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

Figure 5.6. Short‐axis and long‐axis lines for echo views. If only someone had told me this back in 2005, to religiously keep the probe head parallel to the short‐axis (cardiac) and long‐axis (cardiac) lines while fanning, I would have gained proficiency so much faster. Trust these lines and fan while staying on them to achieve your echo views. We can tell from across the room whether or not you are successful by seeing if you are on these lines using a clockface orientation approach (Figures 17.25 and 17.26). Wander from them and everything gets goofy.

      Source: Courtesy of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.

       Failure to Maintain Probe–Skin Contact with the Patient

      Every time you lose probe–skin contact with your patient, you delay the imaging and have to reestablish your acoustic window, losing precious time and potentially increasing risk in hemodynamically fragile (and stressed) patients. There are several recommendations that involve your nonprobe “helper hand,” placed into two broad categories: (1) maintaining probe–skin contact (acoustic window) by moving your patient's loose skin with the probe, and (2) maintaining probe–skin contact (acoustic window) by keeping your patient from swaying and at the same time stabilizing the probe against your patient's body.

      We have found that the sonographer may take advantage of the patient's loose skin by moving the probe and skin together, and moving nearby less haired skin over the external landmark for your desired acoustic window. An example would be while doing Vet BLUE lung ultrasound, without losing probe–skin contact and your acoustic window, slide the probe together with the loose skin one intercostal space caudal and one intercostal space cranial when possible to cover the respective intercostal spaces at each respective Vet BLUE region. Another example is at the SR and HR views where the skin ventral to these views is often more sparsely haired, so your helper hand's thumb can lift or move this region dorsally over your external landmark of the costal arch and sublumbar muscles. By taking advantage of the sparsely haired area, imaging quality is markedly improved, especially in a thickly coated golden retriever, border collie or Siberian husky (see Figures 5.1 and 5.4). Another AFAST location is the CC view. Placing the probe laterally but closer to the midline where there is obvious sparsely hair coated skin markedly improves the image.

Regarding maintaining probe–skin contact, we have some pearls. First, when your patient is standing during the Global FAST approach, use your helper hand to “V trough” the patient by holding both sides of the sternum (Figure 5.7). This is especially helpful for evaluating your TFAST pericardial site (PCS) views but may also be used during Vet BLUE. Second, use your helper hand to brace your probe against the thorax or abdomen for better control of fine probe maneuvers.

Figure 5.7. V trough your patient with your nonprobe helper hand. Your nonprobe helper hand is used as a V trough to keep your patient from swaying and maintaining probe to skin contact. Every time you lose contact, you potentially lose your good acoustic window and precious time. As much as possible, keep all four legs of your patient on the table.

      Source: Courtesy of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.

Third, as often as possible, let the patient have all four legs on the exam tabletop (see Figures 5.4 and 5.7). The only time a three‐legged approach is mandatory is for the Vet BLUE cranial lung region for defining the cranial transition zone of soft tissue of the neck and then sliding caudally to image the first three intercostal spaces. Most of the time, the standing TFAST PCS views and imaging the heart may be done with all four legs on the exam table. By this approach, the patient is not swaying and feels more secure than lifting and extending a foreleg off the table. Fourth, when lifting and extending a foreleg, we lift and extend near the patient's elbow, especially for dogs. Many dogs do not like their paws being handled and associate it with the unpleasant experience of having their nails trimmed (Figure 5.8). Thus, by handling the paws, your patient becomes restless, wary, and tachycardic and may try to bite you!

Other Probe–Skin Contact Issues

       Not Being Aware of Drifting

Drifting is the phenomenon of looking intensely at the ultrasound screen and not realizing that the weight of your hand and gravity has taken you to a place where no man (or woman) has gone before – a bit of an exaggeration which will hopefully help you remember this very common mistake. The Star Trek phrase sounds funny but you started at the costal arch and hypaxial muscles looking for the left kidney, not realizing the probe has made it to the midline at the umbilicus (by drifting). No wonder you cannot find the left kidney! If you double‐check yourself by frequently looking at the screen and then at the probe's external location on your patient, you will get to where you want to go much faster! This also occurs commonly while performing Vet BLUE in standing patients. You think you are at the Caudodorsal Vet BLUE lung region but the weight of your hand has brought you close to the Middle Vet BLUE lung region.

The best way to prevent drifting is to routinely “kickstand” out a finger that solidly touches your patient’s body wall (or have another comfortable part of your hand against the patient's body wall) (Figure 5.9).

Figure 5.8. When extending the foreleg, don’t touch the paw! Gently extend the foreleg with your helper hand placed near the elbow and away from the paw. The paw is sensitive and you may create an uncooperative patient (e.g., may bite, may become resistant to restraint, may become tachycardic) by triggering a negative response. Stay near the elbow. Shown is the acquisition of the right Vet BLUE cranial lung region view.

      Source: Courtesy of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.

Figure 5.9. “Kickstand” your probe hand to prevent drifting. Having some part of your probe hand in contact with the patient will prevent drifting, which is when the sonographer is focused on the screen and unaware that the weight of their probe hand has moved the probe to a different acoustic window. In (A) the probe hand is not braced against the patient, so the sonographer is susceptible to drifting. In (B) the fingers are comfortably spread in contact with the patient's body, thus preventing drifting. Common views for drifting are especially during Vet BLUE and the least gravity‐dependent SR and HR views.

      Source: Courtesy of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.

       Not Checking Where the Probe is Externally on the Patient

      This is really Part 2 of the previous paragraph. A few years