The influence of upright posture on craniospinal, arteriovenous, and abdominal pressures in a chronic ovine in-vivo trial
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. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000641250Publication status
publishedExternal links
Journal / series
Fluids and Barriers of the CNSVolume
Pages / Article No.
Publisher
BioMed CentralSubject
Arterial blood pressure; Cerebrospinal fluid; Hydrocephalus; Intracranial pressure; Ovine model; PhysiologyOrganisational unit
03943 - Meboldt, Mirko / Meboldt, Mirko
09563 - Zeilinger, Melanie / Zeilinger, Melanie
Funding
184913 - Quantitative study on the pathophysiology of hydrocephalus (SNF)
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