Fluids + Imaging Flashcards
Will you see anaemia with haemorrhage? With a severe coagulopathy, what are possible ddx?
* Yes + possible hypovolaemic shock
* Anticoagulant rodenticide toxicity, hepatic failure, DIC, malabsorptive diseases
When might you see mild thrombocytopenia?
Secondary from blood loss/ increased utilisation, DIC
What is a heart murmur? Why would you see a heart murmur with anemia? What else could cause a heart murmur?
* Heart sounds produced when blood flows across one of the heart valves that is loud enough to be heard with a stethoscope– vast majority are due to turbulent blood flow brought on by high velocity blood flow
* the body has a lower than normal number of RBCs therefore the blood is thinner and flows faster than normal
* Structural abnormality (e.g. valve leaflet), fever, hyperthyroidism
In a dog with anticoagulant rodenticide toxicity, what kind of blood transfusion product would be ideal?
Fresh whole blood for the red cells, clotting factors, proteins, and platelets (lack of vitamin K reductase does not allow the activation of vitamin K and therefore lack of clotting— so fresh whole blood with stop bleeding by providing clotting factors that have been lost)
** Max is also hypovolemic and hypoxic shock from severe anemia– so supplementation of red cells is essential
What are possible complications from a transfusion?
* Acute immunological transfusion reaction- acute hemolytic reaction (type II hypersensitivity reaction), febrile non hemolytic reaction, non-hemolytic immunological reaction (type I hypersensitivity)
* delayed immunological transfusion reaction- delayed hemolytic reaction, post transfusion purpura (internal bleeding)
* acute non immunological tranfusion reactions- bacterial contamination of transfused bloods, hemolysis from damaged RBC transfusion, hyperkalaemia/hypocalcemia/hypomagnesemia after massive transfusions, hypothermia, circulatory overload
What are some things you can do to prevent transfusion reactions?
* blood typing (especially cats), cross matching major and minor (especially if second transfusion), test infusion 0.25 m/kg/h over the first 5-10 minutes, use of an in line blood filter, monitor patient parameters every 15-30 minutes during transfusion for acute reactions (demeanor, temperature, pulse rate and quality, BP, RR and character, MM colour, plasma and urine colour), ensure transfusion complete within 4-6 hours to preven bacterial growth, proper collection and storage of blood, appropriate blood donor screening
Dog with anticoagulant rodenticide poisoning, what other treatments over than an infusion?
* Vitamin K1 supplementation
* strict cage rest to prevent further hemorrhage
* oxygen supplementation
* Intravenous fluids
What are X-rays?
A form of electromagnetic radiation
EM radiations of frequencies higher than UV light have enough energy to remove an outer-shell electron from an atom and are therefore called ionising radiation (X-rays, gamma rays, and cosmic rays are ionising radiation). When ionising radiation interacts with atoms it causes the ejection of an electron and creates an ion pair which has the potential to damage cells.
** They can produce damage to molecules and induce temporary or permanent cell damage, causing problems such as mutations or cancer

What are some unusual properties of ionising radiation?
* You cannot see, smell, touch or taste it
* Penetrates all matter
* We do not develop tolerance or immunity to radiation
* There is little difference between how individuals react to a given dose
* Dose is cumulative
* Delayed effects: May take years to see the effects
What does it mean that effects of radiation are stochastic or deterministic?
* Stochastic- increased risk with increased dose– the dose of radiation you receive, a higher dose of radiation will increase the probability of a stochastic effect e.g. a genetic mutation leading to cancer– higher radiation dose or exposure will increase the chance of cancer developing (this is the one that is important in vet med)
** no threshold below which the risk of the effect will cease & effects are cumulative over a lifetime
* Deterministic- inevitable at high doses– in contrast with stochastic effects, the severity of the effect, not the probability, increases with increasing dose. Exposure below a certain threshold will not result in the effect (THERE IS A THRESHOLD). e.g. radiation induced skin burns, uncommon however in medicine
What is the direct effect of ionising radiation? Indirect effect?
* direct effects may damage DNA, protein or other macromolecules
* Indirect effects create free radicles within cytoplasm and these free radical damage macromolecules
** Cell may either repair itself or if DNA damage has occurred a mutation may result, causing cell death, cancer, or birth defects
In Victoria, the use of radiation comes under what department? And which Act? What does it state?
* Department of Health which administers The Radiation Act 2005– species that business must have a management licence to possess a radiation source and conduct a radiation practice & individuals must have a use licence
What is ARPANSA?
* A national governing body – Australian Radiation Protection and Nuclear Safety Agency– responsibility for protecting the health and safety of the people and environment from the harmful effects of ionising radiation. They publish a series of codes and standards then implement in the form of legislation.
RPS 17: Radiation Protection in Veterinary Medicine (2009)
** Also provide “Personal Radiation Monitoring Service”– monitors and records occupational exposure to radiation
What are the three basic methods of monitoring for radiation exposure?
* Thermoluminescent Dosemeter (TLD)- electrons int he crystal structure of the TLD card are excited to high energy levels as a result of irradiation and are trapped in the crystal structure. By heating the material, electrons return to their ground state and light is emitted. The amount of ligh is proportional to the radiation dose that the TLD material has received. Filters are used to allow only certain radiation to pass.
* Film badges- degree of darkening can be measured and will indicate the absorbed dose. But dose to film does not equal dose to tissue.
* pocket dosimeters– different to TLDs and film badges… pocket dosimeters can be read instantaneously– useful when high exposures are expected.
What tissues are more susceptible to radiation?
Rapidly dividing tissue
What is the recommended effective dose limit for occupational exposure? In a single year? What is the avg annual dose for veterinarians?
20 mSv per year, averaged over consecutive years
* 50 mSv in a single year
** Avg annual dose for veterinarians is around 16 microSv = 0.016 mSv
What is the ALARA principle?
* As Low As Reasonably Achievable
** Is the radiograph necessary for the patient and management of the case? Would ultrasound or a blood test answer the clinical question?
* Minimize retaking radiographs, minimize manual restraint, under no circumstances should any part of your body be within the primary x-ray beam
What are the three types of radiation encountered in medical practice?
* Useful beam
* Leakage radiation
* Scatter radiation
How can radiation exposure be minimised ?
Modifying
- Time (take good radiographs the first time around)
- Distance from the radiation source– the energy of the scatter radiation will decrease as distance from the radiation source increases, according to the inverse square law… e.g. so by doubling the distance from the radiation source, you will reduce your radiation exposure by a factor of 4. (avoid manual restraint, use ancillary positioning devices such as sand bags, stand well back)
- Shielding- concrete walls, PPE
How thick should lead PPE be?
Lead equivalent of 0.25 mm will shield scatter radiation with energy of up to 100 keV (electron volt)
What should the local radiation management plan follow?
ARPANSA RPS 17 + ALARA by observing time distance and shielding principles
How are x-rays generated? What elements are necessary for x- ray production?
* Generated in the x-ray tube by firing a high energy electron beam at a tungsten target
- A source of electrons (cathode)
- An obstacle- free path for the passage of high speed electrons
- A target (the anode) in which the electrons can interact, releasing energy in the form of x-rays
- a method of accelerating the electrons- electrical potential difference applied between the cathode and anode

What is the cathode? What is it made of?
* cathode acts as a source of electrons
* it is of a tungsten coiled filament mounted within a molybdenum focusing cup. Tungsten has a high melting point and a high atomic number. When a current is run through the cathode filament, it heats up and releases electrons.




































