1
|
Podgoršak A, Flürenbrock F, Trimmel NE, Korn L, Oertel MF, Stieglitz L, Fernandes Dias S, Hierweger MM, Zeilinger M, Weisskopf M, Schmid Daners M. Toward the "Perfect" Shunt: Historical Vignette, Current Efforts, and Future Directions. Adv Tech Stand Neurosurg 2024; 50:1-30. [PMID: 38592526 DOI: 10.1007/978-3-031-53578-9_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
As a concept, drainage of excess fluid volume in the cranium has been around for more than 1000 years. Starting with the original decompression-trepanation of Abulcasis to modern programmable shunt systems, to other nonshunt-based treatments such as endoscopic third ventriculostomy and choroid plexus cauterization, we have come far as a field. However, there are still fundamental limitations that shunts have yet to overcome: namely posture-induced over- and underdrainage, the continual need for valve opening pressure especially in pediatric cases, and the failure to reinstall physiologic intracranial pressure dynamics. However, there are groups worldwide, in the clinic, in industry, and in academia, that are trying to ameliorate the current state of the technology within hydrocephalus treatment. This chapter aims to provide a historical overview of hydrocephalus, current challenges in shunt design, what members of the community have done and continue to do to address these challenges, and finally, a definition of the "perfect" shunt is provided and how the authors are working toward it.
Collapse
Affiliation(s)
- Anthony Podgoršak
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Fabian Flürenbrock
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Nina Eva Trimmel
- Center for Preclinical Development, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Leonie Korn
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Markus Florian Oertel
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Lennart Stieglitz
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sandra Fernandes Dias
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Melanie Michaela Hierweger
- Center for Preclinical Development, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Melanie Zeilinger
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Miriam Weisskopf
- Center for Preclinical Development, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Marianne Schmid Daners
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
| |
Collapse
|
2
|
A mechatronic test-bench to investigate the impact of ventricular pulsation in hydrocephalus. Biomed Signal Process Control 2022. [DOI: 10.1016/j.bspc.2022.103579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
3
|
Podgoršak A, Trimmel NE, Oertel MF, Qvarlander S, Arras M, Eklund A, Weisskopf M, Schmid Daners M. Intercompartmental communication between the cerebrospinal and adjacent spaces during intrathecal infusions in an acute ovine in-vivo model. Fluids Barriers CNS 2022; 19:2. [PMID: 34983575 PMCID: PMC8725268 DOI: 10.1186/s12987-021-00300-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/19/2021] [Indexed: 12/22/2022] Open
Abstract
Introduction The treatment of hydrocephalus has been a topic of intense research ever since the first clinically successful use of a valved cerebrospinal fluid shunt 72 years ago. While ample studies elucidating different phenomena impacting this treatment exist, there are still gaps to be filled. Specifically, how intracranial, intrathecal, arterial, and venous pressures react and communicate with each other simultaneously. Methods An in-vivo sheep trial (n = 6) was conducted to evaluate and quantify the communication existing within the cranio-spinal, arterial, and venous systems (1 kHz sampling frequency). Standardized intrathecal infusion testing was performed using an automated infusion apparatus, including bolus and constant pressure infusions. Bolus infusions entailed six lumbar intrathecal infusions of 2 mL Ringer’s solution. Constant pressure infusions were comprised of six regulated pressure steps of 3.75 mmHg for periods of 7 min each. Mean pressure reactions, pulse amplitude reactions, and outflow resistance were calculated. Results All sheep showed intracranial pressure reactions to acute increases