ECP 1 Flashcards
Dog and cat HR, RR, temp
HR - Dogs 80-120 bpm
Cats 160 - 220 bpm
RR - 15-25bpm
Temp -
What is Saturated vapor pressure and what helps with
- SVP = measure of liquids ability to evaporate
allows us to predict the maximum percentage of that anaesthetic that can be achieved
Sevoflurane lower saturated pressure than isoflurane
Maximum percentage is lower than isoflurane
What are the 2 things that affect the amount of anesthetic reaching alveoli (at equilibrium reflects the brain)
1) inspired concentration of anesthetic (vaporiser setting)
2) alveolar ventilation - deeper and increased
What are the 3 things that affect anaesthtic uptake into the blood and what does it do to anaesthetic induction
Anything that pulls more anaesthetic from the alveoli will slow anaesthetic induction (alveolar won’t be able to fill up and build concentration gradient)
1) Solubility - MORE soluble taken up from alveoli faster therefore SLOWER induction
2) Cardiac output (CO) - INCREASED more anaesthetic picked up therefore SLOWER indution
3) Alveolar-venosus pressure gradient - INCREASED more movement SLOWER induction
Distribution of inhalant anaesthetic into the tissues what are the 3 things its dictated by and what causes faster
1) % CO to tissues - INCREASED - faster
2) Volume of tissues - LOWER body weight - faster
3) solubility in tissues - INCREASED - faster
MAC what is it, what is it a measure of and the relationship, where measured how differs
The percentage of inhalant in the alveoli that will prevent movement in response to supramaximal noxious stimulus in 50% of the population (equivalent to ED50)
- MAC is a measure of anaesthetic potency (how much concentration needed to accomplish what is needed)
- Higher MAC LESS POTENT -> higher concentation to accomplish anaesthesia
- Measured at equilibrium between alveoli and brain
- AKA - the ED50
- Differs slightly between species
List 2 factors that increase MAC and many more than decrease MAC
Factors that INCREASE MAC - Drugs causing CNS stimulation - Hyperthermia Factors that DECREASE MAC - Drugs causing CNS Depression - Hypotension (<50 mmHg) - Hyponatraemia - Hypothermia - Hypoxaemia (PaO2 < 40 mmHg) - Hypercapnoea (PaCO2 > 95 mmHg) - Pregnancy (need less anaesthetic)
Inhalants 3 CNS effects, 3 respiratory and 4 cardiovascular effects
CNS
1. depression 2. decreased oxygen requirement 3. increased cerebral blood flow
Respiratory
1. minute ventilation reduced as tidal volume reduced 2. bronchodilation 3. Increased PaCO2 -> hypoventilation
Cardiovascular
1. decrease CO 2. decrease aterial BP 3. increase automaticity of myocardium 4. sensitize myocardium to arrhthmogenic effects of catacholamines (halothane - newer less common)
Nitrous oxide why don’t use (3 reasons) and what is main effect
1) Higher MAC in animals compared to humans
○ Not as potent
2) Diffuses in closed gas spaces (gi tract, etc)
○ Pneumothorax, GDV, Colic, Bloat -> further inflate
3) Not inactivated by activated charcoal
○ Exposure risks
○ Environmental pollution
Main effect – “Concentrates” other inhalant in alveoli - speeds up induction (2nd gas effect)
What is the effective dose limit for radiography for vets and the general public, what is the average for vets
Effective dose limit
Occupational - 20mSv per year
General public - 1mSv in a year
Average - 0.015mSv
What makes up quantity of an X-ray and what settings controlled by
he number of x-ray photons produced
- Controlled by the mA setting: higher filament current = more electrons = more Xray photons
- Controlled by the ms setting: longer exposure time = more electrons reach the anode = more Xray photons
- mA and ms are often regarded together, as mAs
What makes up quality of an X-ray and what setting is it controlled by
is the energy of the x-ray photons - Controlled by the kVp setting higher potential difference between cathode & anode - most important for penetrating power = more rapid acceleration of electrons = higher energy electrons = higher energy x-ray photons
What are the 3 movements of xrays and what is this called
- The x-ray photon passes straight through: TRANSMISSION
- The x-ray photons can be absorbed. They undergo the PHOTOELECTRIC EFFECT
- The x-ray photons can be scattered. They undergo the COMPTON EFFECT
What does absorption of x-ray depend on an the effect involved what makes higher absorber
- Absorption of x-ray photons depends on the ENERGY of the photon and the ATOMIC NUMBER of the absorber (bone - calcium)
Photoelectric Effect - 2 things that relate to the probably of photoelectric effect occurring
