How to reduce radiation dose and decrease contrast induced nephropathy

How to Reduce Radiation Dose and Decrease Contrast-Induced Nephropathy in the Cardiac Catheterization Laboratory Vietnam National Congress of Cardiology October 12, 2014 SCAI Fellow’s Course Charles E Chambers, MD, FSCAI, FACC, NCRP President, Society for Cardiovascular Angiography and Interventions Professor of Medicine and Radiology Pennsylvania State University College of Medicine Director, Cardiac Catheterization Laboratories MS Hershey Medical Center, Hershey, PA Society for Cardiovascular Angiography and Intervention Mission Statement SCAI promotes excellence in invasive and interventional cardiovascular medicine through physician education and representation, and the advancement of quality standards to enhance patient care X-ray Image Formation • Ideal X-ray Image – Optimal X-ray imaging requires a kVp (peak tube voltage) and mA (cathode current) that produces the best balance of image contrast, and patient dose Automatic dose rate controls increase x-ray tube output for a specific size and projections for adequate detector entrance dose rate and image quality • X-ray Dose – “Dose” a measure of energy absorbed by tissue – The pt dose is derived from the X-ray photons that enter but not leave • Scattered Radiation – Principal source of exposure to the patient and staff Patient Dose Assessment • Fluoroscopic Time least useful • Total Air Kerma at the Interventional Reference Point (Ka,r , Gy) is the x-ray energy delivered to air 15cm from for patient dose burden for deterministic skin effects • Air Kerma Area Product (PKA , Gycm2) is the product of air kerma and x-ray field area PKA estimates potential stochastic effects (radiation induced cancer) • Peak Skin Dose (PSD, Gy) is the maximum dose received by any local area of patient skin No current method to measure PSD, it can be estimated if air kerma and x-ray geometry details are known Joint Commission Sentinel event, >15 Gy Total Air Kerma at the Interventional Reference Point • a/k/a Reference Air Kerma, Cumulative Dose • Measured at the IRP, may be inside, outside, or on surface of patient • Iso-center is the point in space through which the central ray of the radiation beam intersects with the rotation axis of the gantry Patient Isocenter 15 cm Interventional Reference Point (fixed to the system gantry Focal Spot Air Kerma-Area Product (PKA) • Also abbreviated as KAP, DAP • Dose x area of irradiated field (Gy·cm2) • Total energy delivered to patient: – Good indicator of stochastic risk – Poor descriptor of skin dose = Biologic Effects of Radiation • Deterministic injuries – When large numbers of cells are damaged and die immediately or shortly after irradiation Units of Gy – There is a threshold dose for visible post procedure injury ranging from erythema to skin necrosis • Stochastic injuries – Post radiation damage, cell descendants are clinically important Higher dose, the more likely the process – There is a linear non-threshold dose identifiable for radiation-induced neoplasm and heritable genetic defects This is in units of Sv Radiation Dose Management • Justification of Exposure- benefit must offset risk • ALARA-As Low As Reasonably Achievable • Training • Optimizing Patient Dose- From Onset Of Procedure • Radiation Safety Program- Every Lab as Part of QA Wilhelm Roentgen Radiation Dose Reduction Implementing a Culture & Philosophy of Radiation Safety resulted in a 40% reduction in Cumulative Skin Dose over a yr period Radiation Dose Management in PCI Pre-Procedure • • • • • • Radiation safety program for cath lab Dosimeter use, shielding, training/education Equipment and operator knowledge On screen dose assessment (Ka,r , PKA) Dose saving: store fluoro, adj pulse and frame rate, and last image hold Pre-procedure dose planning – – • assess patient and procedure including patient’s size and lesion(s) complexity Informed patient with appropriate consent Procedure • • • • • • • • • Limit fluoro: use petal only when looking at screen Limit cine: store fluoro if image quality not key Limit magnification, frame rate, and steep angles Use collimation and filters to fullest extent possible Vary tube angle if possible to change skin exposed Position table & image receptor: x-ray tube close to pt increases dose; high image receptor incr scatter Keep pt & operator body parts out of field of view Maximize shielding and distance from x-ray source for all personnel Manage and monitor dose in real time from the beginning of the case Post Procedure Documentation of Dose Follow-up Protocols •Chambers CE Radiation Dose in PCI OUCH…Did that hurt? •JACC Cardiovasc Interv 2011.March Vol (3); 344-6 Contrast Injury to the Kidney Contrast Induced Nephropathy (CIN) Acute Kidney Injury AKIN /KDIGO