Investigations Flashcards
acute coronary syndrome
ECG
- ST elevation or new bundle branch block = STEMI
- no ST elevation – then perform troponin
-> raised troponin (+/- ECG changes) = NSTEMI
-> normal troponin = unstable angina or e.g. MSK chest pain
other:
- Blood (FBC, U+Es, LFTs, lipid profile, TFTs, HbA1C)
- Chest X-ray
- Echocardiogram after the event to assess for functional damage
- CT coronary angiogram - to assess for coronary artery disease
Cardiac Arrest
- Check carotid pulse - gold standard = lack of
- Continuous cardiac monitoring - check if rhythm becomes shockable
- FBCs - check for haemorrhage and subsequent hypovolemia
- Serum electrolytes - abnormalities can cause cardiac arrest e.g. hypo/erkalaemia
- ABG - shows acid base balance (acidosis)
- Cardiac biomarkers - elevated in MI
- POCUS - can identify tamponade, haemorrhage, PE etc (point of care ultrasound)
Cardiac Arrest diagnostic criteria
when the pt is
- unconscious
- apnoeic (not breathing)
- pulseless (no arterial pulse)
gold standard for diagnosis = lack of carotid pulse
Angina
- ECG - should not have ischaemic changes
- Blood tests:
- FBC
- TFT
- LFTs
- Lipid profile
- HBA1C
- U&Es (prior to ACEi + other meds)
- CT coronary angiography (contra in renal impairment)
- myocardial perfusion PECT - shows any damage from an MI
- stress ECHO
- MRI for regional wall motion abnormalities
- coronary angiogram - if the results from the non-invasive tests are inconclusive
Atrial Fibrillation
Bedside
- ECG - definitive diagnosis: absence of p waves with irregularly irregular rhythm
bloods
- routine to look for reversible causes: infection, hyperthyroidism, alcohol use
imaging
- echocardiogram - to see if cardiac cause of the AF
e.g. left atrial dilatation secondary to mitral valve disease
Atrial Flutter (re-entry circuit within right atrium)
ECG
- sawtooth pattern - in leads II, III, aVF
- narrow QRS
- regular rhythm (AV block may make it irregular)
- ventricular rate depends on level of AV block
SVTs - AVRT + AVNRT
(AV re-entry tachycardia, AV nodal re-entry tachycardia)
- ECG
- check digoxin levels
- Chest X-ray
- TFTs
- Cardiac enzymes
Wolff-Parkoinson-White Syndrome
ECG
- short PR
- delta wave (sloped upstroke before QRS)
- left or right axis deviation (depending on where the accessory pathway is)
Routine Bloods (including TFTs)
Complete Heart Block
- ECG
- U&Es
Ventricular Tachycardia
- ECG
- U&Es
- Cardiac enzymes
Heart Failure
- ECG (usually abnormal)
- Echo (assesses myocardial function - can identify pericardial effusion + cardiac tamponade)
- B-type Natriuretic Peptide - released in pressure overload of the heart >100mg/L
- Troponin
- ABG
- Blood tests - troponin, FBCs, U+Es, glucose+HbA1C, LFTs (↑ when reduced CO), TFTs, ↑CRP, D-dimer (PE)
Chest X-ray
- bilateral blunting of costophrenic angles
- pulmonary venous congestion
- pleural effusion
- cardiomegaly
- interstitial or alveolar oedema
ABCDEF mnemonic for CXR in HF
A - alveolar oedema (with batwing perihylar shadowing)
B - Kerley B lines (caused by interstitial oedema)
C - cardiomegaly (cardiothoracic ration >0.5)
D - upper lobe blood diversion
E - pleural effusions (bilateral usually)
F - fluid in the horizontal fissure
Essential & Secondary HTN
if pts have 2 BP readings > 140/90:
- ambulatory 24hr BP monitoring
- or home BP monitoring if 24hr unvailable
following diagnosis, pts have following tests:
- U&Es - check for renal disease (either cause or consequence)
- HbA1C - check for co-existing diabetes - CVS RF
- lipids - hyperlipidaemia is CVS RF
- fundoscopy - check for hypertensive retinopathy
- urine dip - check for renal disease
- ECG - check for left ventricular hypertrophy or ischaemic heart disease
Aortic Valve Disease
GOLD STANDARD
- Echo: shows pressure gradient across the stenotic aortic valve
**Chest X-ray **
- cardiomegaly
- calcified aortic valve
ECG
