Pre-Anesthetic Assessment Flashcards
Define a Tranquillizer
A medicinal drug, which reduces tension or anxiety
Define a Sedative
Promotes a calm state or induces sleep
Define an Anxiolytic
Reduces anxiety
Define a Hypnotic
A sleep-inducing drug
What is Dissociative Anesthesia?
A form of Anaethesia, characterized by catalepsy, catatonia, analgesia and amnesia. Does not necessarily involve a loss of consciousness
What is Neuroleptanalgesia?
The combination of a potent sedative analgesic agent (an opioid) and a tranquilizer
Define an Analgesic
A drug that acts to relieve pain
Define an Analeptic
A restorative drug that works to stimulate the CNS
Define Anaesthesia
‘lack of sensation/feeling’
Define General Anaesthesia
A state of unconsciousness produced by a process of controlled, reversible, intoxication of the central nervous system, whereby the patient neither perceives nor recalls noxious stimuli
What is the Triad of General Anaesthesia?
= NAP
1) Narcosis (sleep): e.g. propofol, isoflurane
2) Analgesia (pain relief): e.g. morphine, fentanyl, lidocaine
3) Progessive Muscle relaxation: e.g. diazepam, atracurium, guaifenesin
What are the 2 main categories of substances used to produce general anaesthesia?
1) Inhalational: liquid at room temp and then vaporize easily, or gas at room temp
2) Non-inhalational: mostly injectable agents (IV, IM, SC, Intraperitoneal, oral or per rectum)
Give examples of Inhalational substances used to produce general anaesthesia
Volatile: Ether, Isoflurane or Sevoflurane
Gas: Nitrous Oxide
Give examples of Non-inhalational substances used to produce general anaesthesia
Propofol
Ketamine
Alfaxalone
What History is important to know at the pre-anaesthetic assessment?
- Exercise intolerance: cardio and resp function
- Coughing: cardio and resp function
- Dyspnea
- Recent trauma: increased suspicion of an undiagnosied condition
- Syncope: cardiovascular, resp, neurological and endocrine suspicions
- Time of last meal: is the patient fasted?
- Polyuria and Polydipsia: these will indicate a degree of dehydration
- Vomiting or diarrhea: indicate a degree of dehydration + can result in aspiration at induction of anesthesia
- Previous anesthetic history
- Other: pregnancy, behaviour, seizures
- Concurrent medications!
If a patient is on Cimetidine or Omeprazole, what interaction might occur with what anaesthetic agent?
increases the duration of action of diazepam and midazolam and the toxicity of lidocaine
If a patient is on Ketoconazole, what interaction might occur with what anaesthetic agent?
increase sedation from midazolam and amitriptyline
If a patient is on Phenobarbital, what interaction might occur with what anaesthetic agent?
speeds metabolism of lidocaine
If a patient is on Propranolol or other Beta blockers, what interaction might occur?
prevent tachycardia in response to pain, hypercarbia etc
If a patient is on ACE inhibitors, what interaction might occur with what anaesthetic agent?
can cause hypotension especially when used with acepromazine
If a patient is on Digoxin, what interaction might occur with what anaesthetic agent?
may increase arrhythmias especially with atropine or glycopyrrolate
If a patient is on NSAID’s or Aspirin, what interaction might occur?
Increased side effects of GI or renal disease, or increase clotting times
If a patient is on Furosemide, what interaction might occur with what anaesthetic agent?
can cause hypokalaemia and reduce the antiarrhythmic effect of lidocaine
If a patient is on Aminoglycoside antibiotics, what interaction might occur with what anaesthetic agent?
can be nephrotoxic; they also increase duration of action of neuromuscular blocking agents
If a patient is on Metoclopramide, what interaction might occur with what anaesthetic agent?
increases tremor if used with acepromazine and can decrease propofol dose for induction (humans)
What are the important factors to consider when doing a pre-anaesthetic physical exam?
- Demeanour: lethargic vs aggressive vs anxious will alter dosing quantities or types of drugs
- BCS + Accurate weight: IM drugs should be given based on actual BW, IV drugs should be given based on lean BW
- Breed: brachycephalic (more likely to collapse trachea and have increased vagal tone. Also more likely to regurgitate) and sight hounds (lower metabolism = slower recovery from anaesthesia, and may be predisposed to certain health issues)
e. g. Dobermans: Van der Waal deficiency = increased bleeding time - Hydration status
- Body temp
- Auscultate the heart and lungs!
- Abdominal palpation
Are Hematology and Biochemistry always necessary before surgery?
No!
For young, healthy patients undergoing routine surgery, provided that clinical examination is adequate, routine hematological and biochemical profiles are unnecessary (and constitute an extra expense) in apparently fit, healthy animals
What parameters are considered to be essential for a GERIATRIC patient, prior to surgery?
- PCV, haemoglobin
- Total plasma protein, albumin
- RENAL: Urea and Creatinine
- HEPATIC: ALT and AP +/- bile acids
- Urine SG and Dipstick
What parameters are considered to be essential for a SICK patient, prior to surgery?
- FULL hematology profile
- Biochemistry (renal + hepatic profile + clotting + electrolytes)
- Urinalysis
- specific tests if certain diseases are suspected (e.g. thyroid levels for a hypo/hyperthyroid patient)
What must be measured in a very young animal (under 3 months in small animals, and under 1 month in large animals), diabetic animal, or an animal with suspected/ confirmed insulinoma?
Glucose (q 30-60 mins)
What must be measured in Dobermanns/ Dobermann mixes?
BMBT + von Willebrand factor
When is pre-surgical xrays indicated in a patient?
- Patients with sig cardiac disease
- Patients with respiratory disease
- Road traffic accidents
- Most tumour removal surgeries, especially mammary, splenic and bone tumours
When is pre-surgical echcardiography indicated in a patient?
- Patients with significant cardiac disease/ murmurs
- Breeds susceptible to DCM: Great Dane, St. Bernard, Wolfhound, Newfoundland, Dobermann
- Cats with hyperthyroid disease: prone to hypertrophic cardiomyopathy
- Patients with splenic tumours: looking for auricle and atrial tumours
When is pre-surgical ECG indicated in a patient?
- Patient with cardiac disease
- If a pulse deficit is detected
- If any arrhythmia (except sinus arrhythmia) is detected
- Giant breed dogs: susceptible to DCM
- Miniature schnauzer (sick sinus syndrome)
- Or a patient with a disease which may lead to an arrhythmia: e.g. hyperkalemia, GDV, splenic tumour or post-traumatic myocarditis
