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
• AFS 4 - positive at all four sites
• AFS 1,2 - positive at one to two sites (DH & CC most common), patients rarely become
• anemic from intra-abdominal hemorrhage
• AFS 3,4 - positive at three to four sites, patients often become anemic, with 25% becoming severely anemic (<25%) warranting
blood transfusions and rarely emergent laparotomy.
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.