Interventional Ultrasound. Cool Diagnostic & Therapeutic Things To Do
With A Needle & A Probe
Basically with sedation and avoidance of vital structures, any cavity or
compartmentalized fluid filled or viscous structure may be drained and analyzed
with cytology and culture. Pericardiocentesis, thoracocentesis,
abdominocentesis, and cystocentesis are the traditional ultrasound guided
drainage procedures that have been performed most historically. US guided
abscess drainage and antibiotic injection into various organs has been a
technique utilized frequently on our team with solid levels of success and is
currently a subject of study. No evidence of complications has been observed.
The reasoning lies in the fact that abscesses tend to have a granulation bed or
organization of tissue that walls them off from the tissue circulation. The body’s
own immune system attempts to sectorialize the abscessing pathology to
minimize systemic affects. This causes reduced blood flow into the abscess or
necrosis itself that may be evidenced on power Doppler assessment or the
abscess and surrounding tissue. If there is no blood flow to the lesion then its
reasonable to assume that even endovenous medications and even the body’s
own immune elements will have difficulty reaching the sectorialized pathology.
Therefore, a clinical sonographer armed with a 2 inch 14-16- IV catheter may
drain an abscess or infected cyst in any organ and follow the drainage procedure
with injection of a body weight dose of antibiotic directly into the lesion with a 22gauge needle. (Images) This has been performed with success and without
complication in our experience in the liver, pancreas, omental abscesses, lung,
prostate, and spleen. We do not recommend this in the kidney for concern for
renal toxicity. Enrofloxacin or other quinolones have been usually the antibiotic of
choice in these procedures but cephalosporins and ampicillin have also been
utilized. There is no way of knowing at the time of the drainage procedure
whether the abscess is septic or not or if the injected antibiotic is actually specific
for the potential bacteria involved. However, considering the spectrum of
antibiotics that may be injected endovenously (criteria for selection of the
antibiotic), we tend to utilize the antibiotic that likely would have an effective
spectrum against the usual pathogens that may dwell in the affected organ.
US-Guided Pericardiocentesis
Pericardial effusions typically cause some level of cardiomegaly on radiographs
but note poor vascular volume in the pulmonary artery and vein. Muffled heart
sounds and electrical alternans on ECG may also be present. In this case the
sonogram is quite direct and simple to diagnose while potential masses may be
elusive. In order to provide immediate relief form the tamponade effect from
pericardial effusion, US-guided pericardiocentesis may be performed safely with
variable results. Some patients need light sedation (propofol ideally) and a local
lidocaine block may be utilized after sterile preparation of the field. Others may
not need any sedation at all. The patient is placed in right lateral recumbency
with a left sided approach by the sonographer. The sonographer stays just above
costochondral junction usually IC 4-5 or 5-6 and aim for right auricle without
hitting it of course. This is where the tumor (if present) usually starts to bleed into
the pericardial sac so aiming there will allow for the most efficient drainage, as it
is max volume. The author prefers a 14 to 16g x 2-inch IV catheter flushed with a
heparin (diluted in saline) flush, as you would utilize in an IV catheter to avoid
clots. After utilizing the same 2-step sampling approach described earlier (step 1
through the body wall, step 2 through the pericardial sac) and the catheter
presence in the pericardial sac can be observed, pull the stylet back a couple of
millimeters so only the Teflon is exposed to avoid the stylet from touching the
epicardium. Attach an IV extension set and ideally a suction unit or 60 cc syringe
(Have a few handy to trade off). Large dog tamponade will usually be 200-350
cc. Sometimes the patient may bounce up once they feel better so best to be
prepared. Other times the patients is lethargic for a while owing to new systemic
volume adjustments. At times the potential cardiac tumors continue to bleed and
fill the pericardium as fast as we can remove it.
Don’t give lasix ever in these
cases, as they need their minimal internal volume that is fighting against the
tamponade. This is not a volume overload disease but a volume contraction
disease. Therefore diuresis will make them worse.
Use propofol IV +/- a local
lidocaine block at needle site if need be. If a little blood leaks from the
pericardium it may assist in an ultrasound guided “fenestration” but of course is
not encouraged. (Images)
How To Make Bubbles In Veterinary Medicine.
The reason to perform a bubble study is to confirm the presence of shunting of
blood from venous to arterial flow such as a Reverse VSD or a Reverse PDA.
