Volumetric Blood Flow Measurement in the Ophthalmic Artery Using Colour Doppler

Zusammenfassung

Hintergrund: Hiermit präsentieren wir eine neue Methode zur Erfassung des Blutvolumens pro Zeit in absoluten Einheiten in der A. ophthalmica. Patienten und Methoden: Bei 8 gesunden jungen Probanden wurden mittels 12 – 3 MHz Linear-Schallkopf und Philips EnVisor HD Farbduplex-Einheit Messungen an der A. ophthalmica vorgenommen. Über eine selbstentwickelte Halterung konnte der Schallkopf in 3 Achsen sowie in Rotation und Neigung fixiert und die relative Position zum Auge mittels Skalen abgelesen werden. Blutflussgeschwindigkeit und Gefäßdurchmesser wurden kontinuierlich über 10 Pulszyklen EKG-synchron erfasst. Daraus wurden das Volumen pro Pulszyklus und weiter der Blutfluss in mL/min bestimmt. Zeitgleich wurden kardiovaskuläre Parameter mittels Finapres erfasst. Kurzzeit- (5 Messungen an Tag 1) und Langzeitvariationskoeffizient (5 Tage 1 Messung tgl.) wurden ermittelt. Ergebnisse: Der mittlere Blutfluss in der A. ophthalmica über alle Messungen lag bei 39,7 mL/min. Der intraindividuelle Variationskoeffizient betrug kurzfristig 24,1 ± 9,2 % und langfristig 32,0 ± 13,8 %. Der interindividuelle Variationskoeffizient betrug 32,8 %. Schlussfolgerungen: Unsere Methode erlaubt bedingt reproduzierbare Volumenflussmessungen in der A. ophthalmica in absoluten Einheiten.

Abstract

Background: Herewith we present a new method for measurement of the volumetric blood flow in absolute units in the ophthalmic artery. Patients and Methods: A Philips EnVisor HD ultrasound unit with a 12 – 3 MHz linear transducer was used to measure flow in the ophthalmic artery in 8 healthy young subjects. The transducer was mounted on a custom-made holder which enabled precise and reproducible positioning in 3 axes as well as in rotation angle. Blood flow velocity and vessel diameter were measured during 10 consecutive heartbeats. The measurements were ECG-gated. Blood vessel diameter and blood flow velocity were calculated in an average heartbeat cycle. Hence blood volume over time within a heartbeat cycle as well as blood flow in mL/min were determined. Simultaneously, cardiovascular parameters have been recorded by Finapres. Short time reproducibility (5 measurements on day 1) and long time reproducibility (5 days once daily) as well as interindividual coefficient of variation were evaluated. Results: Average blood flow in the ophthalmic artery in all measurements was 39.7 mL/min. The short-term intraindividual coefficient of variation was 24.1 ± 9.2 %, the long-term coefficient 32.0 ± 13.8 %. Interindividual coefficient of variation was 32.8 %. Conclusions: Our method allows volumetric blood flow measurements in the ophthalmic artery in absolute units, reproducible to a limited extent.

Schlüsselwörter

Arteria ophthalmica - Volumenfluss - Ultraschall - Farbduplex - Herzzyklus - Geschwindigkeit - Gefäßdurchmesser - Querschnittsfläche

Key words

ophthalmic artery - volumetric blood flow - ultrasound - colour Doppler imaging - cardiac cycle - velocity - vessel diameter - cross-sectional area

References

• 1 Morris R L, Histand M B, Miller C W. The resolution of the ultrasound pulsed Doppler for blood velocity measurements.  J Biomech. 1973;  6 701-710
• 2 Ackroyd N, Lane R, Dart L. et al . Colour-coded carotid Doppler imaging: an angiographic comparison of 324 bifurcations.  Aust N Z J Surg. 1984;  54 509-517
• 3 Miyatake K, Okamoto M, Kinoshita N. et al . Clinical applications of a new type of real-time two-dimensional Doppler flow imaging system.  Am J Cardiol. 1984;  54 857-868
• 4 Licht P B, Christensen H W, Roder O. et al . Volume flow estimation by colour duplex.  Eur J Vasc Endovasc Surg. 1999;  17 219-224
• 5 Michelson G, Schuierer G. Absolute blood flow in the ophthalmic artery.  Fortschr Ophthalmol. 1991;  88 687-689
• 6 Orge F, Harris A, Kagemann L. et al . The first technique for non-invasive measurements of volumetric ophthalmic artery blood flow in humans.  Br J Ophthalmol. 2002;  86 1216-1219
• 7 Doberenz C, Paulus W, Reimers C D. et al . Volume flow rate evaluation in patients with obstructive arteriosclerotic disease.  Cerebrovasc Dis. 2004;  18 312-317
• 8 Rossitti S, Frangos J, Girard P R. et al . Regulation of vascular tone.  Can J Physiol Pharmacol. 1995;  73 544-550
• 9 Erdogmus S, Govsa F. Accurate course and relationships of the intraorbital part of the ophthalmic artery in the sagittal plane.  Minim Invas Neurosurg. 2007;  50 202-208
• 10 Silke B, Spiers J P, Boyd S. et al . Evaluation of non-invasive blood pressure measurement by the Finapres method at rest and during dynamic exercise in subjects with cardiovascular insufficiency.  Clin Auton Res. 1994;  4 49-56
• 11 Wesseling K H. Finger arterial pressure measurement with Finapres.  Z Kardiol. 1996;  85 (Suppl 3) 38-44
• 12 Polska E, Kircher K, Ehrlich P. et al . RI in central retinal artery as assessed by CDI does not correspond to retinal vascular resistance.  Am J Physiol Heart Circ Physiol. 2001;  280 H1442-H1447

1 *Robert Katamay, Cyrille Fleischlin: Both authors contributed equally to this publication.