Hot topics from the 16th annual IVECC symposium (Proceedings)
The clinical utility of ultrasonography in the emergency room has been expanding in recent years. Two techniques recently presented are known as abdominal focused assessment with sonogram for trauma (AFAST) and thoracic focused assessment with sonogram for trauma (TFAST). The combined use of AFAST and TFAST provides a rapid assessment of four spaces (abdominal, retroperitoneal, pleural, pericardial). Examinations are typically performed in the absence of shaving hair.
The AFAST examination has been evaluated with patients in right lateral recumbency, with the following four sites: 1) Diaphragmatic-Hepatic (DH) view, also used to image the pleural and pericardial spaces; 2) Spleno-Renal (SR) view, also used as a window into the retroperitoneal space; 3) Cysto-Colic (CC) view; 4) Hepato-Renal view is a favorable site for abdominocentesis.An abdominal fluid scoring (AFS) system has been shown helpful in predicting severity of hemorrhage, and corresponding with the patient's need for blood transfusion.
• AFS 0 - negative at all four sites
The TFAST examination consists of five sites: 1) Chest tube site (CTS) view, performed bilaterally; 2) Pericardial site (PCS) view, performed bilaterally; 3) Diaphragmatic-Hepatic (DH) view previously highlighted as part of the AFAST exam. The CTS is best for ruling out a pneumothorax (PTX), as well as surveying for lung pathology. The PCS view is best used to evaluate for the presence of pleural or pericardial fluid. This view may also be used to assess volume status via the left ventricular short axis view, as well as "quick peaks" of the left atrial:aortic (LA:Ao) ratio to rule out left-sided heart failure.
Echocardiography and measurement of intravascular volume
As a supplement to traditional techniques used to assess intravascular volume status (heart rate, mucous membrane color and capillary refill time, blood pressure, jugular vein observation and central venous pressure, blood lactate, urine specific gravity and urine output), echocardiography may provide additional information to provide the most accurate assessment of an individual's volume status.
Dilated hepatic veins
Hepatic veins are often distended in patients with chronic fluid overload conditions. When seen in association with ascites, most cases of ascites will be due to a cardiac cause or an obstruction to venous return.
Left atrial size
In the vast majority of dogs and cats with left-sided congestive heart failure, there will be moderate to marked left atrial enlargement present on echocardiogram. Hypovolemia often results in a small left atrium and "triangulation" of the appearance of the left atrium.
Ventricular size and volume
Animals with hypovolemia often have small right and left ventricular internal dimension in diastole and systole, thickening of the walls of the left ventricle and interventricular septum (pseudohypertrophy), and a small pulmonary artery size (unless pulmonary hypertension and/or pulmonary embolism cause the left heart findings). Relatively normal cardiac size means that additional fluids can be given, but that large volume fluid administration is unlikely to help. If cardiac cavity dimensions are increased (specifically LA and LV cavity size) then fluid therapy might result in fluid overload or pulmonary edema, and other approaches to improve blood pressure (vasopressor) or cardiac performance (inotropes) should be considered. Also, cardiac performance can be assessed and reduced contractile function, if present, can provide evidence in support for need for an inotropic agent. Typically, all cardiac chambers are enlarged in cases of fluid overload. The enlargement of cardiac chambers is usually modest, although LV fractional shortening may be slightly reduced in animals with sepsis.