PBL Topic 2 Case 6 Flashcards

1
Q

Identify four functions of the circulation

A
  • Transport nutrients to body tissues
  • Transport waste away from body tissues
  • To conduct hormones
  • To maintain an appropriate environment in all tissue fluids
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2
Q

Identify the two types of circulation

A
  • Pulmonary circulation

- Systemic circulation

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3
Q

Identify the function of the arteries

A
  • Transport blood under high pressure to the tissues from the heart
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4
Q

Identify the function of the arterioles

A
  • Control conduits through which blood is released into the capillaries
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5
Q

Identify the functions of the capilalries

A
  • Exchange nutrients, electrolytes, hormones and other substances between the blood and interstitial fluid
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6
Q

Identify the functions of the venules

A
  • Collect blood from the capillaries into progressively larger veins
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7
Q

Identify the functions of the veins

A
  • Conduits for transport of blood from the venules back to the heart
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8
Q

What is the arterial pressure in the aorta?

A
  • 100 mm/Hg
  • 80 mm/Hg during diastole
  • 120mm/Hg during systole
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9
Q

How does the arterial pressure change following the aorta?

A
  • Decreases
  • High enough to allow nutrients to diffuse through the pores
  • Low enough to allow little plasma to leak through the pores
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10
Q

What is cardiac output and what is its typical value?

A
  • Quantity of blood pumped into the aorta each minute by the heart
  • 5 L/min
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11
Q

Identify two factors that determine blood flow

A
  • Pressure difference

- Vascular resistance

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12
Q

How do you calculate blood pressure?

A
  • Cardiac Output x Peripheral Resistance
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13
Q

How do you calculate cardiac output?

A
  • Stroke Volume x Heart Rate
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14
Q

How do you calculate stroke volume?

A
  • End Diastolic Volume - End Systolic Volume
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15
Q

Identify three factors that affect stroke volume

A
  • Preload
  • Contractility
  • Afterload
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16
Q

Identify three factors that affect heart rate

A
  • Hormones
  • Temperature
  • Pain
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17
Q

Identify three factors that affect vessel resistance

A
  • Viscosity of the blood
  • Vessel length
  • Vessel radius
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18
Q

Identify 5 factors that increase blood flow

A
  • Increase in metabolism
  • High altitudes
  • Pneumonia
  • Carbon monoxide poisoning
  • Cyanide poisoning
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19
Q

Outline Vasodilator Theory

A
  • Increase in oxygen demand
  • Formation of vasodilator substances
  • Including histamine, adenosine and nitric oxide
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20
Q

Outline Oxygen Lack Theory

A
  • Increase in oxygen demand
  • Natural dilation of vessels in absence of oxygen
  • Cyclical opening of precapillary sphincters (vasomotion)
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21
Q

Outline Reactive Hyperaemia

A
  • Increase in oxygen demand
  • E.g. occlusion
  • Rapid blood flow through tissue for a few seconds
  • Repay oxygen deficit
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22
Q

Outline Active Hyperaemia

A
  • Increase in oxygen demand
  • E.g. exercise
  • Rate of blood flow increases through vessel
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23
Q

Outline Metabolic Theory of Auto-regulation of Blood Flow

A
  • Rise in arterial pressure
  • Excess flow of oxygen and nutrients
  • Vasoconstriction
  • Reduced blood flow
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24
Q

Outline Myogenic Theory of Auto-regulation of Blood Flow

A
  • Rise in arterial pressure
  • Stretching of vessel
  • Vasoconstriction
  • Reduced blood flow
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25
Q

What stimulates nitric oxide release for vasodilation?

A
  • Rapid flow of arteries causes sheer stress due to viscous drag
  • Release of bradykinin and histamine
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26
Q

How does nitric oxide cause vasodilation?

A
  • Combines with guanylyl cyclase
  • Formation of cGMP
  • A second messenger to activate protein Kinase G
  • De-phosphorylation of myosin light chains
  • Sequestration of intracellular Ca2+
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27
Q

What is the function of prostacyclin (Prostaglandin I2)?

