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Is it time to stop checking postural BP?
Background: We often obtain lying and standing blood pressure measurements (OVS – orthostatic vital signs) in our patients, particularly if they have had a syncopal episode. A positive result is usually defined as a drop in systolic BP of >20mmHg, a drop in diastolic BP of >10mmHg, or an increase in heart rate of >30bpm (all measured 3 minutes after standing). We know that OVS are common in asymptomatic nursing home residents, and that they vary according to time of day (Ooi, 1997). We also know that OVS are not helpful in determining the severity of non-blood volume loss, like diarrhoea and vomiting (McGee, 1999). The current paper adds to this picture, considering the utility of OVS in the workup of patients presenting with syncope.
The paper: A systematic review looking to determine the utility of OVS in diagnosing orthostatic syncope, and to determine to what extent OVS can rule out serious life-threatening causes of syncope. Four prospective cohort studies were included, involving over 2,000 patients. They found an average rate of OVS of 25% in undifferentiated ED patients, regardless of their presenting complaint or final diagnosis. Of those ultimately diagnosed with orthostatic hypotension, only 69% had OVS by numbers. Of those ultimately diagnosed with another cause of syncope, 13% had OVS by numbers. (Journal of Emergency Medicine, December 2018)
The bottom line: The finding of a postural blood pressure drop is not very sensitive or specific for a final diagnosis of orthostatic hypotension
Note: If OVS are positive, this is sometimes a false positive (i.e. an incidental, asymptomatic finding, not related to the actual cause of the patient’s syncope). The risk is that you stop looking for another cause. Conversely, if OVS are negative in the ED, this is sometimes a false negative (i.e. there is no BP drop now, but there was when the patient had their syncope). The risk is that you assume it’s fine, and don’t stop some of their twenty anti-hypertensive medications.
Expert commentary:"A really interesting topic. In light of this evidence clinicians should be mindful when prescribing IV fluids for patients who have postural hypotension: only consider doing so when the patient is symptomatic and intravascularly depleted." (Dr Dwynwen Roberts, ED consultant)
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By Barrie StevensonBackground: We often obtain lying and standing blood pressure measurements (OVS – orthostatic vital signs) in our patients, particularly if they have had a syncopal episode. A positive result is usually defined as a drop in systolic BP of >20mmHg, a drop in diastolic BP of >10mmHg, or an increase in heart rate of >30bpm (all measured 3 minutes after standing). We know that OVS are common in asymptomatic nursing home residents, and that they vary according to time of day (Ooi, 1997). We also know that OVS are not helpful in determining the severity of non-blood volume loss, like diarrhoea and vomiting (McGee, 1999). The current paper adds to this picture, considering the utility of OVS in the workup of patients presenting with syncope.
The paper: A systematic review looking to determine the utility of OVS in diagnosing orthostatic syncope, and to determine to what extent OVS can rule out serious life-threatening causes of syncope. Four prospective cohort studies were included, involving over 2,000 patients. They found an average rate of OVS of 25% in undifferentiated ED patients, regardless of their presenting complaint or final diagnosis. Of those ultimately diagnosed with orthostatic hypotension, only 69% had OVS by numbers. Of those ultimately diagnosed with another cause of syncope, 13% had OVS by numbers. (Journal of Emergency Medicine, December 2018)
The bottom line: The finding of a postural blood pressure drop is not very sensitive or specific for a final diagnosis of orthostatic hypotension
Note: If OVS are positive, this is sometimes a false positive (i.e. an incidental, asymptomatic finding, not related to the actual cause of the patient’s syncope). The risk is that you stop looking for another cause. Conversely, if OVS are negative in the ED, this is sometimes a false negative (i.e. there is no BP drop now, but there was when the patient had their syncope). The risk is that you assume it’s fine, and don’t stop some of their twenty anti-hypertensive medications.
Expert commentary:"A really interesting topic. In light of this evidence clinicians should be mindful when prescribing IV fluids for patients who have postural hypotension: only consider doing so when the patient is symptomatic and intravascularly depleted." (Dr Dwynwen Roberts, ED consultant)