Name: measurement of the hepatic venous pressure gradient and transjugular liver biopsy
Uploaded: 2020-06-18T12:30:00
Description: Watch this Scientific Journal Video about Measurement of the Hepatic Venous Pressure Gradient and Transjugular Liver Biopsy at JoVE.com

The Vienna General Hospital and the Medical University of Vienna kindly provides the infrastructure for the Vienna Hepatic Hemodynamic Laboratory. Previous members of the Vienna Hepatic Hemodynamic Laboratory and coworkers should be acknoweledged for their valuable input that helped to continuously improve the methodology of HVPG measurement and transjugular liver biopsy at our institution. In addition, we thank the nurses of the Division of Gastroenterology and Hepatology who are an essential part of the Vienna Hemodynamic Laboratory and continuously provide patients with excellent care.

The protocol described here complies with the guidelines of the human research ethics committee of the Medical University of Vienna.
1. Preparations
<ol>
	<li>Use a specialized room dedicated/approved for procedures using x-ray equipped with a digital x-ray fluoroscopy&#160;system (Figure 1A), a monitor system (Figure 1B), a pressure recorder and transducer (Figure 1<st...

While HVPG measurements require considerable resources and trained personal with interventional skills and expertise in the reading of pressure tracings, it improves prognostication and might guide treatment decisions, and thus, facilitates personalized medicine. In addition, the opportunity to safely obtain liver biopsy specimens via the transjugular route in the same session is another argument in favor of implementing hepatic hemodynamic laboratories at tertiary care centers. Indeed, guidelines support the use of HVPG...

Patients with cirrhosis are at risk for developing complications mostly related to portal hypertension (PHT), such as ascites or bleeding from gastric or esophageal varices1,2,3. The risk of hepatic decompensation is related to the degree of PHT2. Measurement of the hepatic venous pressure gradient (HVPG) is the gold standard to estimate portal venous pressure in patient with cirrhosis, i.e. assessing the severity of sinusoidal&#160;portal hypertension4. An HVPG of &#8805;6 mm Hg to 9 mm Hg indicates elevated portal pressure (&#39;subclinical portal hypertension&#39;), while an HVPG &#8805;10 mm Hg defines CSPH. This protocol provides a detailed description of the equipment and the procedure and also highlights potential pitfalls and offers advice for troubleshooting.
Clinically, measurement of HVPG is indicated (i) to establish the diagnosis of sinusoidal&#160;portal hypertension, (ii) to identify patients at risk for hepatic decompensation by diagnosing CSPH (HVPG &#8805;10 mm Hg), (iii) to guide pharmacological therapy in primary or secondary prophylaxis of variceal bleeding, and (iv) to assess the risk of hepatic failure after partial hepatectomy2,4. HVPG is used as an established surrogate marker for improvement and/or worsening of liver fibrosis/function, since a decrease in HVPG translates into a clinically meaningful benefit5, whereas higher HVPG values are associated with an increased variceal bleeding risk6. Based on observations on changes in HVPG in patients under non-selective beta-blocker (NSBB) or etiological therapies, a decrease in HVPG of 10% is considered to be clinically relevant7,8.
To date, there are no alternative, non-invasive parameters reflecting the degree of portal pressure with similar accuracy as HVPG. Even if HVPG is actually an &#8216;indirect&#8217; way to measure portal pressure, it strongly correlates and thus accurately reflects &#8216;directly&#8217; measured portal pressure in patients with cirrhosis9. Importantly, HVPG measurements should be performed using a balloon catheter to maximize the assessed amount of liver parenchyma10,11,12. Although HVPG measurements are invasive, resource-intensive, and require interventional skills and expertise in interpreting the reliability and plausibility of pressure readings, this method is the current gold standard for diagnosing and monitoring portal hypertension in patients with cirrhosis13,14,15.
Simple laboratory values, such as platelet count, may help to estimate the likelihood for CSPH. However, platelet count, or non-invasive scores that include platelet count, have limited predictive value16. Imaging modalities showing splenomegaly17 or portosystemic collaterals18 in patients with cirrhosis suggest the presence of CSPH, but are not helpful for quantifying the actual degree of portal hypertension. Novel non-invasive imaging tools, such as elastography of the liver19 and/or of the spleen20 are useful for ruling-in or ruling-out the presence of CSPH. Still, none of the available methods is able to directly measure dynamic changes in portal pressure21.
The prognostic value of HVPG has been underlined by several landmark studies, showing that a HVPG &#8805;10 mm Hg (i.e. CSPH) is predictive for the formation of varices8 (and for the development of complications related to portal hypertension22, while a (pharmacologically-induced) decrease of HVPG modulates the respective risk of variceal growth23 and decompensation7. HVPG-response is the only established surrogate for the effectiveness of NSBBs in preventing (recurrent) variceal bleeding. If HVPG decreases to a value of &#8804;12 mm Hg or is reduced by &#8805;10-20% during NSBB treatment, patients are protected from variceal bleeding and survival is increased24,25. Similarly, HVPG-response also decreases the incidence of ascites and related complications in patients with compensated cirrhosis5,26. Several studies have provided evidence supporting the use of HVPG-guided therapy27,28,29,30,31,32. Thus, in centers with sufficient experience, HVPG-response may&#160;guide treatment decisions, facilitating personalized medicine for patients with portal hypertension.
Moreover, measuring of HVPG might serve as a surrogate endpoint for proof-of-concept studies assessing the effectiveness of novel treatments for cirrhosis and/or portal hypertension being translated from bench to bedside, such as sorafenib33,34, simvastatin35,36, taurine37, or emricasan38. Ultimately, measurements of HVPG can also provide important prognostic information about the risk for development of HCC39 and for liver failure post hepatic resection40.
The infrastructure to measure HVPG should be readily available at secondary and tertiary care centers. Since the technique of HVPG measurement requires specialized training and equipment, it seems rational for academic and transplant centers to establish a hepatic hemodynamic laboratory, facilitating state-of-the-art diagnosis and management of portal hypertension. Large volume centers perform several hundred HVPG measurements per year. Based on our experience, sufficient expertise to perform accurate HVPG measurements is usually obtained after 50-100 supervised HVPG measurements.

