Name: endotoxin activity assay for the detection of whole blood endotoxemia in critically ill patients
Uploaded: 2019-06-24T12:30:00
Description: Watch this Scientific Journal Video about Endotoxin Activity Assay for the Detection of Whole Blood Endotoxemia in Critically Ill Patients at JoVE.com

We thank Paolo Bragan&#242; and Lisa Mathiasen, Ph.D. for their review of the assay protocol methodology. Dario Winterton, MD provided substantial help reviewing the manuscript for English language proficiency.

The protocol is conducted according to institutional guidelines relating to the handling of human biospecimens and following the current standard operative procedures of our clinical laboratory. The use of EA data and clinical information of patients being tested follows the guidelines of our institution&#8217;s human research ethics committee.
1. Laboratory Equipment and Assay Kit Contents
<ol>
	<li>Store the EA kit at 2&#8211;8 &#176;C when not in use.</li>
	<li>Each EA test consis...

<ol>
	<li>Akira, S., Takeda, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toll-like+receptor+signalling.">Toll-like receptor signalling.</a> Nature Reviews Immunology. 4 (7), 499-511 (2004).</li><li>Takeda, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+and+integration+of+innate+immune+recognition+systems:+the+Toll-like+receptors.">Evolution and integration of innate immune recognition systems: the Toll-like receptors.</a> Journal of Endotoxin Research. 11 (1), 51-55 (2005).</li><li>Ulevitch, R. J., Tobias, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recognition+of+gram-negative+bacteria+and+endotoxin+by+the+innate+immune+system.">Recognition of gram-negative bacteria and endotoxin by the innate immune system.</a> Current Opinion in Immunology. 11 (1), 19-22 (1999).</li><li>Natanson, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotoxin+and+tumor+necrosis+factor+challenges+in+dogs+simulate+the+cardiovascular+profile+of+human+septic+shock.">Endotoxin and tumor necrosis factor challenges in dogs simulate the cardiovascular profile of human septic shock.</a> The Journal of Experimental Medicine. 169 (3), 823-832 (1989).</li><li>Suffredini, A. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cardiovascular+response+of+normal+humans+to+the+administration+of+endotoxin.">The cardiovascular response of normal humans to the administration of endotoxin.</a> The New England Journal of Medicine. 321 (5), 280-287 (1989).</li><li>Singer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Third+International+Consensus+Definitions+for+Sepsis+and+Septic+Shock+(Sepsis-3).">The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3).</a> JAMA: The Journal of the American Medical Association. 315 (8), 801-810 (2016).</li><li>Gupta, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culture-Negative+Severe+Sepsis:+Nationwide+Trends+and+Outcomes.">Culture-Negative Severe Sepsis: Nationwide Trends and Outcomes.</a> Chest. 150 (6), 1251-1259 (2016).</li><li>Ikeda, T., Ikeda, K., Suda, S., Ueno, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Usefulness+of+the+endotoxin+activity+assay+as+a+biomarker+to+assess+the+severity+of+endotoxemia+in+critically+ill+patients.">Usefulness of the endotoxin activity assay as a biomarker to assess the severity of endotoxemia in critically ill patients.</a> Innate Immunity. 20 (8), 881-887 (2014).</li><li>Dellinger, R. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Targeted+Polymyxin+B+Hemoperfusion+on+28-Day+Mortality+in+Patients+With+Septic+Shock+and+Elevated+Endotoxin+Level.">Effect of Targeted Polymyxin B Hemoperfusion on 28-Day Mortality in Patients With Septic Shock and Elevated Endotoxin Level.</a> The EUPHRATES Randomized Clinical Trial. JAMA: The Journal of the American Medical Association. 320 (14), 1455-1463 (2018).</li><li>Marshall, J. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnostic+and+prognostic+implications+of+endotoxemia+in+critical+illness:+results+of+the+MEDIC+study.">Diagnostic and prognostic implications of endotoxemia in critical illness: results of the MEDIC study.</a> The Journal of Infectious Diseases. 190 (3), 527-534 (2004).</li><li>Levin, J., Bang, F. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clottable+protein+in+Limulus;+its+localization+and+kinetics+of+its+coagulation+by+endotoxin.">Clottable protein in Limulus; its localization and kinetics of its coagulation by endotoxin.</a> Thrombosis et Diathesis Haemorrhagica. 19 (1), 186-197 (1968).</li><li>Marshall, J. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+endotoxin+activity+in+critically+ill+patients+using+whole+blood+neutrophil+dependent+chemiluminescence.">Measurement of endotoxin activity in critically ill patients using whole blood neutrophil dependent chemiluminescence.</a> Critical Care. 6 (4), 342-348 (2002).</li><li>Grimaldi, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+Level+of+Endotoxemia+Following+Out-of-Hospital+Cardiac+Arrest+Is+Associated+With+Severity+and+Duration+of+Postcardiac+Arrest+Shock.">High Level of Endotoxemia Following Out-of-Hospital Cardiac Arrest Is Associated With Severity and Duration of Postcardiac Arrest Shock.