A
  • Vasodilator
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28
Q

What is the function of endothelin-1?

A
  • Vasoconstrictor
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29
Q

What is EDRF?

A
  • Endothelium Derived Relaxing Factor
  • Composed of Nitric Oxide
  • Vasodilator
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30
Q

Identify three factors that are responsible for angiogenesis

A
  • Vascular Endothelial Growth Factor (VEGF)
  • Fibroblast Growth Factor
  • Angiogenin
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31
Q

Outline the process of angiogenesis

A
  • Dissolution of basement membrane
  • Reproduction of endothelial that stream outward through vessel
  • Formation of cords that fold over into a tube
  • Formation of a capillary loop when two tubes join
  • Blood flow through capillary loop
  • Invasion of smooth muscle cells
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32
Q

Outline the process of collateral circulation

A
  • Dilation of small vascular loops that connect the vessel above to the blocked vessel below
  • Dividing of these small vascular loops forming multiple small collateral channels
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33
Q

Identify two ways that noradrenaline can enter the circulation

A
  • Release from sympathetic nerve endings

- Sympathetic nerves cause adrenal medulla to secrete large amounts

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34
Q

Identify what occurs when noradrenaline binds to alpha receptors

A
  • Activated G protein activates Phospholipase C
  • PIP2 is converted into IP3 and DAG
  • IP3 mobilises calcium ions which are involved in vasoconstriction
  • DAG actives protein kinases which phosphorylate other proteins resulting in cellular response
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35
Q

Identify the function of a1 and a2 receptors and where they are located

A
  • a1 receptors on smooth muscle cause vasoconstriction

- a2 receptors on presynaptic membrane cause negative feedback

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36
Q

Identify what occurs when noradrenaline binds to beta receptors

A
  • Activated G protein activates adenylyl cyclase
  • Conversion of ATP to cAMP
  • Activation of protein kinases
  • Phosphorylation of proteins results in cellular response
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37
Q

Identify the function of B1, B2 and B3 receptors and where they are located

A
  • B1 receptors on sinus node and cardiac muscle increase heart rate and contraction force
  • B2 receptors on smooth muscle in coronary arteries cause vasodilation
  • B2 receptors on airway smooth muscle cause bronchodilation
  • B3 receptors cause lipolysis
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38
Q

What percentage of the cardiac output do the kidneys recieve?

A
  • 20% (1L/min)
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39
Q

Where and how is renin stored?

A
  • Stored as prorenin in juxtaglomerular cells of the kidneys
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40
Q

What is the function of renin?

A
  • Acts on angiotensinogen to release
  • To release 10-amino acid peptide angiotensin 1
  • When arterial pressure falls
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41
Q

What is the role of Angiotensin Converting Enzyme? Where does this function take place?

A
  • Conversion of Angiotensin I to Angiotensin II (8-amino acid peptide)
  • Lung
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42
Q

Identify two functions of Angiotensin II

A
  • Powerful vasoconstrictor
  • Decrease sodium and water excretion
  • Thereby increasing arterial pressure
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43
Q

What is the function of Aminopeptidase A?

A
  • Removes a single amino acid from Angiotensin II

- To form Angiotensin III

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44
Q

Identify two functions of Angiotensin III

A
  • Stimulates aldosterone secretion
  • Regulates thirst
  • Increases secretion of ADH
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45
Q

How does Angiotensin II act on smooth muscle cells?

A
  • Via Phospholipase C Second Messenger System
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46
Q

How is Angiotensin II inactivated?

A
  • By angiotensinases
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47
Q

When is ANP secreted?

A
  • Volume overload

- In response to stretching of the atria

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48
Q

Identify four functions of ANP

A
  • Increase diuresis and natriuresis
  • Vasodilation
  • Increase vascular permeability
  • Inhibit release of angiotensin II
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49
Q

What is the affect of ANP on renal glomerular afferent and efferent arterioles?