<table border="0" cellpadding="0" cellspacing="0" style="width:1628px;" width="1627">
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		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:315px;">10 mL Luer-Lock syringe</td>
			<td style="width:335px;">Braun</td>
			<td style="width:317px;">REF 4617100V, LOT 17G03C8</td>
			<td style="width:661px;">Luer-Lock Syringe for connection with the aspiration biopsy set</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10 mL Syringe 2x</td>
			<td>Braun</td>
			<td style="width:317px;">REF 4606108V</td>
			<td>Snonpyrogenic, nontoxic 10 mL syringe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10 F liver biopsy&#160; introducer sheath set</td>
			<td>Cook Medical</td>
			<td style="width:317px;">REF RCFW-10.0-38, REF G07600</td>
			<td>Percutaneous Sheath Introducer Set (TJBX), 10F Port, 13cm, Check-Flo Performer Introducer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">18 G needle for biopsy introducer sheat</td>
			<td>Arrow International</td>
			<td style="width:317px;">REF AN-04318</td>
			<td>Introducer Needle for TJBX Set, 18 G, 6.35 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">21 G needle</td>
			<td>Henke Sass Wolf</td>
			<td style="width:317px;">REF 0086, Fine-Ject 21Gx2&#34;</td>
			<td>Sterile injeciton needle, 21 Gx2&#34;, 0.8 x 50 mm, for local anesthesia</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3-way channels</td>
			<td>Becton Dickinson</td>
			<td style="width:317px;">BD Connecta Luer-Lok, REF 39402</td>
			<td>Three way channel with Luer-Lok connection system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">7.5 F catheter introducer sheath set</td>
			<td>Arrow International</td>
			<td style="width:317px;">REF SI_09875-E</td>
			<td>Percutaneous Sheath Introducer Set, 7.5 F Port</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Aspiration TJLBX set</td>
			<td>Cook Medical</td>
			<td style="width:317px;">REF RMT-16-51.0-TJL, REF G20521</td>
			<td>TJ Liver Access and Biopsy Needle Set (Aspiration Set), 9 F-45 cm, 16 G-50.5 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Balloon catheter</td>
			<td>Gerhard Pejcl Medizintechnik Austria</td>
			<td style="width:317px;">REF 500765B</td>
			<td>Ferlitsch HVPG Catheter, 7F-65cm, Balloon:2.5mL, Pressure 50-90 kPa, GW: 0.032&#34;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blade 11 scalpel</td>
			<td>Medi-Safe Surgicals</td>
			<td style="width:317px;">MS Safety Scalpel REF /Batch 18012424</td>
			<td>11 blade safety scalpels, retractable, single use, 10 scalpels per package</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blunt tip fill needle</td>
			<td>Becton Dickinson</td>
			<td style="width:317px;">REF 303129</td>
			<td>Sterile blunt tip fill needle, single use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Contrast media (dye)</td>
			<td>Dr. Franz K&#246;hler Chemie GmbH, Bensheim, GER</td>
			<td style="width:317px;">ZNR 1-24112</td>
			<td>Peritrast 300 mg Iod/mL, 50 mL, contrastmedia</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Core TJLBX set</td>
			<td>Cook Medical</td>
			<td style="width:317px;">REF RMT-14XT-50.5-LABS-100, REF G08285</td>
			<td>TJ Needle Introducer and Bx-Needle 7 F-53.5 cm, 14 G-53.5 cm/20 mm, 18 G-60 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digital x-ray fluoroscope system</td>
			<td>Siemens</td>
			<td style="width:317px;">Model No 07721710</td>
			<td>ARCADIS Varic, mobile x-ray fluoroscope system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Disinfectant solution</td>
			<td>Gebro Pharma</td>
			<td style="width:317px;">1-20413</td>
			<td>Isozid-H</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Face mask</td>
			<td>MSP Medizintechnik GmbH</td>
			<td style="width:317px;">REF HSO36984</td>
			<td>Surgical face mask from double fleece, with tie, 50 pieces</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Guide wire for biopsy introducer sheat</td>
			<td>Arrow International</td>
			<td style="width:317px;">REF AW-14732</td>
			<td>Marked Spring-Wire Guide, TJBX Set, 0.032&#34;, 0.81 mm, 68 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Infusion line</td>
			<td>Rosstec Medical Products b Cardea GmbH &#38; Co</td>