of intrathecal pressure, with four of six sheep showing clear cranio-spinal communication. During bolus infusions, the increases of mean pressure for intrathecal, intracranial, arterial, and venous pressure were 16.6 ± 0.9, 15.4 ± 0.8, 3.9 ± 0.8, and 0.1 ± 0.2 mmHg with corresponding pulse amplitude increases of 2.4 ± 0.3, 1.3 ± 0.3, 1.3 ± 0.3, and 0.2 ± 0.1 mmHg, respectively. During constant pressure infusions, mean increases from baseline were 14.6 ± 3.8, 15.5 ± 4.2, 4.2 ± 8.2, and 3.2 ± 2.4 mmHg with the corresponding pulse amplitude increases of 2.5 ± 3.6, 2.5 ± 3.0, 7.7 ± 4.3, and 0.7 ± 2.0 mmHg for intrathecal, intracranial, arterial, and venous pulse amplitude, respectively. Outflow resistances were calculated as 51.6 ± 7.8 and 77.8 ± 14.5 mmHg/mL/min for the bolus and constant pressure infusion methods, respectively—showing deviations between the two estimation methods. Conclusions Standardized infusion tests with multi-compartmental pressure recordings in sheep have helped capture distinct reactions between the intrathecal, intracranial, arterial, and venous systems. Volumetric pressure changes in the intrathecal space have been shown to propagate to the intraventricular and arterial systems in our sample, and to the venous side in individual cases. These results represent an important step into achieving a more complete quantitative understanding of how an acute rise in intrathecal pressure can propagate and influence other systems.
Collapse
Affiliation(s)
- Anthony Podgoršak
- Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Nina Eva Trimmel
- Division of Surgical Research, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Markus Florian Oertel
- Department of Neurosurgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sara Qvarlander
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umea University, Umeå, Sweden
| | - Margarete Arras
- Division of Surgical Research, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Anders Eklund
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umea University, Umeå, Sweden
| | - Miriam Weisskopf
- Division of Surgical Research, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | | |
Collapse
|
4
|
Huang AP, Kuo LT, Lai DM, Yang SH, Kuo MF. Antisiphon device: a review of existing mechanisms and clinical applications to prevent overdrainage in shunted hydrocephalic patients. Biomed J 2021; 45:95-108. [PMID: 34411787 PMCID: PMC9133390 DOI: 10.1016/j.bj.2021.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/01/2021] [Accepted: 08/06/2021] [Indexed: 11/25/2022] Open
Abstract
Overdrainage of cerebrospinal fluid is one of the most notorious complications after ventriculoperitoneal shunt implantation. Siphon effect plays a major role in the development of overdrainage. Various overdrainage-preventing devices have been invented to counteract the siphon effect. Though some of the devices are designed to reduce the flow instead of providing antisiphoning effect, they are generally called antisiphon devices (ASDs). The basics of siphoning, the mechanisms and physical properties of currently available devices are described in this article. The clinical efficacy, shunt survival, and considerations on patient factors are also discussed. There are three kinds of ASD design, diaphragm, gravitational, and flow reducing devices. Flow reducing ASD is always open and the flow it controls is relatively stable. On the other hand, it may not provide sufficient flow in nocturnal intracranial pressure elevations. Diaphragm and gravitational devices are sensitive to the position of the patients. Diaphragm device is sensitive to the external pressure and the relative position of the device to the mastoid process. The gravitational device is sensitive to the angle between the axis of the device and the head. Many studies showed encouraging results with gravitational devices. Studies regarding diaphragm devices either showed better or similar outcomes comparing to differential pressure valves. Clinical studies regarding flow-reducing devices and head-to-head comparison between different mechanisms are warranted. This review aims to provide a useful reference for clinical practice of hydrocephalus.