A
  • Dilation of afferent arterioles
  • Constriction of efferent arterioles
  • Increased filtration pressure
  • Increases glomerular filtration
  • Enhanced sodium excretion
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50
Q

Identify the three regions of the vasomotor centre

A
  • Vasoconstrictor Area
  • Vasodilator Area
  • Sensory Area
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51
Q

Identify the function of the vasoconstrictor centre

A
  • Excites preganglionic vasoconstrictor neurons of the sympathetic nervous system
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52
Q

Identify the function of the vasodilator area

A
  • Fibres project upwards

- Inhibit vasoconstrictor activity

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53
Q

Identify the function of the sensory area

A
  • Receives sensory nerve signals from glossopharyngeal and vagus nerves
  • Output from these helps to activate either the vasodilator or vasoconstrictor area
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54
Q

Identify the function of the lateral portions of the vasomotor centre

A
  • Transmits impulses through the sympathetic nerve fibres to increase heart rate and contractility
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55
Q

Identify the function of the medial portions of the vasomotor centre

A
  • Transmits parasympathetic impulses through the vagus nerve to decrease heart rate and contractility
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56
Q

Identify the main baroreceptors and their associated nerves

A
  • Carotid baroreceptors, located in bifurcation of carotid artery, transmit signals via glossopharyngeal nerve (via Hering’s nerves)
  • Aortic baroreceptors, located in the aortic arch, transmit signals through vagus nerve
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57
Q

Identify an effect of increased blood pressure on the vasomotor centre and sinus onde

A
  • Stimulation of caridioinhibitory centre
  • Inhibition of cardioaccelerator
  • Increased parasympathetic activity and decreased sympathetic activity to sinus node
  • Decrease in heart rate
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58
Q

Identify the effect of decreased blood pressure on the vasomotor centre and sinus node

A
  • Stimulation of cardioaccelerator centre
  • Inhibition of caridioinhibitory centre
  • Increased sympathetic activity and decreased parasympathetic activity to sinus node
  • Increase in heart rate
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59
Q

Explain why nicotine can stimulate postganglionic neurons

A
  • Membranes of these neurones contain nicotinic receptors
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60
Q

Explain how chronic nicotine use contributes to cardiovascular disease

A
  • Nicotine stimulates noradrenaline and adrenaline from adrenal medulla
  • Sympathetic components result in tachycardia, and increased cardiac output
  • Persistent high blood pressure and increased work on the heart
61
Q

Why does the effect of nicotine persist for many minutes to several hours?

A
  • Nicotine is note destroyed by cholinesterase
62
Q

What is meant by hypertension?

A
  • Chronic elevation of arterial blood pressure
63
Q

What is essential hypertension?

What is the percentage of cases of hypertension where this applies?

A
  • Hypertension in which a specific underlying cause cannot be found
  • 95%
64
Q

What is secondary hypertension?

What is the percentage of cases of hypertension where this applies?

A
  • Hypertension as a consequence of a specific underlying disease
  • Leading to sodium retention and peripheral vasoconstriction
  • 5% of cases
65
Q

In which ethnic groups is hypertension most common?

A
  • Black Americans

- Japanese

66
Q

Outline how to measure blood pressure

A
  • Ensure machine is validated and properly calibrated
  • Remove tight clothing from arm and support the arm at the level of the heart
  • Use appropriate size cuff
  • Lower the blood pressure slowly (2mm/Hg per second)
  • Use phase V (disappearance of sounds) to measure diastolic BP
67
Q

What are the optimal, normal and high normal blood pressures?

A
  • Optimal = 120/80
  • Normal = 130/85
  • High Normal = 140/90
68
Q

What are the blood pressures for Grade 1, Grade 2 and Grade 3 hypertension?

A
  • Grade 1 = 150/95
  • Grade 2 = 160/100
  • Grade 3 = 180/110
69
Q

Identify six non-humoral causes of hypertension?

A
  • Genetic influence
  • Low birth weight
  • Obesity
  • Alcohol intake
  • Sodium intake
  • Acute pain or stress
70
Q

Identify three hormonal systems that have been implicated in the pathogenesis of hypertension?