			<td style="width:317px;">REF 220010, 100m</td>
			<td>Infusion line, Luer-Lok for connection of balloon catheter and pressure transducer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lidocaine 2%</td>
			<td>Gebro Pharma</td>
			<td style="width:317px;">Xylanaest, ZNR 17.792, 20mg/1mL (2%)</td>
			<td>Sterile vials Xylanest including 2% Lidocain hydrochloride for local anesthesia</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Midazolame</td>
			<td>Roche</td>
			<td style="width:317px;">Dormicum, ZNr 1-18809, Midazolam 5mg/5mL</td>
			<td>Sterile vials Dormicum including Midazolam for sedation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Monitor system</td>
			<td>Datex-Ohmeda by GE</td>
			<td style="width:317px;">Type F-CMREC1</td>
			<td>Patient monitoring system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Patient bench</td>
			<td>Silerlen-MAQET</td>
			<td style="width:317px;">Model No 7474.00A</td>
			<td>Mobile patient bench for x-ray fluoroscopy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pressure bag</td>
			<td>Ethox Corp</td>
			<td style="width:317px;">REF 4005</td>
			<td>Pressure Infuser Bag 500 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pressure recorder</td>
			<td>Edwards Lifesciences</td>
			<td style="width:317px;">Ref T001631A, Lot 61202039</td>
			<td>TruWave 3 cc/150 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pressure transducer</td>
			<td>Edwards Lifesciences TM</td>
			<td style="width:317px;">REF T001631A</td>
			<td>Pressure Monitoring Set (1x), 3 cc/150 cm, TruWave TM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Recording software&#160;</td>
			<td>Datex Ohmeda by GE</td>
			<td style="width:317px;">Software S/5 is property of Instrumentarium Corp of Datex-Ohmeda TM</td>
			<td>Datex-Ohmeda S/5TM Collect - Software to record pressure tracings of the patient monitor system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile coat</td>
			<td>Lohmann &#38; Rauscher International GmbH &#38; Co</td>
			<td style="width:317px;">REF 19351</td>
			<td>Surgical Gown, Different sizes, e.g. L-130 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile gauze</td>
			<td>Hartmann</td>
			<td style="width:317px;">REF 401798, 10x10cm gauze</td>
			<td>10 x 10 cm sterile gauze, 10 pieces per package</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile gloves</td>
			<td>Meditrade</td>
			<td style="width:317px;">REF 9021</td>
			<td>Gentle Skin sterile gloves, different sizes, e.g. 7.5</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile saline solution</td>
			<td>Fresenius Kabi</td>
			<td style="width:317px;">NaCl 0.9%, B009827 REV 03</td>
			<td>Physiologic Saline Solution 0.9% NaCl, 309 mosmol/L, pH-Wert: 4.5-7.0</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile saline vessel</td>
			<td>KLS Martin</td>
			<td style="width:317px;">REF K8A,&#160; 18/10 Jonas</td>
			<td>Sterilizable Metal Vessel for sterile saline</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile table cover</td>
			<td>Hartmann</td>
			<td style="width:317px;">REF 2502208</td>
			<td>Table Cover, Foliodrape 150 x 100 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile towel</td>
			<td>BARRIER by M&#246;lnlycke Health Care</td>
			<td style="width:317px;">REF 706900</td>
			<td>Adhesive OP-Towel, 100 x 100 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sterile US probe cover sheath</td>
			<td>Websinger</td>
			<td style="width:317px;">REF 07014</td>
			<td>Sterile ultrasound probe cover, 20 x 60 cm, inluding two sterie adhesive tapes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stiff guidewire</td>
			<td>Cook Medical</td>
			<td style="width:317px;">REF TSMG-35-180-4-LES, G46729</td>
			<td>Lunderquist Extra Stiff Wire Guide, 0.035&#34;-.89 mm, 180 cm, 4 cm flexible tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Surgical cap</td>
			<td>BARRIER by M&#246;lnlycke Health Care</td>
			<td style="width:317px;">REF 620500, PCS 100, Colour Green</td>
			<td>Surgical Cap</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrasound device</td>
			<td>FUJIFILM SonoSite</td>
			<td style="width:317px;">Model M-Turbo, REF P17000-17</td>
			<td>Mobile ultrasound system</td>
		</tr>
	</tbody>
</table>

