Читать книгу Point-of-Care Ultrasound Techniques for the Small Animal Practitioner - Группа авторов - Страница 263

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.