table top while maintaining a longitudinal (sagittal) plane in patients placed in lateral recumbency. Holding the probe like a pencil for many who have learned to scan patients in dorsal recumbency usually becomes problematic at the DH view for the caudal vena cava. Holding the probe on top and keeping the thumb on the probe marker and a finger out to prevent drifting works best.
Patient Positioning
Lateral Recumbency
Right lateral (RL) recumbency is generally preferred over left lateral (LL) recumbency for AFAST because RL recumbency is standard positioning for electrocardiographic and echocardiographic evaluation (Figures 6.2 and 6.3; see also Figure 6.1). Moreover, the left kidney (a window into the retroperitoneal space) at the AFAST SR view and the gallbladder at the DH view (by directing the probe in the gravity‐dependent region or toward the tabletop) are readily imaged. RL recumbency over LL is preferred positioning for abdominocentesis because anatomically the spleen lies more on the left side of dogs and cats. LL recumbency may be used in cases in which injury prohibits RL positioning, or the right retroperitoneal space warrants imaging. In a more recent study evaluating RL versus LL recumbency, abdominal FAST time was shorter in LL recumbency and both kidneys were more reliably imaged (McMurray et al. 2016). However, this is probably due to training bias, as we could argue the same in RL recumbency (Lisciandro 2014a,b), and moreover, TFAST echo views are more easily acquired in RL recumbency. When combining AFAST and TFAST, RL recumbency is clearly advantageous. AFAST on a cat is shown in Chapter 39. See Chapters 17, 19, and 20 for echo views.
Figure 6.2. AFAST and its five views performed in right lateral recumbency in a dog. (A) AFAST unlabeled and (B) AFAST labeled. The order is always the same as follows: DH to SR to CC to HRU to HR5th bonus view. The final HR5th bonus view is not part of the abdominal fluid score. The AFAST images and their proportionality should look nearly the same regardless of positioning. DH, diaphragmatico‐hepatic view; DH1, DH 1 of 2 views; DH2, DH 2 of 2 views; SR, spleno‐renal view; CC, cysto‐colic view; HRU, hepato‐renal umbilical view; HR5th, hepato‐renal 5th bonus view; HRU1, 1 of 2 views; HRU2, 2 of 2 views. DIA, diaphragm; FF, free fluid; GB, gallbladder; LIV, liver; LK, left kidney; RK, right kidney; SI, small intestine. AFAST views are nearly identical no matter the positioning because the respective target organs are imaged with the same methodology.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood. TX. Illustration by Hannah M. Cole, Adkins, TX.
Modified Lateral‐Sternal
Modified lateral‐sternal recumbency positioning may be used for AFAST in stressed patients by allowing the forelegs to be in sternal and moving the hindlegs together laterally (placed same side as the sonographer) (Figure 6.4). In the modified lateral‐sternal positioning the AFS may be estimated because the patient isn't purely in a lateral recumbent position.
Standing/Sternal
In respiratory‐compromised patients AFAST is performed in standing or sternal knowing that the fluid scoring system is not validated in this positioning but still provides clinical information regarding the presence or absence of effusion. Whatever the AFAST options for positioning (lateral, modified lateral‐sternal, standing/sternal), a negative AFS negates the need for moving the patient to lateral recumbency. Serial exams are always mandated as standard of care for a second opportunity to detect negative AFAST changing to positive, and for rescoring the patient (Lisciandro et al. 2009; Lisciandro 2011, 2014a; Boysen and Lisciandro 2013). See Chapters 36 and 37 for the most efficient ways to perform AFAST in standing‐sternal positioning.
Figure 6.3. AFAST and its five views performed in left lateral recumbency in a dog. Shown is AFAST unlabeled in left lateral recumbency with the same images as Figure 6.2A and B. The order is analogous and always the same as follows: DH to HR to CC to SRU to SR5th bonus view. The final SR5th bonus view is not part of the abdominal fluid score. DH, diaphragmatico‐hepatic view; DH1, DH 1 of 2 views; DH2, DH 2 of 2 views; SR, spleno‐renal view; CC, cysto‐colic view; HRU, hepato‐renal umbilical view; HR5th, hepato‐renal 5th bonus view; HRU1, 1 of 2 views; HRU2, 2 of 2 views. DIA, diaphragm; FF, free fluid; GB, gallbladder; LIV, liver; LK, left kidney; RK, right kidney; SI, small intestine. Note that the images should look identical for each AFAST view regardless of positioning (including standing/sternal, modified sternal). AFAST views are nearly identical no matter the positioning because the respective target organs are imaged with the same methodology.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX. Illustration by Hannah M. Cole, Adkins, TX.
Considerations When Performing AFAST in Standing or Sternal Positioning
If AFAST is negative in standing or sternal positioning, then moving the patient to lateral recumbency is unnecessary. However, if the AFAST examination is positive in standing or sternal, then move the patient to lateral recumbency (if unstable, delay until more stable) and wait for three minutes for fluid to settle before assigning an AFS (Lisciandro et al. 2009; Lisciandro 2011; Boysen and Lisciandro 2013).
When performing AFAST in standing or sternal, the sonographer must keep in mind the following points.
As long as the AFAST is negative and the target organs are imaged at each respective view, the AFAST is complete.
When free intraabdominal fluid is present, it will pool in different regions relative to the target organs because gravity‐dependent locations differ from lateral recumbency, being at the probe head, in the near‐field, for the DH, CC, and SR/HR umbilical views.
The gravity‐dependent regions within the lumen of the gallbladder and urinary bladder also differ from lateral recumbency and the sonographer must consider the direction of the beam (its scanning plane) to best detect and interpret findings.
The