measurement of the hepatic venous pressure gradient and transjugular liver biopsy

Here we provide a detailed protocol describing the clinical procedure of hepatic venous pressure gradient (HVPG) measurement in patients with advanced chronic liver disease followed by an instruction for transjugular biopsy. Under local anesthesia and ultrasound guidance, a catheter introducer sheath is placed in the right internal jugular vein. Using&#160;fluoroscopic guidance, a balloon catheter is advanced into the inferior vena cava (IVC) and inserted into a large hepatic vein. Correct and sufficient wedge position of the catheter is ensured by injecting contrast media while the balloon is blocking the outflow of the cannulated hepatic vein. After calibrating the external pressure transducer, continuous pressure recordings are obtained with triplicate recordings of the wedged hepatic venous pressure (WHVP) and free hepatic venous pressure (FHVP). The difference between FHVP and WHVP is referred to as HVPG, with values &#8805;10 mm Hg indicating clinically significant portal hypertension (CSPH). Before removing the catheter, pressure readings obtained in the IVC at the same level, as well as the right atrial pressure are recorded.
Finally, a transjugular liver biopsy can be obtained via the same vascular route. Different systems are available; however, core biopsy needles are preferred over aspiration needles, especially for cirrhotic livers. Again, under fluoroscopic guidance a biopsy needle introducer sheath is advanced into an hepatic vein. Next, the transjugular biopsy needle is gently advanced through the introducer sheath: (i) in case of aspiration biopsy, the needle is advanced into the liver parenchyma under aspiration and then removed quickly, or (ii) in case of a core biopsy, the cutting-mechanism is triggered inside the parenchyma. Several separate passages can be safely performed to obtain sufficient liver specimens via transjugular biopsy. In experienced hands, the combination of these procedures takes about 30-45 min.

In compensated patients with well-preserved liver function (i.e. without any history of hepatic decompensation, such as ascites or variceal bleeding) the measured HVPG values might be normal or in the range of subclinical portal hypertension (HVPG 6&#8211;9 mm Hg). However, compensated patients might develop CSPH (HVPG &#8805;10 mm Hg) which indicates an increased risk for developing varices or hepatic decompensation. In turn, patients with esophageal or gastric varices, HVPG is usually in the range of CSPH, if not patie...

Watch this Scientific Journal Video about Measurement of the Hepatic Venous Pressure Gradient and Transjugular Liver Biopsy at JoVE.com

Measurement of the Hepatic Venous Pressure Gradient and Transjugular Liver Biopsy

Here, we present a protocol for measurement of hepatic venous pressure gradient (HVPG),the gold standard to diagnose clinically significant portal hypertension. Moreover, we describe how to perform a transjugular liver biopsy within the same session.

Here we provide a detailed protocol describing the clinical procedure of hepatic venous pressure gradient (HVPG) measurement in patients with advanced ...