</a> Critical Care Medicine. 43 (12), 2597-2604 (2015).</li><li>Klein, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+EUPHRATES+trial+(Evaluating+the+Use+of+Polymyxin+B+Hemoperfusion+in+a+Randomized+controlled+trial+of+Adults+Treated+for+Endotoxemia+and+Septic+shock):+study+protocol+for+a+randomized+controlled+trial.">The EUPHRATES trial (Evaluating the Use of Polymyxin B Hemoperfusion in a Randomized controlled trial of Adults Treated for Endotoxemia and Septic shock): study protocol for a randomized controlled trial.</a> Trials. 15, 218 (2014).</li><li>Bottiroli, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+and+clinical+significance+of+early+high+Endotoxin+Activity+in+septic+shock:+An+observational+study.">Prevalence and clinical significance of early high Endotoxin Activity in septic shock: An observational study.</a> Journal of Critical Care. 41, 124-129 (2017).</li><li>Kaukonen, K. M., Bailey, M., Suzuki, S., Pilcher, D., Bellomo, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mortality+related+to+severe+sepsis+and+septic+shock+among+critically+ill+patients+in+Australia+and+New+Zealand.">Mortality related to severe sepsis and septic shock among critically ill patients in Australia and New Zealand.</a> JAMA: The Journal of the American Medical Association. 311 (13), 1308-1316 (2014).</li><li>Biagioni, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotoxin+activity+levels+as+a+prediction+tool+for+risk+of+deterioration+in+patients+with+sepsis+not+admitted+to+the+intensive+care+unit:+a+pilot+observational+study.">Endotoxin activity levels as a prediction tool for risk of deterioration in patients with sepsis not admitted to the intensive care unit: a pilot observational study.</a> Journal of Critical Care. 28 (5), 612-617 (2013).</li><li>Roth, R. I., Levin, F. C., Levin, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+detection+of+bacterial+endotoxin+in+plasma+with+the+Limulus+test.">Optimization of detection of bacterial endotoxin in plasma with the Limulus test.</a> The Journal of Laboratory and Clinical Medicine. 116 (2), 153-161 (1990).</li><li>Yaguchi, A., Yuzawa, J., Klein, D. J., Takeda, M., Harada, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+intermediate+levels+of+the+Endotoxin+Activity+Assay+(EA)+with+other+biomarkers+in+the+assessment+of+patients+with+sepsis:+results+of+an+observational+study.">Combining intermediate levels of the Endotoxin Activity Assay (EA) with other biomarkers in the assessment of patients with sepsis: results of an observational study.</a> Critical Care. 16 (3), (2012).</li><li>Earley, Z. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Burn+Injury+Alters+the+Intestinal+Microbiome+and+Increases+Gut+Permeability+and+Bacterial+Translocation.">Burn Injury Alters the Intestinal Microbiome and Increases Gut Permeability and Bacterial Translocation.</a> PLoS One. 10 (7), (2015).</li><li>Munster, A. M., Smith-Meek, M., Dickerson, C., Translocation Winchurch, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Incidental+phenomenon+or+true+pathology?.">Incidental phenomenon or true pathology?.</a> Annals of Surgery. 218 (3), 321 (1993).</li><li>Clementi, A., Virz&#236;, G. M., Brocca, A., Ronco, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Role+of+Endotoxin+in+the+Setting+of+Cardiorenal+Syndrome+Type+5.">The Role of Endotoxin in the Setting of Cardiorenal Syndrome Type 5.</a> Cardiorenal Medicine. 7 (4), 276-283 (2017).</li><li>Virz&#236;, G. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiorenal+Syndrome+Type+5+in+Sepsis:+Role+of+Endotoxin.">Cardiorenal Syndrome Type 5 in Sepsis: Role of Endotoxin.</a> in Cell Death Pathways and Inflammation. Kidney and Blood Pressure Research. 41 (6), 1008-1015 (2016).</li><li>Mignon, F., Piagnerelli, M., Van Nuffelen, M., Vincent, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+empiric+antibiotic+treatment+on+plasma+endotoxin+activity+in+septic+patients.">Effect of empiric antibiotic treatment on plasma endotoxin activity in septic patients.</a> Infection. 42 (3), 521-528 (2014).</li><li>Klein, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Daily+variation+in+endotoxin+levels+is+associated+with+increased+organ+failure+in+critically+ill+patients.">Daily variation in endotoxin levels is associated with increased organ failure in critically ill patients.</a> Shock. 28 (5), 524-529 (2007).</li></ol>

Septic shock is still nowadays associated with a mortality as high as 40%, although this rate varies according to the considered reports16. The need for novel and better biomarkers is advocated by most experts in the fields in order to aid clinicians in early diagnosis, better management, and prognostication of patients with septic shock6.
Performing an EA test does not require previous technical knowledge or sophisticated laboratory equipment, a...

