The Head-Up Tilt Test for Grading the Orthostatic Response

 

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)