Diagnosing portal hypertension in patients with advanced chronic liver disease has important prognostic implications. Assessing the severity and treatment response allows for individualized treatment approaches in these patients. Measurement of the hepatic venous pressure gradient, or HVPG, is the gold standard for diagnosing of portal hypertension in patients with advanced chronic liver disease.The prognostic value of HVPG and the clinical benefits of a decrease in HVPG have been established over a broad spectrum of etiologies of advanced chronic liver disease and also disease severity. HVPG measurement provides important insights into the complex interplay between portal hypertension and the related pathophysiological mechanisms that drive the development of clinical events in cirrhosis. Before placement, flush the balloon catheter with contrast medium and inflate and deflate the balloon several times with the catheter tips submerged in saline to check the integrity of the instrument.No air bubbles should occur. Moisten the outside of the balloon catheter with additional sterile saline solution before inserting the catheter into the vascular access sheath. Advance the catheter under fluoroscopic guidance into the inferior cava vein, or IVC, using slight rotations to align the tip of the catheter toward the back of the patient to advance from the right atrium to the IVC.To advance the catheter from the IVC into the hepatic vein, repeatedly moved the tip of the balloon catheter to the right toward the suspected area of the junction of the hepatic veins and the IVC to obtain access to the hepatic veins. Advance the catheter to a stable position that allows repeat measurement of the free hepatic venous pressure at a two to four centimeter distance from the opening of the junction into the IVC with sufficient space for the inflated balloon. Confirming its efficient wedge position of the balloon catheter in the hepatic vein is critical for obtaining reliable readings.This is confirmed by dye injection and the fluoroscopy. To check the adequacy of the vein occlusion, inflate the balloon with about two milliliters of air and about five milliliters of contrast dye until the hepatic vein distal to the inflated balloon can be visualized. Observe the stasis of the contrast medium and exclude any wash out due to insufficient occlusion of the venous lumen by the balloon or the presence of shunts.Then deflate the balloon and flush the lumen of the catheter with saline. To assess the hepatic venous pressure gradient, use an infusion line to connect to the vascular lumen of the balloon catheter to the pressure transducer and begin recording the free hepatic venous pressure with the tip of the balloon two to four centimeters from the opening of the hepatic vein to the IVC. The wave form of the curve of the free hepatic venous pressure gradient might show slight oscillations related to the heartbeat.Inflate the balloon and continue recording the wedge hepatic venous pressure until the measurement becomes a stable horizontal line with no variations over time. After repeating the free and wedge hepatic venous pressures at least three times record pressure in the IVC at the level of the ostium of the hepatic vein as well as the right atrial pressure. Before beginning the biopsy procedure, flush the biopsy needle introducer sheath with sterile saline.Check the system for smooth access and advance the biopsy needle introducer sheath into a hepatic vein as demonstrated for the balloon catheter. Gently advance the 16 gauge needle through the biopsy needle introducer sheath into the hepatic vein. To load the transjugular core liver biopsy needle, pull the grip until the shooting mechanism is loaded.Advance the core biopsy set through the biopsy needle until the tip of the core biopsy set approaches the end of the biopsy needle in the hepatic vein. Instruct the patient to hold their breath and advance the core biopsy set into the liver parenchyma. Pull the trigger of the shooting mechanism to perform the core biopsy and advise the patient to breathe normally.Remove the needle without removing the needle introducer sheath and harvest the liver sample. When all of the biopsies have been obtained inject five to 10 milliliters of contrast medium over the catheter introducer sheath to rule out perforation of the liver capsule and remove the biopsy needle introducer sheath. In a cirrhotic patient with varices or with portal hypertensive ascites, the HPVG values are expected to be at least greater to or equal to 10 millimeters of mercury.In this example, the continuous green line indicates the recorded free hepatic venous pressure of five millimeters of mercury and discontinuous red line indicates the recorded wedged hepatic venous pressure of 26 millimeters of mercury. Thus, the calculated hepatic venous pressure gradient in this patient is 21 millimeters of mercury which indicates clinically significant portal hypertension Major complications of HVPG measurement and transjugular liver biopsy are rare and mainly related to the central venous access. Here, the use of ultrasound guided central venous access will largely reduce the risk of these complications.Adequate training of central venous access development is critical to reduce the risk of major complications of HPVG measurement. Non-invasive tests are not sufficiently accurate for assessing the severity of portal hypertension in patients with CSPH and have limited accuracy for monitoring the evolution of portal hypertension after etiologically and medical therapies.

measurement-hepatic-venous-pressure-gradient-transjugular-liver

Research

JoVE Journal

Medicine

Epidural Intracranial Pressure Measurement in Rats Using a Fiber-optic Pressure Transducer

Elevated intracranial pressure (ICP) is a significant problem in several forms of ischemic brain injury including stroke, traumatic brain injury and cardiac arrest. This elevation may result in further neurological injury, in the form of transtentorial herniation1,2,3,4, midbrain compression, neurological deficit or increased cerebral infarct2,4. Current therapies are often inadequate to control elevated ICP in the clinical setting5,6,7 . Thus there is a need for accurate methods of ICP measurement in animal models to further our understanding of the basic mechanisms and to develop new treatments for elevated ICP.
In both the clinical and experimental setting ICP cannot be estimated without direct measurement. Several methods of ICP catheter insertion currently exist. Of these the intraventricular catheter has become the clinical 'gold standard' of ICP measurement in humans8. This method involves the partial removal of skull and the instrumentation of the catheter through brain tissue. Consequently, intraventricular catheters have an infection rate of 6-11%9. For this reason, subdural and epidural cannulations have become the preferred methods in animal models of ischemic injury. 
Various ICP measurement techniques have been adapted for animal models, and of these, fluid-filled telemetry catheters10 and solid state catheters are the most frequently used11,12,13,14,15. The fluid-filled systems are prone to developing air bubbles in the line, resulting in false ICP readings. Solid state probes avoid this problem (Figure 1). An additional problem is fitting catheters under the skull or into the ventricles without causing any brain injury that might alter the experimental outcomes. Therefore, we have developed a method that places an ICP catheter contiguous with the epidural space, but avoids the need to insert it between skull and brain. 
An optic fibre pressure catheter (420LP, SAMBA Sensors, Sweden) was used to measure ICP at the epidural location because the location of the pressure sensor (at the very tip of the catheter) was found to produce a high fidelity ICP signal in this model. There are other manufacturers of similar optic fibre technologies13 that may be used with our methodology. Alternative solid state catheters, which have the pressure sensor located at the side of the catheter tip, would not be appropriate for this model as the signal would be dampened by the presence of the monitoring screw. 
Here, we present a relatively simple and accurate method to measure ICP. This method can be used across a wide range of ICP related animal models.