When severe right sided overload and eccentric hypertrophy is present in
patients with exercise intolerance (cyanosis), the clinical sonographer may
suspect a reverse VSD or reverse PDA owing to Eisenmenger’s physiology;
reversal of flow owing to equalization for right sided compared to left sided
pressures.
Procedure: An IV catheter is placed in the cephalic vein. Take 20 cc
saline or Hetastarch and draw a few cc of air into the syringe. Agitate the syringe
and remove the free air. Dr. Peter Modler demonstrates the materials necessary
on the attached PowerPoint “How To Make Bubbles.”
If reverse PDA is
suspected then image the abdominal aorta as close to the body wall as possible.
Then inject about 10 cc of the agitated saline into the cephalic vein. If a reverse
PDA is present then the bubbles will be seen in the abdominal aorta. In a normal
patient where a closed venous system is present, the bubbles would dissolve in
the pulmonary capillary bed. In the case of reverse VSD, image the heart in 5chamber right parasternal long axis and concentrate on the region of the
interventricular septum where a relatively large defect will usually be present if
the patient is starting to reverse the flow from a long standing VSD. If reversal of
flow is present then the bubbles will enter the right atrium to right ventricle and
cross into the left ventricle and aorta through the defect. The bubbles are then
ejected into the aortic circulation without dissolution in the pulmonary
circulation.
More “How To” procedures are present and being developed in the
“Resources” Tab of sonopath.com instructional library.
Sonographic Aspects Of The UGELAB (Ultrasound-Guided Endoscopic
Laser Ablation) Procedure For Lower Urinary Transitional Cell Carcinomas
In Dogs
Introduction: Transitional cell carcinoma (TCC) of the bladder and
urethra has locally invasive and obstructive aspects. Ultrasound guided
endoscopic diode laser ablation (UGELAB) is a palliative treatment designed to
combat obstruction of the distal urinary tract and maintain urine flow. Ultrasound
monitoring of this process is essential to increase tumor ablation efficacy and
prevent perforation of the urinary tract that would otherwise be a “blind”
intervention with endoscopy and laser alone.
Methods: The GE Logic E ultrasound machine was utilized with either a 5-10
mHz micorconvex probe or 12 mHz linear probe to monitor the progression of the
Hyperechoic Tissue Necrosis Line (HTNL) created by the diode laser ablation of
the tumor. Power Doppler application allows for precise guidance of diode laser
into tumor vasculature allowing for tumor “starvation” from its blood supply. Storz
2.7 endoscope and diode laser 980 wave-length were utilized.
Results: The UGELAB procedure maximized tumor volume reduction, minimized
obstructive tumor bulk, increased urethral and ureteral patency, eliminated tumor
vasculature, abated clinical signs, and increased survival quality and duration in
more than 50 patients with variable survival times after other traditional therapies
for transitional cell carcinoma were found to be ineffective. Two patients died or
were euthanized to this point owing to perforation during the procedure.
Discussion: Ultrasound guidance of the UGELAB procedure allows for very
accurate application of laser energy significantly decreasing the chances of
complications secondary to perforation. Most patients experience immediate
relief of symptoms and client response to treatment has been extremely positive.
Keywords: TCC: transitional cell carcinoma, Ultrasound, Diode Laser, Endoscopy
Abscess Drainage & Injections
“ADAIN” Procedure
The unneutered male dog is of course most frequently subject to prostatitis,
benign prostatic hypertrophy (BPH), prostatic carcinoma, and prostatic
abscesses. Neutering is usually curative along with antibiotic treatment for
prostatitis and BPH, and carcinoma largely carries a poor prognosis but is under
investigation for alternative treatments such as chemotherapeutic implants,
NSAID effectiveness, fluoroscopy guided chemotherapy, and palliative stent
placement. Prostatic abscesses however traditionally necessitate surgical
marsupialization, which is invasive and incurs significant expense and
hospitalization. Therefore, we developed the Abscess Drainage Antibiotic
Injection and Neuter (“ADAIN”) procedure for these patients. The abscess is
drained with a 14 to 16 g IV catheter with attached extension set and syringe until
only a minimal cavity is left. Enrofloxacin (body weight sid dose) in then injected
directly into the abscess and the patient is neutered simultaneously and treated
as outpatient with dual therapy antibiotics such as Enrofloxacin/metroniodazole
or similar combination. This procedure has been effective in nearly 100% of the
cases in our experience without complication. (Images)
In addition, we have also had success draining abscesses that often form in
prostatic carcinomas, which usually occur in neutered males. Often we have
observed that the abscess formation in the prostatic tumor may be the cause of
the new onset of clinical signs that may have been stable previously. Therefore
drainage and antibiotic injection, reducing the volume expansion of the abscess
within the tumor, may allow for some palliative treatment in these cases.