The Lipopolysaccharide (LPS), also known as endotoxin, is a key component of the membrane structure of Gram-negative (GN) bacteria. It makes up about 10% of the cell wall, being vital for the outer membrane integrity and homeostasis. Moreover, it is a potent activator of the host innate immune system1,2.
In vitro exposure of innate immune system cells to LPS leads to changes in the expression of multiple genes3. Administration of very small quantities of LPS in healthy human volunteers triggers the cascade of acute systemic inflammation, whereas sepsis and septic shock may arise with higher endotoxin concentrations4,5.
Sepsis is a life-threatening condition which, if not promptly recognized, can lead to multi-organ failure and death. Septic patients must be treated in a timely manner, with aggressive resuscitation, adequate antibiotic therapy, optimal source control, and prompt organ support strategies. The diagnosis of the etiology of sepsis is primarily based on clinical recognition and culture-based pathogen detection6. However, results of microbial cultures may take up to 48 h and are inconclusive in up to 30% of cases7. Early identification and intervention may lead to better patient outcomes. In patients in whom sepsis is suspected, decisions are often made on the basis of physiological and biochemical parameters, without a clear sign of endotoxemia.
The measurement of the Endotoxin Activity (EA) can be obtained by means of a commercial assay (see Table of Materials) in whole blood. It can be used as a biomarker of systemic endotoxemia for the early stratification of disease severity, particularly in patients at risk for developing septic shock8. The assay was used to guide Polymyxin B hemoperfusion therapy in a recently published double-blind randomized-controlled clinical trial in patients with septic shock9. In critically ill patients, the MEDIC study showed increased EA levels to be associated with multiple organ dysfunction, intensive care unit (ICU) length of stay, and mortality10.
Different assays have been developed to detect endotoxin. The Limulus Amoebocyte Lysate (LAL) assay, either as a gel-clot, turbidimetric, or chromogenic test, has been so far the most frequently adopted for the estimation of serum endotoxin. It is based on the ability of endotoxin to induce coagulation of the hemolymph of the horseshoe crab, Limulus polyphemus. However, this assay has some limitations in terms of specificity. In particular, it can also be activated by microbial products other than endotoxin, such as components of the fungal cell wall, and it can be inhibited by various human plasma proteins11.
During the last decade the measurement of EA has been developed and validated as a biomarker of circulating endotoxemia. Compared to the LAL test, EA is quicker and easier to implement in the clinical setting. Moreover, it has been shown to be more accurate than LAL in whole blood, with increased sensitivity and specificity, both in vitro and in vivo12.
Despite its initial implementation as an early diagnostic tool for the rapid identification of GN bacteria as sepsis causative agents, the EA level has also been studied as a biomarker of disease severity. In this context, it has been shown to be particularly useful to assess the hypoperfusion state due to ongoing critical illness, such as septic shock or post-cardiac arrest syndrome13. More recently, since the development of hemopurification systems, a positive EA result has also been proposed as a screening tool to accurately identify potential candidates for such therapy14. We recently conducted an observational retrospective study on the prevalence and clinical significance of early high levels of EA in 107 patients with septic shock. In line with other recent results, we found that EA is a promising marker of disease severity in patients with septic shock15.
The aim of the present manuscript is to describe the method to perform the EA assay, either at the bedside or in the laboratory, and to describe its potential use in a representative scenario of septic shock. This technique can detect LPS activity by measuring the enhanced oxidative burst in neutrophils following their priming by complexes of an anti-endotoxin antibody and LPS. The increased respiratory burst is detected by a chemiluminometer and the amount of light emitted is considered proportional to the amount of endotoxin in the blood sample. The assay requires few reagents, takes about 30 min to perform and uses as little as 40 &#181;L of whole blood12.

<table border="0" cellpadding="0" cellspacing="0" style="width:727px;" width="726">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:184px;">EAA kit</td>
			<td style="width:141px;">Spectral Medical Inc.</td>
			<td style="width:133px;">EAAST-20</td>
			<td style="width:268px;">Package with 20 tests + 1 quality control</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:184px;">Smart Line TL</td>
			<td style="width:141px;">Berthold</td>
			<td style="width:133px;">EAASL</td>
			<td>Luminometer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:184px;">Incubator shaker</td>
			<td style="width:141px;">GRANT</td>
			<td style="width:133px;">ES-20</td>
			<td>Mini-incubator shaker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:184px;">Vortexer</td>
			<td style="width:141px;">VWR</td>
			<td style="width:133px;">444-2790</td>
			<td>Vortex instrument</td>
		</tr>
	</tbody>
</table>

endotoxin activity assay for the detection of whole blood endotoxemia in critically ill patients