A novel technique to record the pressures within the skull is described. The minimally invasive method uses a fibre-optic pressure sensing system to accurately measure intracranial pressure (ICP) in anaesthetized rats without causing significant brain trauma. The technique may be used in a wide range of experimental models.

Elevated intracranial pressure (ICP) is a significant problem in several forms of ischemic brain injury including stroke, traumatic brain injury and ...

Measurement of the Pressure-volume Curve in Mouse Lungs

In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential phenotypic changes are best assessed by measurement of the changes in lung elasticity. To best understand specific mechanisms underlying such pathologies in mice, it is essential to make functional measurements that can reflect the developing pathology. Although there are many ways to measure elasticity, the classical method is that of the total lung pressure-volume (PV) curve done over the whole range of lung volumes. This measurement has been made on adult lungs from nearly all mammalian species dating back almost 100 years, and such PV curves also played a major role in the discovery and understanding of the function of pulmonary surfactant in fetal lung development. Unfortunately, such total PV curves have not been widely reported in the mouse, despite the fact that they can provide useful information on the macroscopic effects of structural changes in the lung. Although partial PV curves measuring just the changes in lung volume are sometimes reported, without a measure of absolute volume, the nonlinear nature of the total PV curve makes these partial ones very difficult to interpret. In the present study, we describe a standardized way to measure the total PV curve. We have then tested the ability of these curves to detect changes in mouse lung structure in two common lung pathologies, emphysema and fibrosis. Results showed significant changes in several variables consistent with expected structural changes with these pathologies. This measurement of the lung PV curve in mice thus provides a straightforward means to monitor the progression of the pathophysiologic changes over time and the potential effect of therapeutic procedures.

Here we present a protocol to simply and reliably measure the lung pressure-volume curve in mice, showing that it is sufficiently sensitive to detect phenotypic parenchymal changes in two common lung pathologies, pulmonary fibrosis and emphysema. This metric provides a means to quantify the lung&#8217;s structural changes with developing pathology.

In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential ...

Isolated Hepatic Perfusion as a Treatment for Liver Metastases of Uveal Melanoma

Isolated hepatic perfusion (IHP) is a procedure where the liver is surgically isolated and perfused with a high concentration of the chemotherapeutic agent melphalan. Briefly, the procedure starts with the setup of a percutaneous veno-venous bypass from the femoral vein to the external jugular vein. Via a laparotomy, catheters are then inserted into the proper hepatic artery and the caval vein. The portal vein and the caval vein, both supra- and infrahepatically, are then clamped. The arterial and venous catheters are connected to a heart lung machine and the liver is perfused with melphalan (1 mg/kg body weight) for 60 min. This way it is possible to locally perfuse the liver with a high dose of a chemotherapeutic agent, without leakage to the systemic circulation.
In previous studies including patients with isolated liver metastases of uveal melanoma, an overall response rate of 33-100% and a median survival between 9 and 13 months, have been reported. The aim of this protocol is to give a clear description of how to perform the procedure and to discuss IHP as a treatment option for liver metastases of uveal melanoma.

Here, we present a protocol how to perform an isolated liver perfusion (IHP) with melphalan and we also discuss IHP as a treatment option for liver metastases of uveal melanoma.

Isolated hepatic perfusion (IHP) is a procedure where the liver is surgically isolated and perfused with a high concentration of the chemotherapeutic ...

Generation of a Humanized Mouse Liver Using Human Hepatic Stem Cells

A novel animal model involving chimeric mice with humanized livers established via human hepatocyte transplantation has been developed. These mice, in which the liver has been repopulated with functional human hepatocytes, could serve as a useful tool for investigating human hepatic cell biology, drug metabolism, and other preclinical applications. One of the key factors required for successful transplantation of human hepatocytes into mice is the elimination of the endogenous hepatocytes to prevent competition with the human cells and provide a suitable space and microenvironment for promoting human donor cell expansion and differentiation. To date, two major liver injury mouse models utilizing fumarylacetoacetate hydrolase (Fah) and uroplasminogen activator (uPA) mice have been established. However, Fah mice are used mainly with mature hepatocytes and the application of the uPA model is limited by decreased breeding. To overcome these limitations, Alb-toxin receptor mediated cell knockout (TRECK)/SCID mice were used for in vivo differentiation of immature human hepatocytes and humanized liver generation. Human hepatic stem cells (HpSCs) successfully repopulated the livers of Alb-TRECK/SCID mice that had developed lethal fulminant hepatic failure following diphtheria toxin (DT) treatment. This model of a humanized liver in Alb-TRECK/SCID mice will have functional applications in studies involving drug metabolism and drug-drug interactions and will promote other in vivo and in vitro studies.

Here, we present a novel humanized mouse liver model generated in Alb-toxin receptor mediated cell knockout (TRECK)/SCID mice following the transplantation of immature and expandable human hepatic stem cells.

