Plethysmography implies volume measurement procedures including air, impedance or strain gauge methods. Vascular plethysmography is a non-invasive measurement of the systolic blood pressure of a leg compared with that of an arm to determine circulatory capacity. The test is usually performed to rule out vascular blockages in the arms or legs, usually in combination with Doppler ultrasound.

See also Oculoplethysmography, and Pulse Volume Recording.

(OPG) The Oculoplethysmography is used to detect a hemodynamically significant stenosis of the carotid circulation, by measuring the arrival times of pulses in the eye and ear. Indirectly the blood flow in the ophthalmic artery is measured, which branches off the carotid artery and supplies blood to the eye. A delay between pulse arrival in the eye and ear is an indication of a hemodynamically significant stenosis in the vessel whose corresponding pulse is delayed.
Other ultrasound or angiography procedures are necessary to confirm the diagnosis and have also replaced this technique.

See also Plethysmography and Ultrasound Biomicroscopy.

A-scans are used in ophthalmologic scanning, to detect and monitor pregnancy problems, and screen intracranial mass lesions by using A-modes.
A-scan ultrasound biometry, commonly referred to as an A-scan, is a routine diagnostic test used in ophthalmology. The A-scan provides data on the shape of the eye, which is a major determinant in common sight disorders.
Ultrasound scanners used in this type of test require usually direct contact with the eye.

See also A-Mode, Oculoplethysmography, Ultrasound Biomicroscopy, B-Scan, C-Scan and D-Scan.

Pulse volume recording is a method in which air-filled cuffs are placed segmentally on a limb and a difference in the limb volume associated with arterial pulsation is translated into a waveform. Evaluation of waveform change in this plethysmographic technique indicates the probability of the presence of an obstruction.

See also Plethysmography.