Name: maintenance of a lateral fluid percussion injury device
Uploaded: 2023-04-21T14:10:00
Description: Watch this Scientific Journal Video about Maintenance of a Lateral Fluid Percussion Injury Device at JoVE.com

The authors would like to thank Custom Design &#38; Fabrication Inc. for their technical assistance and support. This work was funded by the National Institutes of Health grants R01NS120099-01A1 and R37HD059288-19.

1. Cleaning the LFPI cylinder
<ol>
	<li>Carefully detach the syringes attached to the transducer housing and fill port, as well as the cable connected to the pressure transducer (see Figure 1 for a schematic of injury device components).</li>
	<li>While being careful not to drop the cylinder, unscrew the hand knobs at the back of the device from the cylinder clamps to free the cylinder.</li>
	<li>Remove the piston at the end of the cylinder, transducer, transducer housing,...

<ol>
	<li>Centers for Disease Control and Prevention. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surveillance+Report+of+Traumatic+Brain+Injury-related+Emergency+Department+Visits,+Hospitalizations,+and+Deaths.">Surveillance Report of Traumatic Brain Injury-related Emergency Department Visits, Hospitalizations, and Deaths.</a> Centers for Disease Control and Prevention, U.S. Department of Health and Human Services. , (2014).</li><li>Dewan, M. 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J., Borg, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Summary+of+the+WHO+Collaborating+Centre+for+neurotrauma+task+force+on+mild+traumatic+brain+injury.">Summary of the WHO Collaborating Centre for neurotrauma task force on mild traumatic brain injury.</a> Journal of Rehabilitation Medicine. 37 (3), 137-141 (2005).</li><li>Pavlovic, D., Pekic, S., Stojanovic, M., Popovic, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traumatic+brain+injury:+neuropathological,+neurocognitive+and+neurobehavioral+sequelae.">Traumatic brain injury: neuropathological, neurocognitive and neurobehavioral sequelae.</a> Pituitary. 22 (3), 270-282 (2019).</li><li>Dixon, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+fluid+percussion+model+of+experimental+brain+injury+in+the+rat.">A fluid percussion model of experimental brain injury in the rat.</a> Journal of Neurosurgery. 67 (1), 110-119 (1987).</li><li>McIntosh, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traumatic+brain+injury+in+the+rat:+characterization+of+a+lateral+fluid-percussion+model.">Traumatic brain injury in the rat: characterization of a lateral fluid-percussion model.</a> Neuroscience. 28 (1), 233-244 (1989).</li><li>Ma, X., Aravind, A., Pfister, B. 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The techniques outlined above demonstrate how to properly maintain an LFPI device. Routine cleaning and monitoring are necessary to keep the LFPI device functioning correctly and reliably. Additionally, due to the invasive nature of the LFPI procedure, it is imperative that the device be cleaned thoroughly to prevent infection of laboratory animals. 
Avoiding the formation of air bubbles in the device is crucial for obtaining optimal injuries and pressure waveforms. Air bubbles alter the chara...

