Medical response to a major radiologic emergency - handout
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Medical response to a major radiologic emergency - handout

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Summary of preparatory reading for MUHC ED Disaster Preparedness Course for Residents

Summary of preparatory reading for MUHC ED Disaster Preparedness Course for Residents

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Medical response to a major radiologic emergency - handout Medical response to a major radiologic emergency - handout Document Transcript

  • Adapted from Wolbarst et al, Medical Response to a Major Radiologic Emergency: A Primer for Medical and Public Health Practitioners. Radiology: Volume 254: Number 3—March 2010 Medical Response to a Major Radiologic Emergency Planning in radio-nuclear (R/N) events revolves around 4 basic scenarios  Detonation of a nuclear weapon  Meltdown of a nuclear reactor,  Explosion of a large radiologic dispersal device (“dirty bomb”)  Surreptitious placement of a radiation exposure device in a public area of high population density Basic concepts in Radiological exposures  Units (traditional vs SI) are in almost all emergency situations numerically equivalent  Absorbed dose is a measure of the actual energy deposited in an irradiated mass  Equivalent dose adds a measure of biological impact of the radiation type  Effective dose is an aggregation of per tissue/organ estimates of the Equivalent dose weighted for the sensitivity of the organs involved, giving an estimate of the impact of absorbed dose on an organism Health effects of radiation Depend on:  Dose absorbed  Part of the body exposed  Rate  Route  Type (ɑ, β, γ, x rays or neutrons) Stochastic effects o Random effects of transformation of genetic material within 1 or more cells, with increasing probability of occurrence with dose, but may occur even at low dose. E.g. carcinogenesis Farooq Khan MDCM PGY3 FRCP-EM McGill University November 14 th 2011
  • Adapted from Wolbarst et al, Medical Response to a Major Radiologic Emergency: A Primer for Medical and Public Health Practitioners. Radiology: Volume 254: Number 3—March 2010 Deterministic effects o Predictable dose-dependent effect of radiation-induced acceleration of cellular processes, damage or apoptosis leading to organ dysfunction. Can be acute or late in onset. General Principles of Radiation Safety Direct exposure to ionizing radiation o Patients nearby during or after a R/N event, irradiated but not rendered radioactive or contaminated themselves. Contamination with radioactive materials o Patients around contaminated objects, environments or people having now contaminated themselves through various routes. HCPs should wear PPE and keep exposure as low as reasonable achieved (ALARA). ALARA principles  Minimize time  Maximize distance  Use shielding when appropriate,  Ensure prompt removal or containment of contamination Type of radiological contamination  ɑ-particles: large, slow moving, deposit energy locally, cannot traverse epidermis. Internal hazards  β- particles: can penetrate several cm into skin. Internal and external hazard  γ and x-rays: non-particulate, high energy radiation capable of penetrating the whole body and require lead or concrete shielding. Internal and external hazards External contamination  Clothing should be removed and placed in identified radio-hazard bags  Surveys with sealed radiation detection equipment should start with open wounds, then facial orifices followed by skin  Nasal and buccal swabs should be taken for analysis  Gentle irrigation of wounds followed by usual scrubbing of skin is appropriate, use waterproof paper for run-off into plastic garbage containers or bags that can be disposed of separately. Dab away excess fluid 1 gauze at a time. Perform another detection survey after irrigation before proceeding with surgical closure; small amounts of contamination is acceptable before closure.  Repeat survey-wash-rinse sequence until readings drop to 2-3× background levels.  Whole body shower is rarely needed. Internal contamination  Via inhalation, ingestion, percutaneous transdermal, or open wounds/abrasions.  Little can or needs to be done acutely  Specialized equipment and expertise is required to assess for and prevent organ uptake (e.g. iodine in the thyroid, or radium, americium or plutonium in the bone)
