Download High risk

Contrast Media
IRTB 2013
Dr Lyn Jones
North Bristol NHS Trust
Flow rates

Dependent on inner
diameter and length
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3F 6-8 mls/s
4Fr 16-18 ml/s
5F 20-25 ml/s.
Hand injection
maximum 5-6mls/sec
Pump injectors

Slow the rate and
increase the volume in
slow flow arteries and for
rotational programmes
 Slow the rate rise to
prevent catheter recoil
 Max PSI should be
documented on the
catheter hub
 Dilute if i.a. injection for
CT

Examples
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Bilateral iliac: 20mls at
10mls/sec
Arch aortogram: 35mls at
15mls/sec
Single leg run off: 10mls at
5mls/sec
SMA/Coeliac: 35mls at
6mls/sec
Rotational renal transplant:
20mls at 7 mls/sec
Post EVAR CT: 100mls
diluted 50/70 mix with
saline at 8 mls/sec
Contrast reactions

Warmth and/or pain, particularly uncomfortable
for direct arterial injection
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Flushing, metallic taste, headache
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Can be reduced by slower injection
Dose dependent
N&V
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ICM less painful for intra-arterial injection
Dilute contrast when direct injection into smaller
vessels
Doesn’t matter how fast you give it
Anaphylactic reactions
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Potentially life threatening
Constitutes 4:10,000 severe or life-threatening
reactions
Anaphylaxis
 Know
the protocols
 Know where your crash trolleys are
 High risk patients:
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Investigation justified?
Use alternative investigation or alternative
contrast?
Omit contrast medium?
Steroid prophylaxis?
• PO/IV?
• Must be started 24 hours prior to administration.
Contrast Terminology
HOCM
 Tri–iodinated benzoic acid
(Ionic contrast, therefore
charged particle)
 High Osmolality
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1500-2300 mOsm/kg water
(monomers)
690 mOsm/kg water
(dimers)
c/w Plasma Osmolality 280303 mOsm/kg water
LOCM
 Tri-iodinated substituted
ring compound
 Side chains make molecule
highly hydrophilic to
increase solubility without
dissociation
 Low Osmolality


580 mOsm/kg water
(monomers)(Ultravist/Niopam/
Optiray/Omnipaque)
272 mOsm/kg
(dimers)(Visipaque)(Saline
added to increase osmolality)
also called isosmolar or ICM
HOCM v. LOCM
HOCM
 1:40,000 Mortality
 Higher incidence of
adverse reactions
 5% Allergy
 Higher incidence of
contrast induced
nephropathy (CIN)
 Not for use
intravascularly
LOCM
 1:170,000 mortality
 4:10,000 severe or lifethreatening reactions
 Intravascular use: 8090% intravenous, 1020% intra-arterial
Contrast media adverse effects CIN

Contrast media induced nephropathy (CIN) is
the sudden rapid deterioration of renal
function resulting from contrast media
administration and with no alternative clinical
explanation
 ↑ SCr ≥ 0.5mg/dl or ↑ SCr ≥ 25%
 First described 1954 but became a concern
only since the development of nonionic low
osmolar contrast media (LOCM) in the 1980s;
significantly reduced systemic and CNS
toxicities
Bartels ED et al. Acta Med Scand 1954 150: 297-302
Mechanism of CIN

Direct renal tubule
toxicity
 Vasoconstriction in
vasa recta leading to
medullary ischemia
which exacerbates
toxicity
 Transient fall in GFR
due to osmotic effects
Incidence of CIN
– concept of Hospital Induced
Nephropathy (No control arm in published
trials)
 Negligible in patients with normal renal
function, but if renal insufficiency then:
 Intra-arterial ICM administration 8%-57%
 Controversial
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Increases as GFR falls below 60ml/min/1.73sqm
Mehran R et al,J Am Coll Cardiol 2004 44 1393-9
 Intravenous
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ICM administration ~ 5%
Increases as GFR falls below 45ml/min/1.73sqm
Romano G et al, Eur Heart J 2008 29 2569 -76
Significance of CIN
 Controversial
 Development
of CIN is associated with
increased length of hospitalization, need for
dialysis (<1%) and long term mortality
 But no causal relationship yet proven; CIN
may simply be an indicator of patients likely
to fare poorly under any circumstances
Contrast-induced nephropathy: what are the true clinical
consequences? Rudnick M and Feldman H Clin J Am Soc
Nephrol 2008; 3 (1): 263-272
Renal Function - Chronic
Stage GFR*
Description
1
90+
Normal kidney function
2
60-89
Mild reduction renal function
3A
3B
4
45-59
30-44
15-29
Moderate reduction renal function
5
<15 or on Very severe/end-stage renal failure
Severe reduction renal function
dialysis
* All GFR values are normalized to an average surface area (size) of 1.73m2
Which Iodinated Contrast
Medium?
 LOCM
has reduced rate of CIN over HOCM
 Pharmacokinetics of all currently used
iodinated contrast media are similar
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Low lipid solubility
Extremely low chemical activity with bodily fluids
Relatively low molecular weights
Half time in patients with normal renal function of
1-2 hours
“extracellular tracers” = class of compound
Controversy over choice of
iodinated contrast medium
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A meta-analysis of the renal safety of isosmolar iodixanol
compared with low-osmolar contrast media McCullough PA,
J Am Coll Cardiol 2006; 48 (4): 692-9
GE unit ordered to pay $11.3 million over false advertising
claims against competitor; judge denies request that GE
subsidiary Amersham disgorge $1 billion in profits Toulant C
Available at
http://www.law.com/jsp/article.jsp?id=1202429880602 (last
accessed 01/01/2010)
Nephrotoxicity of iso-osmolar contrast media meta-analysis
of randomized controlled trials Heinrich MC et al. Radiology
2009 250 (1) 68-86
Cardiac angiography in renally impaired patients (CARE)
study: a randomised double-blind trialof contrast-induced
nephropathy in patients with chronic kidney disease
Solomon RJ et al. Circulation 2007 115: 3189-96
Choice of radiographic iodinated
contrast medium (RICM)
 Both
LOCM and ICM are acceptable for
intravenous administration. No evidence to
distinguish CIN risk even in high risk
patients
 Limited evidence that ICM carries a
smaller risk than LOCM for intra-arterial
administration but both acceptable
Ellis J and Cohan R, Radiol Clin N Am 2009 47 801 - 811
Reduction in risk of CIN