A
  • Renin-angiotensin
  • Natriuretic
  • Kallikrein-kinin
71
Q

Outline the changes that occur in resistance vessels in the pathophysiology of hypertension

A
  • Increase in wall thickness
  • Rarefaction (decreased density)
  • Resulting in increased peripheral resistance and left ventricular hypertrophy
72
Q

Outline the changes that occur in larger vessels in the pathophysiology of hypertension

A
  • Thickening of the media
  • Increase in collage
  • Secondary deposition of calcium
  • Resulting in loss of arterial compliance
73
Q

Outline the changes that occur in the renal vasculature in the pathophysiology of hypertension

A
  • Reduced renal perfusion
  • Activation of angiotensin II by renin-angiotensin system
  • Reduced glomerular filtration rate
  • Reduction in natriuresis and diuresis
74
Q

Outline the cerebral changes that occur in the pathophysiology of hypertension

A
  • Lacunae and reversible neurological deficits

- Resulting in dementia and stroke

75
Q

Identify the two main causes of death in hypertension

A
  • Cerebrovascular Disease

- Coronary Artery Disease

76
Q

What is malignant hypertension?

A
  • Blood pressure rises rapidly
  • With characteristic fibrinoid necrosis
  • Which leads to renal failure, heart failure, aortic dissection or stroke
77
Q

Identify 6 investigations that should be carried out in hypertensive patients

A
  • Urinalysis for blood, protein and glucose
  • Blood glucose
  • Blood urea, electrolytes and creatinine
  • Serum total and HDL cholesterol
  • Fasting blood for lipids
  • 12-lead ECG
78
Q

Identify specific investigations carried out when urea and creatinine are elevated and what they are used to detect

A
  • Renal ultrasound to detect kidney disease

- Renal angiography to detect renal artery stenosis

79
Q

Identify specific investigations carried out when ECG shows evidence of coronary artery disease and what they are used to detect

A
  • Echocardiogram to detect left ventricular hypertrophy

- CXR to detect cardiomegaly or heart failure

80
Q

How do the target blood pressures of hypertensive patients differ between those with and without diabetes?

A
  • Without diabetes: 140/85

- With diabetes: 130/80

81
Q

What is the threshold for offering drug treatment to hypertensive patients?

A
  • BP > 160/100

or

  • BP > 140/90 and 10-year CVD risk of at least 20% or existing CVD or target organ damage
82
Q

Identify five lifestyle measures than obviate the need for drug therapy in hypertensive patients

A
  • Correcting obesity
  • Reducing alcohol intake
  • Smoking cessation
  • Taking regular exercise
  • Increased consumption of fruit, vegetables and oily fish
83
Q

Identify the four classes of drugs that are used to treat hypertension

A
  • ACE Inhibitors e.g. Ramipril
  • Beta Blockers e.g. Bisoprolol
  • Calcium Channel Blocker e.g. amlodipine
  • Diuretic e.g. Chlortalidone
84
Q

What is the treatment given to young caucasians in Step 1 and why is this the case?

A
  • ACE Inhibitor

- These patients are more likely to have renin hypertension

85
Q

What is the treatment given to older or black patients in Step 1 and why is this the case?

A
  • Calcium Channel Blocker or Diuretic

- These patients are more likely to have low renin hypertension

86
Q

What is the rationale for Step 2 in the treatment of hypertension?

A
  • Two drugs of different groups are used
  • E.g. Ace Inhibitor and Calcium Channel Blocker
  • E.g. Ace Inhibitor and Diuretic
87
Q

What is the rationale for Step 3 in the treatment of hypertension?

A
  • ACE Inhibitor is combined with a calcium-channel blocker and diuretic
  • Beta blocker may be used if this is not sufficient to achieve target blood pressure
88
Q

Outline the mechanism of action of thiazide diuretics

A
  • Bind to Cl- site of the distal tubular Na/Cl co-transport system
  • Natriuresis and Diuresis
  • Reduced blood pressure and vasodilation
89
Q

In which patients are thiazide diuretics ineffective?