  • Adapted from Wolbarst et al, Medical Response to a Major Radiologic Emergency: A Primer for Medical and Public Health Practitioners. Radiology: Volume 254: Number 3—March 2010 Protection of personnel o Personnel in the proximity of or in contact with a few individuals who are lightly contaminated externally will be exposed to ionizing radiation, although this generally (depending on the isotopes) involves very little risk. o Personnel dealing with a multitude of more heavily contaminated patients, on the other hand, may accumulate a substantial dose over time, unless they are careful and follow standard precautions against any hazardous materials. Moreover, they can inadvertently transfer contamination to themselves and from there to others. Planning and training Protocol should be scalable, user-friendly, and directly outline each participant’s role. Planning should be community-wide including:  Medical personnel, local public safety, public health, psychologic services, and emergency management officials, together with first responders from fire departments, EMS, law enforcement, and other agencies. At the ED level involve:  Radiation safety staff, the radiology and radiation oncology departments, security and communications, hospital administration, clinical affairs, and public relations. Components of plan include:  Personnel and resource management  Worker health and safety o Establish common transport pathways, safe areas for family etc. In addition to PPE  Communication o Establish and routinely test redundant systems, have back-ups for systems that could be incapacitated by a nuclear blast. View slide
  • Adapted from Wolbarst et al, Medical Response to a Major Radiologic Emergency: A Primer for Medical and Public Health Practitioners. Radiology: Volume 254: Number 3—March 2010 ARS See separate ARS handout for further details. View slide
  • Adapted from Wolbarst et al, Medical Response to a Major Radiologic Emergency: A Primer for Medical and Public Health Practitioners. Radiology: Volume 254: Number 3—March 2010 General Management Principles:  Dose estimated by  time to onset vomiting,  lymphocyte depletion rates,  distance from radioactive source o Confirmed by dicentric chromosome analysis of swabs/tissues etc  Triage patients to o Mild exposure  Many individuals who arrive at the ED will be physically intact but emotionally traumatized o Severe potentially life threatening exposure  With excellent supportive care, victims may recover following acute whole-body exposures of 5–6 Sv o Highly likely to be fatal exposure  Patients rarely survive >10 Sv  Combined injury leads to more effects at low doses  in chaotic situation track the contamination status, diagnosis, and treatment of patients by attach a hard copy of the medical record package, or at least a brief note, either to clothing or to a cord hung around the neck  heavy internal contamination is suspected, significant intervention may be required early on to prevent incorporation of radionuclides into critical organs
  • Adapted from Wolbarst et al, Medical Response to a Major Radiologic Emergency: A Primer for Medical and Public Health Practitioners. Radiology: Volume 254: Number 3—March 2010 Use diagnostic risk assessment and management algorithm below as a guide, tailored to specific situation
  • Adapted from Wolbarst et al, Medical Response to a Major Radiologic Emergency: A Primer for Medical and Public Health Practitioners. Radiology: Volume 254: Number 3—March 2010 Immediate General Medical Care and Monitoring of the Heavily Exposed but Potentially Salvageable Patient First priority:  Acutely life- and limb-threatening medical and surgical conditions  Concurrent collection of medical history and the history of the event Once the patient is stabilized:  Management of direct exposure and of external and internal contamination,  Signs and symptoms of radiation injury and/or illness might not appear for hours to days and sometimes weeks. Loss of fluids and electrolytes:  particularly problematic in infants, children, and the elderly Medication  Antiemetics o Phenothiazines, like prochlorperazine or chlorpromazine not very effective o 5-HT 3 receptor inhibitors like ondansetron (Zofran) may be required for radiation-induced vomiting  Pain control  Antimicrobials o not needed immediately (infections do not appear for days) o prophylaxis if doses high enough to cause ARS o infection-directed antibiotics, antivirals, antifungals and antihelminthic agents  G-CSF and GM-CSF Surgical Intervention  Try to do surgeries within 24-36h of exposure while patients are: o not immunocompromised, o have better wound healing o no bleeding diathesis Bone marrow stem cell transplant  For exposures of 6-10 Sv without comorbid conditions Internal contamination  GM counters screen for γ and β (which is also detected by scintillators) ɑ and neutron difficult to detect  Once in the body, nearly all radioisotopes behave chemically exactly like stable isotopes of the same element  Thus management similar to treatment of poisoning, best carried out by EM physicians and medical toxicologists  Reduce uptake and/or enhance clearance with standard decon and detox techniques i.e. antacids or a cathartic e.g. castor oil or Mg sulphate  Specific countermeasures for significant contamination by identified radionuclides, e.g. KI for radioiodines, Zn/CA-DTPA for plutonium/americium, Prussian Blue for Cesium and Thallium, HCO3 - for uranium renal toxicity Children  Higher risk of pulmonary contamination (hyperventilate)  Tissues more sensitive to carcinogens  Psychologically less resilient