intro to anaesthesia Flashcards
what is anaesthesia
loss of sensation to the entire or part of the body
what is analgesia
The absence of pain in response to stimulation which would normally be painful.
No loss of consciousness, retains some feeling and/or movement
(able to functional normally, just without pain)
explain the difference between anaesthesia and analgesia
anaesthsia: loss of sensation to part or whole body (uncocious)
analgesia: pain relief without causing unconciousness
give me examples of when anaesthesia is used
Facilitation of immobilisation for radiographs
Surgical or invasive medical procedures
Safe handling of fractious patients (agressive)
Transportation of wild and exotic animals
Euthanasia
Humane slaughter of food animals
what are the different types of anaesthesia
- general (completely unconcious, cannot be woken up even if experiencing pain)
-local (anaesthetising part of the body by temporarioy aboloshing the transmission of impulses along nerve fibre) (remember ur dental surgery and u felt the electric shock when given local)
-regional (cannot feel pain to a large body area, eg whole leg)
factors affecting anaesthesia
- human factors
Inadequate obtainment of history of the patient (pre opp)
Failure to perform adequate physical examination (pre opp)
Lack of familiarity with the anaesthetic machine and drugs being used (opp)
Incorrect administration of drugs
Personnel who are fatigue, pre-occupied or inattentive - Equipment factors
Exhausted carbon dioxide absorber
Empty oxygen tank
Mis-assembly of the anaesthetic machine
Endotracheal tube problems
Vapouriser problems
Pop-off valve problems - anaesthetic agent factor (choice of drug)
An anaesthetist should be familiar with the adverse side effects and contraindications of the respective drugs used.
(Multi-drug use to achieve balanced anaesthesia can be safer than using a single drug, provided the dosages of the individual drugs are appropriately reduced) - patient variation factor
Type of patient: old, young, sick
Species and breed dispositions
Dogs and cats vs pocket pets
Brachycephalic breeds
Underlying medical conditions
E.g., liver/kidney failure, heart murmur
Helps us determine the anaesthetic risk.
what is included in a minimum patient database (patient evaluation)
- patient history ( from client+ past medical history)
-physical examination ( species, breed, gender, age, steralisation status, body weight, BCS score tempremant, bad: fractious)
measuring vital signs (temp. pulse, respiration, mm colour, capillary refil time)
-diagnostic tests (CBC, biochem, UA, FA, radiographs) - ASA classification (for anesthetic risk)
components of a physical examination
-signalment (age, sex, breed, whole/steralised, weight: BCS 1(skinny)-5(fatty)
-patient disposition ( temprement)
-vitals )temp, pulse, resp, heart, mm, crt)
-examination of all major organ system
what are the different ASA status
1: healthy (blood test normal)
2. mild systemic disease (geriatirc, obease)
3. obvious system disease (poorly controlled diabetes,anemia, fever)
4. severe systemic disease (severe dehydration,shock,high fever)
5. patient will die with/without surgery (severe trauma, advanced cardiac, kindney,liber, endocrine disease)
classE: emmergency ( c section)
what is pharmacokinetics
action of the body on drugs
what is pharmacodynamics
action of the drugs on the body (dhamaka due to drugs)
what are the different medicinal use of drugs
CSP
cure diseases: when disease is elimated, drug is withdrawn (stopped)
-supress diseases (control symptoms and maintain health without curing)
-prevent diseases (primary: prevent from getting the diseases. secondary: prevent current disease from progression)
what are drugs and how can they be classified
Drugs are natural or synthetic substances that alter the biological function of living organisms through their chemical actions.
Drug use:
Medicinal – treatment, prevention, diagnosis of disease.
Non-medicinal (social) – recreational purposes.
what is the nature of drug (porperties, characteristics)
physical:
1. state ofdrug at room temp: solid (tablet/capsule) liquid(oral syrup/ injectables) gas (anaesthetic gases)
- drug size
- drug shape (lock and key theory-> drug shape is complementory to receptor site
induced fit theory-> drug shape is not exactly complemetory to receptor site-> drug binds to recptor site and induce the recptor to undergo conformational change which allows for better binding)
size and shape of drug are key factor that setermune the binding selectivity. higher binding selectivity (bind more specifically) -> are specific in its action (can on fit into one type of receptor)
chemical:
organic or inorganic compounds. organic: contains a carbon basis, can be further classified into weak acid/ base electrolyte)
For a drug to carry out its appropriate action, it must:
be transported to the target site from the site of administration
interact with the receptor (can be activated/not)
(drug-receptor interaction)
be inactivated or excreted at a reasonable rate (appropriate/safe action of drugs-> must be excreted once done)
Requirements for drug-receptor interaction:
1.Appropriate size & shape to bind to the receptors by either:
Lock and key model
Induced-fit mode
2.Appropriate electrical charges for chemical forces of interaction to form
Chemical forces of interaction:
Covalent
Very Strong
Not reversible
Electrostatic
Ionic bonds – relatively strong
Hydrogen bonds - weak
van der Waals - very weak
Hydrophobic
weakest
what are the two main types of responses when drugs bind to receptors:
for drugs to exert and effect-> needs to be bound to a protein )eg receptor)
two possible response
Drugs that produce a change in the cell functioning are called agonists. (start a change)
Drugs that stop a normal function of the cell are called antagonists. (stop normal function)
Pharmacokinetics (PK)
Refers to the action of the body on a drug
It is the study of the movement/transformation of drug substances through body compartments (Absorption, Distribution, Metabolism, Excretion).
These properties are of great importance in the choice of drug type and drug administration route.
4 types of drug receptors
Intracellular receptors
Ligand-gated ion channels
Enzyme-linked receptors
G protein-coupled receptors
- Intracellular receptors
receptors located inside cell, ligand (drug) must be lipid soluble to corss the plasma membrane and bind to the receptor-> form receptor-ligand complex that moves to the nucleus-> binds to DNA causing gene expression (follwing the instruction)
response time: hrs to days
- Ligand- gated ion channel
ion channels located in plasma membrane
binding of ligant can cause the ion channel to open/close-> causing influx/exflux
or block the channel
affect intercellular ion concentration-> altered membrane potention-> changes in cell excitation
response time: within a few miliseconds
- Enzyme-linked receptors
ligand bind to receptor on the plasma membrane-> conformational change to the receptor-> activation/inhibitation of ezyme activity (changes, sometimes it fits the siganlling molecules smtimes it doesnt)
response time: minutes to hours
- G protein-coupled receptors
activation
receptors are linked to protein and associated at rest (usually at rest)
3 subunits: a- and By subunits
ligand binding causes a conformational change-> GTP is exchanged for GDP on the a-subunit -> a subunit dissociates from By subunit-> these subunits interact with other effectors, enzymes and ion channels
termination
GTPase hydrolyses GTP on the a-subunit to GDP -> a-subuit dissocates from the effectpr and reassociate with the By subunit-> interaction is terminated
response time: sec to mins
which dose response curve is preferred and why
sigmoid curve over hyperbolic curve. sigmoid curve is preferred as it plots the response of the drug with greater precision. This makes it easier to compare 2 drugs. (uses log function which gives us more realistic resuts)
