john p. riordan, md. objectives: 1. to review common implantable medical devices. 2. to appreciate...
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John P. Riordan, MD
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Objectives:1. To review common implantable medical devices.
2. To appreciate the signs and symptoms associated with malfunctioning of these devices.
3. To gain the necessary familiarity with these devices to both troubleshoot them and speak intelligently with consultants regarding them.
4. Disclaimer?
“Please! Remain in your seats, I beg you! We are not children here, we are scientists!I assure you there is nothing to fear!”
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Time to get going?
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Conflict of Interests:Traditional hierarchy of
study design
Randomized trials: Double blind RCT with
blinded ascertainment and analysis
Double blind RCT Single blind RCT Unblinded RCT
Observational Studies Cohort Case Control
Descriptive Studies With comparison groups Without comparison groups
Alternative evidence hierarchy
Things I believe Things I believe despite the
available data
Randomized controlled clinical trials that agree with what I believe
Other prospectively collected data
Expert opinion
Randomized controlled clinical trials that don’t agree with what I believe
What you believe that I don’t
Adapted from Bleck TP, BMJ 2000; 321:239
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“Hearts and Kidneys are tinker toys! I am talking about the central nervous
system!”
Old stuff:
Ventriculo-peritoneal (VP)
Ventriculo-atrial (VA)
Ventriculo-pleural (VPL)
Lumbar-peritoneal (LP)
New stuff:
Endoscopic Third Ventriculostomy (ETV)
Deep brain stimulators
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Shunted patient presents with bulging fontanelle, irritability, vomiting and lethargy….or not
Intra-ventricular Complications (device failure): Ventricular obstruction> distal catheter
occlusion>migration>>>disconnection/breaking (3%) Greatest in infancy
Abdominal Complications: inguinal hernia or hydrocele (higher incidence following
placement in first few months of life) Abdominal CSF pseudocysts (infectious, inflammatory) Ascities
Vascular Complications: VA shunts: higher risk of distal obstruction due to migration,
displacement and thrombosis. Subdural hematoma
C. Di Rocco, Et al, Childs Nerv Syst (2006)
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Physical Examination of Patients With Cerebrospinal Fluid Shunts: Is There Useful Information in Pumping the Shunt?
Joseph H. Piatt, Jr 1992;89;470 Pediatrics
Theory: 1 way flow. If depresses easily then outflow is patent. If fills rapidly then inflow is patent.
200 consecutive patients
Poor sensitivity and poor negative predictive value
Conclusion: “Unfortunately, there is no convenient or inexpensive way to make a disposition on the hydrocephalic patient with symptoms suggestive of CSF shunt malfunction. Keeping in mind the morbidity attached to delay in the diagnosis of shunt malfunction, the responsible physician must have a low threshold for ordering definitive brain imaging and must not be deflected by reassurances from pumping the shunt valve.”
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Fast MRI What is fast?
What is the benefit?
What are the limitations? Lack of sensitivity in detection of extra-axial and
parenchymal blood products Decreased catheter delineation.
“SEDA-GIVE?”
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Slit Ventricle Syndrome
Headaches lasting 10-90 minutes
Normal or small ventricles on imaging studies
Multiple subtypes responding to multiple different management strategies (medical and surgical)
Primarily a disorder of patients shunted in infancy
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Infections:Think about it early!
Most (70%) 1 month
85% within 9 months
Typically skin organisms
Often requires removal of shunt
Think about infection in VA shunts with fever
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Intra-thecal Analgesia Drug effect:
Narcotics- constipation, sweating, nausea, urinary retention, vomiting, insomnia (common)
Local anesthetics- Ca Channel blockers Alpha 2 agonists- sedation,
hypotension, nausea, dry mouth
NMDA antagonists GABA agonists
Catheter related complications: migration, coiling, obstruction, breakage.
Intrathecal granuloma- beware cord compression
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E.V.A.R.
Endoleak: persistent blood flow outside stent graft but inside aneurysmal sac.
20% ( depending on imaging surveillance techniques).
Types I-IV
Endotension: larger aneurysm without leak
www.vascular.co.nz
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Left Ventricular Assist Device
I.N.T.E.R.M.A.C.S.: 1092 pt. cohort 6/06-3/09 45% BTT, 42%BTC, 9%DT Overall survival isolated
device 74% Most pulsatile likely
underestimates current survival
Pulsatile devices: more than half require
replacement for infection or malfunction over 2 years
Continuous-flow: smaller, less pump pocket
infection less physiologic due to
continuous flow
“For what we are about to see next, we must enter quietly into the realm of genius.”
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Stroke infection Device malfunction Kidney and Liver dysfunction Right heart failure Depression or anxiety High incidence of GI bleeds Suction arrhythmias Hemolysis
Reprinted with the permission of Thoratec Corporation
Complications:
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Feeding tubes 101 Clogging:
• The old carbonated beverage trick??• Pancreatic enzymes with bicarbonate??• High Pressure??
Displacement:
• Track can close within hours. • 1-2 weeks to form a track (longer if immunocompromised).• Best to replace same type of tube if possible• X-ray study for confirmation? If so, which type??
