Get Through SBAs Flashcards
1
Q
What is the intralipid dose for a 70kg man?
A
- initial bolus 100mls 20% lipid emulsion over 1 min
- plus IV infusion 1000ml/hr
- after 5 mins -> 2 repeat 100ml boluses
- double to 2000ml/hr if required
- max dose 850mls (>?)
2
Q
What is the response time of a Severinghaus electrode?
A
2-3 mins
3
Q
How does the Severinghaus electrode work?
A
- modified pH electrode, measures CO2 tension
- H+ sensitive glass probe encased in nylon mesh impregnated with bicarb solution
- 2 electrodes placed on either side of the probe, one in the glass electrode and one in the buffer
- plastic membrane permeable to CO2 separates sample from system
- CO2 from the sample diffuses across the semi-permeable membrane
- -> reacts with bicarbonate and water in the mesh -> changes pH
4
Q
What is the half life of Ketorolac?
A
6hrs
5
Q
What is the equivalent analgesic dose of 10mg of ketorolac?
A
10mg ketorolac = 50mg pethidine = 6mg morphine
6
Q
How does ketorolac work?
A
COX inhibitor, prevents formation of prostaglandins. Inhibits platelet aggregation, may prolong bleeding time.
CIs: bronchospasm, angioedema, nasap polyps.
7
Q
What receptors do cyclizine, metaclopramide, ondansetron, hyoscine/atropine and droperidol work on?
A
Cyclizine - histamine
Metaclopramide - dopaminergic
Ondansetron - 5HT3 (serotonin)
Hyosine/atropine - muscarinic
Droperidol - dopaminergic
8
Q
What does the ABG directly measure?
A
- Hb
- electrolytes
- PaCO2
- PaO2
- pH
9
Q
What does the ABG indirectly (derive) measure?
A
- HCO3
- BE
- O2 content
- sats
10
Q
How many days does lithium take to take effect?
A
10 days
11
Q
What do fundal parietal cells produce?
A
0.15M hydrochloric acid
Helps protein breakdown, pepsinogen, augments iron absorption, kills pathogens.
12
Q
What do chief cells produce?
A
Pepsin (proteolytic enzyme)
13
Q
What do parietal cells in the stomach produce?
A
Intrinsic factor.
Important for B12 absorption, forms complex which is absorbed in terminal ileum)
14
Q
What errors can you get in ABGs with prolonged storage at room temp, rapid cooling, air bubbles, clots or dilution with heparin?
A
Prolonged storage at room temp
- ongoing cellular metabolism
- lowered pH, pO2 and glucose
- increased pCO2 due to aerobic metabolism
- increased lactate due to anaerobic metabolism
Rapid cooling
- haemolysis -> increased K+
Air bubbles
- decreased pCO2 and increased pO2
Clots
- increased K+
Dilution with heparin
- decreased pCO2
- decreased BE
- decreased bicarb
15
Q
What parts of the ECG corresponds with systole and diastole?
A
- systole - beginning of QRS until end of T wave
- diastole - end of T wave until beginning next QRS
16
Q
How does trimethoprim work?
A
Inhibits production of purines and pyrimidine bases by inhibition of the enzyme dihydrofolate reductase.
Adverse effects can be lessened by giving folinic acid.
More potent than sulfamethoxazole.
17
Q
What is surfactant?
A
Contains phospholipids and apoproteins.
Prevents alveolar collapse by variably changing surface tension.
As alveoli empty - concentration of surfactant increases which reduces surface tension -> prevents emptying of small alveoli into large.
18
Q
What is the ejection fraction?
A
Fraction of end diastolic volume that is ejected during systole.
19
Q
What is stroke work?
A
Work done by the myocardium with each contraction, can be calculated from area contained in pressure-volume loop.
If pre-load increases - volume increases - stroke work increases.
If afterload increases - pressure increases - stroke work increases.
20
Q
How does sugammadex work?