Collapse
Affiliation(s)
- An-Ping Huang
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Lu-Ting Kuo
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Dar-Ming Lai
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shih-Hung Yang
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Meng-Fai Kuo
- Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
| |
Collapse
|
5
|
Dual SA, Llerena Zambrano B, Sündermann S, Cesarovic N, Kron M, Magkoutas K, Hengsteler J, Falk V, Starck C, Meboldt M, Vörös J, Schmid Daners M. Continuous Heart Volume Monitoring by Fully Implantable Soft Strain Sensor. Adv Healthc Mater 2020; 9:e2000855. [PMID: 32893478 DOI: 10.1002/adhm.202000855] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/12/2020] [Indexed: 12/11/2022]
Abstract
Cardiothoracic open-heart surgery has revolutionized the treatment of cardiovascular disease, the leading cause of death worldwide. After the surgery, hemodynamic and volume management can be complicated, for example in case of vasoplegia after endocarditis. Timely treatment is crucial for outcomes. Currently, treatment decisions are made based on heart volume, which needs to be measured manually by the clinician each time using ultrasound. Alternatively, implantable sensors offer a real-time window into the dynamic function of our body. Here it is shown that a soft flexible sensor, made with biocompatible materials, implanted on the surface of the heart, can provide continuous information of the heart volume after surgery. The sensor works robustly for a period of two days on a tensile machine. The accuracy of measuring heart volume is improved compared to the clinical gold standard in vivo, with an error of 7.1 mL for the strain sensor versus impedance and 14.0 mL versus ultrasound. Implanting such a sensor would provide essential, continuous information on heart volume in the critical time following the surgery, allowing early identification of complications, facilitating treatment, and hence potentially improving patient outcome.
Collapse
Affiliation(s)
- Seraina A. Dual
- Product Development Group Zurich ETH Zurich Tannenstrasse 3 Zurich 8092 Switzerland
- Cardiothoracic Surgery Stanford University Stanford CA 94305‐5101 USA
| | - Byron Llerena Zambrano
- Laboratory of Biosensors and Bioelectronics ETH Zurich Gloriastrasse 35 Zurich 8092 Switzerland
| | - Simon Sündermann
- DZHK (German Center for Cardiovascular Research) Partner Site Berlin 10785 Berlin Germany
- Department of Cardiovascular Surgery Charité—Universitätsmedizin Berlin Charitéplatz 1 10117 Berlin Germany
- Department of Cardiothoracic and Vascular Surgery German Heart Center Berlin Augustenburger Pl. 1 13353 Berlin Germany
| | - Nikola Cesarovic
- Department of Cardiothoracic and Vascular Surgery German Heart Center Berlin Augustenburger Pl. 1 13353 Berlin Germany
- Department of Health Sciences and Technology Tannenstrasse 3 Zürich 8092 Switzerland
- Division for Surgical Research University Hospital Zurich and University of Zurich Rämistrasse 100 Zürich 8091 Switzerland
| | - Mareike Kron
- Division for Surgical Research University Hospital Zurich and University of Zurich Rämistrasse 100 Zürich 8091 Switzerland
| | | | - Julian Hengsteler
- Laboratory of Biosensors and Bioelectronics ETH Zurich Gloriastrasse 35 Zurich 8092 Switzerland
| | - Volkmar Falk
- DZHK (German Center for Cardiovascular Research) Partner Site Berlin 10785 Berlin Germany
- Department of Cardiovascular Surgery Charité—Universitätsmedizin Berlin Charitéplatz 1 10117 Berlin Germany
- Department of Cardiothoracic and Vascular Surgery German Heart Center Berlin Augustenburger Pl. 1 13353 Berlin Germany
- Department of Health Sciences and Technology Tannenstrasse 3 Zürich 8092 Switzerland
| | - Christoph Starck
- DZHK (German Center for Cardiovascular Research) Partner Site Berlin 10785 Berlin Germany
| | - Mirko Meboldt
- Product Development Group Zurich ETH Zurich Tannenstrasse 3 Zurich 8092 Switzerland
| | - János Vörös
- Laboratory of Biosensors and Bioelectronics ETH Zurich Gloriastrasse 35 Zurich 8092 Switzerland
| | | |
Collapse
|
6
|
