Anaesthetics Flashcards
3 A’s of anaesthesia
Amnesia
Analgesia
Akinesia
Induction agent you CANNOT use in porphyria
Thiopentone
Induction agent used for RSI
Thiopentone
Induction agent you CAN’T use in sepsis
Etomidate
How long do induction agents last
4-10 minutes
MAC of sevoflourane
2%
MAC of isoflourane
1.15%
Indication of isoflourane
Organ donation - doesn’t affect blood flow to organs
Indication for desflourane as maintenance
Long operation (doesn’t accumulate in fat)
Anti-emetics given DURING surgery
Dexamethasone
Ondansetron
Post-op anti-emetic
Cyclizine
Define amnesia in terms of anaesthetics
Lack of response and recall to noxious stimuli (e.g. unconscious)
What are the biggest cannulas?
Orange Grey White Green pink blue yellow violet
Effect of propofol on HR and BP
Reduces both HR and BP
Effect of thiopentone on HR and BP
Drops BP
Increases HR
Which anaesthetic tends to be used in neurosurgery and why?
Thiopentone –> antiepileptic properties and neuroprotective
When would etomidate be used for induction?
Haemodynamic instability e.g. heart failure
Which induction agent has the highest incidence of PONV
Etomidate
Why cannot etomidate be used in septic shock?
Causes adreno-cortical suppression
What maintenance agent would you use for organ donation and why?
Isoflourane because it has the least effect on blood flow
What maintenance agent is commonly used in children?
Sevoflourane
What maintenance agent is commonly used in long procedures and why?
Desflurane - less accumulates in fat so more rapid onset and offset
What is the mac of sevoflourane?
2%
MAC of desflourane
6%
MAC of isoflurane
1.15%
Which short acting opioids are most commonly used and fastest acting?
Most common = fentanyl
Fastest acting = remifentanyl (IV infusion)
Side effects of NSAIDS as pain relief
Gastric and renal SEs
Interfere with clotting
(CI in asthma)
What does activating alpha receptors in vascular smooth muscle cause and which commonly used drugs do this?
Induces smooth muscle contraction (vasoconstriction). Works through second messenger (cAMP) model. Happens in both arteries and veins but more pronounced affect in arteries.
Vasopressors (systemic vasoconstrictors) –> metaraminol, phenylephrine, ephedrine.
What does activating beta receptors in vascular smooth muscle cause and which commonly used drugs do this?
Beta receptors are mainly in cardiac smooth muscle. Activating them causes cardiac stimulation (increased HR, contractility, cardiac output) and increased vasodilation systemically.
Ionotropes = adrenaline, ephedrine, dobuatmine
What does hypertension during anaesthesia indicate?
Inadequate anaesthesia - give more + analgesics
Difference between crystalloid and colloid fluids
Crystalloid = crystalline solids dissolved in water e.g. NaCl. Either hypotonic or isotonic.
Colloid = high molecular weight particles e.g. albumin. Expand intravascular volume. Risk of anaphylaxis.
What is Hartmann’s V 0.9% saline
Both isotonic crystallines.
Hartmann’s contains sodium, chloride, potassium, lactate
At what % of blood volume loss would you consider blood replacements and activating MHP
30% volume loss = blood replacement
MHP = >70ml/kg blood loss
What is the MHP
RBCs, FFP, platelets in 1:1:1
Ondansentron MOA
Serotonin blocker
Dexamethasone MOA
Steroid
Cyclizine MOA
Anti-histamine
Prochlorperazine MOA
Phenothiazine
Pre-op assessment
PMHx -
AIRWAY - teeth, dentures, neck pain
BREATHING/RESP - asthma, cough, trouble breathing, smoker
CIRCULATION - CV problems, lying flat, orthopnoea, exercise tolerance
GI - GORD, last meal
OTHER - diabetes, epilepsy, CKD, thyroid, stroke
MEDS - anticoagulation/antiplatelets, insulin, analgesia
ANA Hx - problems (MH, ICU, pain, PONV, airway), FHx, Pain relief
EXAMINATION - mallampatti (class 1-4), neck and jaw movements, pregnancy, BMI
ASA GRADE and PRE-OP IX
ASA Grades
- Grade I: healthy, no systemic disease
- Grade 2: mild systemic disease, no functional limitations
- Grade 3: severe systemic disease, substantive functional limitations
- Grade 4: severe systemic disease which is a constant threat to life
- Grade 5: at point of death, not expected to survive with or without operation
- Grade 6: brain-stem dead, organs being donated
Investigations indicated in everyone above >80
FBC
U&E
ECG
(if ASA 3/4: clotting, lung function/ ABG)
When would CXR be indicated as pre-op investigation?
If ICU admission or respiratory disease in ASA 3 or 4
Fasting time for: Solid food Clear fluids Alcohol Breast feeding Children water
Solid food - 6 hours Clear fluids - 2 hours Alcohol - 24 hours Breast feeding - 4 hours Children water - 30ml max one hour before
Lignocaine dose
3mg/kg (7mg/kg w adrenaline)
Bupivicaine dose
2mg/kg (2mg/kg)
Prilocaine dose
6mg/kg (9mg/kg)
Anti-emetic generally used in surgery
Dexamethasone
Anti-emetic generally used post-surgery
Ondansentron
Give an example of colloid fluids
Gelofusine
Isoplex
Gelaspan
Give an example of colloid fluids
Gelofusine
Isoplex
Gelaspan
Adult requirements for fluid and electrolytes for maintenance?
25-30ml/kg water
1mmol / kg potassium, sodium, chloride
50-100g/day glucose
