Intravenous sodium bicarbonate verifies intravenous position of catheters in ventilated patients.

BACKGROUND: Extravasation is the unintentional injection or leakage of fluids into the perivascular or subcutaneous space resulting in potential tissue injury. In this 2-part prospective, controlled study, we assessed the safety of subcutaneously injected sodium bicarbonate in rats first. In the second part, the diagnostic utility of using IV diluted sodium bicarbonate to confirm placement of IV catheters in endotracheally intubated and ventilated rats and patients was tested. Diluted sodium bicarbonate was created using undiluted standard 8.4% (1 mEq/mL) sodium bicarbonate mixed in a 1:1 ratio with sterile water to achieve a final diluted concentration of 4.2% (0.5 mEq/mL). METHODS: Sodium bicarbonate (8.4% and 4.2%) was injected subcutaneously into 10 rats, and skin samples were evaluated. The hemodynamic and ventilatory effects of IV bicarbonate (2 mL/kg) in ventilated rats were measured. Subsequently, in 20 ASA physical status I and II mechanically ventilated patients, the effects of 50 mL of diluted 4.2% sodium bicarbonate or 0.9% normal saline, injected in a randomized order, were analyzed. RESULTS: Part 1: Undiluted (8.4%) subcutaneous sodium bicarbonate resulted in a small area of skin necrosis in 10% of skin samples (3 of 30) taken from rats. Minimal effects (mild scale crust and foci of regenerative epidermis beneath) were detected when a diluted solution was used. In ventilated rats, IV injection of diluted bicarbonate caused a significant increase in end-tidal carbon dioxide, whereas subcutaneous injection had no effect. In humans, diluted bicarbonate resulted in an end-tidal carbon dioxide increase (mean of 38 ± 5 to 45 ± 7 mm Hg) within 7 breaths. Injected normal saline did not result in any changes. Sodium bicarbonate was easily differentiated from normal saline injection by anesthesiologists observing the change in end-tidal carbon dioxide concentrations immediately after injection. CONCLUSION: The injection of diluted sodium bicarbonate (in mechanically ventilated patients) can be used to reliably identify the correct location of an IV catheter by an increase in the exhaled carbon dioxide concentration. Although we found no skin damage with 4.2% (0.5 mEq/mL) sodium bicarbonate, safety and efficacy should be further evaluated in future studies.

Using high titer West Nile intravenous immunoglobulin from selected Israeli donors for treatment of West Nile virus infection.

BACKGROUND: West Nile Virus (WNV) is endemic in Israel and a significant level of antibodies is present in the population due to natural exposure. Anecdotal cases suggested that the presence of anti-WNV antibodies in intravenous immunoglobulin (IVIG) from Israeli donors (IVIG-IL) assisted the recovery of patients with severe WNV infection. METHODS: To enhance the therapeutic efficacy of IVIG-IL against WNV infection, OMRIX Biopharmaceuticals, Israel, have developed a strategy for selection of plasma units from a 10% fraction of Israeli blood donors with anti-WNV antibodies. Positive units were processed into pharmaceutical grade WNV IVIG (WNIG). Following inoculation with WNV, mice received i.p. injections of different doses (0.01-8 mg/mouse) of IVIG-IL or WNIG, according to the specific experimental protocol. RESULTS: WNIG was about 10 times more potent (per gr of IgG) than was regular IVIG-IL when tested by ELISA and neutralization assays. In a mouse lethal WNV infection model, prophylactic treatment with WNIG was at least 5-10-fold more potent as compared to treatment with IVIG-IL. Treatment with WNIG during active encephalitis, three or four days following WNV infection, had a significant protective effect. WNIG was also very effective in protecting immunosuppressed mice. Indeed, treatment of dexamethasone-immunosuppressed mice with 0.2 or 1.0 mg WNIG 4 h after virus infection, led to 100% survival. CONCLUSION: IVIG produced from selected plasma donated in WNV endemic regions can be used to produce WNV IVIG with superior activity for therapeutic and prophylactic measures.

A method to measure thrombin activity in a mixture of fibrinogen and thrombin powders.