A
It binds to rocuronium/vecuronium to form complexes which removes drug from the neuromuscular junction.
Both roc + sugammadex bind to plasma proteins.
21
Q
What is the metabolism of sugammadex?
A
Renal excretion of unchanged product of sugammadex, no metabolites formed.
22
Q
What is the elimination 1/2 life of sugammadex?
A
1.8hrs
23
Q
What is the plasma clearance of sugammadex?
A
88ml/min
24
Q
How much sugammadex is excreted in the 1st 24hrs?
A
> 90%
25
What is the therapeutic dose of sugammadex?
Ranges from 2-16 mg/kg
26
How does a resistance wire measure temperature?
Incorporate length of platinum.
Very accurate between 0 - 100C.
Slow response.
Resistance of wire increases linearly with temperature.
27
How does a thermistor work?
Composed of metal oxide.
Respond rapidly to small temperature changes.
Increased temperature causes an exponential fall in resistance.
28
How does a thermocouple measure temperature?
2 different metals give rise to a potential difference (Seebeck effect).
Potential difference dependent on temperature, as temperature increases the potential difference increases.
29
How does Frank Starling work in the heart?
* muscle fibres stretch as preload increases - which increases force of contraction/stroke volume up to a point then plateaus
* increased afterload (SVR) tends to decrease CO
* any rhythm which disrupts synchronised contraction of cardiac muscle will decrease CO
* AF -\> lowers ejected volume as atrial kick is lost (contributes to EDV)
* increased diastolic pressure augments cardiac muscle perfusion - helps an ischaemic myocardium
30
What are the SEs of thiazide diuretics?
* can cause an attack in gout (hyperuricaemia)
* can cause LDL cholesterolaemia, increased risk in hyperlipidaemic patients
* young HTN pt with tachycardia will benefit from B-blockade
* not a good option in impaired renal function as they can't increase sodium output in a failing kidney
* better for african caribbean and elderly patients
31
What is relative humidity?
The absolute humidity/ mass of water required to fully saturate the gas
32
How does the Von Recklinghaus oscillometer work?
33
What ECG changes do you get in hypothermia?
At 30C - J waves (benign and no clinical significance) and ventricular arrhythmias.
At 28C - VF.
34
What is the order of steps in getting drug approval?
1. In vitro/animal studies
2. Phase I (drug safety and dosage in small group volunteers (100))
3. Phase II (assess effectiveness + detect adverse effects in larger group (500))
4. Phase III (confirm effectiveness + monitor SEs in much bigger group and longer duration (5000))
5. FDA approval
6. Post marketing testing (Phase IV)
35
What is double burst stimulation?
* 2 bursts of supramaximal current (50-60 mA)
* 50Hz 750ms apart
* each burst contains 3 impulses of 0.2ms each and separated by 20ms
* tactile evaluation more accurate than TOF
36
What is TOF?
4 impulses of supramaximal current at 2Hz 0.5s apart
37
How does caffeine work?
Inhibits breakdown of cAMP - augments beta adrenoceptor activity
38
How does nicotine work?
Stimulates ACh receptors on adrenal medulla which releases adrenaline and noradrenaline.
39
What effect does ACh release have on M2 receptors in the heart?
Hyperpolarization of pacemaker cells, increases the time for cells to reach threshold
40
What are the risks of TURP?
Hyponatraemia which increases intravascular volume and decreases serum osmolality.
CVS
* bradycardia, hypo/hypertension, wide QRS, ST elevation, VT/VF
Resp
* pulmonary odemea secondary to fluid overload
CNS
* confusion, coma, seizures, visual disturbance
Increased risk in prolonged procedures (\>60mins), haemorrhage leading to absorption of irrigant fluid from open prostatic sinuses, increased height of irrigant (increased hydrostatic pressure/increased absorption of irrigant).
41
What is the treatment for hyponatraemia caused by TURP?
Hypertonic 3% saline or haemofiltration
42
What is the potential in the myocardium vs the skin in volts?