Classification • Definition: an increase in • Stage serum Cr from baseline of – 1.5 to 1.9 fold increase in Cr >25%, or absolute >0.25 or – Absolute increase >0.3 mg/dl 0.5 mg/dl • Stage • Baseline renal disease – 2-2.9 fold increase in Cr increases risk as assessed by eGFR or CrCl; age, sex , and • Stage obesity factors in estimating – >3 fold increase in serum Cr eGFR/CrCl – Absolute increase >4 mg/dl • Renal dysfunction is – Acute increase >0.5 mg/dl identifiable by 48 hrs and AKIN-Acute Kidney Injury Network most often returns to KDIGO-Kidney Disease: Improvement in Global Outcomes baseline by 7-10 days Acute Kidney Injury from Contrast Incidence/Predictors NCDR Report • 985,737 patients underwent PCI at 1,253 sites from June 2009- June 2011with AKIN criteria • Overall Incidence 7.1% with: – Stage 1-6.0%; stage 2-0.5%; stage 3-0.3% ; dialysis 0.3% • Predictors – – – – STEMI Cardiogenic shock Pre-existent renal disease Contrast volume Outcomes (In-hospital) • No AKI – MI-2.1% – Bleeding -1.4% – Death-0.5% • AKI – MI-3.8% – Bleeding -6.4% – Death-9.6% • Dialysis – MI -7.9% – Bleeding -15.8% – Death-34.3% Tsai et al Contemporary Incidence, Predictors, and Outcomes of AKI in pts undergoing PCI JACC Interv 2014 Vol7 #1; Pg 1-9 Pre-procedural Clinical Risk Factors for Contrast Induced Nephropathy • Modifiable Risk Factors – Contrast volume – Hydration status – Concomitant nephrotoxic agents – Recent contrast administrations • Non-modifiable Risk Factors – Diabetes/Chronic kidney disease – Shock/hypotension – Advanced age (> 75 yrs) – Advanced congestive heart failure Klein LW, Sheldon MA, Brinker J, Mixon TA, Skeldiong K, Strunk AO, Tommaso CL, Weiner B, Bailey SR, Uretsky B, Kern M, Laskey W The use of radiographic contrast media during PCI: A focused review Cathet Cardiovasc Int 2009; 74: 728-46 Multi-factorial Predictors of CIN Cardiac Complication in Patients with CIN Post PCI • Mayo Clinic Registry of 7,586 pts post PCI • Patients with CIN had increased rates of: – CABG p=0.004 – Q-MI p< 0.001 – CK Rise p[...]...Procedure Related Issues to Minimize Exposure to Patient and Operator • Utilize radiation only when imaging is necessary • Minimize use of cine • Minimize steep angle X-ray beam • Minimize use of magnification modes • Minimize frame rate of fluoroscopy and cine • Keep the image receptor close to the patient • Utilize collimation to the fullest extent possible • Monitor real time radiation dose DRAPED: • D-distance:... • R-receptor: keep image receptor close to patient and collimate • A-angles: avoid steep angles • P-pedal: keep foot off pedal except when looking at the monitor • E: extremities-keep patient/operator extremities out of the beam • D -dose: limit cine, adjust frame rate, where personal dosimeter Inverse Square Law This relationship shows that doubling the distance from a radiation source will decrease. .. useful for the prevention of contrast- induced AKI (Level of Evidence: A ) Contrast Dose • Maximal Allowable Contrast Dose (MACD) – 5 cc contrast x body wgt (kg)/ baseline Cr – Brown et al, Circ Interv, 2010 • Volume to Creatinine Clearance Ratio – Contrast volume/ CrCl – Laskey, JACC 2007, unselected population, 3.7 ratio – Gurm et al, JACC, 2011, 3 concern Contrast Type • Low osmolar or... history/exam Biopsy only for uncertain diagnosis as the wound from the biopsy may result in a secondary injury potentially more severe than the radiation injury Radiographic Contrast Media Classification is based upon the agent’s ability to dissociate (ionic) or not dissociate (nonionic) into ionic particles Ionic Monomer Ionic Dimer Nonionic Monomer Nonionic Dimer Contrast Injury to the Kidney Contrast. .. Risk of Contrast Induced Acute Renal Injury/CIN • Manage Medications – • Withhold, if clinically appropriate, potentially nephrotoxic drugs including aminoglycoside antibiotics, anti-rejection medications and nonsteroidal antiinflammatory drugs (NSAID) Manage Intravascular Volume (Avoid Dehydration) – • Administer a total of at least 1L of isotonic (normal) saline beginning at least 3 hrs before and continuing... Guidelines 3.2 Contrast- Induced Acute Kidney Injury Recommendations Class I 1 Patients should be assessed for risk of contrast- induced AKI before PCI (Level of Evidence: C) 2 Patients undergoing cardiac catheterization with contrast media should receive adequate preparatory hydration (Level of Evidence: B) 3 In patients with chronic kidney disease (creatinine clearance 60 ml/1.73 m2 • NSAID stop if possible • N-acetylcysteine, mixed reviews, no clear benefit • Statins (+/_); theophyline (-) • Optimize hydration status – High risk: eGFR 75 yrs) – Advanced congestive heart failure Klein LW, Sheldon MA, Brinker J, Mixon TA, Skeldiong K, Strunk AO, Tommaso CL, Weiner B, Bailey SR, Uretsky