertebral canal accompanied by sudden cardiopulmonary disturbances: low end‐tidal carbon dioxide pressure, tachycardia and reduction in oxygen in the blood. One dog became dyspnoeic and one died.     

Fatal air embolism during anesthesia for laparoscopy in a dog

A 13-year-old dog went into cardiopulmonary arrest after insufflation of the abdominal cavity with nitrogen for laparoscopy. Resuscitation was unsuccessful. Necropsy findings included a punctured spleen and confirmed the development of air embolism.     

Fatal intraoperative pulmonary fat embolism during cemented total hip arthroplasty in a dog

A 3-year-old, German shepherd dog died suddenly during cemented total hip arthroplasty. Gross necropsy findings included severe pulmonary edema and congestion as well as congestion of the liver and kidneys. Acute pulmonary embolism was suspected as the cause of death. Microscopic examination of hematoxylin and eosin-stained, formalin-fixed, and oil red O-stained frozen tissue sections confirmed the presence of large numbers of fat globules in blood vessels in the lungs, liver, and kidneys. Fat embolism during total hip arthroplasty is a common surgical complication in humans, but it is uncommon in veterinary cases and is rarely a cause of death.     

Partial anomalous pulmonary venous connection in a dog

A 2-year-old male intact Belgian Malinois was presented for exercise intolerance. A grade III/VI left basilar systolic murmur was detected. Echocardiography revealed moderate right atrial and ventricular dilation and increased pulmonic outflow velocity. Thoracic radiographs showed right heart enlargement and a dilated caudal vena cava. In addition, on the left lateral projection, an enlarged aberrant right cranial pulmonary lobar vein was suspected to be diverging ventrally from the course of the right cranial lobar bronchus and inserting more ventrally than normal in the region of the right atrium. A left-to-right pulmonary vascular shunt was suspected, and the patient underwent further diagnostics under general anesthesia. An agitated saline study was positive, suggestive of a concurrent right to left shunt. A right heart catheterization was performed. Angiography was inconclusive. Oximetry testing revealed an increase in oxygen saturation within the right atrium at the level of the caudal cava supportive of a left-to-right shunt in this region. Computed tomography angiography revealed a large single pulmonary vein that anomalously entered into the caudolateral aspect of the right atrium (left-to-right shunt) and was suspicious for a small arteriovenous malformation between the right caudal pulmonary artery and the right pulmonary vein returning to the left atrium (right to left shunt). The patient was diagnosed with a partial anomalous pulmonary venous connection and a possible arteriovenous malformation.     

Fatal venous air embolism in a cat undergoing dental extractions

A five‐year‐old domestic shorthair cat underwent general anaesthesia and tooth extractions. Immediately after use of a high‐speed, air‐driven, water‐cooled dental drill, the cat suffered cardiac arrest and attempted resuscitation was unsuccessful. Post‐mortem radiographs showed air in the vena cava, right atrium, right auricle and right ventricle, hepatic and renal veins. These findings were confirmed at post‐mortem examination. The cause of death was massive air embolism. There are reports of fatal venous air embolism in the human literature from the use of high‐speed, air‐driven, water‐cooled dental drills. In this case, we believe that the air jet from the cooling system provided an enormous pressure gradient allowing air entry through an alveolar bone fracture or the inflamed gingival tissues. This is the first report of fatal venous air embolism associated with the use of a high‐speed dental drill in the veterinary literature.     

An unusual pulmonary embolism after a fatal traumatic missile injury

Extract

While embolism following detachment of thrombi in veins of the pelvis and legs is not unusual. particularly in human medicine, other tissue and foreign body emboli in the lungs are much less common. Pulmonary embolism in man, for example. has been caused by the release of fat from traumatic injury sites, amniotic fluid into the maternal circulation following strong uterine contractions. air during intravenous fluid therapy. bone marrow after skeletal trauma, brain after severe head injury, liver following hepatic trauma or severe parenchymal necrosis. trophoblastic tissue during pregnancy, atheromatous material from severe arteriosclerosis, tumour metastases. cotton wool fibres by insertion of a needle into a vein and also. rarely. by vascular embolisation of a bullet(1)(2). In animals, pulmonary emboli are essentially derived from either thrombi, neoplasms or fat(3). Although skeletal muscle emboli have been experimentally induced in pulmonary arteries by parenteral injection of muscle tissue(4), this form of pulmonary embolism in clinical material has apparently not been described. This paper reports the finding of multiple skeletal muscle emboli in the lungs of a kangaroo after a fatal gunshot wound to the chest.     

Two occurrences of presumptive venous air embolism in a gelding during cystoscopy and perineal urethrotomy

A 14‐year‐old Arabian gelding presented for evaluation of macroscopic haematuria. Routine cystoscopy was performed under standing sedation during which the horse collapsed with apparent seizure activity. General anaesthesia was induced and the horse recovered neurologically normal. Four days later, during a perineal urethrotomy procedure, the horse experienced a similar collapse with seizure‐like activity. General anaesthesia was again induced and cystoscopy performed through the urethrotomy incision. A ventral bladder mass was visualised and sampled. Cytology confirmed a neoplastic process and the horse was subjected to euthanasia. Histopathology confirmed transitional cell carcinoma. Air embolism was the suspected cause of loss of consciousness and seizure activity in both instances.