A
  • In patients with glomerular filtration rates below 30 mL/min
90
Q

Identify the main unwanted effect in thiazide diuretics

A
  • Erectile dysfunction
91
Q

When are angiotensin II receptor antagonists prescribed?

A
  • In patients who are intolerant to ACEI

- Since they do not affect bradykinin metabolism or produce cough

92
Q

Outline the mechanism of action of angiotensin II receptor antagonists

A
  • Block the formation of angiotensin II, a powerful vasodilator
  • Inhibit secretion of aldosterone resulting in natriuresis
  • Reducing vascular resistance, improving tissue perfusion and reducing cardiac afterload
93
Q

Identify the main unwanted effect in ARAs

A
  • Hypotension
  • Hyperkaleamia (less water = increased [K+] (relative concentration))
  • Renal dysfunction
94
Q

Identify three contra-indications for ARAs

A
  • Pregnancy
  • Renal artery stenosis
  • Previous angioedema
95
Q

Identify an example of a calcium channel blocker

A
  • Amlodipine,

- Which belongs to the dihydropyridine class

96
Q
  • Identify the mechanism of action calcium channel blockers
A
  • Bind to a1 subunit of L-type calcium channel
  • Preventing it from opening
  • Reducing influx of Ca2+
  • Resulting in coronary dilation
97
Q

Why do calcium channels demonstrate use/voltage-dependence?

A
  • Block more effectively in cells in which the calcium channels are most active / depolarised
98
Q

Identify three side effects of calcium channel blockers

A
  • Flushing
  • Headaches
  • Ankle swelling
99
Q

What causes the ankle swelling caused by calcium channel blockers?

A
  • Arteriolar dilation

- Increased permeability of post-capillary venules

100
Q

What is a Background Question?

A
  • General questions about a clinical problem or disease process
101
Q

What is a Foreground Question?

A
  • Questions centred around an individual patient
102
Q

What does the acronym PICO stand for?

A
  • P = Patient / Problem
  • I = Intervention
  • C = Comparison / Control
  • O = Outcome
103
Q

What is primary literature?

A
  • Original reports of research studies
  • Published in scientific journals
  • Used to help answer complex foreground questions
104
Q

What is a Bibliographic Database?

A
  • Collection of primary literature
105
Q

Identify four examples of Bibliographic Databases

A
  • Medline
  • PubMed
  • PsycInfo
  • EMBASE
106
Q

What is a Secondary Source of Evidence?

A
  • Evidence regarding a particular question that has already been searched for and appraised
107
Q

Identify four examples of Secondary Sources of Evidence

A
  • Cochrane Library
  • BestBETs
  • Essential Evidence Plus
  • Clinical Evidence
108
Q

Identify four examples of Secondary Journals

A
  • ACP Journal Club
  • Evidence Based Medicine
  • Clinical Inquiries
  • Bandolier
109
Q

What are categorical variables and how are they summarised?

A
  • Qualitative variables
  • In a frequency distribution
  • As bar graphs or pie charts
110
Q

What are numerical variables and how are they summarised?

A
  • Quantitative variables
  • In a frequency distribution with intervals and ranges
  • As histograms or frequency polygons
111
Q

What is meant by the term Central Tendency?

A
  • A single numerical capturing the typical distribution
112
Q

What is the mean and how is it calculated?

A
  • Mathematical term for average

- Dividing the sum of all values by the number of observations

113
Q

What is the median and how is it calculated?

A
  • Middle observation

- When the data are ranked in increasing order

114
Q

What is the mode?

A
  • The value that occurs most often
115
Q

What is spread?

A
  • The degree by which the values are clumped around a measure of central tendency
116
Q

How is the range calculated? What is the limitation of the range?

A
  • Difference between the highest and lowest value

- Does not give any indication for intermediate values

117
Q

What does the standard deviation show?