A novel animal model involving chimeric mice with humanized livers established via human hepatocyte transplantation has been developed. These mice, in ...

Method of Direct Segmental Intra-hepatic Delivery Using a Rat Liver Hilar Clamp Model

Major hepatic surgery with inflow occlusion, and liver transplantation, necessitate a period of warm ischemia, and a period of reperfusion leading to ischemia/reperfusion (I/R) injury with myriad negative consequences. Potential I/R injury in marginal organs destined for liver transplantation contributes to the current donor shortage secondary to a decreased organ utilization rate. A significant need exists to explore hepatic I/R injury in order to mediate its impact on graft function in transplantation. Rat liver hilar clamp models are used to investigate the impact of different molecules on hepatic I/R injury. Depending on the model, these molecules have been delivered using inhalation, epidural infusion, intraperitoneal injection, intravenous administration or injection into the peripheral superior mesenteric vein. A rat liver hilar clamp model has been developed for use in studying the impact of pharmacologic molecules in ameliorating I/R injury. The described model for rat liver hilar clamp includes direct cannulation of the portal supply to the ischemic hepatic segment via a side branch of the portal vein, allowing for direct segmental hepatic delivery. Our approach is to induce ischemia in the left lateral and median lobes for 60 min, during which time the substance under study is infused. In this case, pegylated-superoxide dismutase (PEG-SOD), a free radical scavenger, is infused directly into the ischemic segment. This series of experiments demonstrates that infusion of PEG-SOD is protective against hepatic I/R injury. Advantages of this approach include direct injection of the molecule into the ischemic segment with consequent decrease in volume of distribution and reduction in systemic side effects.

A unique rat liver hilar clamp model was developed for studying the impact of pharmacologic molecules in ameliorating ischemia-reperfusion injury. This model includes direct cannulation of the portal supply to the ischemic liver segment via a branch of the portal vein, allowing for direct hepatic delivery.

Major hepatic surgery with inflow occlusion, and liver transplantation, necessitate a period of warm ischemia, and a period of reperfusion leading to ...

Measurement of Natural Killer Cell-Mediated Cytotoxicity and Migration in the Context of Hepatic Tumor Cells

Natural killer (NK) cells are a subset of the cytotoxic lymphocyte population of the innate immune system and participate as a first line of defense by clearing pathogen-infected, malignant, and stressed cells. The ability of NK cells to eradicate cancer cells makes them an important tool in the fight against cancer. Several new immune-based therapies are under investigation for cancer treatment which rely either on enhancing NK cell activity or increasing the sensitivity of cancer cells to NK cell-mediated eradication. However, to effectively develop these therapeutic approaches, cost-effective in vitro assays to monitor NK cell-mediated cytotoxicity and migration are also needed. Here, we present two in vitro protocols that can reliably and reproducibly monitor the effect of NK-cell cytotoxicity on cancer cells (or other target cells). These protocols are non-radioactivity-based, simple to set up, and can be scaled up for high-throughput screening. We also present a flow cytometry-based protocol to quantitatively monitor NK cell migration, which can also be scaled up for high-throughput screening. Collectively, these three protocols can be used to monitor key aspects of NK cell activity that are necessary for the cells&#39; ability to eradicate dysfunctional target cells.

Evasion of natural killer (NK) cell-mediated eradication by cancer cells is important for cancer initiation and progression. Here, we present two non-radioactivity-based protocols to evaluate NK cell-mediated cytotoxicity toward hepatic tumor cells. Additionally, a third protocol is presented to analyze NK cell migration.

Natural killer (NK) cells are a subset of the cytotoxic lymphocyte population of the innate immune system and participate as a first line of defense by ...

Murine Precision-Cut Liver Slices as an Ex Vivo Model of Liver Biology

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic fatty liver disease, metabolic liver disease, and liver cancer) requires experimental manipulation of animal models and in vitro cell cultures. Both techniques have limitations, such as the requirement of large numbers of animals for in vivo manipulation. However, in vitro cell cultures do not reproduce the structure and function of the multicellular hepatic environment. The use of precision-cut liver slices is a technique in which uniform slices of viable mouse liver are maintained in laboratory tissue culture for experimental manipulation. This technique occupies an experimental niche that exists between animal studies and in vitro cell culture methods. The presented protocol describes a straightforward and reliable method to isolate and culture precision-cut liver slices from mice. As an application of this technique, ex vivo liver slices are treated with bile acids to simulate cholestatic liver injury and ultimately assess the mechanisms of hepatic fibrogenesis.

This protocol provides a simple and reliable method for the production of viable precision-cut liver slices from mice. The ex vivo tissue samples can be maintained under laboratory tissue culture conditions for multiple days, providing a flexible model to examine liver pathobiology.