Intraoperative Ultrasound
Intraoperative ultrasound: We utilize this technique to be used on any
abdominal organ but is especially effective in case of infiltrative, focal and
multifocal GI lesions. The problem is that the surgeon cannot often see what the
clinical sonographer is observing from a transabdominal sonographic
perspective. If the organ serosa is not visibly affected, the surgeon will simply
perform a “shopping spree” of intestinal biopsies as opposed to a precise
sampling procedure of the most representative lesion that we observe
sonographically. Hence we may identify and resect the most representative
mural lesions with this method. Procedure: Acoustic gel is placed into a double
surgical glove to keep the outside exposed glove sterile. Cold sterilize the
ultrasound probe with alcohol before putting it in the glove. Pull the glove tight on
top the probe to ensure adequate probe/gel/glove coupling occurs to avoid any
air entrapment. Have the surgeon exteriorize the bowel or expose the target
organ to be sampled. A technician pours saline on the bowel (or other organ) as
a coupling agent. Scan the organ to define the most representative region of the
mural pathology that was observed transabdominally. Then define the best
healthy tissue where the infiltrative pattern or pathology subsides and resect the
lesion at this identified point of healthy tissue proximal and distal to the affected
region. This procedure should take the sonographer 10 minutes or so and the
surgeon may do the rest. (Images)
More on this technique may be seen in our abstract from ECVIM 2009
(Intraoperative Ultrasound for Precise Biopsy and Resection of Transabdominally
Detected Intestinal Lesions in 3 cats. Lindquist, Casey,
Frank)
www.sonopath.com/resources.html
INTRAOPERATIVE ULTRASOUND FOR PRECISE
BIOPSY
TRANSABDOMINALLY DETECTED INTESTINAL LESIONS IN 3
CATS.
E. Lindquist1, D. Casey2, J. Frank1.
1SonoPath.com & Sound
Technologies New Jersey Mobile Associates, Sparta, NJ, USA. 2 SonoPath.com,
Sparta, NJ, USA.
The purpose of this study was to preliminarily evaluate the utility of intraoperative
ultrasound to enhance the sonographer/surgeon symbiotic precision in obtaining
representative histopathology that corresponds to that found during the
transabdominal sonogram. We performed intraoperative intestinal sonograms on
3 different feline patients that demonstrated focal loss of mural intestinal detail
across the submucosal layer of small intestine during their transabdominal
sonograms. These lesions were localized with a 12 MHz linear probe and
surgically resected in each patient. Then random samples were obtained in areas
selected by the surgeon and were more sonographically consistent with simple
inflammatory bowel disease, without loss of mural detail, and regions that
maintained well-defined curvilinear wall layering during intraoperative
sonographic examination.
Sterile technique was utilized by means of a double layered surgical glove
partially filled with acoustic gel. The intestinal tissue was bathed in physiologic
solution during the procedure to maintain acoustic coupling while the surgeon
extended portions of the intestine to be imaged intraoperatively. When the
precise lesions with loss of mural detail were identified, the intestinal pathology
was surgically resected and placed in separate formalin jars.
The 3 feline patients revealed the following histopathological results:
1) FelMNDSH16YR: Surgeon selected sample (stomach): Mild chronic
lymphoplasmacytic gastroenteritis. Focal lesion identified with ultrasound (ileum):
Low grade lymphosarcoma.
2) FelFSDSH14YR: Surgeon selected sample (jejunum): mucosal lymphocytic
infiltrative disease. Focal lesion identified with ultrasound (jejunum): Low-grade
lymphosarcoma with lymphoid clusters observed in submucosa and muscularis.
Muscular hypertrophy.
3) FelMNDSH15YR: Surgeon selected sample (small intestine): mild mixed
inflammation and mural enteritis. Focal lesion identified with ultrasound (small
intestine): Severe, segmental pyogranulomatous mural enteritis with focal
ulceration. Suspect for feline infectious peritonitis.
In the pilot study population of
these 3 cats, it was found that intraoperative ultrasound may be utilized to
identify transabdominally detected lesions and delineate the extent for resection
at laparotomy when serosal pathology is not evident to serve as a landmark for
the surgeon. These findings merit a more thorough study with a larger study
population to detect the usefulness of intraoperative ultrasound.