ACC lectures Flashcards
steps in interpreting ECG
- HR
- Heart rhythm
- Cardiac axis
- P waves
- P-R interval
- QRS complex
- Q-waves
- ST segment
- T waves
how to interpret heart rhythm
mark out R-R intervals and check that they are the same
what does cardiac axis measure
direction of electrical spread within the heart
what are the 3 types of cardiac axis
normal
Left
Right
what is right axis deviation
biphasic lead I
lead II + III are positive
right ventricular hypertrophy
what is left axis deviation
Lead I positive
lead II + III negative
waves are LLLeaving each other
seen in heart conduction defects
how should p-waves be interpretd
are they present?
p wave followed by QRS
do p waves look normal
saw tooth ?
how long should the P-R interval be?
120-200ms
3-5 small squares
what does a prolonged P-R interval suggest
AV block
what is first degree heart block
P-R interval > 200ms ( 5 small squares)
what is mobitz type 1 (wenkebach)
PR interval slowly increases then drops
what is mobitz type 2
PR interval is fixed but there are dropped beats
what is third degree heart block
P and QRS unrelated
are three factors should be considered when examining QRS complex
Width
height
morphology
interpret the width of QRS
narrow = < 0.12s broad = > 0.12
interpret the height of QRS
small
tall = ventricular hypertrophy
what is a pathological Q wave
25% size of the R wave
what is the ST segment
end of S and start of T wave
what is ST elevation
1-2mm increase in more than 1 lead
MI
what is ST depression
drop in ST in 2 or more Leads
myocardial ischaemia
what are Tall t-waves a sign of
Hyperkalaemia
hyperacute stemi
what are inverted T waves a sign of
ichaemia
bundle branch block
PE
what are biphasic t waves
ischaemia
hypokalaemia
what details to confirm when looking at ECG
name / DOB
date and time film was taken
any previous imaging
how to assess image quality
RIPE
rotation - clavicle equidistant from spinous processes
inspiration - 5-6 anterior ribs / lung apcies / both costophrenic angles / lateral rib edges
projection - AP vs PA
exposure - left hemidiagpharm visible / vertebrae visible behind heart
interpretation of A in CxR
tracheal deviation?
masses in trachea
pushing of trachea = large pleural effusion / Tension Pneumo
pulling of tracha = consolidation with lobar collapse
check carina visibility
left + right bronchus
interpretation of B in CxR
inspect lungs into 3 zones check for asymmetry increase airspace shadowing may suggest pathology absent lung markings = pneumothorax check pleura
interpretation of C in CxR
check for cardiomegaly–> PA ONLY
assess heart orders ( if not present it suggests consolidation in lungs)
interpretation of D in CxR
see if free gas below diagphargm
interpretation of E in CxR
bone abnormalities soft tissue injuries tubes lines artificial valves pacemaker
what is the normal range for pH
7.35-7.45
what is the normal range for Pa02
11-13
what is the normal range for PaC02
4.7-6
what is the normal range for HCO3
22-26
what is normal base excess
-2 to +2
what is always important to consider when interpreting ABG
patient clinical condition
Fi02
whats the first step in ABG interpretation
Oxygenation
is pateint hypoxic
if patient on oxygen then Pa02 should be 10 less than concentration
define stages of hypoxaemia
<10kPa on air = hypoxic
< 8kPa on air = severely hypoxic
what are the two types of resp failure
type 1 low oxyge but normal co2
type 2 = hyoxaemia with hypecapnia
whats the second step of interpreting ABG
pH
metabolic or respiratory
compensation or nah?
whats the third step of interpreting ABG
PaC02
is it normal or abnormal?
is it affecting the pH
what is the 4th step in ABG interpretation
HCO3-
normal?
does it fit with pH
what are the causes of respiratory acidosis
inadequate alevolar ventilation leading to C02 retention respiratory depression gullian barre asthma COPD
what are the causes of respiratory alkalosis
hyperventilation anxiety hypoxia PE pneumothorax
what are the causes of metabolic acidosis
DKA
lactic acidosis
aspirin overdose
what are the causes of metabolic alkalosis
vomitting / diarrhoea
loop diuretics / heart failure