Lipopolysaccharide, also known as endotoxin, is a fundamental component of gram-negative bacteria and plays a crucial role in the development of sepsis and septic shock. The early identification of an infectious process that is rapidly evolving to a critical illness might prompt a quicker and more intensive treatment, thereby potentially leading to better patient outcomes. The Endotoxin Activity (EA) assay can be used at the bedside as a reliable biomarker of systemic endotoxemia. The detection of elevated endotoxin activity levels has been repeatedly shown to be associated with an increased disease severity in patients with sepsis and septic shock. The assay is quick and easy to perform. Briefly, after sampling, an aliquot of whole blood is mixed with an anti-endotoxin antibody and with added LPS. Endotoxin activity is measured as the relative oxidative burst of primed neutrophils as detected by chemioluminescence. The assay&#39;s output is expressed on a scale from 0 (absent) to 1 (maximal) and categorized as &#8220;low&#8221; (&#60;0.4 units), &#8220;intermediate&#8221; (0.4&#8211;0.59 units), or &#8220;high&#8221; (&#8805;0.6 units). The detailed methodology and rationale for the implementation of the EA assay are reported in this manuscript.

A 72 year-old man was admitted to the Emergency Department (ED) of an academic urban hospital. A few days earlier he had presented to his primary care physician complaining of burning on urination. A short-course therapy with oral phosphomycin was recommended. His medical history included hypertension, uncomplicated type-2 diabetes and benign prostatic hyperplasia. His medications included enalapril, atorvastatin, tamsulosin and metformin.
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Watch this Scientific Journal Video about Endotoxin Activity Assay for the Detection of Whole Blood Endotoxemia in Critically Ill Patients at JoVE.com

Endotoxin Activity Assay for the Detection of Whole Blood Endotoxemia in Critically Ill Patients

We hereby present a protocol to measure at the bedside the endotoxin activity of human whole blood samples. The Endotoxin Activity assay is a simple test to perform and may be a useful biomarker in critically ill patients with sepsis.

Lipopolysaccharide, also known as endotoxin, is a fundamental component of gram-negative bacteria and plays a crucial role in the development of sepsis ...

Sepsis can lead to multi-organ failure and death. The endotoxin is a fundamental component of gram-negative bacteria. Elevated circulating levels of endotoxin might identify patient at higher risk to develop a more severe disease.The Endotoxin Activity Assay can be used as a simple, quick, and reliable biomarker of systemic endotoxemia. The early detection of this toxin might help clinicians treating patients with septic shock. In patient with septic shock, the early identification of a rapidly evolving condition might prompt a quicker and more intensive life support therapy, potentially leading to better outcomes.Demonstrating this procedure will be Lisa Mathiasen, a molecular biologist who collaborates with our research group. To begin this procedure, set out an EA test kit and unpack the five different kinds of tubes. Use tube number one, the Control tube, to measure the basal activity of the non-specific oxidative burst of patient's neutrophils in the absence of a specific antibody.Use tube number two, the Sample tube, to measure the oxidative burst in response to the LPS-antibody complex. Use tube number three, the Max tube, to measure the maximal oxidative burst of patient's neutrophils in response to an excess of endotoxin. Use tube number four, the LPS tube, as a source of exogenous endotoxin.And use tube number five, the Aliquot tube, for blood storage. Collect patient blood samples in sterile tubes containing EDTA anticoagulant, and store them at room temperature before running the EA test. Before starting the test, turn on the chemiluminometer and incubator shaker and warm the incubator to 37 degrees Celsius.First, place the EA tubes to be used in tube racks, and remove the caps. Use a combipipette to transfer one milliliter of the EA reagent from the bottle into tubes number one, number two, and number three by pipetting down the side of the tubes. Gently invert the blood collection tube 20 times to mix the patient's blood sample.Then, pipette 0.5 milliliters of patient blood into tube number four and tube number five. Vortex tube number four for 10 seconds. Place the tube racks with all of the EA test tubes into the incubator shaker.Close the lid, and incubate at 37 degrees Celsius for 10 minutes. After this, open the incubator lid and remove the tube racks from the shaker. Vortex tube number five.Using a sterile tip, pipette 40 microliters of blood into tubes number one and number two, in duplicate. Vortex tube number four. Using the same pipette tip, transfer 40 microliters of blood from tube number four into tube number three, in duplicate.Vortex the six final test tubes one by one. Place the tube racks back into the incubating shaker, and close the lid. Set the shaker to 100 rpm, and start the motion for 14 minutes.Insert the EA labeled chipcard into the chemiluminometer, and press Start. After the 14-minute incubation, follow the instructions displayed on the chemiluminometer. Gently vortex each tube for 10 seconds before placing it onto the sample holder of the chemiluminometer.Open the sample drawer, and place tube number one into the sample holder. Then, close the sample drawer, and wait for the relative light unit reading. Repeat this reading process for tubes two and three and all duplicates, as outlined in the text protocol.After all of the tubes have been processed, the EA results will be calculated and printed automatically. Repeat the entire assay process for each blood sample that needs to be tested. Store the EA Assay kit and its components in the original sealed package at a temperature between two and 25 degrees Celsius.In this study, an Endotoxin Activity Assay is performed to detect whole blood endotoxemia in critically ill patients. An EA value of less than 0.40 EA units indicates a low endotoxin activity level, equal to a low circulating LPS concentration, which represents a low risk of progression to a severe disease state. A result between 0.40 and 0.59 EA units indicates an intermediate endotoxin activity level, which represents an intermediate risk for the development of severe sepsis and septic shock.Results equal to or greater than 0.60 EA units indicates a high endotoxin activity level, which represents a high risk for septic shock and poor patient outcomes. Blood from tubes number four and five must be mixed with the correct test tube. Extra care must be taken to follow the correct order indicated in the protocol.Every tube is run in duplicates, potentially leading to mistakes in this phase. After its introduction, the EA Assay has been proposed as a biomarker for the risk stratification of patient with systemic hypoperfusion. Also, it has been studied as a screening test to select patients for advanced hemopurification treatment strategies.