○ Lower energy photon (low kVp level) hits an electron and is absorbed
○ Higher atomic number absorber = high electron density = photon more likely to collide and be absorbed
BONE - biggest absorber in body
Compton effect what type of photon undergoes this and then what occurs
Compton scatter is likely to occur with dense absorbers, large volumes of tissue, and high kVp settings
- High energy photon (high kVp settings) = hits an electron and is deflected, losing some energy
- Scatter radiation has low energy
- Scatter radiation does not travel along the path of the primary beam so just darkens the image without giving useful information
Ejects an electron so is also an ionising event
What are the 3 main negative effects of scatter radiation
Scatter radiation has no use in diagnostic radiology Negative effects of scatter radiation 1. Increase operator dose 2. Increase patient dose 3. Decrease image contrast
What is/result from with quantum mottle, double exposure and moire artefact
IMAGE ARTEFACTS
Quantum mottle
- Underexposure of a digital image -> not enough photons -> not clear depiction of anatomy -> low mAs
Double exposure
- Digital radiograph appears as two clear images
Moire artefact
- Occurs when a grid with the wrong grid ratio is used and misaligned
○ Creates a pattern of interference with the digital read-out frequency
Edge definition what are the 3 components and what makes edge definition is sharpest with
1) focal spot size - smaller focal spot better edge
2) focal spot to film distance - larger distance (generally 1m) the better edge
3) object to film distance -> smaller the distance the better edge definition
What are the 3 common antiseptics for skin preparation and their characteristics
1) Chlorhexidine gluconate
- G+/G- bacteria, viruses and fungi NOT sporicidal
- residual action (6 hours), not inactivated by organic materal, diluted in wounds 0.05%
- not compatible with iodine
2) Povidone-iodine
- bactericidal, fungicidal, virucidal may be sporicidal
- low residual activity, inactivated by organic material
- high incidence of skin reactions
3) alcohols
- ○ Most RAPID and effective antibacterial antiseptic (including MRSA & MRSP)
○ Bactericidal, fungicidal, variable against viruses and ineffective against spores.
○ Most effective at 70%
○ Evaporates very quickly - minimal residual effect so never used ALONE
○ Tissue necrosis in open wounds
Monofilament vs multifilament what are the advantages and disadvantages and which is preferred
Monofilament: preferred - Less pliable - Poorer handling, increased memory - Less tissue drag - Less knot security, more knots required. Multifilament: - Greater strength and pliability - Improved handling compared to monofilament - Increased capillarity - Increased tendency for bacterial colonization - Avoid in contaminated environments - Greater tissue drag - Increased knot security
What are the characteristics of positive contrast agents and the 2 main examples
Positive contrast agents have high atomic number and are efficient absorbers of x-rays
1) Barium - not IV or to go outside GIT tract
2) Iodinated contrast (non-ionic) - IV and excreted in kidney
What are the percentages in terms of body water within the body
Total Body Water = 60% of BW (kg)
- ICF (intracellular fluid) = 67% of Total body water
- ECF (extracellular fluid) = 33% of Total Body water
○ Interstitial - 75% of ECF
○ Intravascular - 25% of ECF
Total blood volume (dogs) = 25% of 33% of 60% = about 8% BW or 80ml/kg Cats about 60ml/kg
Clinical assessment of shock what are the clinical signs for milk, moderate and severe and which shock doesn’t go through this pathway
Mild -> increase pulse and heart rate due to sympathetic drive body responding
Moderate -> heart rate increased, starting to get pale, femoral pulse reduced, metatarsal bearable
Severe -> grey/white, dull, severely decreased pulses
- All go through this pathway except for distributive
Distributive shock what are the main clinical signs in dogs and cats
- Hyperdynamic (early)
○ Hyperaemic mucous membranes
○ Fast CRT
○ Tachycardia, tachypnea (bounding pulses)
○ Normotension or hypertension
○ Tall narrow pulses
Cats are different! - always pale, smaller increases in heart rate
Blood transfusion target, how to achieve and what need to do
○ Replace what is lost (estimate) ○ Target PCV > 20% - To increase PCV by 1% ○ Packed red blood cells: 1ml/kg ○ Whole blood: 2ml/kg - Cats: always blood type
leukogram what are the 3 main types and characteristics
- Is there evidence of an inflammatory response?
