OSCE interpretation Flashcards

1
Q

What is the normal calibration of an ECG

A

25 mm/s and 10 mm/1mV

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2
Q

Normal adult’s heart rates?

A

Normal: 60-100 bpm
Tachycardia: > 100 bpm
Bradycardia: < 60 bpm

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3
Q

2 methods to calculate HR on ECG

Why might you choose one over the other?

A
  1. 300 / number of large squares
  2. 6 x number of QRS in 10 seconds

Only the second option works for irregularly irregular rhythms

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4
Q

Normal cardiac axis?

A

In healthy individuals, you would expect the axis to lie between -30° and +90º
Normally, if the electrical activity is towards a lead then this lead positive. The closer to it, the more positive the lead is.

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5
Q

Describe right axis deviation

A
  • Depolarisation is distorted to the right
  • Between 90 and 180
  • Moves toward leads III, away from lead II and massively away from lead I
  • See increased positivity in III, slightly less positivity in II and almost negativity in lead I
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6
Q

Describe left axis deviation

A
  • Depolarisation is distorted to the left
  • Between - 30 and - 90
  • Moves towards aVL, far away from III, and away from II to the other side of I
  • Lead III is hugely negative
  • Lead II is negative
  • Lead I is positive
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7
Q

What to look for with P waves

A
  • Are they present?
  • Is so, are they each followed by a QRS?
  • Do the P waves look normal? Duration, direction, shape
  • If P waves are absent, is there any atrial activity?
    o Sawtooth baseline –> flutter waves
    o Choatic baseline –> fibrillation waves
    o Flat line –> no atrial activity at all
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8
Q

Normal PR interval

A

120 - 200 ms (1.2 - 2 s)

3-5 small squares

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9
Q

Shortened PR interval causes?

A
  • P wave is originating from somewhere closer to AV node so conduction takes less time - some people have smaller atria, or SA node is not in fixed place
  • Atrial impulse is getting to the ventricle via a faster shortcut, e.g. accessory pathway, Wolf-Parkinson White syndrome
  • Would see delta waves in WPW syndrome
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10
Q

Three things to look at with QRS

A
  • Width
  • Height
  • Morphology
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11
Q

Width of QRS

A
  • Narrow (< 0.12 seconds)

- Broad (> 0.12 seconds)

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12
Q

Causes of broad QRS

A
  • Bundle branch block
  • Ventricular ectopics
  • Ventricular arrhythmias
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13
Q

Causes of narrow QRS

A
  • Atrial ectopics
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14
Q

Height of QRS

A
  • Small (< 5 mm in limb leads or < 10 mm in chest leads)

- Tall - imply ventricular hypertrophy

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15
Q

Morphology problems of QRS

A
  • Delta waves (WPW if with tachyarrhythmias)

- Q waves

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16
Q

What are pathological Q waves

A

> 25% the size of the R wave that follows it
OR
2mm in height and > 40ms in width

17
Q

R and S waves

A
  • In lead V1 the S wave is larger than the R wave
  • The transition to R being the larger wave should occur in lead V3 or V4
  • If it occurs into V5 or V6 this is poor R wave progression
  • Can be a sign of previous MI or in very large people due to poor lead position
18
Q

ST elevation in mm/squares

A
  • > 1 mm (1 small square) in 2 or more contiguous limb leads
    OR
  • > 2 mm in 2 or more chest leads
19
Q

ST depression in mm/squares

A
  • > 0.5 mm in > 2 contiguous leads
20
Q

T waves

Tall

A

> 5 mm in limb leads
AND
10 mm in chest leads

21
Q

T waves
Tall
Height

A

> 5 mm in limb leads
AND
10 mm in chest leads

22
Q

T waves
Tall
Causes

A
  • Hyperkalaemia

- Hyperacute STEMI

23
Q

T waves
Inversion
Causes

A
  • Ischaemia
  • Bundle branch block
  • PE
  • LVH
  • HOCM
  • General illness
24
Q

Biphasic T waves

Causes

A
  • Ischaemia

- Hypokalaemia

25
Q

Flattened T waves

Causes

A
  • Ischaemia

- Electrolyte imbalances

26
Q

U waves

What are they?

A
  • > 0.5 mm deflection after the T wave

- Best seen in V2 or V3

27
Q

U waves

Causes

A
  • Electrolyte imbalances
  • Hypothermia
  • Secondary to antiarrhythmic therapy (digoxin, amiodarone)
28
Q

What does a small square on an ecg represent

A

0.04 seconds

29
Q

What does a large square on an ecg represent

A

0.2 seconds

30
Q

ECG: How many large squares in 1 second

A

5

31
Q

ECG: How many large squares in 1 minute

A

300

32
Q

Spirometry

Reference ranges

A

FEV1: >80% predicted
FVC: >80% predicted
FEV1/FVC ratio: >0.7

33
Q

Spirometry

Details that need to be checked

A
Name
Age
Gender
Height
Ethnicity