Traumatic brain injury (TBI) is caused by a sudden force applied to the head. Following primary injuries resulting from the physical impact, TBI survivors commonly experience secondary injuries, including cognitive deficits and neurological dysfunctions that are associated with physiological responses to the initial injury1. It is estimated that roughly 69 million individuals worldwide suffer from TBI annually2. In the United States alone, approximately 2.5 million TBI-related emergency room visits and hospitalizations occur each year, making TBI one of the leading causes of disability and death among children and young adults3. TBI can be classified as mild, moderate, or severe, with mild TBI (mTBI) accounting for approximately 70%-90% of TBI cases4. Histological and cognitive TBI pathology can occur within minutes to hours of injury, and the effects of TBI can persist for months to years after initial damage5.
The development of experimental models has been instrumental in understanding the effects and underlying mechanisms of TBI. One such model, the lateral fluid percussion injury (LFPI), is commonly used to assess TBI in vivo. LFPI closely reproduces pathologies associated with human TBI, including vascular disruptions, hemorrhages, neuronal loss, inflammation, gliosis, and molecular disturbances6,7,8. The LFPI technique is used for a diverse set of experimental applications, including modeling pediatric TBI, as well as chronic neurodegenerative conditions, such as chronic traumatic encephalopathy9,10. LFPI is a well-defined and reproducible method of experimental TBI that allows for the severity of the injury to be adjusted11. The LFPI device has several important components, including: a pendulum with a weighted hammer, a piston, a fluid-filled cylinder, a pressure transducer, a digital oscilloscope, and a small tube at the end of the cylinder with a Luer lock which attaches to a hub on the animal&#39;s skull (Figure 1). LFPI works by swinging the pendulum into the piston, creating a wave of pressure through the fluid (degassed deionized water or saline) into the brain of the attached animal; this increases intracranial pressure, thus replicating the mechanical features and biological changes of TBI12. Additionally, animals used in LFPI experiments undergo a craniectomy in order to expose the brain to the impact of the fluid pressure of the device.
Routine maintenance and monitoring are necessary to ensure that the LFPI device is accurately functioning. The following methods are vital in preventing the introduction of contaminating air bubbles into the device. Here, we demonstrate methods to properly clean, fill, and assemble the LFPI device. We will also discuss oscilloscope outputs and mouse righting times as ways to confirm the viability of the LFPI.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2 - 10 mL syringes with Luer lock capability</td>
			<td></td>
			<td></td>
			<td>Ensures that needle is secure and reduces possible leaks of fluid&#160;</td>
		</tr>
		<tr>
			<td>Degassed fluid</td>
			<td></td>
			<td></td>
			<td>Helps to reduce air bubble formation during injury procedure</td>
		</tr>
		<tr>
			<td>Fluid Percussion Injury (FPI) device (Model 01-B)</td>
			<td>Custom Designs &#38; Fabrications Inc.</td>
			<td>N/A</td>
			<td>Injury device used to model TBI in rodents</td>
		</tr>
		<tr>
			<td>Mild detergent</td>
			<td></td>
			<td></td>
			<td>Allows to thoroughly clean the LFPI cylinder&#160;</td>
		</tr>
		<tr>
			<td>Petroleum Jelly</td>
			<td></td>
			<td></td>
			<td>Used as a water-repellent and protects LFPI device form rust</td>
		</tr>
		<tr>
			<td>Teflon tape</td>
			<td></td>
			<td></td>
			<td>Helps with tight seal of pipe joints on the LFPI device</td>
		</tr>
		<tr>
			<td>*Materials other than the LFPI device can be purchased from any reliable company.</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

maintenance of a lateral fluid percussion injury device

Traumatic brain injury (TBI) accounts for roughly 2.5 million emergency room visits and hospitalizations annually and is a leading cause of death and disability in children and young adults. TBI is caused by a sudden force applied to the head and, to better understand human TBI and its underlying mechanisms, experimental injury models are necessary. Lateral fluid percussion injury (LFPI) is a commonly used injury model due to similarities in the pathological changes found in human TBI compared to LFPI, including hemorrhages, vascular disruption, neurological deficits, and neuron loss. LFPI employs a pendulum and a fluid-filled cylinder, the latter having a moveable piston at one end, and a Luer lock connection to stiff, fluid-filled tubing at the other end. Preparation of the animal involves performing a craniectomy and attaching a Luer hub over the site. The next day, the tubing from the injury device is connected to the Luer hub on the animal's skull and the pendulum is raised to a specified height and released. The impact of the pendulum with the piston generates a pressure pulse which is transmitted to the intact dura mater of the animal via the tubing and produces the experimental TBI. Proper care and maintenance are essential for the LFPI device to function reliably, as the character and severity of the injury can vary greatly depending on the condition of the device. Here, we demonstrate how to properly clean, fill, and assemble the LFPI device, and ensure that it is adequately maintained for optimal results.

We tested the effects of air bubble contamination in an LFPI device on waveform formation. We injected air bubbles into the device and compared the oscilloscope outputs with oscilloscope data collected from a non-contaminated LFPI device. Conditions were as follows: non-contaminated, injection of 5 mL of air, injection of 10 mL of air, and injection of 15 mL of air. We kept the pendulum at a consistent height for all impacts for all conditions, and we performed 15 impacts per condition.
When p...

