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

Incidental findings of soft tissue gas in canine and feline thoracic computed tomographic examinations

Computed tomography (CT) is a commonly used modality in small animal veterinary medicine. Anecdotally, gas bubbles are frequently identified in small animals undergoing thoracic CT examination. The aim of this retrospective observational study was to record the occurrence and prevalence of vascular and extravascular gas in routine thoracic CT examinations in dogs and cats. Patients with any clinical signs of diseases   related to soft tissue gas were excluded. A total of 84 canine studies and 90 feline studies were included, detecting gas in 66.7% of all studies, with gas more likely to be detected in canine studies (75.0%) than in feline cases (58.9%) (P = 0.009). Canine studies were more likely to have gas detected in postcontrast studies than in precontrast studies (P = 0.016). Intravascular gas was detected in 65.5% of all included studies (75% canine and 56.7% feline). Extravascular gas was detected in 13.8% of all studies (14.3% canine, 13.3% feline), with gas detected in the vertebral canal of 8.62% of all studies (canine 11.9%, feline 5.56%) and within fascial planes in 5.75% of all studies (canine 2.38%, feline 8.89%). In conclusion, gas bubbles were identified in the majority of canine and feline thoracic CT studies without clinical evidence of a pathologic etiology.

B-mode and color Doppler ultrasonography of normal external jugular vein in donkeys (Equus asinus)

Background

Although the jugular vein is a major important blood vessel in equine, the literature lacks this vessel's normal B-mode and Doppler ultrasonographic examinations in donkeys. Therefore, this study aimed to determine the reference ranges of B-mode and Doppler ultrasonographic indices of jugular veins in healthy adult donkeys (Equus asinus) and the possible effect of examination side (left and right), gender, and body condition on the ultrasonographic measurements of this vessel. B-mode and Doppler ultrasound imaging of the external jugular vein was conducted on 20 adult healthy donkeys of both sexes.

Results

In all donkeys, the jugular vein was 4.01 to 8.1 mm from the body surface. The longitudinal and transverse venous diameters ranged from 3.94 to 10.5 mm and from 0.88 to 1.9 cm, respectively. Moreover, the vein areas varied from 0.61 to 2.83 cm². The reference values of superficial and deep wall thickness (SWT and DWT) were 0.56 ± 0.2 and 0.6 ± 0.13 mm, respectively. The blood velocity, blood follow rate, and congestion index of the external jugular vein can be expected in adult healthy donkeys as a range value from 8.4 to 13.5 cm/sec, from 0.33 to 1.78 ml/min, and from 0.06 to 0.27 cm.sec, respectively. Generally, the vein showed laminar monophasic waveforms. The examination side and gender have no significant effect on the ultrasound measurements of the vein (P > 0.05). Donkeys with a body condition score (BCS) ≥ 3 revealed increases in the depth of the vein (P < 0.05).

Conclusions

The results of this study can be used as reference values and provide a basis for comparison when evaluating donkeys with diseases that affect blood flow in the external jugular vein.

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

OBJECTIVE

To evaluate the effect of changes in intra-abdominal pressure (IAP) on medial saphenous venous pressure (MSVP) and hemodynamics in normal horses.

DESIGN

Experimental, in-vivo study.

SETTING

University Teaching Hospital.

ANIMALS

Convenience sample of 7 mixed breed horses; 5 geldings, and 2 mares.

INTERVENTIONS

Pneumoperitoneum was induced in horses under standing sedation with carbon dioxide gas using a laparoscopic insufflator for a total of 60 minutes to simulate clinical elevation in IAP. Pressure was increased stepwise to 20 mm Hg over 30 minutes, and maintained at that pressure for 30 minutes to evaluate the effect of sustained intra-abdominal hypertension. The MSVP and vital parameters were recorded, along with direct arterial blood pressure from the transverse facial artery.

MEASUREMENTS AND MAIN RESULTS

As IAP increased, MSVP increased in a stepwise manner, in concert with changes in IAP. The consistency in measurement between MSVP and IAP was high (intraclass correlation coefficient = 0.92; P < 0.001) and repeated measures correlation was excellent (r = 0.98; P < 0.001). Heart rate was unchanged over the course of the experiment (P = 0.09), however, respiratory rate increased with increasing IAP (P < 0.001). Arterial blood pressure also increased with insufflation (P < 0.001), with a significant difference at an IAP of 15 mm Hg (P = 0.04).

CONCLUSIONS

This report provides preliminary data demonstrating a strong correlation between equine MSVP and changes in IAP, similar to that observed in other species. Further investigations are needed to evaluate this relationship, and to confirm these results in clinical patients.

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

Background

Venous 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/Objectives

Our objective was to describe the surrounding circumstances, clinical signs, treatment, progression, and outcome of venous air embolism in hospitalized horses.

Animals

Thirty‐two horses with acute onset of compatible clinical signs associated with IV catheter disconnection or damage.

Methods

Multicenter retrospective study. Data extracted from clinical records included signalment, presenting complaint, catheter details, clinical signs, treatments, and outcome.

Results

Most 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 Importance

The 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.