Dual effect of the Valsalva maneuver on autonomic nervous system activity, intraocular pressure, Schlemm\u2019s canal, and iridocorneal angle morphology

Li Sun,Wei Chen,Hong Zhang,Tian Hu,Qiongfang Xu,Zhiqi Chen,Junming Wang,Jingmin Guo,Yan Xiang

doi:10.1186/s12886-019-1275-y

Li Sun, Wei Chen + Show 7 more

Open Access

https://doi.org/10.1186/s12886-019-1275-y

Copy DOI

Abstract

BackgroundThe Valsalva maneuver (VM) is widely used in daily life, and has been reported to cause high intraocular pressure (IOP). This study aimed to assess changes in IOP, the Schlemm’s canal (SC), autonomic nervous system activity, and iridocorneal angle morphology in healthy individuals during different phases of the VM.MethodsThe high frequency (HF) of heart rate (HR) variability, the ratio of low frequency power (LF) and HF (LF/HF), heart rate (HR), IOP, systolic (SBP) and diastolic blood pressure (DBP), the area of SC (SCAR), pupil diameter (PD), and some iridocorneal angle parameters (AOD500, ARA750, TIA500 and TISA500) were measured in 29 young healthy individuals at baseline, phase 2, and phase 4 of the VM. SBP and DBP were measured to calculate mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP). HF and the LF/HF ratio were recorded using Kubios HR variability premium software to evaluate autonomic nervous system activity. The profiles of the anterior chamber were captured by a Spectralis optical coherence tomography device (anterior segment module).ResultsCompared with baseline values, in phase 2 of the VM, HR, LF/HF, IOP (15.1 ± 2.7 vs. 18.8 ± 3.5 mmHg, P < 0.001), SCAR (mean) (7712.112 ± 2992.14 vs. 8921.12 ± 4482.79 μm2, P = 0.039), and PD increased significantly, whereas MOPP, AOD500, TIA500, and TISA500 decreased significantly. In phase 4, DBP, MAP, AOD500, ARA750, TIA500and TISA500 were significantly lower than baseline value, while PD and HF were remarkably larger than baseline. The comparison between phase 2 and phase 4 showed that HR, IOP (18.8 ± 3.5 vs. 14.7 ± 2.9 mmHg, P < 0.001) and PD decreased significantly from phase 2 to phase 4, but there were no significant differences in other parameters.ConclusionsThe expansion and collapse of the SC in different phases of the VM may arise from changes in autonomic nervous system activity. Further, the effects of the VM on IOP may be attributed to changes in blood flow and ocular anatomy.Trial registrationThis observational study was approved by the ethics committee of Tongji Hospital (Registration Number: ChiCTR-OON-16007850, Date: 01.28.2016).

Highlights

The Valsalva maneuver (VM) is widely used in daily life, and has been reported to cause high intraocular pressure (IOP)
We previously reported that a decrease in IOP was associated with sympathetic nerve stimulation during aerobic exercise [14], while parasympathetic stimulation caused by the waterdrinking test may cause collapse of Schlemm’s canal (SC) and an increase in IOP [15]
There was a significant change in BP during the phase 4 of the VM, including diastolic blood pressure (DBP) (77.50 ± 9.56 vs. 72.63 ± 8.99 mmHg, P = 0.004) and mean arterial pressure (MAP) (91.15 ± 10.36 vs. 87.51 ± 7.32 mmHg, P = 0.028), while there were no changes in other BP values different states

Summary

Introduction

The Valsalva maneuver (VM) is widely used in daily life, and has been reported to cause high intraocular pressure (IOP). This study aimed to assess changes in IOP, the Schlemm’s canal (SC), autonomic nervous system activity, and iridocorneal angle morphology in healthy individuals during different phases of the VM. In phase 1, increasing intrathoracic pressure caused by the initial straining during the maneuver translates to the arterial circulation. In phase 2, the strain is maintained, increased intrathoracic pressure and decreased venous return cause a decrease in blood pressure, with a reflexive increased heart rate (HR) because of reduced parasympathetic and increased sympathetic nervous system activity. In phase 3, release of the strain causes a rapid drop in intrathoracic pressure leading to a transient drop of blood pressure. In phase 4, the impediment to venous return to the heart is removed, and blood is ejected into the constricted vasculature by the heart, causing a pressure overshoot. Parasympathetic activity is reflexively increased, resulting in a relatively quick slowing down of the heart [5,6,7,8]

Objectives

Methods

Results

Discussion

Conclusion