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Manual Muscle Testing:  A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients

Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, and persistent nerve and muscle impairments after hospital discharge.1-6 Using an explicit protocol with a structured approach to training and quality assurance of research staff, manual muscle testing (MMT) is a highly reliable method for assessing strength, using a standardized clinical examination, for patients following ARDS, and can be completed with mechanically ventilated patients who can tolerate sitting upright in bed and are able to follow two-step commands. 7, 8 
This video demonstrates a protocol for MMT, which has been taught to &ge;43 research staff who have performed &gt;800 assessments on &gt;280 ARDS survivors. Modifications for the bedridden patient are included. Each muscle is tested with specific techniques for positioning, stabilization, resistance, and palpation for each score of the 6-point ordinal Medical Research Council scale.7,9-11 Three upper and three lower extremity muscles are graded in this protocol: shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and ankle dorsiflexion. These muscles were chosen based on the standard approach for evaluating patients for ICU-acquired weakness used in prior publications. 1,2.

Survivors of acute respiratory distress syndrome (ARDS) and critical illness frequently develop long-lasting muscle weakness. Manual muscle testing (MMT) is a standardized clinical examination commonly used to measure strength of peripheral skeletal muscle groups. This video demonstrates MMT using the 6-point Medical Research Council scale.

Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, ...

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&beta; using a Whole Blood Stimulation Assay

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues as well as altered cytokine homeostasis. The innate immune system plays a crucial role in recognizing pathogens and other endogenous danger stimuli. One of the major cytokines released by innate immune cells is Interleukin (IL)-1. Therefore, we utilize a whole blood stimulation assay in order to measure the secretion of inflammatory cytokines and specifically of the pro-inflammatory cytokine IL-1&beta; 1, 2, 3.
Patients with genetic dysfunctions of the innate immune system causing autoinflammatory syndromes show an exaggerated release of mature IL-1&beta; upon stimulation with LPS alone. In order to evaluate the innate immune component of patients who present with inflammatory-associated pathologies, we use a specific immunoassay to detect cellular immune responses to pathogen-associated molecular patterns (PAMPs), such as the gram-negative bacterial endotoxin, lipopolysaccharide (LPS). These PAMPs are recognized by pathogen recognition receptors (PRRs), which are found on the cells of the innate immune system 4, 5, 6, 7. A primary signal, LPS, in conjunction with a secondary signal, ATP, is necessary for the activation of the inflammasome, a multiprotein complex that processes pro-IL-1&beta; to its mature, bioactive form 4, 5, 6, 8, 9, 10.
The whole blood assay requires minimal sample manipulation to assess cytokine production when compared to other methods that require labor intensive isolation and culturing of specific cell populations. This method differs from other whole blood stimulation assays; rather than diluting samples with a ratio of RPMI media, we perform a white blood cell count directly from diluted whole blood and therefore, stimulate a known number of white blood cells in culture 2. The results of this particular whole blood assay demonstrate a novel technique useful in elucidating patient cohorts presenting with autoinflammatory pathophysiologies.

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&#946; using a Whole Blood Stimulation Assay

We describe a simple immunoassay to measure the production of pro-inflammatory cytokines, such as IL-1 beta production, in patients presenting with autoinflammatory phenotypes. By activating cells in whole blood cultures with pathogen-associated molecular patterns, specifically with lipopolysaccharide, cytokine secretion can be conveniently evaluated in whole blood supernatants.

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues ...