Tachatos N, Chappel E, Dumont-Fillon D, Meboldt M, Daners MS. Posture related in-vitro characterization of a flow regulated MEMS CSF valve. Biomed Microdevices 2020; 22:21. [PMID: 32088807 DOI: 10.1007/s10544-020-0471-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Overdrainage in upright position is one of the most prevalent issues in treating hydrocephalus with a cerebrospinal fluid (CSF) shunt. Anti-siphon devices (ASDs) are employed to reduce this problem. A novel microelectromechanical system (MEMS)-based valve, termed Chronoflow device, aims to regulate CSF drainage indifferently of the body posture. With this study, the suitability of this MEMS-based valve is evaluated regarding its use for the treatment of hydrocephalus, particularly for the prevention of overdrainage and blockage. In total, four Chronoflow devices were tested. An established in-vitro hardware-in-the-loop (HIL) test bed was used to investigate the valves regarding their pressure-flow characteristics, their behaviors towards CSF dynamics, and their capabilities to prevent CSF overdrainage in upright position. Additionally, a contamination test was conducted to evaluate the susceptibility of the device to blockage due to particles. All valves tested regulated the drainage rate at similar nominal flows and independently of posture. The pressure-flow relation measured, however, was notably higher than numerically calculated. Regarding the CSF dynamics, the first three valves tested led to a decreased steady-state intracranial pressure in supine position and showed stable drainage rate in upright position. During the transitional phase from supine to upright and vice versa, the valves continuously adjusted the outflow resistance, which resulted in a stable transitional phase preventing overdrainage. Yet, the fourth valve showed continuous overdrainage in upright position due to an increased nominal flow. However, after several test iterations the nominal flow decreased and stabilized at a level similar to that of the first three valves tested. The contamination test showed that most particles initially adhere to the pillars and spread throughout the cavity of the valve as the concentration of particles increases, thereby affecting the displacement of the membrane. The devices generally provide a stable flow regulation and prevent overdrainage in upright position. Specifically, their drainage behaviors during the posture changes are very effective. However, they also showed high hysteresis and sensitivity towards particle contamination, which resulted in initial increased and altering nominal flows after many test iterations. This result suggests that the MEMS design presented lacks robustness. Yet, an upstream filter and specific coatings on the fluid pathway may increase significantly its reliability.
Collapse
Affiliation(s)
- Nikolaos Tachatos
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, CLA G 21.1, 8092, Zurich, Switzerland
| | | | | | - Mirko Meboldt
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, CLA G 21.1, 8092, Zurich, Switzerland
| | - Marianne Schmid Daners
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, CLA G 21.1, 8092, Zurich, Switzerland.
| |
Collapse
|
7
|
Batliner M, Weiss M, Dual SA, Grass B, Meboldt M, Schmid Daners M. Evaluation of a novel flow-controlled syringe infusion pump for precise and continuous drug delivery at low flow rates: a laboratory study. Anaesthesia 2019; 74:1425-1431. [PMID: 31373391 DOI: 10.1111/anae.14784] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2019] [Indexed: 12/25/2022]
Abstract
Syringe infusion pumps are used for the administration of short-acting drugs in anaesthesia and critical care medicine, but are prone to flow irregularities at low flow rates. A flow-controlled syringe infusion pump using an integrated flow sensor for feedback control represents a new approach to overcoming these limitations. This study compares the performance of a prototype flow-controlled syringe pump both at start-up, and during vertical displacement manoeuvres, with that of a standard infusion syringe pump. The novel pump almost completely eliminated delays at start-up and flow irregularities during hydrostatic pressure changes. Related fluctuations in plasma drug concentration were minimised and the known disadvantages of standard syringe infusion pumps currently used in clinical practice were reduced. Besides providing fast start-up to steady-state flow and precise continuous drug delivery at low flow rates during hydrostatic pressure changes, the new pump offers the potential for the development of target-controlled infusion algorithms for short-acting cardiovascular and other drugs.
