Biology subjects

Faryami, A.

Publications and source records attributed to Faryami, A..

4 recordsLinked to original sources

bioRxiv2022

The Development and Validation of a Portable, Benchtop, Hydrostatic Model to Acquire and Analyze Quantitative Data on Unused and Failed Hydrocephalus Catheters

IntroductionDespite the prevalence of shunt failure in the treatment of hydrocephalus and the near-constant need for shunt revisions, there are a limited number of methods that yield quick, quantifiable measures of catheter obstruction. We developed and assessed a gravity-driven device that measures flow through ventricular catheters. The model provides neurosurgeons with a quick, simple device that can send useful data to researchers. It can also be used by researchers to quantitatively compare catheter obstruction between different models of catheters. The model was used in this study to quantitatively analyze unused ventricular catheters used in the treatment of hydrocephalus; failed hydrocephalus catheters from our catheter biorepository were also quantitatively analyzed using the same device. The mechanisms of catheter obstruction are still poorly understood, but the literature suggests that resistance to fluid flow plays a significant role. MethodsCatheters of three manufacturing companies were inserted into the benchtop model, which records time, flow rate, and pressure data using sensors. The relative resistances of catheters across six design models were evaluated. Experiments were performed to evaluate changes in the relative resistance of a catheter when the catheters holes were progressively closed. Relative resistance of explanted catheters from our catheter biorepository was also measured. ResultsExperimental results showed significant differences (P < 0.05) between the relative resistances of different catheter models just after being removed from their packaging. Furthermore, a trend of increasing resistance was observed in the experiments on catheters with manually plugged ventricular catheter holes. Data from five individual benchtop models were compared, and the differences in measured data between the models were found to be negligible. A significant increase (P < 0.05) in relative resistance was observed in explanted catheters. ConclusionThe current study is meant both to validate the proposed model and to examine data on differences in relative resistance among catheter models. From these experiments, we can rapidly correlate clinical patient cohorts to identify mechanisms of luminal shunt obstruction. Collecting data for predictive analyses of potential patient outcomes is an area of potential future work, assuming sufficient sample size.

bioengineering↗

bioRxiv2022

Applications of a Novel Reciprocating Positive Displacement Pump in the Simulation of Pulsatile Arterial Blood Flow

Pulsatile arterial blood flow plays an important role in vascular system mechanobiology, especially in the study of mechanisms of pathology. Limitations in cost, setup time, sample size, and control across current in-vitro and in-vivo methods prevent future exploration of novel treatments. Presented is the verification of a novel reciprocating positive displacement pump aimed at resolving these issues through the simulation of human ocular, human fingertip and skin surface, human cerebral, and rodent spleen organ systems. A range of pulsatile amplitudes, frequencies, and flow rates were simulated using pumps made of 3D printed parts incorporating a tubing system, check valve and proprietary software. Volumetric analysis of 430 total readings across a flow range of 0.025ml/min to 16ml/min determined that the pump had a mean absolute error and mean relative error of 0.041 ml/min and 1.385%, respectively. Linear regression of flow rate ranges yielded R2 between 0.9987 and 0.9998. Waveform analysis indicated that the pump could recreate accurate beat frequency for flow ranges above 0.06ml/min at 70BPM. The verification of accurate pump output opens avenues for the development of novel long-term in-vitro benchtop models capable of looking at fluid flow scenarios previously unfeasible, including low volume-high shear rate pulsatile flow.

bioengineering↗

bioRxiv2021

Testing and Validation of Reciprocating Positive Displacement Pump for Benchtop Pulsating Flow Model of Cerebrospinal Fluid Production and Other Physiologic Systems

BackgroundThe flow of physiologic fluids through organs and organs systems is an integral component of their function. The complex fluid dynamics in many organ systems are still not completely understood, and in-vivo measurements of flow rates and pressure provide a testament to the complexity of each flow system. Variability in in-vivo measurements and the lack of control over flow characteristics leave a lot to be desired for testing and evaluation of current modes of treatments as well as future innovations. In-vitro models are particularly ideal for studying neurological conditions such as hydrocephalus due to their complex pathophysiology and interactions with therapeutic measures. The following aims to present the reciprocating positive displacement pump, capable of inducing pulsating flow of a defined volume at a controlled beat rate and amplitude. While the other fluidic applications of the pump are currently under investigation, this study was focused on simulating the pulsating cerebrospinal fluid production across profiles with varying parameters. MethodsPumps were manufactured using 3D printed and injection molded parts. The pumps were powered by an Arduino-based board and proprietary software that controls the linear motion of the pumps to achieve the specified output rate at the desired pulsation rate and amplitude. A range of [Formula] to [Formula] was tested to evaluate the versatility of the pumps. The accuracy and precision of the pumps output were evaluated by obtaining a total of 150 one-minute weight measurements of degassed deionized water per output rate across 15 pump channels. In addition, nine experiments were performed to evaluate the pumps control over pulsation rate and amplitude. Resultsvolumetric analysis of a total of 1200 readings determined that the pumps achieved the target output volume rate with a mean absolute error of -0.001034283 [Formula] across the specified domain. It was also determined that the pumps can maintain pulsatile flow at a user-specified beat rate and amplitude. ConclusionThe validation of this reciprocating positive displacement pump system allows for the future validation of novel designs to components used to treat hydrocephalus and other physiologic models involving pulsatile flow. Based on the promising results of these experiments at simulating pulsatile CSF flow, a benchtop model of human CSF production and distribution could be achieved through the incorporation of a chamber system and a compliance component.

bioengineering↗

bioRxiv2020

Open-source 3D printed Ventilation Device

COVID-19 is an acute respiratory tract infection caused by a coronavirus known as SARS-CoV-2. The common signs of infection include respiratory symptoms such as shortness of breath, breathing difficulties, dry cough, fever, and in some patients, severe acute respiratory syndrome, kidney failure, and death. 312,009 deaths from COVID-19 has been reported as of today. While respiratory symptoms are commonly caused by the infection, the use of mechanical ventilation is required for some patients. The following is intended to review the development and testing of a 3D printed and open-source mechanical ventilation device that is capable of adjusting breathing rate, volume, and pressure simultaneously and was designed according to the latest clinical observations of the current pandemic. The intuitive design of this device along with the use of primarily 3D printed or readily available components allow the rapid manufacturing and transportation of this ventilation device to the impacted regions.

bioengineering↗