Rapid Point-of-Care Assay of Enoxaparin Anticoagulant Efficacy in Whole Blood

There is the need for a clinical assay to determine the extent to which a patient's blood is effectively anticoagulated by the low-molecular-weight-heparin (LMWH), enoxaparin. There are also urgent clinical situations where it would be important if this could be determined rapidly. The present assay is designed to accomplish this. We only assayed human blood samples that were spiked with known concentrations of enoxaparin. The essential feature of the present assay is the quantification of the efficacy of enoxaparin in a patient's blood sample by degrading it to complete inactivity with heparinase. Two blood samples were drawn into Vacutainer tubes (Becton-Dickenson; Franklin Lakes, NJ) that were spiked with enoxaparin; one sample was digested with heparinase for 5 min at 37 &deg;C, the other sample represented the patient's baseline anticoagulated status. The percent shortening of clotting time in the heparinase-treated sample, as compared to the baseline state, yielded the anticoagulant contribution of enoxaparin. We used the portable, battery operated Hemochron 801 apparatus for measurements of clotting times (International Technidyne Corp., Edison, NJ). The apparatus has 2 thermostatically controlled (37 &deg;C) assay tube wells. We conducted the assays in two types of assay cartridges that are available from the manufacturer of the instrument. One cartridge was modified to increase its sensitivity. We removed the kaolin from the FTK-ACT cartridge by extensive rinsing with distilled water, leaving only the glass surface of the tube, and perhaps the detection magnet, as activators. We called this our minimally activated assay (MAA). The use of a minimally activated assay has been studied by us and others. 2-4 The second cartridge that was studied was an activated partial thromboplastin time (aPTT) assay (A104). This was used as supplied from the manufacturer. The thermostated wells of the instrument were used for both the heparinase digestion and coagulation assays. The assay can be completed within 10 min. The MAA assay showed robust changes in clotting time after heparinase digestion of enoxaparin over a typical clinical concentration range. At 0.2 anti-Xa I.U. of enoxaparin per ml of blood sample, heparinase digestion caused an average decrease of 9.8% (20.4 sec) in clotting time; at 1.0 I.U. per ml of enoxaparin there was a 41.4% decrease (148.8 sec). This report only presents the experimental application of the assay; its value in a clinical setting must still be established.

Demonstration of a rapid quantitative assay of the inhibition of blood coagulation by the low-molecular-weight-heparin, enoxaparin. The contribution of enoxaparin is assessed by removing its influence through digestion with heparinase. A fuller description of the assay is detailed in our published paper.1 The assay still requires clinical confirmation.

There is the need for a clinical assay to determine the extent to which a patient's blood is effectively anticoagulated by the ...

Real-time Cytotoxicity Assays in Human Whole Blood

A live cell-based whole blood cytotoxicity assay (WCA) that allows access to temporal information of the overall cell cytotoxicity is developed with high-throughput cell positioning technology. The targeted tumor cell populations are first preprogrammed to immobilization into an array format, and labeled with green fluorescent cytosolic dyes. Following the cell array formation, antibody drugs are added in combination with human whole blood. Propidium iodide (PI) is then added to assess cell death. The cell array is analyzed with an automatic imaging system. While cytosolic dye labels the targeted tumor cell populations, PI labels the dead tumor cell populations. Thus, the percentage of target cancer cell killing can be quantified by calculating the number of surviving targeted cells to the number of dead targeted cells. With this method, researchers are able to access time-dependent and dose-dependent cell cytotoxicity information. Remarkably, no hazardous radiochemicals are used. The WCA presented here has been tested with lymphoma, leukemia, and solid tumor cell lines. Therefore, WCA allows researchers to assess drug efficacy in a highly relevant ex&#160;vivo condition.

The whole blood cytotoxicity assay (WCA) is a cytotoxicity assay developed by incorporating high-throughput cell positioning technology with fluorescence microscopy and automated image processing. Here, we describe how lymphoma cells treated with an anti-CD20 antibody can be analyzed real-time in human whole blood to provide quantitative cellular cytotoxicity analysis.

A live cell-based whole blood cytotoxicity assay (WCA) that allows access to temporal information of the overall cell cytotoxicity is developed with ...

Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance

Candida glabrata can rapidly acquire mutations that result in drug resistance, especially to azoles and echinocandins. Identification of genetic mutations is essential, as resistance detected in vitro can often be correlated with clinical failure. We examined the feasibility of using whole genome sequencing (WGS) for genome-wide analysis of antifungal drug resistance in C. glabrata. The aim was torecognize enablers and barriers in the implementation WGS and measure its effectiveness. This paper outlines the key quality control checkpoints and essential components of WGS methodology to investigate genetic markers associated with reduced susceptibility to antifungal agents. It also estimates the accuracy of data analysis and turn-around-time of testing.
Phenotypic susceptibility of 12 clinical, and one ATCC strain of C. glabrata was determined through antifungal susceptibility testing. These included three isolate pairs, from three patients, that developed rise in drug minimum inhibitory concentrations. In two pairs, the second isolate of each pair developed resistance to echinocandins. The second isolate of the third pair developed resistance to 5-flucytosine. The remaining comprised of susceptible and azole resistant isolates. Single nucleotide polymorphisms (SNPs) in genes linked to echinocandin, azole and 5-flucytosine resistance were confirmed in resistant isolates through WGS using the next generation sequencing.&#160;Non-synonymous SNPs in antifungal resistance genes such as FKS1, FKS2, CgPDR1, CgCDR1 and FCY2 were identified. Overall, an average of 98% of the WGS reads of C. glabrata isolates mapped to the reference genome with about 75-fold read depth coverage. The turnaround time and cost were comparable to Sanger sequencing.
In conclusion, WGS of C. glabrata was feasible in revealing clinically significant gene mutations involved in resistance to different antifungal drug classes without the need for multiple PCR/DNA sequencing reactions. This represents a positive step towards establishing WGS capability in the clinical laboratory for simultaneous detection of antifungal resistance conferring substitutions.

Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance

This study implemented whole genome sequencing for analysis of mutations in genes conferring antifungal drug resistance in Candida glabrata. C. glabrata isolates resistant to echinocandins, azoles and 5-flucytosine, were sequenced to illustrate the methodology. Susceptibility profiles of the isolates correlated with presence or absence of specific mutation patterns in genes.

Candida glabrata can rapidly acquire mutations that result in drug resistance, especially to azoles and echinocandins. Identification of genetic mutations ...

How to Administer Near-Infrared Spectroscopy in Critically ill Neonates, Infants, and Children

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated hemoglobin molecules. A probe placed on the skin emits light that is absorbed, scattered, and reflected by the underlying tissue. Detectors in the probe sense the amount of reflected light: this reflects the organ-specific ratio of oxygen supply and consumption - independent of pulsatile flow. Modern devices enable the simultaneous monitoring at different body sites. A rise or dip in the rSO2 curve visualizes changes in oxygen supply or demand before vital signs indicate them. The evolution of rSO2 values in relation to the starting point is more important for interpretation than are absolute values.
A routine clinical application of NIRS is the surveillance of somatic and cerebral oxygenation during and after cardiac surgery. It is also administered in preterm infants at risk for necrotizing enterocolitis, newborns with hypoxic ischemic encephalopathy and a potential risk of impaired tissue oxygenation. In the future, NIRS could be increasingly used in multimodal neuromonitoring, or applied to monitor patients with other conditions (e.g., after resuscitation or traumatic brain injury).

This protocol is designed to assist clinicians to measure regional tissue oxygenation at different body sites in infants and children. It can be used in situations where tissue oxygenation is potentially compromised, particularly during cardiopulmonary bypass, when using non-pulsatile cardiac-assist devices, and in critically ill neonates, infants and children.

Near infrared spectroscopy (NIRS) calculates regional tissue oxygenation (rSO2) using the different absorption spectra of oxygenated and deoxygenated ...

Infrared Thermography for the Detection of Changes in Brown Adipose Tissue Activity

Measuring brown adipose tissue (BAT) activity by positron emission tomography computed tomography (PET-CT) via the accumulation of 18F-fluorodeoxyglucose (FDG) after a meal or in obese or diabetic patients fails as the method of choice. The main reason is that 18F-FDG competes with the postprandial high glucose plasma concentration for the same glucose transporter on the membrane of BAT cells. In addition, BAT uses fatty acids as a source of energy as well, which is not visible with PET-CT and could be changed along with glucose concentration in obese and diabetic patients. Therefore, to estimate the physiological importance of BAT in animals and humans, a new infrared thermography method used in recent publications is applied.
After overnight fasting, BAT activity was measured by infrared thermography before and after a meal in human volunteers and&#160;female wild-type mice. The camera software calculates the object&#39;s temperature using distance from the object, skin emissivity, reflected room temperature, air temperature, and relative humidity. In mice, the shaved area above the BAT was a region of interest for which average and maximal temperatures were measured. The phase of the estrous cycle in female mice was determined after an experiment by vaginal smears stained with cresyl violet (0.1%) stain solution. In healthy volunteers, two skin areas of the neck were selected: the supraclavicular area (above the collarbone, where BAT cells are present) and the interclavicular area (between the collarbones, where there is no BAT tissue detected). BAT activity is determined by the subtraction of those two values. Also, the average and maximal temperatures of skin areas could be determined in animals and human participants.
Changes in BAT activity after a meal measured by infrared thermography, a non-invasive and more sensitive method, were shown to be sex, age, and phase of the estrous cycle dependent in laboratory animals. As part of diet-induced thermogenesis, BAT activation in humans was also proven to be sex, age, and body mass index dependent. Further determining the pathophysiological changes in BAT activity after a meal will be of great importance for participants with high glucose plasma concentrations (obesity and diabetes mellitus type 2), as well as in different laboratory animals (knock-out mice). This method is also a variable tool for determining possible activating drugs that could rejuvenate BAT activity.

Here, we present a protocol for measuring brown adipose tissue activity after a meal in humans and laboratory animals.

Measuring brown adipose tissue (BAT) activity by positron emission tomography computed tomography (PET-CT) via the accumulation of 18F-fluorodeoxyglucose ...

