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:
(1) heart rate in beats per minute
(2) systolic blood pressure in mm Hg
(3) diastolic blood pressure in mm Hg
(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:
(1) lightheadedness
(2) blurred vision
(3) palpitations
(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:
Orthostatic Symptoms |
Testing Grade |
Diagnosis |
none to mild |
Grade III |
sustained orthostatic hypotension, asymptomatic |
moderate to severe |
Grade IV |
sustained orthostatic hypotension, symptomatic |
For those patients who do not show orthostatic hypotension:
Heart Rate |
Blood Pressure |
Symptoms |
Testing Grade |
increase >= 10 to <= 30 bpm |
stable |
none |
Grade 0 |
increase > 30 bpm; standing < 120 bpm |
stable; pulse pressure reduced by >= 50% |
mild |
Grade I |
increase > 30 bpm; standing >= 120 bpm |
pulse pressure reduced by >= 50%; stable but may be increased with oscillations |
moderate to severe |
Grade II |
where:
• I assume the pulse pressure is reduced by < 50% in Grade 0.
Testing Grade |
Diagnosis |
Grade 0 |
normal |
Grade I |
mild orthostatic intolerance (MOI) |
Grade II |
postural tachycardia syndrome (POTS) |
Specialty: Cardiology
ICD-10: ,