Postural hypotension + PE Flashcards
What are the causes of postural/orthostatic hypotension?
- Hypovolaemia
- Autonomic dysfunction: diabetes, Parkinson’s
- Drugs: diuretics, antihypertensives, L-dopa, phenothiazines, antidepressants, sedatives
- Alcohol
What is pulmonary artery occlusion pressure?
- Indirect measure of left atrial pressure and thus filling pressure of the left heart
- The low resistance within the pulmonary venous system allows this useful measurement to be made
- The most accurate trace is made by inflating the balloon at the catheter tip and ‘floating’ it so that it occludes the vessel
- If it is not possible to occlude the vessel in this way then the measurement gained will be the pulmonary artery end diastolic pressure.
How do you interpret POAP?
How do you work out systemic vacsular resistance (SVR)?
- Derived from aortic pressure, right atrial pressure and cardiac output
- SVR = 80(mean aortic pressure-mean right atrial pressure)/cardiac output
What are the textbook features of a pulmonary embolism?
- Chest pain: typically pleuritic
- Dyspnoea
- Haemoptysis
- Tachycardia
- Tachypnoea
Which features make a PE more likely?
- Tachypnea (respiratory rate >16/min) - 96%
- Crackles - 58%
- Tachycardia (heart rate >100/min) - 44%
- Fever (temperature >37.8°C) - 43%
It is interesting to note that the Well’s criteria for diagnosing a PE use tachycardia rather than tachypnoea
What is the Wells criteria?
What is the clinical probability simplified scores?
- PE likely - more than 4 points
- PE unlikely - 4 points or less
Investigations if PE is “likely” (more than 4 points)?
- Arrange an immediate computed tomography pulmonary angiogram (CTPA)
- If there is a delay in getting the CTPA then give low-molecular-weight heparin until the scan is performed.
Investigations if PE is “unlikely”?
- Arrange a D-dimer test
- If this is positive arrange an immediate computed tomography pulmonary angiogram (CTPA).
- If there is a delay in getting the CTPA then give low-molecular-weight heparin until the scan is performed.
- If the patient has an allergy to contrast media or renal impairment a V/Q scan should be used instead of a CTPA.
What should all patients with signs and symptoms of PE have?
- Should have a history taken
- Examination performed
- Chest x-ray to exclude other pathology
- If a PE is still suspected PE Wells score should be performed
What is the advantage of CTPA over V/Q scan?
- CTPA is now the recommended initial lung-imaging modality for non-massive PE
- Speed
- Easier to perform out-of-hours
- A reduced need for further imaging and the possibility of providing an alternative diagnosis if PE is excluded
- CTPA negative = patients do not need further investigations or treatment for PE
When is V/Q scanning used?
- V/Q scanning may be used initially if:
- Appropriate facilities exist
- Chest x-ray is normal
- No significant symptomatic concurrent cardiopulmonary disease
- V/Q scanning is also the investigation of choice if there is renal impairment(doesn’t require the use of contrast unlike CTPA)
What is sensitivity of D-dimers?
- Sensitivity = 95-98%
- Poor specificity
What ECG changes are seen in PE?
- Large S wave in lead I, a large Q wave in lead III and an inverted T wave in lead III - ‘S1Q3T3’
- However, this change is seen in no more than 20% of patients
- RBBB and RAD also associated with PE
- Sinus tachycardia may also be seen
What is the disadvantage of CTPA?
- Peripheral emboli affecting subsegmental arteries may be missed
- Significant complication rate compared to other investigations
What is the managemengt of PE?