- left ventricular hypertrophy - increased QRS voltage, left axis deviation, poor R wave progression
- absent Q waves
- AV block
- Left axis deviation
Mitral Valve Disease
ECG
- broad P wave indicative of atrial enlargement
X-ray
- cardiomegaly
- enlarged left atrium + ventricle
Echocardiography
- to diagnose and assess severity
Right Heart Valve Disease
Echocardiography
- detect and quantify tricuspid regurgitation and heart function
ECG
- usually non-specific
- may all show peaked P waves or incomplete right bundle branch block
Cardiac MR
- evaluating right ventricular size and function
Cardiac catheterisation
- may be required prior to surgery to assess for coronary artery disease
Asthma (chronic)
Peak flow
- measurement of how quickly you can blow air out of lungs
- lower in the morning
- variability > 20% (which is high)
Fractional exhaled nitric oxide (FeNO)
- measures levels of NO in breath
- high level of NO when you breathe out can be a sign of inflamed airways
- > 40 ppb in adults
- > 35 ppb in children
Spirometry
- FEV1/FVC < 0.7
- performed before and after bronchodilator
Bloods
- total IgE and eosinophils will be raised
- can also test specific allergens
Chest X-ray
- to exclude other causes of wheeze
BDR - bronchodilator reversibility
- an improvement in lung function in reponse to a beta-2-agonist
Anaphylaxis
serum levels of mast cell tryptase can be measured to confirm diagnosis
- 1st sample ASAP after starting treatment
- 2nd sample within 1-2hrs (no later than 4hrs symptom onset)
- 3rd sample after complete recovers (as a baseline)
COPD
Bloods
- FBC - polycythaemia due to chronic hypoxia
- ABG - ↓pO +/- ↑pCO2 (may be acute or compensated type 2 resp failure)
ECG
- p-pulmonale - right atrial enlargement
- right ventricular hypertrophy if there is cor pulmonale
Chest X-ray
- hyperinflated chest - >6 anterior ribs
- bullae
- decreased peripheral vascular markings
- flattened hemidiaphragms
Spirometry - can be performed at diagnosis or to monitor progression
- FEV1/FVC ratio < 0.7 (as per GOLD criteria)
- increased TLC
- ↓ TLCO (transfer factor for CO) -> seen in pts with significant emphysema without signifiant bronchitis element
Other
- sputum culture
- BNP + echocardiogram - assess for HF
- serum alpha-1 antitrypsin - genetic cause in young pt
Allergic Bronchopulmonary Aspergillosis
- eosinophilia
- CXR
- positive RAST (radioallergosorbent) test to aspergillus
- positive IgG preciptins
- raised IgE
Extrinsic Allergic Alveolitis
- imaging: upper/mid zone fibrosis
- bronchoalveolar lavage: lymphocytosis
- serologic assays for specific IgG antobodies
- NO eosinophila
oral allergy syndrome
clinical diagnosis
- standard IgE RAST + skin prick testing to identify common allergens
- skin prick testing with culprit foods
Respiratory Failure
ABG
- PaO2 < 8 kPa
- PaCO2 > 6 kPa
pulse oximeter
spirometry
FiO2 - fraction of inspired oxygen
- patients may be on supplementary oxygen therapy causing PaO2 to be normal - but inapropriately low for the fraction of oxygen they are consuming
ECG
- to check for arrhythmias due to hypoxaemia or acidosis
DVT general investigations
2 level DVT Wells score
- score ≥ 2 = DVT likely
- score ≤ 1 = DVT unlikely
D-dimer (protein fragment made after blood clot has dissolved)
- can only exclude DVT not confirm it
proximal leg ultrasound
digital subtraction venography is technically gold standard or CT/MR venogram
ECG
- sinus tachycardia
Diagnostic Criteria and Algorithm for DVT
Well’s score ≥2
- proximal leg ultrasound (within 4 hrs otherwise anticoag + d-dimer then US within 24 hrs)
- if positive: DVT, start anticoag
- if negative: D-dimer (-ve D-dimer = unlikely, +ve = stop interim anticoag, repeat prox leg US 6-8 days later)
Well’s score ≤ 1
- perform D-dimer (within 4 hrs otherwise start interim anticoag)
- if negative: DVT unlikely
- if positive: conduct proximal leg ulstrasound (within 4 hrs, otherwise start anticoag then US within 24 hrs)
