Atropine is used for
Bradycardia caused by opioids; Reflex-bradycardia caused by alpha2-agonists (high BP);
AV-blocks & SA-blocks
ACP effects
Calming; Vasodilator; Depression of thermoregulation; Decreases BP; Antihistaminic;
Depression of platelet function
diazepam and midazolam
For old animals with poor general circulation; Decreases anxiety; Relaxes muscles;
High dose can caused respiratory depression
alpha 2 agonists
Sedative effect; Emetic; Antagonisable by atipamezole; Detomidine; Medetomidine;
Dexmedetomidine; Xylazine
medetomidine and xylazine
Using a general dose - phases of sedation, induction & maintenance cannot be
separated; Not recommended for old, cardiac & diabetic patients; Cause circulatory &
respiratory depression
opioid drugs
Major analgesics; Side effects are bradycardia & respiratory depression; Can be
antagonised by naloxone; Morphine; Fentanyl; Buprenorphine; Butorphanol
(Torbugesic); They all have differing levels of efficacy
opioid receptors
μ (Mu); k (Kappa); δ (Delta)
fentanyl
full agonist opioid drug; 15-30 minute duration of effect; may be redosed
morphine
Full agonist opioid drug; 4-6 hours duration of effect; Use high dose IV in mastocytoma
patients; Must not be redosed!
full opioid agonists
morphine; fentanyl
short duration of action
fentanyl
Partial μ-agonist
buprenorphine
Partial μ-antagonist & k-agonist
butorphanol
Weak μ-agonist
tramadol
propofol
Can be used in almost all patient groups; Short duration of action; Can be redosed;
High dose and rapid application lead to respiratory depression
application of propofol
slowly; IV; to effect
ketamine
Moderate analgesic effect; Benzodiazepines may help avoid catalepsy (muscle rigidity);
Eyes remain open, therefore the cornea may desiccate
safe inhalant anaesthetics
isoflurane, sevoflurane, desflurane
inhalant anaesthetics
1 MAC causes muscle relaxation in 50% of cases; 2 MAC causes muscle relation in
100% of cases; Short induction and recovery; Hypnotic; Muscle relaxant; No analgesic
effect
local anaesthetic
Blocks nerve cells; Types - Terminal, conductive, paravertebral, epidural & spinal;
Possible side effects – Cardiovascular & CNS signs, cell toxicity
Pancuronium; Atracurium; Vecuronium; Rocuronium
Central muscle relaxants; Peripheral depolarising muscle relaxants; Local anaesthetics
pain
Complex, multidimensional negative experience; No linear correlation between degree
of pathological changes and intensity of pain; Simultaneous nociceptive effects add up;
Function – Physiological or pathological; Origin – Organic or psychogenic; Duration –
Acute or chronic
pathological pain
Hyperalgesia: Mild noxious stimuli resulting in intense pain sensation; Allodynia: No
pain provocation, but pain sensation occurs; Analgesia can be combined; Pain impulse
may be inhibited by pain killers
ascending pathway of nociception
Transduction → Transmission → Modulation → Projection → Perception
modern concepts of pain management
Pre-emptive (prophylactic) analgesia; Multimodal analgesia; No gap should appear
intraoperative analgesic effect
Ketamine CRI; Lidocaine + fentanyl CRI; Local anaesthetic + opioids
purpose of anaesthesia machines
Administration of appropriate oxygen flow; Administration of appropriate inhalant
concentration; Elimination of exhales CO2
mixing part of the anaesthesia machine
gas source; flow meter; vaporiser
breathing circuit of the anaesthesia machine
‘Y’piece; resevoir bag; CO2 absorbent canister
oxygen by-pass
emergency option; concentration of inhalational anaesthetic in the circuit can be quickly reduced; pure3 O2 can directly enter the circuit
optimal breathing tubes are
ribbed; short and wide
optimal size of reservoir bag
5 times the respiratory volume
the absorbent cannister is part of the
open system; semi open system; semi closed system
CO2 absorption
The absorbent canister contains absorbing soda; The absorbing soda granules have a
rough surface; Exhaustion of the soda is indicated by discoloration
pop-off valve (adjustable pressure limiting value)
Prevents excessive pressure in the circuit & lungs; Is open during spontaneous
breathing; Is set to 20 cmH2O during manual or mechanical ventilation
advantages of semi open narcosis system
Low-resistance; Small mechanical dead space; Anaesthetic concentration can be
quickly modified
advantages of a closed narcosis systems
Low gas consumption; Low inhalational anaesthetic consumption; Cheap
narcosis system types
Semi-open system; Semi-closed circuit; Closed circuit
indications for mechanical ventilation
Severe hypoxia; Severe hypercapnia; Excessive work of breathing; Open thorax;
Hypoventilation caused by hypothermia; Neuromuscular blockade
IPPV
Airway pressure is higher than atmospheric pressure during inspiration; Airway
pressure falls to atmospheric pressure during passive expiration; Cannot be used in
large dogs
physiological dead space
anatomical + alveolar dead space
inspiration
Spontaneous inspiration is caused by decreasing interpleural pressure; IPPV
inspiration is caused by increasing interpleural pressure; Expiration is spontaneous in
both cases
CNS effects of IPPV
Controlled hyperventilation reduces CO2 level in the blood; Reduced CO2 level causes
arterial vasoconstriction; Arterial vasoconstriction decreases intracranial pressure
volume controlled time cycled mechanical ventilation
Common in veterinary medicine; Constant flow during inspiration; Inspiratory phase
ends after pre-set inspiratory time
triggering types (initiation of inspiratory phase)
time; pressure; flow
parameters of ventilation
Tidal volume – 10-15 ml/BWkg; Inhalation:Exhalation time ratio – 1:2-1:3; Target
values 35-45mmHg etCO2 & 100% SpO2
blood pressure measuring methods
invasive direct; non-invasive doppler; non invasive oscillometric