○ Neutrophilia and/or monocytosis
○ Left shift (bands) or toxic change -> ALWAYS INFLAMMATORY - Is there evidence of stress response?
○ Lymphopenia (most consistent finding)
○ +/- mature neutrophilia
○ +/- monocytosis (dogs) - Is there a physiologic leucocytosis?
○ Mature neutrophilia and lymphocytosis in young animal
What are the 3 main questions when assessing liver damage
- Is there evidence of cell damage?
○ Increased ALT, AST, GLDH, SDH - Is there evidence of cholestasis?
○ Increased bilirubin, ALP, GGT - Is there evidence of hepatic insufficiency?
○ Decreased urea, cholesterol, albumin, glucose
○ Increased unconjugated bilirubin
Acepromazine what is it, main effects, onset of action, duration
- Dopamine antagonist - sedation- reduces anxiety and awareness
- DOESN’T lower the seizure threshold
- Anti-emetic, anti-histamine, anti-nausea
- Anti-arrythmia - decrease myocardial sensitivity to catecholamines -> reduced risk of dying!!!!
○ Only drug to show this in dogs, horses maybe cats - IM - 30-40mins onset of action, IV 10-15mins
Lasts 6-8 hours - Prolonged especially for short procedure
Acepromazine downfalls, what patients good for and contraindications
- Causes vasodilation
- No reversal drug
- Stallions -> priapism - use with caution - not permanent
○ Worried in recovery as can step on them
GOOD - Healthy active patients
- Some cardiac patients (afterload reducer) - mitral valve regurgitation good
○ NOT CARDIAC FAILURE or DCM (no problem with afterload anyway)
Contraindications - Severe liver dysfunction
○ Liver metabolism - Not if in a hurry
What are the 6 main effects of alpha2-agonists
1) dose-dependent sedation (way stronger than ACE) / hypnosis
2) Analgesia (very good)
3) Muscle relaxation (very good)
4) respiratory depression (mild)
5) initial period of hypertension, followed by a more prolonged normotensive (?) phase
○ Reflex bradycardia - LOW HR
6) cardiac arrhythmias (where A-V blocks 1 and 2) -> no ventricular complex
Alpha-2 agonist, the 4 main types and how long last, what good for
Examples
- Xylazine - 15-30mins - pre-med
- Romifidine/ Meditomidine (dog) - 45mins
- Detomidine - 1 hour
Good for:
- Aggressive animals - PROFUND SEDATION
- Diagnostics - short procedures as can reverse
- CV and hemodynamically stable
- GOOD ANAGLESIA FOR VISCERAL ANAGLESIA - muscle relaxation - GOOD FOR COLICKY HORSES
Alpha-2 agonist side effects and contraindications
Side effect:
- Diuresis - horse problem which is often why urinary catheter is placed
- Anti-insulin -> increase glycogen -> hyperglycaemic
○ Can use in diabetics as already insulin insensitivity
Contraindications
- Functional cardiac problems or haemodynamic instability (profound anaemia, dehydration, hypovolaemia)