Collapse
Affiliation(s)
- M Batliner
- Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - M Weiss
- Department of Anaesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - S A Dual
- Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - B Grass
- Department of Intensive Care and Neonatology, University Children's Hospital Zurich, Zurich, Switzerland
| | - M Meboldt
- Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| | - M Schmid Daners
- Product Development Group Zurich, ETH Zurich, Zurich, Switzerland
| |
Collapse
|
8
|
Gehlen M, Eklund A, Kurtcuoglu V, Malm J, Schmid Daners M. Comparison of anti-siphon devices-how do they affect CSF dynamics in supine and upright posture? Acta Neurochir (Wien) 2017; 159:1389-1397. [PMID: 28660395 DOI: 10.1007/s00701-017-3249-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/07/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Three different types of anti-siphon devices (ASDs) have been developed to counteract siphoning-induced overdrainage in upright posture. However, it is not known how the different ASDs affect CSF dynamics under the complex pressure environment seen in clinic due to postural changes. We investigated which ASDs can avoid overdrainage in upright posture best without leading to CSF accumulation. METHODS Three shunts each of the types Codman Hakim with SiphonGuard (flow-regulated), Miethke miniNAV with proSA (gravitational), and Medtronic Delta (membrane controlled) were tested. The shunts were compared on a novel in vitro setup that actively emulates the physiology of a shunted patient. This testing method allows determining the CSF drainage rates, resulting CSF volume, and intracranial pressure in the supine, sitting, and standing posture. RESULTS The flow-regulated ASDs avoided increased drainage by closing their primary flow path when drainage exceeded 1.39 ± 0.42 mL/min. However, with intraperitoneal pressure increased in standing posture, we observed reopening of the ASD in 3 out of 18 experiment repetitions. The adjustable gravitational ASDs allow independent opening pressures in horizontal and vertical orientation, but they did not provide constant drainage in upright posture (0.37 ± 0.03 mL/min and 0.26 ± 0.03 mL/min in sitting and standing posture, respectively). Consequently, adaptation to the individual patient is critical. The membrane-controlled ASDs stopped drainage in upright posture. This eliminates the risk of overdrainage, but leads to CSF accumulation up to the volume observed without shunting when the patient is upright. CONCLUSIONS While all tested ASDs reduced overdrainage, their actual performance will depend on a patient's specific needs because of the large variation in the way the ASDs influence CSF dynamics: while the flow-regulated shunts provide continuous drainage in upright posture, the gravitational ASDs allow and require additional adaptation, and the membrane-controlled ASDs show robust siphon prevention by a total stop of drainage.
Collapse
Affiliation(s)
- Manuel Gehlen
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
- The Interface Group, Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Anders Eklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Vartan Kurtcuoglu
- The Interface Group, Institute of Physiology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Jan Malm
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Marianne Schmid Daners
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, CLA G 21.1, 8092, Zürich, Switzerland.
| |
Collapse
|
9
|
Asgari M, de Zélicourt DA, Kurtcuoglu V. Barrier dysfunction or drainage reduction: differentiating causes of CSF protein increase. Fluids Barriers CNS 2017; 14:14. [PMID: 28521764 PMCID: PMC5437537 DOI: 10.1186/s12987-017-0063-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 05/09/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Cerebrospinal fluid (CSF) protein analysis is an important element in the diagnostic chain for various central nervous system (CNS) pathologies. Among multiple existing approaches to interpreting measured protein levels, the Reiber diagram is particularly robust with respect to physiologic inter-individual variability, as it uses multiple subject-specific anchoring values. Beyond reliable identification of abnormal protein levels, the Reiber diagram has the potential to elucidate their pathophysiologic origin. In particular, both reduction of CSF drainage from the cranio-spinal space as well as blood-CNS barrier dysfunction have been suggested ρas possible causes of increased concentration of blood-derived proteins. However, there is disagreement on which of the two is the true cause. METHODS We designed two computational models to investigate the mechanisms governing protein distribution in the spinal CSF. With a one-dimensional model, we evaluated the distribution of albumin and immunoglobulin G (IgG), accounting for protein transport rates across blood-CNS barriers, CSF dynamics (including both dispersion induced by CSF pulsations and advection by mean CSF flow) and CSF drainage. Dispersion coefficients were determined a priori by computing the axisymmetric three-dimensional CSF dynamics and solute transport in a representative segment of the spinal canal. RESULTS Our models reproduce the empirically determined hyperbolic relation between albumin and IgG quotients. They indicate that variation in CSF drainage would yield a linear rather than the expected hyperbolic profile. In contrast, modelled barrier dysfunction reproduces the experimentally observed relation. CONCLUSIONS High levels of albumin identified in the Reiber diagram are more likely to originate from a barrier dysfunction than from a reduction in CSF drainage. Our in silico experiments further support the hypothesis of decreasing spinal CSF drainage in rostro-caudal direction and emphasize the physiological importance of pulsation-driven dispersion for the transport of large molecules in the CSF.