A
  • Indication of the degree to which the values are clumped around the mean
118
Q

Approximately what percentage of values fall within 1SD?

A
  • 68%
119
Q

Approximately what percentage of values fall within 2SDs?

A
  • 95%
120
Q

Approximately what percentage of values fall within 3SDs?

A
  • 99.7%
121
Q

Identify three causes of outliers and when it is acceptable to exclude outliers in the final statistical analysis

A
  • Measurement
  • Interpretation
  • Calculation
  • If the outlier is caused by one of the above factors
122
Q

What is a test statistic? How is this related to critical value?

A
  • A numerical summary of the data

- Test statistic must be greater than critical value for hypothesis to be statistically significant

123
Q

What does the null hypothesis state?

A
  • When one variable is tested against another, there will be no difference / association between the variables
124
Q

What is the p value?

A
  • Probability of observing the results of a trial if the null hypothesis is true
  • p value close to 1 indicates a correct null hypothesis
  • p value close to 0 indicates an incorrect null hypothesis
125
Q

A p value of less than X is usually considered to be statistically significant

A
  • X = 0.05
126
Q

What does the Shapiro Wilk (W) test show?

A
  • Whether data is normally distributed
127
Q

What is skewness and how is this shown on a distribution curve?

A
  • Measure of asymmetry of the distribution
  • Positive = Distribution skewed to right (p on its back)
  • Right = Distribution skewed to left
128
Q

What does the T-test (T) show?

A
  • Difference between two means
129
Q

When is the one sample T-test used?

A
  • To compare a sample mean with the population mean(e.g. junior doctors compared to population)
130
Q

When is the unpaired T-test used?

A
  • To compare a mean in two independent groups (e.g. smokers vs non-smokers)
131
Q

When is the paired T-test used?

A
  • To compare a mean of a single group at two separate points in time (e.g. before and after treatment)
132
Q

What is the difference between a one- and two-tailed tailed T-test?

A
  • Two-tailed assumes that the results may go in either direction
  • One tailed means good reason to predict direction of difference
133
Q

What is the Pearson’s Correlation Coefficient (R)

A
  • How two variables are related
134
Q

What is the difference between positive and negative correlation?

A
  • Positive = As one variable increases so does the other

- Negative = As one variable increases the other decreases

135
Q

Identify two statistical packages used to help give a value for the correlation and p value?

A
  • StatsDirect

- SPSS

136
Q

How are correlations presented?

A
  • Scatter plots
137
Q

What is linear progression

A
  • Method used to predict the value of one variable from another known variable
138
Q

How is linear progression calculated?

A
  • Straight line that best fits data
  • Two circles representing two data points are then drawn as a possible regression
  • The arrows illustrate the deviation of variance of the data points
139
Q

What is a forest plot?

A
  • Graphical depiction of pooled treatment result

- From a meta-analysis, where results of different studies are pooled together?

140
Q

How is the Point Effect Estimate represented on a Forest Plot?

A
  • Blue square of each study

- Size is proportional to statistical weight of each study

141
Q

How is the Overall Effect Estimate represented on a Forest Plot?

A
  • Black diamond
142
Q

What is the confidence interval and how is the confidence interval of each study represented?

A
  • Certainty of point effect estimate

- Each horizontal line

143
Q

Identify two factors that narrow the confidence interval

A
  • Large samples

- Reduced variability

144
Q

How can you tell that there is a significant difference between two treatments based on the confidence interval?

A
  • The confidence interval does not cross the vertical line of no effect
145
Q

What are the odds of an event and how is it calculated?

A
  • Probability of an event not occurring

- (Number of Events / Number of Patients - Number of Events)

146
Q

What is the risk of an event and how is it calculated?

A
  • Probability of an event occurring

- (Number of Patients / Number of Events)

147
Q

What does an odds or risk ratio greater than 1 indicate?

A
  • Increased risk or odds among the exposed compared to the unexposed
148
Q

What does an odds or risk ratio less than 1 indicate?

A
  • Decreased risk or odds among the exposed compared to the unexposed