The influence of upright posture on craniospinal, arteriovenous, and abdominal pressures in a chronic ovine in-vivo trial

Anthony Podgoršak; Nina Eva Trimmel; Markus Florian Oertel; Margarete Arras; Miriam Weisskopf; Marianne Schmid Daners

doi:10.1186/s12987-023-00485-6

The influence of upright posture on craniospinal, arteriovenous, and abdominal pressures in a chronic ovine in-vivo trial

Fluids Barriers CNS. 2023 Nov 9;20(1):83. doi: 10.1186/s12987-023-00485-6.

Authors

Anthony Podgoršak¹, Nina Eva Trimmel², Markus Florian Oertel³, Margarete Arras², Miriam Weisskopf², Marianne Schmid Daners⁴

Affiliations

¹ Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
² Center for Preclinical Development, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
³ Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
⁴ Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland. marischm@ethz.ch.

Abstract

Introduction: Most investigations into postural influences on craniospinal and adjacent physiology have been performed in anesthetized animals. A comprehensive study evaluating these physiologies while awake has yet been completed.

Methods: Six awake sheep had telemetric pressure sensors (100 Hz) implanted to measure intracranial, intrathecal, arterial, central venous, cranial, caudal, dorsal, and ventral intra-abdominal pressure (ICP, ITP, ABP, CVP, IAPcr, IAPcd, IAPds, IAPve, respectively). They were maneuvered upright by placing in a chair for two minutes; repeated 25 times over one month. Changes in mean and pulse pressure were calculated by comparing pre-chair, P0, with three phases during the maneuver: P1, chair entrance; P2, chair halftime; P3, prior to chair exit. Statistical significance (p ≤ .05) was assessed using repeated measures ANOVA.

Results: Significant mean pressure changes of (P1 - P0) and (P3 - P0) were measured at - 12.1 ± 3.1 and - 14.2 ± 3.0(p < .001), 40.8 ± 10.5 and 37.7 ± 3.5(p = .019), 9.7 ± 8.3 and 6.2 ± 5.3(p = .012), 22.3 ± 29.8 and 12.5 ± 12.1(p = .042), and 11.7 ± 3.9 and 9.0 ± 5.2(p = .014) mmHg, for ICP, ITP, IAPds, IAPcr, IAPca, respectively. For pulse pressures, significant changes of (P1 - P0) and (P3 - P0) were measured at - 1.3 ± 0.7 and - 2.0 ± 1.1(p < .001), 4.7 ± 2.3 and 1.4 ± 1.4(p < .001), 15.0 ± 10.2 and 7.3 ± 5.5(p < .001), - 0.7 ± 1.8 and - 1.7 ± 1.7(p < .001), - 1.3 ± 4.2 and - 1.4 ± 4.7(p = .006), and 0.3 ± 3.9 and - 1.0 ± 1.3(p < .001) mmHg, for ICP, ITP, ABP, IAPds, IAPcr, IAPca, respectively.

Conclusions: Pressures changed posture-dependently to differing extents. Changes were most pronounced immediately after entering upright posture (P1) and became less prominent over the chair duration (P2-to-P3), suggesting increased physiologic compensation. Dynamic changes in IAP varied across abdominal locations, motivating the abdominal cavity not to be considered as a unified entity, but sub-compartments with individual dynamics.

Keywords: Arterial blood pressure; Cerebrospinal fluid; Hydrocephalus; Intracranial pressure; Ovine model; Physiology.

Publication types

Clinical Trial, Veterinary

MeSH terms

Animals
Blood Pressure
Posture* / physiology
Sheep