Understanding the mechanisms of liver injury, hepatic fibrosis, and cirrhosis that underlie chronic liver diseases (i.e., viral hepatitis, non-alcoholic ...

Quantitative Analysis of Liver Stiffness Distribution

A Three-Dimensional Digital Model for Early Diagnosis of Hepatic Fibrosis Based on Magnetic Resonance Elastography

Hepatic fibrosis is an early stage of liver cirrhosis, and there are no better non-invasive and convenient methods for the detection and evaluation of the disease. Despite the good progress made with the liver stiffness map (LSM) based on magnetic resonance elastography (MRE), there are still some limitations that need to be overcome, including manual focus determination, manual selection of regions of interest (ROIs), and discontinuous LSM data without structural information, which makes it impossible to evaluate the liver as a whole. In this study, we propose a novel three-dimensional (3D) digital model for the early diagnosis of hepatic fibrosis based on MRE.
MRE is a non-invasive imaging technique that employs magnetic resonance imaging (MRI) to measure the liver stiffness at the scanning site through human-computer interaction. Studies have indicated a significant positive correlation between the LSM obtained through MRE and the degree of hepatic fibrosis. However, for clinical purposes, a comprehensive and precise quantification of the degree of hepatic fibrosis is necessary. To address this, the concept of Liver Stiffness Distribution (LSD) was proposed in this study, which refers to the 3D stiffness volume of each liver voxel obtained by the alignment of 3D liver tissue images and MRE indicators. This provides a more effective clinical tool for the diagnosis and treatment of hepatic fibrosis.

Author Spotlight: Advancing Hepatic Fibrosis Diagnosis Using Magnetic Resonance Elastography and AI 

The objective of this study was to develop a novel three-dimensional digital model for the early diagnosis of hepatic fibrosis, which includes the stiffness of each voxel in the patient's liver and can thus, be used to calculate the distribution ratio of the patient's liver at different fibrosis stages.

Hepatic fibrosis is an early stage of liver cirrhosis, and there are no better non-invasive and convenient methods for the detection and evaluation of the ...

In Situ Mouse Liver Perfusion Model to Study Metabolic Responses to Substrates

Hepatic Glucose Production, Ureagenesis, and Lipolysis Quantified using the Perfused Mouse Liver Model

The liver has numerous functions, including nutrient metabolism. In contrast to other in vitro and in vivo models of liver research, the isolated perfused liver allows the study of liver biology and metabolism in the whole liver with an intact hepatic architecture, separated from the influence of extra-hepatic factors. Liver perfusions were originally developed for rats, but the method has been adapted to mice as well. Here we describe a protocol for in situ perfusion of the mouse liver. The liver is perfused antegradely through the portal vein with oxygenated Krebs-Henseleit bicarbonate buffer, and the output is collected from the suprahepatic inferior vena cava with clamping of the infrahepatic inferior vena cava to close the circuit. Using this method, the direct hepatic effects of a test compound can be evaluated with a detailed time resolution. Liver function and viability are stable for at least 3 h, allowing the inclusion of internal controls in the same experiment. The experimental possibilities using this model are numerous and may infer insight into liver physiology and liver diseases.

Author Spotlight: Investigating Hepatic Adaptations and Prediabetic Progression in Liver Diseases 

Here, we present a robust method for in situ perfusion of the mouse liver to study the acute and direct regulation of liver metabolism without disturbing the hepatic architecture but in the absence of extra-hepatic factors.

The liver has numerous functions, including nutrient metabolism. In contrast to other in vitro and in vivo models of liver research, the isolated perfused ...

Extraction of 3D Region of the Liver for Hepatic Fibrosis Diagnosis

To begin, open MATLAB software. Ensure that the IDEAL data have a horizontal resolution of 256 by 256 pixels with a pixel spacing of 1.5625 millimeters and a slice thickness of 10 millimeters. Copy all DICOM data to a customized working directory, and navigate to the directory containing the data in MATLAB's working directory.Then execute the description name function to add descriptive names to the folders for each sequence. Add a description name to each image sequence folder. To check images of IDEAL, change the directory of different phase folders.Execute the slice view function to view the impact sequences for each phase. Next, quickly browse the different sequences using the scroll bar at the bottom of the GUI. Select the MRI IDEAL outphase sequence to depict liver tissue boundaries.Initiate the Mimics software. Select new project, and in the ensuing dialogue box, navigate to the folder containing the IDEAL outphase images. Click next, followed by the convert button to enter into the sequence heading state.To create an empty mask, from the mask dialogue box, click on the new button and select the maximum threshold. Using the edit masks tool located beneath the segment label, delimit the area of the liver in all horizontal views. To generate the 3D spatial part of the liver, select the outlying liver mask and click on the calculate part for mask button.Next, click file, then export, and select the DICOM command. In the pop-up dialogue box, choose the liver mask, and set the file path and names, then click the OK button to complete the export of the 3D region of the liver to the specified DICOM files.