Contrast-Enhanced Ultrasonography Enables the Detection of a Cold Pressor Test-Induced Increase in Renal Microcirculation in Healthy Participants

Mariëlle C Hendriks-Balk; Aikaterini Damianaki; Erietta Polychronopoulou; Wendy Brito; Menno Pruijm; Gregoire Wuerzner

doi:10.3389/fcvm.2022.899327

Contrast-Enhanced Ultrasonography Enables the Detection of a Cold Pressor Test-Induced Increase in Renal Microcirculation in Healthy Participants

Front Cardiovasc Med. 2022 May 20:9:899327. doi: 10.3389/fcvm.2022.899327. eCollection 2022.

Authors

Mariëlle C Hendriks-Balk¹, Aikaterini Damianaki¹, Erietta Polychronopoulou¹, Wendy Brito¹, Menno Pruijm¹, Gregoire Wuerzner¹

Affiliation

¹ Service of Nephrology and Hypertension, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.

Abstract

Background: Renal microcirculation is essential for regulation of the glomerular filtration rate, the reabsorption of salt and water from the interstitium, and hence the blood pressure. Renal ultrasonography coupled to Doppler analysis and contrast-enhanced ultrasound enables the study of renal perfusion. So far, physiologic interventions have rarely been performed to assess the renal perfusion. The objective of our study was to measure the renal perfusion in response to a cold pressor test (CPT).

Methods: Healthy adult participants were exposed to a 2 min CPT or a sham exposure (body temperature). Systemic hemodynamics, renal resistive index (RRI) and renal perfusion index (PI) were measured before and during the CPT or the sham exposure. Renal responses were compared using a paired Student's t-test or Wilcoxon signed rank test. Pearson correlation test was used to test association of variables of interest.

Results: Forty-one normotensive participants (21 women) were included in the study. Mean blood pressure and heart rate both increased with the CPT. The RRI decreased from 0.60 ± 0.05 arbitrary units (AU) to 0.58 ± 0.05 AU (p < 0.05) and the PI increased from 2,074 AU (1,358-3,346) to 3,800 AU (2,118-6,399) (p < 0.05) (+66% (24-106%)). Compared to the sham exposure, the increase in PI with the CPT was more marked. There was a negative association between the increase in heart rate and mean blood pressure with the RRI (r: -0.550, p = 0.002 and r: -0.395, P = 0.016), respectively.

Conclusion: Doppler Ultrasound and CEUS enable the detection of physiological changes within the macro- and microvascular renal circulation. The CPT decreases the RRI and increases the PI. Whether these changes are present in pathological states such as diabetes or hypertension will need additional studies.

Keywords: blood pressure; cold pressor test; contrast-enhanced ultrasound (CEUS); microcirculation; renal perfusion; renal resistive index (RRI).