Point-of-Care Ultrasound Techniques for the Small Animal Practitioner. Группа авторов

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Point-of-Care Ultrasound Techniques for the Small Animal Practitioner - Группа авторов


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total bilirubin, and gamma‐glutamyl transferase (GGT).

       Cranial abdominal organomegaly discovered on physical examination/palpation and abdominal radiography (or both).

       Abnormal serum bile acid levels or resting ammonia levels.

       Decreased albumin, cholesterol, blood urea nitrogen (BUN).

       Persistent hypoglycemia.

       Prolonged anorexia (especially cats).

       Vomiting.

       Objectives

       Recognize liver masses (single, multifocal).

       Recognize regional changes in liver echogenicity.

       Recognize venous congestion.

       Recognize gallbladder wall abnormalities.

       Recognize gallbladder luminal conditions such as mucocele, choleliths, biliary sludge, and gallbladder mass lesions.

       Recognize signs supportive of biliary obstruction, abnormal biliary contents (choleliths and inspissated bile), which when found should prompt referral for a complete detailed abdominal ultrasound study by a veterinary radiologist or internist with advanced training.

      When imaging the liver, a 5–10 MHz curvilinear probe may be used depending on the size of the animal. Generally, higher frequency probes (7.5–10 MHz) are used for smaller dogs and cats and lower frequency probes (5 MHz) are used for large dogs to allow for deeper penetration. The depth of field should be adjusted initially (increased) to visualize the interface of the diaphragm and liver in the far‐field. Gain should also be adjusted to maximize image quality. Adjustments in depth, gain, and focus position will be made repeatedly during the exam to optimize penetration and image quality.

      The patient is most commonly imaged in dorsal recumbency with the transducer placed on the ventral abdomen just caudal to the xiphoid process, and the liver scanned in transverse and sagittal planes. This position generally allows for adequate visualization of the liver in smaller dogs and cats. In deep‐chested dogs or larger animals, additional approaches through the right and left intercostal spaces may also be needed. The presence of an overlying gas‐distended stomach or colon may also interfere with adequate visualization of the liver in dorsal recumbency. In these instances, positioning the patient in right and/or left lateral recumbency will cause the gas to rise to the upside (least gravity‐dependent) of the patient, and scanning planes can be obtained from below the gas‐filled structure.

      Pearl: Best practice is to perform a Global FAST prior to moving and restraining your patient in dorsal recumbency to make sure the patient is stable (ruling out pleural and pericardial effusion, obvious cardiac and pulmonary conditions, poor volume status via caudal vena cava charcterization) and thus not hemodynamically fragile in which dorsal recumbency risks patient decompensation.

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      Large volumes of gas or ingesta can prevent complete visualization of the left side of the liver. A large amount of gas or stool in the descending colon may also interfere with imaging of the left side of the liver. If the stomach or colon interferes with imaging, the patient should be repositioned in right lateral recumbency and a left intercostal approach used. Alternatively, the patient can be reimaged following fasting and/or colonic evacuation if necessary and if the patient is stable. However, in the authors’ opinion, some food within the stomach and a full colon can provide natural contrast for evaluation of the gastric and colon walls, and evacuation of the colon is rarely needed.

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