Consider a pathway or documentation form!
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Gastrostomy Tube-Related Complaints in the Pediatric Emergency Department
Identifying Opportunities for Improvement
Heather Saavedra, MD et alPediatric Emergency Care, Volume 25, Number 11, November 2009.
Major 5% vs. Minor 95%
G: Most common complaint dislodgement 119/159 required replacement 97% success ¾ ED attending Beware of balloon migration into pylorus causing outlet
obstruction Button vs. adjustable length
GJ: Most common complaint malfunction (clogging) 86% replaced by IR Beware aspiration pneumonia due to malpositioning
“Two nasty lookin' switches over there, but I'm not going to be the first”
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T.K.A. Most common
replacement
Growing demand
Implant suvival x>90% at 15 years
Early (x<2yrs): Infection, Instability, malalignment, malposition
Late (x>2yrs): polyethylene wear, aseptic loosening, instability
N.Y. Times
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“You know, I'm a rather brilliant surgeon. Perhaps I can help you with that hump”….but first, “Get me a
sed rate, CRP, and x-ray…..”
H and P
LAB: WBC? Peripheral leukocyte counts usually not elevated.
Imaging: Plain film 9 A.C.R
A.A.O.S.: clinical practice guideline dx of periprosthetic joint infections: Strong: aspiration for “abnormal” SED AND/OR CRP Inconclusive: We are unable to recommend for or against CT or
MRI as a diagnostic test for periprosthetic joint infection Strong: We recommend against initiating antibiotic treatment
in patients with suspected periprosthetic joint infection until after cultures from the joint have been obtained
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Types of dialysis access
AV fistula (biologic materials)- end to side vein to artery anastomosis-need to mature (at least 30 days) higher rate primary failure. More difficult to cannulate Most common?, What
doctor?
Grafts (synthetic conduit)-ready for use earlier polytetrafluoroethylene
Tunneled Catheters-under fluoro tip in RA
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Bleeding under a pile of gauze!!!
What type of site?
Is the patient anti-coagulated?
Were they just stuck?
What do you do first, second and finally?
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Infections
Systemic Bloodstream Suppurative thrombophlebitis Distant infections- endocarditis, metastatic abscesses
Local Colonization- isolate w/out Exit or insertion site- purulent d/c often gram stain/cx
positive. +/- pain, erythema, tenderness. Port/reservoir- implantable devices, check skin over
reservoir Tunnel infection- x>2cm from entrance site“Treatment of line infections varies by institution and often
depends on the clinical scenario”
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Fistula<Graft<CatheterFistula
treat as SBE with 6 weeks of antibiotic therapy
Graft
most require both antibiotic and surgical therapy
Catheter
exit site- w/out systemic sx. And –blood cx.-topical.
If tunnel infection parenteral abx pending tunnel site culture. Failure-new site
Bacteremia-parenteral antibiotics +/- removal based on response to treatment and severity of symptoms
NKF K/DOQI Guidelines 2000
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What are the flow problems?
Venous hypertension
High output heart failure- fistulas (uncommon)
Aneurysm/pseudo
Steal
Ischemic Monomelic Neuropathy- early nerve sensori-motor dysfunction without skin or muscle ischemia
Thrombosis higher in grafts early vs. late
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The Hemodialysis Reliable Outflow GraftHeRO
FDA 2008 approved as a graft for hemodialysis patients who have exhausted all other access options
At least as good as standard graft
Candidates need: Brachial artery >3mm,
Cardiac EF >20%, SBP >100, absence of infection
Clotting is main complication due to length of tubing
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Would it change your thinking if she had one of
these…. Mechanical
phlebitis- difficult to distinguish from infection. Usually present < 10 days from insertion
Withdrawal occlusion/complete occlusion- thrombotic vs. non-thrombotic
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“He vould have an enormous schwanzstucker.”
Infection (8-20%) Less common in first time
surgeries Most should have device
removed if significant infection. Select patients with mild infections may be amenable to salvage procedure.
Coated devices Gram +, gram -, anaerobes
Erosion- consider above
Pain- not uncommon for 4-6 weeks following surgery if pain getting worse instead of better see above
MRI often imaging modality of choice
Hossein Sadeghi-Nejad, MD, J Sex Med 2007; 4:296-309
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Complications of percutaneous procedures
E. Chen, A. Nemeth , American Journal of Emergency Medicine (2011) 29 802-810.
Introduction:
Vascular: Venous: vena caval filters, venous access
catheters/ports, transvenous hepatic and renal bx., TIPS.
Arterial: uterine artery embolization, ERAR, Chemoembolization.
Non-vascular: Feeding tubes, Biliary drains, nephrostomy/ureteral
stents
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Conclusions:
Patients with implantable devices are special
You must include evaluation of the device in your history and physical exam.
Often, specialized device specific testing is required to identify dysfunction.
“Frankenstein Clause”
"What the hell are you doing in the bathroom day and night!? Why don't you get out of there, give someone else a chance!"