90mV but at the skin it is reduced to only 1-2 mV
43
What kind of waves is the ECG signal composed of?
Complex arrangement of superimposed sine waves.
44
What is bandwidth and what is the value for an ECG?
A range of frequencies, it must include the fundamental frequency and 8 further harmonics.
Typically **0.5 - 80Hz** for the ECG.
Lower bandwidth will result in artefacts from breathing.
Higher bandwidth will result in interference from muscle twitches or electric equipment,
45
How many litres in a C size oxygen cylinder?
170L
46
How many litres in size D oxygen cylinder?
340L
47
How many litres in Size E oxygen cylinder?
680L
48
HOw many litres in size F oxygen cylinder?
1360L
49
How many litres in size G oxygen cylinder?
3400L
50
How is GTN metabolised?
By denitration to **nitric oxide** (potent vasodilator).
In vivo, nitric oxide is an endothelial derived relaxing factor derived from **L-arginine.**
Rapidly diffuses into myocytes one synthesised - induces relaxation via **guanate cyclase** pathway.
51
What marker would you use to estimate total body water?
Isotopic H2O (deuterium)
52
What marker would you use to measure ECF?
Mannitol or Inulin
53
What marker would you use to estimate the volume of plasma?
Tracer labelled albumin or Evan's blue dye
54
What is absolute risk reduction?
The incidence in the treatment group minus the incidence in the control group.
55
What is the number needed to treat?
NNT = 1 / ARR
56
What is the treatment for propranolol or Beta blocker OD?
Glucagon (improves inotropy)
57
What is present in whole blood?
RBCs, WBCs, platelets, plasma
58
What is uncoagulated blood which is centrifuged made of?
* Cellular components.
* Fluid phase = plasma
* water
* ions
* nutrients - glucose and AAs
* hormones
* proteins including albumin, immunoglobulins, clotting factors and fibrinogen
59
What is the fluid component of coagulated whole blood?
Serum - devoid of clotting factors (otherwise same as plasma)
60
What is sensitivity?
True +ves / true +ves + false -ves
61
What is specificity?
true -ves / true -ves plus false +ves
62
What is the best anticoagulant for a pregnant women with DVTs that won't cross the placenta or be found in breastmilk?
Heparin (large - can't cross placenta or be secreted in breast milk)
63
What are RBCs derived from?
Myeloid lineage of haemopoetic pluripotent stem cells.
Start as proerythroblasts containing DNA.
Mature in bone marrow + synthesise Hb -\> expell DNA.
This makes it a reticulocyte which matures over 1-2 days.
Remaining RNA lost to become mature RBC which is anucleate.
64
What are essential for RBC production?
Iron for Hb
Vit B12 and folate for synthesis of nucleic acids for DNA (if decreased = macrocytic anaemia)
65
Where is it most accurate to measure core temperature?
* lower oesophagus
* nasopharynx
* blood with Swan Ganz catheter
* tympanic (although inaccurate if wax)
66
What signs would you see in amitriptyline overdose?
* coma
* tachycardia
* prolonged QRS
* anticholinergic signs
67
What would lithium cause in overdose?
Coma + bradyarrhythmias
68
What would MAO inhibitors cause in overdose?
Sympathomimetic effects like HTN, tachycardia, hyperthermia, sweating
69
What can cause polycythaemia?
* primary bone marrow (polycythaemia rubra vera)
* iatrogenic (overtransfusion, over treatment with EPO)
* secondary to chronic hypoxic drive
* adaptation to altitude
* can be relative due to loss of plasma volume in burns or extreme dehydration)
70
Why are polycythaemia patients at higher risk of bleeding?
Due to platelet/clotting factor dilution
71
What will increase and decrease the Reynolds number?
Increase
* density
* velocity
* diameter/length
Decrease
* viscosity
72
What are causes of microcytic anaemia?