Collapse
Affiliation(s)
- Mahdi Asgari
- The Interface Group, Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland
| | - Diane A de Zélicourt
- The Interface Group, Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Vartan Kurtcuoglu
- The Interface Group, Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland. .,Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland. .,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
10
|
Gehlen M, Kurtcuoglu V, Schmid Daners M. Is posture-related craniospinal compliance shift caused by jugular vein collapse? A theoretical analysis. Fluids Barriers CNS 2017; 14:5. [PMID: 28209177 PMCID: PMC5314698 DOI: 10.1186/s12987-017-0053-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 02/06/2017] [Indexed: 11/10/2022] Open
Abstract
Background Postural changes are related to changes in cerebrospinal fluid (CSF) dynamics. While sitting up leads to a decrease in cranial CSF pressure, it also causes shifts in the craniospinal CSF volume and compliance distribution. We hypothesized that jugular vein collapse in upright posture is a major contributor to these shifts in CSF volume and compliance. Methods To test this hypothesis, we implemented a mathematical lumped-parameter model of the CSF system and the relevant parts of the cardiovascular system. In this model, the CSF and the venous system are each divided into a cranial and a spinal part. The pressures in these cranial and spinal portions differ by the posture-dependent hydrostatic pressure columns in the connecting vessels. Jugular collapse is represented by a reduction of the hydrostatic pressure difference between cranial and spinal veins. The CSF pressure–volume relationship is implemented as a function of the local CSF to venous pressure gradient. This implies that an increase in CSF volume leads to a simultaneous displacement of blood from adjacent veins. CSF pulsations driven by the cardiovascular system are introduced through a pulsating cranial arterial volume. Results In upright posture, the implemented CSF pressure–volume relationship shifts to lower cranial CSF pressures compared to the horizontal position, leading to a decrease in cranial CSF pressure when sitting up. Concurrently, the compliance of the spinal compartment decreases while the one of the cranial compartment increases. With this, in upright posture only 10% of the CSF system’s compliance is provided by the spinal compartment compared to 35% in horizontal posture. This reduction in spinal compliance is accompanied by a caudal shift of CSF volume. Also, the ability of the spinal CSF compartment to compensate for cerebral arterial volume pulsations reduces in upright posture, which in turn reduces the calculated craniospinal CSF flow pulsations. Conclusion The mathematical model enabled us to isolate the effect of jugular collapse and quantify the induced shifts of compliance and CSF volume. The good concordance of the modelled changes with clinically observed values indicates that jugular collapse can be considered a major contributor to CSF dynamics in upright posture.
Collapse
Affiliation(s)
- Manuel Gehlen
- Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland. .,The Interface Group, Institute of Physiology, University of Zurich, Zurich, Switzerland.
| | - Vartan Kurtcuoglu
- The Interface Group, Institute of Physiology, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, and the Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Marianne Schmid Daners
- Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| |
Collapse
|