How common is this? An elderly man is admitted to an inpatient facility following a fall at home. During his consultation, you find out that he felt "giddy" before falling. It's happened a few times in the past as well.
Quite reasonably, you instruct the nurse to measure supine and standing blood pressure. You specifically request the nurse to measure the BP after the patient has been lying or standing for a full three minutes.
The nurse informs you that the BP fell by 10/5 mm Hg when the gentleman stood. You are reassured and leave it at that.
But have you missed the diagnosis here?
The normal response to being stood is for the systolic BP to fall slightly and for the diastolic BP to rise slightly. Therefore, the pulse pressure narrows.
More importantly though, the pulse rate speeds up slightly. Apart from the vasoconstriction involved in raising the standing BP, the heart beats slightly faster to maintain the systolic BP at a nearly constant level.
In autonomic failure, be it peripheral, i.e. diabetes, amyloid, or central, as in Parkinsons and Parkinkons plus syndromes and much less commonly in primary autonomic failure, both systolic and diastolic BP fall. More significantly, the pulse rate, instead of rising, remains invariant. It neither rises nor falls. Most patients with autonomic failure also have postprandial hypotension.
Vasovagal syncope is more common than autonomic failure, with two principal types- cardioinhibitory- due to excessive parasympathetic activity, and vasodepressor- due to interruption of sympathetic outflow.
In cardioinhibitory syncope, the pulse rate actually falls on standing. The BP falls too. Some patients may develop asystole.
In vasopdepressor syncope, there is sinus tachycardia. The BP falls.
In postural orthostatic tachycardia sydrome (POTS), the patient's pulse rate increases by >30 beats per minute upon standing. The BP does not fall.
Therefore, the following is a guide to using the blood pressure & pulse rate to differentiate between various types of syncope- standing BP and pulse compared with supine.
Old subject- BP falls by >20/10, pulse rate remains unchanged- autonomic failure
Old or young subject- BP falls, pulse rate falls or becomes asystolic (ECG may show 1st degree block in other cases)- cardioinhibitory syncope
Young subject- BP falls, becomes tachycardic- vasodepressor syncope
Young subject- BP does not fall, pulse rate increases by >30/minute- POTS
Any age- BP does not fall, pulse rate increases by <30/minute- normal response.
Quite reasonably, you instruct the nurse to measure supine and standing blood pressure. You specifically request the nurse to measure the BP after the patient has been lying or standing for a full three minutes.
The nurse informs you that the BP fell by 10/5 mm Hg when the gentleman stood. You are reassured and leave it at that.
But have you missed the diagnosis here?
The normal response to being stood is for the systolic BP to fall slightly and for the diastolic BP to rise slightly. Therefore, the pulse pressure narrows.
More importantly though, the pulse rate speeds up slightly. Apart from the vasoconstriction involved in raising the standing BP, the heart beats slightly faster to maintain the systolic BP at a nearly constant level.
In autonomic failure, be it peripheral, i.e. diabetes, amyloid, or central, as in Parkinsons and Parkinkons plus syndromes and much less commonly in primary autonomic failure, both systolic and diastolic BP fall. More significantly, the pulse rate, instead of rising, remains invariant. It neither rises nor falls. Most patients with autonomic failure also have postprandial hypotension.
Vasovagal syncope is more common than autonomic failure, with two principal types- cardioinhibitory- due to excessive parasympathetic activity, and vasodepressor- due to interruption of sympathetic outflow.
In cardioinhibitory syncope, the pulse rate actually falls on standing. The BP falls too. Some patients may develop asystole.
In vasopdepressor syncope, there is sinus tachycardia. The BP falls.
In postural orthostatic tachycardia sydrome (POTS), the patient's pulse rate increases by >30 beats per minute upon standing. The BP does not fall.
Therefore, the following is a guide to using the blood pressure & pulse rate to differentiate between various types of syncope- standing BP and pulse compared with supine.
Old subject- BP falls by >20/10, pulse rate remains unchanged- autonomic failure
Old or young subject- BP falls, pulse rate falls or becomes asystolic (ECG may show 1st degree block in other cases)- cardioinhibitory syncope
Young subject- BP falls, becomes tachycardic- vasodepressor syncope
Young subject- BP does not fall, pulse rate increases by >30/minute- POTS
Any age- BP does not fall, pulse rate increases by <30/minute- normal response.
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