blood pressure measurement at right atrial (RA) height
10cm height difference results in a deviation of 7.36mmHg
cuff size for BP measuring
Patients of different sizes require different sized of cuff; Optimal cuff width is 40% of
the leg’s circumference; Wider cuffs produce lower BP values and vice versa
the MAP (mean arterial pressure) is
closer to diastolic pressure than to systolic pressure
urine production during general anaesthesia
1-2ml/BWkg/hour
pulse oximetry
Non-invasive; Continuous measurement; Measurement of O2 saturation of Hb; Sensor
can be placed on the tongue or ear; In case of transmission-type sensors, one side emits,
while the other detects light; Absorption depends on
oxyhaemoglobin:deoxyhaemoglobin ratio
correlation between paO2 & SpO2
can be shown on a sigmoid curve
cause of pule-oximeter malfunction
total light absorption; improper contact; interference with electrosurgical devices
capnometry
Physiological range of etCO2: 35-45 mmHg; Capnogram may be divided into 4 phases;
Exhausted CO2 absorbent soda lime increases inhaled CO2 level
correlation between paCO2 & etCO2
Positive correlation; PaCO2 > etCO2; The difference in small animals is 2-5mmHg
capnography types
side flow and main flow measuring
capnograph phases
Inhalation → Exhalation begins → Exhalation ends → Inhalation begins
causes of decreasing etCO2
Acute respiratory distress (hyperventilation); Acute circulatory distress (decreased
heart minute-volume); Acute metabolic distress
causes of zero etCO2 on the capnography’s display
Capnography performs calibration; Cardiac arrest; Respiratory arrest; Tube
malposition; Tube disconnection
causes of rebreathed CO2
Exhausted soda lime; Suck one-way valve; Large dead space
core temperature can be measured by
Pharyngeal probes; Oesophageal probes; Rectal probes
warming hypothermic patient
heating pads; infared lamps; covers and head mirrors
close control of blood glucose is needed in
Very small patients; Very young patients; Cachectic patients; Weak patients; Diabetic
patients; Insulinoma patients
monitoring anesthetized patients involves assessment of
The stage of narcosis; Pain markers; Patient’s parameters
which statements are true
The generator determines the capacity of the x-ray machine; Greater capacity allows
for shorter exposure time; The most common reasons for motion blurring is panting
which statement is false
Reduction of the exposure time will increase the motion blurring
what is the role of collimator
Setting the size of the x-ray beam
what are the exposure factors
kV; mA; s
what is not an exposure factor
kW
which statements are true
The kVp describes the strength (penetrating power) of the x-ray beam; The mA
describes the number of x-ray photons; The same mAs can be recreated from different
time components
which statement is false
To maintain the same exposure, if increasing the mAs, you must elevate kVp too
what is the normal range of tube voltage in small animal radiography
40-100 kVp
the use of the grid
improves the image contrast; filters the scattered beam
what is not a normal component of an indirect digital system (CR)
x-ray film
what are normal components of an indirect digital system (CR)
X-ray tube; collimator; PSP plate
which statements are true
The x-ray radiation is electromagnetic radiation; X-ray beams cannot be deflected by a
magnetic field; Particles with higher energy have a higher penetrating power
which statement is false
the elementary unit of the x-ray beam is the electron
which statement is true
fluoroscopy can be digital or analogue
which statements are false
Some digital technologies use x-ray films; DR systems can be digital or analogue; The
picture of CR systems can be static or dynamic
which statements is true
the fluoroscope is also called ‘C-arm’
which statements are false
Fluoroscopy causes very low radiation exposure; Fluoroscopy is mainly used for static
examinations; During fluoroscopy, the x-ray tube is generally above the animal
the negatively charged particle of an atom is the
electron
as x-rays pass through materials, they have the ability to
Cause some substances to fluoresce (emit visible light); Completely remove an electron
from an atom, leaving the atom positively charged; Cause chemical changes that can
kill cells
which statement is true
Electromagnetic radiation with higher frequency has more penetrating power through
space and matter
which statement is false
X-rays can be detected by magnetic fields; X-rays with longer wavelengths penetrate
farther than x-rays with shorter wavelengths; Gamma rays are required for the
production of a radiograph
electrons travel
toward the anode in an x-ray tube
x-ray photons travel
away from the anode in an x-ray tube
way to increase penetrating power of x-rays
increasing kVp
The milliamperage-seconds (mAs) for 100mA and 1/10sec is:
10mAs
According to Sante’s rule, if a cat’s abdomen measures 8cm & FFD is 100cm, kVp is:
56
increasing the film object distance
the resulting image is larger
one percent of the energy produced at the anode is in the form of
x-rays
the temperature of the filament withing the cathode is controlled by
the time setting
what are characteristics of the x-rays
their intensity increases as SID (source image distance) decreases
what is not true for x-rays
Their total number produced is determined by kV; Longer wavelengths have more
penetrating power; They diverge from a light source
potential difference between the anode and the cathode is measured in
kilovolts
which statement is true
Higher kVp settings allow for lower mAs and lower exposure time
which of the following increases radiographic density
thinner body parts
which statement is true
the abdomen, thorax and femur all have equal scale of contrast