The overall goal of this procedure is to facilitate the investigation, modeling, and experimental modification of systemic inflammation and its downstream effects in humans. This method can help answer many of the key questions that still prevail today about the pathogenesis of critical illnesses. We believe that Intravenous Endotoxin Challenge, and this is many of the vascular, blood, endocrine, immunological, as well as organ-specific changes that mimic those observed in pathological inflammatory states.
The main advantages of this technique are the ability to access and potentially pharmacologically modify both the early and late phases of inflammation, triggered by biologically relevant stimulus. The implications of this technique extend toward the diagnosis and therapy of critical illnesses, such as sepsis, as it partially replicates clinically-observed physiological and immunological alterations. Helping me demonstrate the procedural, Alexander Maini, an experienced clinician, has a minimum of at least one medically qualified investigator is required for the procedure.
On the day of the procedure, use aseptic non-touch technique, to reconstitute a fresh vile of 10, 000 units of clinical center reference endotoxin and five milliliters of sterile water for injection. Then place the vile on a vortex shaker for at least one hour to ensure all of the endotoxin enters into the solution. Next, arrange a bed with the head at 45 degrees in an appropriate location with access to additional clinical assistance and resuscitation equipment, if required, and confirm that the required clinical and experimental equipment are functional.
Before beginning the procedure, confirm that the patient has provided written consent and has previously undergone a health screen, including a clinical history, examination, and core investigations. Ask the participant about any new illnesses or symptoms since undertaking the health screen, and confirm the compliance with the protocol-specific instructions. Ensure the participant has voided the bladder and bowel.
Then, after a weight check, ask the participant to lie on the prepared bed in a comfortable position. Next, using aseptic non-touch technique, insert an intravenous cannula for the administration of the endotoxin, followed by the intravenous placement of a second intravascular line with large bore cannula in the antecubital fossa for the administration of fluids and the ongoing blood draw. After the lines have been inserted, draw and discard five milliliters of blood.
And then obtain a blood sample for baseline tests. Flush the line with 10 milliliters of 0.9 percent sodium chloride, and attach clinical monitoring equipment, as appropriate. Then record the baseline routine clinical observations on an appropriate vital sign chart.
Subjective symptom scoring should additionally be performed to monitor the participant experience. When the participant and endotoxin are ready, draw a weight-adjusted dose of the solution into a one milliliter syringe. Here, two nanograms per kilogram will be administered.
To administer the endotoxin. flush the first cannula with 0.9 percent sodium chloride to ensure that the instrument is correctly cited and patented, and then deliver the endotoxin bolus dose in under two minutes into a three-way tap at the hub of the IV line. It is vital that the endotoxin is administered rapidly and in its entirety, to ensure a consistent interparticipant response.
Please also note that the volunteers will not report some traumatic alterations immediately, with the onset occurring instead at around 60 minutes. After the bolus IV endotoxin has been completely delivered, flush the line with 10 more milliliters of 0.9 percent sodium chloride, to ensure that all of the toxin enters the circulation. Then, monitor the participant for a minimum of eight hours, recording and reviewing the vital signs and any clinical observations at a minimum of once per hour.
Continuous monitoring, such as three lead cardiac monitoring, may also be undertaken. Routinely administer two to three liters of IV crystalloid fluid to the participant over six to eight hours to replace insensible losses and to substitute routine fluid intake, if nil by mouth. Predetermined samples, for instance, of blood or urine, may be obtained at any point following the endotoxin administration.
When all of the participants observations have returned to baseline, or are demonstrating a consistent trend to normal, have the attending clinician confirm that the participant's symptoms have settled and that sensation of the monitoring is permissible. Then remove all of the monitoring equipment and intravascular lines, and discharge the participant. A bolus of two nanograms per kilogram reliantly elicits the features of Systemic Inflammatory Response Syndrome, including a raised core temperature, heart, and respiratory rates and white blood cell count.
These responses are accompanied by the release of humoral mediators of inflammation, including pro-inflammatory cytokines, like tumor necrosis factor alpha, and acute phase proteins, like c-reactive protein. Metabolism, in both the central and peripheral tissues is also altered and multiple organ-specific functional alterations are elicited, including a variety of flu-like symptoms, such as headache, myalgia, and nausea that peak in intensity around one to two hours and largely abate by six hours. The procedure of Intravenous and Endotoxin Challenge can typically be completed in eight hours, depending on the individual volunteer's responses.
While attending this procedure, it's important to remember that the safety of the participant is paramount. This procedure may be adapted with the addition of focus investigations, or with the administration of pharmacologocally active compounds to further understand the specific physiological and immunological parameters of interest. After watching this video, you should have a good understanding of how to safely induce a systemic inflammatory response in humans, via the screening and consenting of healthy humans before and their monitoring after the administration of endotoxin.
Don't forget that endotoxin injection is potentially hazardous and that precautions, including ensuring the availability of resuscitation equipment and additional clinical support, should always be taken while performing this procedure.
