Week 1: Diagnostics (tests, imaging) Flashcards
In a 100% sensitive test,
what would a POSITIVE or NEGATIVE result mean
POSITIVE: may be true or false positive
NEGATIVE: excludes condition
In a 100% specific test,
what would a POSITIVE or NEGATIVE result mean
POSITIVE: confirms condition
NEGATIVE: may be true or false negative
In terms of true/false positive/negative, how do you calculate SENSITIVITY
SENSITIVITY
True positive/ (true positive + false negative)
In terms of true/false positive/negative, how do you calculate SPECIFICITY
SPECIFICITY
True negative/ (true negative + false positive)
In terms of true/false positive/negative, how do you calculate POSITIVE PREDICTIVE VALUE
True positive/ (True positive + false positive)
In terms of true/false positive/negative, how do you calculate NEGATIVE PREDICTIVE VALUE
True negative/ (True negative + false negative)
D dimer has high sensitivity and low specificity. How does this help diagnosis of PE?
Negative result excludes PE.
Positive result may be due to false positives
What type of scan should be done in a pt with suspected fracture who is
- young
- old
Young: xray
Old: CT
What type of scan should be done in a pt with cord compression who is
- young
- old
All ages: MRI
What 4 factors must be considered before giving a patient CT contrast
- Allergy to contrast
- Impaired renal function
- Bleeding risk
- Children, pregnant woman (due to radiation exposure)
What is proteomics?
Name some examples
Looking at proteins
eg Gel electrophoresis
What is metabolomics?
Name some examples
Looking at sugars, nucleotides, amino acids, lipids
eg mass spectrometry
What ABG anomalies might one find in
- early organ failure
- late organ failure
Early: respiratory alkalosis
Late: lactic acidosis
Components of qSOFA
- Hypotension s<100
- Altered mental status
- Tachypnoea RR>22
ESR increases with increasing age.
TRUE/FALSE
TRUE.
ESR increases with increasing age.
ESR is higher in men
TRUE/FALSE
FALSE.
ESR is higher in women
Why is ESR higher in anaemia
RBC have less haematocrit so upward flow of plasma is slower
So RBC sink faster
Why is ESR higher in macrocytosis
RBC have smaller surface area to volume ratio (bigger sized RBC)
So RBC sink faster
Is V/Q or CTPA better for foetus?
CTPA -> less radiation than V/Q
Thus slight increased risk of childhood cancer with V/Q compared to CTPA
Is V/Q or CTPA better for mum?
V/Q -> lower risk of maternal breast cancer
do not do CTPA if mum has had breast cancer before
If there is abnormal CXR, should one do a V/Q or CTPA
CTPA if abnormal CXR
CT SPINE is indicated within 1h (in head injury) in a pt who is alert, stable and what other conditions?
Any 1 of the following
- Age >65yo
- Dangerous mechanism of injury (eg RTA)
- Focal peripheral neurology
- Paresthesia in limbs
CT SPINE is indicated within 1h (in head injury) in a less than fully conscious person and what other conditions?
Any 1 of the following
- GCS >13 on initial assessment in ED
- Intubated
CT SPINE is indicated within 1h (in head injury) in what sort of imaging criteria
- Unable to position pt for adequate xray
- Suspicious xray
- Multi focal CT needed as part of trauma investigation
- Need definitive answer before surgery
