A patient suspected of having disordered orthostatic response can be tested using a head-up tilt test. Low proposed a grading scheme for the physiologic and clinical response patterns to testing.
Testing is usually performed on a table specifically designed for the test.
(1) The patient is evaluated after being in a supine position for at least 5 minutes.
(2) The table is then tilted with the head up and the patient's response is monitored.
Parameters while supine:
(1) heart rate in beats per minute
(2) systolic blood pressure in mm Hg
(3) diastolic blood pressure in mm Hg
Parameters with head-up:
(4) orthostatic symptoms
heart rate increment on heads-up =
= (heart rate when tilted up) - (heart rate when supine)
pulse pressure =
= (systolic blood pressure) - (diastolic blood pressure)
change in pulse pressure =
= (pulse pressure when supine) - (pulse pressure when heads up)
percent reduction in pulse pressure =
= ((pulse pressure when supine) - (pulse pressure when heads up)) / (pulse pressure when supine)
mean blood pressure =
= ((systolic blood pressure) + (2 * (diastolic blood pressure))) / 3
Orthostatic symptoms are graded from none to severe (none, mild, moderate or severe). Symptoms include:
(2) blurred vision
(4) weakness of the lower limbs
The patient response is separated into 2 groups depending on whether there has been a significant reduction in the blood pressure on head-up tilting.
Orthostatic hypotension involves:
(1) reduction in systolic blood pressure >= 30 mm Hg
(2) reduction in diastolic blood pressure >= 15 mm Hg
(3) reduction in mean blood pressure >= 20 mm Hg
For those patients showing orthostatic hypotension:
none to mild
sustained orthostatic hypotension, asymptomatic
moderate to severe
sustained orthostatic hypotension, symptomatic
For those patients who do not show orthostatic hypotension:
increase >= 10 to <= 30 bpm
increase > 30 bpm; standing < 120 bpm
stable; pulse pressure reduced by >= 50%
increase > 30 bpm; standing >= 120 bpm
pulse pressure reduced by >= 50%; stable but may be increased with oscillations
• I assume the pulse pressure is reduced by < 50% in Grade 0.
mild orthostatic intolerance (MOI)
postural tachycardia syndrome (POTS)
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