An Educational Video Demonstration of How to Prone a Critically Ill Intubated Patient

Early in the coronavirus disease 2019 (COVID-19) pandemic, it was reported that prone position was beneficial for mechanically ventilated COVID-19 patients with acute respiratory distress syndrome (ARDS). However, for staff in some small and large hospitals, experience with this intervention was low. Select hospitals were able to assemble proning teams; but, as facilities began to experience staffing shortages, they found proning teams unsustainable, and less specialized staff needed to learn how to safely prone patients.
Proning is a high-risk procedure-a lack of a standard approach can result in staff confusion and poor patient outcomes, including unintentional endotracheal tube (ET) loss, vascular access dislodgement, and skin breakdown. Given the acuity and high patient volume, translating a complex procedure into written policy may not be entirely effective. Critical care nurses, respiratory therapists, physical therapists, wound nurses, nurse practitioners, physician assistants, and medical doctors need to be prepared to safely perform this procedure for an acutely ill COVID-19 patient.
Communication, teamwork, and multidisciplinary collaboration are critical for complication avoidance. Interventions to prevent tube and vascular access dislodgement, skin breakdown, and brachial plexus and soft tissue injury must be implemented during the procedure. Repositioning the patient in the prone position, as well as returning the patient to supine positioning, should be components of a comprehensive proning plan.

Proning a critically ill patient with severe acute respiratory distress syndrome (ARDS) is a complex but beneficial procedure. Excellent communication skills, team work, and multidisciplinary collaboration are critical for patient and staff safety. A standard procedure should be utilized when proning ventilated patients with tubes, drains, and vascular access devices.

Early in the coronavirus disease 2019 (COVID-19) pandemic, it was reported that prone position was beneficial for mechanically ventilated COVID-19 ...

A Modified Sonographic Algorithm for Image Acquisition in Life-Threatening Emergencies in the Critically Ill Newborn

The use of routine point-of-care ultrasound (POCUS) is increasing in neonatal intensive care units (NICUs), with several centers advocating for 24 h equipment availability. In 2018, the sonographic algorithm for life-threatening emergencies (SAFE) protocol was published, which allows the assessment of neonates with sudden decompensation to identify abnormal contractility, tamponade, pneumothorax, and pleural effusion. In the study unit (with a consulting neonatal hemodynamics and POCUS service), the algorithm was adapted by including consolidated core steps to support at-risk newborns, aiding clinicians in managing cardiac arrest, and adding views to verify correct intubation. This paper presents a protocol that can be applied in the NICU and the delivery room (DR) in relation to three scenarios: cardiac arrest, hemodynamic deterioration, or respiratory decompensation. 
This protocol can be performed with a state-of-the-art ultrasound machine or an affordable handheld device; the image acquisition protocol is carefully detailed. This method was designed to be learned as a general competence to obtain the timely diagnosis of life-threatening scenarios; the method aims to save time but does not represent a substitute for comprehensive and standardized hemodynamic and radiological analyses by a multidisciplinary team, which might not universally be on call but needs to be involved in the process. From January 2019 to July 2022, in our center, 1,045 hemodynamic consultation/POCUS consults were performed with 25 patients requiring the modified SAFE protocol (2.3%), and a total of 19 procedures were performed. In five cases, trained fellows on call resolved life-threatening situations. Clinical examples are provided that show the importance of including this technique in the care of critical newborns.

Here, we present a protocol that can be applied in the neonatal intensive care unit and the delivery room in relation to three scenarios: cardiac arrest, hemodynamic deterioration, or respiratory decompensation. This protocol can be performed with a state-of-the-art ultrasound machine or an affordable handheld device; an image acquisition protocol is carefully detailed.

The use of routine point-of-care ultrasound (POCUS) is increasing in neonatal intensive care units (NICUs), with several centers advocating for 24 h ...

Assessing Blood Hypercoagulation of EV-Rich Plasma

Determination of the Procoagulant Activity of Extracellular Vesicle (EV) Using EV-Activated Clotting Time (EV-ACT)

The role of extracellular vesicles (EV) in various diseases is gaining increased attention, particularly due to their potent procoagulant activity. However, there is an urgent need for a bedside test to assess the procoagulant activity of EV in clinical settings. This study proposes the use of thrombin activation time of EV-rich plasma as a measure of EV's procoagulant activity. Standardized procedures were employed to obtain sodium-citrated whole blood, followed by differential centrifugation to obtain EV-rich plasma. The EV-rich plasma and calcium chloride were added to the test cup, and the changes in viscoelasticity were monitored in real-time using an analyzer. The natural coagulation time of EV-rich plasma, referred to as EV-ACT, was determined. The results revealed a significant increase in EV-ACT when EV was removed from plasma obtained from healthy volunteers, while it significantly decreased when EV was enriched. Furthermore, EV-ACT was considerably shortened in human samples from preeclampsia, hip fracture, and lung cancer, indicating elevated levels of plasma EV and promotion of blood hypercoagulation. With its simple and rapid procedure, EV-ACT shows promise as a bedside test for evaluating coagulation function in patients with high plasma EV levels.

Author Spotlight: Deciphering Coagulation Disorders in Traumatic Brain Injury Patients 

This protocol investigates the use of extracellular vesicle (EV)-rich plasma as an indicator of the coagulative ability of EV. EV-rich plasma is obtained through a process of differential centrifugation and subsequent recalcification.

The role of extracellular vesicles (EV) in various diseases is gaining increased attention, particularly due to their potent procoagulant activity. ...