* iron deficiency
* increased requirements (pregnancy)
* increased loss (chronic bleeding)
* decreased iron intake (malnutrition)
* chronic disease
73
What are causes of normocytic anaemia?
* acute blood loss
* haemolytic disease (sickle cell/autoimmune)
* chronic renal and liver disease
* bone marrow failure
74
What causes macrocytic anaemia?
* B12/folate deficiency
* alcoholism
* hypothyroidism
* pregnancy (dilutional)
* bone marrow infiltration
75
What are the problems associated with ultrasonic nebulization?
* droplets of various sizes (1 micrometre = alveoli, 20 micrometers = upper resp tract, breathing system, trachea)
* large volumes of H20 can be nebulized and deposited in alveoli causing pulmonary oedema
* small diameter droplets carry infection readily
* as more water added, increased density, which increases Reynolds number and makes turbulent flow more likely
76
What are causes of inaccurate pulse oximetry?
* low perfusion
* diathermy/motion artefact/lights
* metHb (eg from LAs, sodium nitroprusside) will underread
* methylene blue or indocyanine dye used in thyroid surgery causes inaccurately low readings
* smokers will have a high level of carboxyHb (10-15%) which OVERestimates sats
* bilirubin doesn't interfere as not absorbed at wavelengths used by pulse oximeter
77
What is the formula for calculating the total amount of drug in the body?
Total amount of drug in body = volume of distribution x plasma concentration
78
Does cryprecipitate require cross matching?
No, it only contains fibrinogen
79
What does plasma contain?
Clotting factors
Fibrinogen
H2O
Salts
Proteins (albumin/immunoglobulins)
80
What does FFP contain?
Albumin
Most clotting factors
Very little fibrinogen
81
How often can you repeat the TOF?
15 seconds
82
Which electrode goes proximally when setting up the TOF monitor?
Positive proximally (minimizes current?)
83
How does warfarin work?
Prevents recycling of Vit K to oxidized form.
Oxidized Vit K is required to mature precursors of clotting factors (II, VII, IX, X) by gamma carboxylation of glutamic acid residues.
Takes 72hrs to full effect.
84
What are the complications associated with blood transfusion?
Immunity/incompatibility
* ABO + rhesus / other blood group haemolytic reactions - may be acute/delayed
Febrile reactions
* non-haemolytic
Hypersensitivity reactions
* rashes
Risk of infection
* bacterial/viral (hepatitis, CMV, HIV), fungal, prion diseases
Biochemical disturbance
* hyperkalaemia, hypocalcaemia, iron overload, acidosis
Haematological
* dilutional coagulopathy, DIC, polycythaemia
Cardiac
* fluid overload and cardiac failure
Resp
* pulmonary oedema + TRALI
Other
* hypothermia, shift of O2 curve left
85
What is the order of the bits in the circle system?
* excess gas exits via APL valve before passing through CO2 absorber - improves efficiency
* FGF enters downstream - not wasted through APL valve
* plenum vaporizers have high resistance so are not suitable for VIC (vaporizers in circuit)
* Goldman (low resistance) used if VIC needed
86
What are the acquired causes of immunodeficiency?
* HIV/AIDS
* diabetes
* chemo/radiotherapy
* drugs
* steroids
* methotrexate
* azothioprine
* burns
* trauma
* splenectomy
87
What are the class IA antiarrhythmics?
Sodium Channel Blockers
Prolong AP
Quinidine, procainamide
88
What are the Class IB antiarrhymics?
Sodium channel blockers.
Shorten AP.
Lignocaine, melexitine, phenytoin.
89
What are the Class IC antiarrhythmics?
Sodium channel blockers.
No effect on AP.
Flecainide.
90
What are the class II antiarrhythmics?
Beta blockers
91
What are the class III antiarrhythmics?
Potassium channel blockers.
Sotalol.
92
What are the Class IV antiarrhythmics?
Calcium channel blockers.
Verapamil, diltiazem.
93
