The retinal venous pressure at different levels of airway pressure
- PDF / 406,974 Bytes
- 6 Pages / 595.276 x 790.866 pts Page_size
- 29 Downloads / 169 Views
BASIC SCIENCE
The retinal venous pressure at different levels of airway pressure Sofie Heimann 1
&
Richard Stodtmeister 1 & Lutz E. Pillunat 1 & Naim Terai 1
Received: 6 May 2020 / Revised: 29 May 2020 / Accepted: 6 June 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Purpose To investigate retinal venous pressure (RVP) as a function of airway pressure (AirP) during the Valsalva maneuver (VM) in human subjects. Methods Forty-three healthy volunteers (age, 22.0 (2.3) years) (median and interquartile range) were investigated using the following instruments: dynamic contour tonometer, contact lens dynamometer (CLD), and aneroid manometer. The following measurements were performed in their left eyes: tonometry and dynamometry during VM at different levels of airway pressure (AirP = 0, 10, 20, 30, and 40 mmHg). Results The median RVP during spontaneous breathing (AirP = 0) was 19.7 (6.4) (median in mmHg (interquartile range)) and the intraocular pressure (IOP) in mydriasis was 16.3 (3.1) mmHg. Spontaneous pulsation occurred in 58.1% of the subjects. RVP increased nonlinearly. The coefficient of variation of four individual measurements of RVP at each pressure level averaged 8.1 (7.6) %. At different AirP levels of 10, 20, 30, and 40 mmHg, the following RVPs were measured: 29.6 (12.6); 34.2 (12.8); 38.0 (10.5); and 40.3 (11.0), respectively. The rise of RVP (Δ RVP) during VM was significantly higher than that of Δ IOP (p < 0.0001, Wilcoxon test). Δ RVP between 0 and 40 mmHg AirP was 20.6 mmHg and Δ IOP 1.5 mmHg. The steepest slope of the RVP/AirP curve was observed at the first step from 0 to 10 mmHg of AirP (Δ RVP = 9.9 mmHg). Conclusion A nonlinear relationship between RVP and AirP was found during VM. Small rises in AirP increase the RVP and affect retinal circulation. Keywords Airway pressure . Retinal venous pressure . Intraocular pressure . Ophthalmodynamometry . Tonometry . Valsalva maneuver
Introduction During the Valsalva maneuver (VM), the intraocular pressure (IOP) increases due to elevated airway pressure (AirP) [1–3]. This may be explained by an increased pressure in the veins of the head [4], resulting in enhanced filling of the choroid and impairment of the aqueous humor drainage. Various studies have shown that playing brass and woodwind instruments (implementing VM) causes a temporary elevation in IOP and blood pressure (BP), depending on the tone frequency [5, 6]. In a recent study, it was also shown that retinal venous pressure (RVP) increases during VM [7], but
the quantitative dependency of RVP on AirP has not been investigated. A decisive factor for a sufficient supply of oxygen is the perfusion pressure in the prelaminar layer of the papilla. At this site, the venous outflow encounters a higher resistance as it takes place via the central vein of the retina [8]. As a consequence, significant elevations in RVP may lead to an insufficient blood supply and to damage of the optic nerve. Contact lens dynamometry (CLD) makes the RVP accessible in a simple manner. In the
Data Loading...