Watch this Scientific Journal Video about Maintenance of a Lateral Fluid Percussion Injury Device at JoVE.com

Maintenance of a Lateral Fluid Percussion Injury Device

Proper care and maintenance are essential for a lateral fluid percussion injury (LFPI) device to function reliably. Here, we demonstrate how to properly clean, fill, and assemble an LFPI device, and ensure that it is adequately maintained for optimal results.

Traumatic brain injury (TBI) accounts for roughly 2.5 million emergency room visits and hospitalizations annually and is a leading cause of death and ...

Our protocol demonstrates how to maintain the LFPI device properly. It highlights the importance of routine cleaning and monitoring to avoid malfunctioning of the device in inconsistent injuries. So LFPI is an injury model used to assess TBI in vivo.It closely reproduces pathologies that are associated with human TBI, thus making it one of the most well-defined methods of experimental TBI. Given that the LFPI is used to reproduce human TBI symptoms, it allows us to set up experiments that investigate different aspects of traumatic brain injuries in the hope of finding therapeutic measures. Air bubbles in the fill port or transducer are particularly difficult to remove due to the limited visibility in those areas.When filling those areas, be patient, slow, and careful not to introduce air. To begin, carefully detach the syringes attached to the transducer housing and fill port and the cable connected to the pressure transducer. Unscrew the hand knobs at the back of the device from the cylinder clamps to free the cylinder.Remove the piston at the end of the cylinder, transducer, transducer housing, and plunger O-rings. Drain fluid out of the cylinder, add a mild detergent such as dishwashing detergent to the cylinder, and scrub lightly using a dish or bottle brush. To ensure that all the detergent is rinsed off completely, fill the cylinder with water and rinse thoroughly.Apply a thin layer of petroleum jelly to the piston plunger and attach the piston plunger with the plunger protruding approximately 32 millimeters from the cylinder. Apply a thin layer of petroleum jelly to the other O-rings as well and attach them to the cylinder except for the O-ring on the fill port. Wrap Teflon tape twice around the transducer's threads.Connect a 10-milliliter syringe filled with degassed fluid and free of air bubbles to the Luer lock hub on the transducer housing. Hold the transducer with the threaded end pointing upward and completely fill the well inside the threaded region of the transducer with the degassed fluid. The goal here is to fill the transducer well without introducing any air bubbles.Be careful not to damage the delicate membrane at the bottom of the well. With the cylinder placed at an angle to prevent air from reentering the transducer housing, attach the transducer housing to the cylinder and use a wrench to tighten it snugly. Remove the cap from the fill port and cylinder once the degassed fluid reaches approximately two-thirds of the cylinder capacity.Place the cylinder horizontally and finish filling the cylinder with degassed fluid. Replace the cap at the fill port and close all stopcocks. Manipulate the cylinder to work any air bubbles to the fill port.Open the stopcock on the fill port and inject fluid using the syringe on the transducer housing to force any air bubbles out of the port. Inspect the entire device and ensure that there are no air bubbles. Add a 10-milliliter syringe filled with degassed fluid to the Luer lock hub on the fill cap and reattach the cylinder to the base using the hand screws.Ensure that the cylinder is horizontal and lined up with the center of the weighted hammer on the pendulum. The image of the pressure waveform produced by a properly cleaned and functioning LFPI device is shown in this figure. When performing an injury or testing the LFPI device, the pressure waveform should show a single sharp peak.The presence of air bubbles in the device will result in a waveform with several short peaks. The oscilloscope outputs for the noncontaminated, 5 milliliter of air injection, 10 milliliter of air injection, and 15 milliliter of air injection are shown here. The techniques shown in this video reduce the likelihood of gases being introduced into the device and help remove any small pockets of gas that may be contaminating the fluid.Therefore, removing air bubbles is the most crucial step to remember when using the LFPI device. So after this procedure, our lab is able to induce injuries in mice and use live brain slices in order to record neuronal activity. You can actually find one of our videos on this on JoVE's website.This device has been a game changer in the world of TBI. It is currently the most widely used method to induce injury in animal models and has paved the way to find better therapeutics for human TBI.

Research

JoVE Journal

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