Identify patients at risk
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Acute kidney injury/ARF
Chronic renal disease
• eGFR < 40ml/min/1.73sqm for intra-venous ICM
• eGFR < 60ml/min/1.73sqm for intra-arterial ICM

Dose Reduction or Elimination (consider alternative
agents)
 Hydration
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Optimal regime not known, IV, earlier and longer
probably better
Consider N acetyl cysteine
Evaluate risks/benefits of ICM for individual patient
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No absolute renal contraindication to ICM administration
Most CIN resolves without untoward clinical effects
Alternative agents – CO2
CO2 is an endogenous, invisible, compressible,
soluble, non-viscous and buoyant gas provides a
relatively low contrast, negative contrast agent
Advantages
 Eliminated by one pass through the lungs
 Lacks allergic potential and renal toxicity
 Low viscosity (1/400 that of iodinated contrast)
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Easy delivery through microcatheter or between catheter
and wire
Flows readily into bleeding sites
Allows superior opacification of portal vein via wedge
portal venography or parenchymal injection
Alternative agents - CO2
Disadvantages
 Potential neurotoxicity and cardiac ischemia
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Invisible
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Rises to non-dependent portion of a larger diameter vessel; potential
to overestimate stenoses and may not fill dependent vessels
Prone position and head elevated position contraindicated
Compressible
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Potential undetected air contamination; use sealed delivery system
Buoyant
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Contraindicated in cerebral and coronary circulations, thoracic aorta,
brachial artery or if the patient has a significant AV shunt
Potential excessive volumes or explosive delivery (use of finite
volume plastic bag delivery system is recommended)
Caution with intestinal ischemia, pulmonary compromise,
AAA and N2O anaesthesia
Alternative agents - CO2
Advice
 Disposable cylinder, individually tested with
initial test venous injection and pulmonary artery
imaging
 Use closed system and never connect CO2
cylinder directly
 Flush regularly with CO2, not saline
 Wait 2-5 minutes between injections to minimise
risk of ischemia
 Change patient position and use vasodilators
 Use high resolution DSA with high frame rate
and scene summation soft ware to optimise
image
Hawkins I et al. Radiol Clin N Am 2009 47 813-825
Alternative imaging - Gadolinium
Alternative imaging - Gadolinium
 For
allergy to RICM, obtain MRA for
diagnosis then use Duplex and low dose
GdCM to guide plasty (painful intra-arterial
injection and poor opacification)
 Nephrotoxicity at equi-attenuating volumes
worse than LOCM, so no use if renal
function↓
 Risk of Nephrogenic Systemic Fibrosis
(NSF) if patient has renal compromise
Nephrogenic Systemic Fibrosis (NSF)
Gadolinium chelates
 High
risk—Omniscan (gadodiamide),
OptiMARK (gadoversetamide), Magnevist
(gadopentetic acid)
 Medium risk—MultiHance (gadobenic
acid), Primovist (gadoxetic acid), Vasovist
(gadofosveset)
 Low risk—Gadovist (gadobutrol),
ProHance (gadoteridol), Dotarem
(gadoteric acid)
MHRA Medicines and Healthcare products Regulatory Agency and CHM
Commission on Human Medicines in Drug Safety Update
January 2010 Volume 3, Issue 6 page 3-5
Contrast Media Summary
 LOCM
has excellent safety profile currently
(0.04% life-threatening reactions)
 Optimize administration protocols for
individual radiographic equipment
 Caution in patients with Renal Compromise
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Justification, optimization, dose reduction
Hydration (+/- NAC)
Consider use of alternative agents (CO2)
Nephrogenic Systemic Fibrosis (NSF)
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First cases diagnosed in 1997, but correlation with
exposure to GdCM first reported in 2006
 Variable clinical picture
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early erythema, pain, neuropathy inflammatory reaction,
gastroenteritis, lungs, eyes
late skin thickening and hardening, contractures,
disabilities
Gadolinium salts present in affected skin supports
causality
 Depends on stability of chelate; related to free Gd
Gadolinium chelates