Thrombin and fibrinogen powders are the active components of advanced surgical hemostasis products including the EVARREST Fibrin Sealant Patch. Measuring the enzymatic activity of thrombin in the presence of fibrinogen is challenging, as hydration of the powders in a neutral aqueous environment will cause the enzyme to rapidly react with the fibrinogen to form a fibrin clot, which in turn binds and entraps the enzyme thus preventing subsequent measurement of thrombin activity. A novel approach has been developed to overcome this challenge. After isolation of the mixture of powders, an alkaline carbonate solution is used to solubilize the proteins, while reversibly inhibiting the activity of thrombin and preventing clot formation. Once the powders have been fully solubilized, thrombin activity can be restored by neutralization in a buffered fibrinogen solution resulting in fibrin clot formulation. The rate of clot formation can be quantified in a coagulometer to determine the thrombin activity of the original powder. Samples coated with powders containing fibrinogen and varying amounts of thrombin were tested using the method described herein. The results demonstrated that the method could consistently measure the activity of (alpha) thrombin in the presence of fibrinogen over a broad range of thrombin activity levels. The test was successfully validated according to International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use Guidelines and thus is suitable for use as part of a commercial manufacturing process. A method has been developed that enables thrombin activity to be measured in a mixture of fibrinogen and thrombin powders.

Toward molecular targeting with specific intravenous immunoglobulin preparation.

Intravenous immunoglobulin (IVIg) is used successfully for therapy of inflammatory and autoimmune diseases, especially in cases of conventional therapy resistance. Within the broad spectrum of immunoregulatory activities of IVIg in vitro and in vivo, the anti-idiotypic activity neutralizing the related idiotypes is one of the main mechanisms. Furthermore, IVIg addresses integrins associated with inflammation and immune response thrombosis, such as the RGD (Arg-Gly-Asp) motif, expressed on a large number of cell surface and matrix proteins. In addition, during the last years, anti-Fas activity of IVIg was reported. We fractionated IVIg specific preparation (sIVIg) based on the multispecificities of the IVIg compound. We have generated an IVIg fraction that will show specific activity for lupus idiotypes in vitro. In NZBxW.F1 mice, results showed 200 times more beneficial effect. Using a peptide phage display library technology, we have identified a panel of lupus-related synthetic idiotypes that are mimetics of the idiotypes presented in patients with systemic lupus erythematosus. A column composed of these synthetic lupus-related idiotypes was used to prepare a large amount lupus-specific IVIg. Using the same approach, we prepared anti-anti-beta-2-glycoprotein-I (beta2GPI) specific IVIg for antiphospholipid syndrome (APS). This APS-specific IVIg reduced the fetal loss induced by anti-beta2GPI antibodies by improving the implantation process in a mouse model. Others prepared specific preparations of IVIg to RGD or for Fas. The molecular targeting with specific IVIg may be used for therapeutical purposes, using a smaller amount of IVIg, and targeting more specifically autoimmune diseases, thrombosis, or inflammatory condition.

The binding of fibrin sealant to collagen is influenced by the method of purification and the cross-linked fibrinogen-fibronectin (heteronectin) content of the 'fibrinogen' component.

Two fibrinogen preparations, each an intermediate in the manufacture of the 'fibrinogen' component of a commercial human tissue sealant, were made from a common cryoprecipitate source. The first preparation, prepared according to the process described by Schwartz et al. had a higher ratio of clottable to total protein than the second preparation, prepared according to that by Martinowitz and Bal but a much lower ratio of fibronectin to fibrinogen. After clotting with thrombin and solubilization and reduction of the clots, sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a much higher content of high molecular weight polymers of fibrin(ogen) in the second preparation than in the first. The second preparation bound to collagen more strongly than did cryoprecipitate and much more strongly than did the first one. Experiments with highly purified proteins showed that fibronectin was essential in promoting progressive binding of fibrinogen to collagen under the action of activated factor XIII (transglutaminase). It was concluded that, because of their method of purification from cryoprecipitate, preparations of fibrinogen differ in their content of fibronectin and heteronectin. The binding of these proteins to collagen may improve the adhesion of tissue sealant clots to the extracellular matrix.

Temperature-controlled laser-soldering system and its clinical application for bonding skin incisions.

Laser tissue soldering is a method of repairing incisions. It involves the application of a biological solder to the approximated edges of the incision and heating it with a laser beam. A pilot clinical study was carried out on 10 patients who underwent laparoscopic cholecystectomy. Of the four abdominal incisions in each patient, two were sutured and two were laser soldered. Cicatrization, esthetical appearance, degree of pain, and pruritus in the incisions were examined on postoperative days 1, 7, and 30. The soldered wounds were watertight and healed well, with no discharge from these wounds or infection. The total closure time was equal in both methods, but the net soldering time was much shorter than suturing. There was no difference between the two types of wound closure with respect to the pain and pruritus on a follow-up of one month. Esthetically, the soldered incisions were estimated as good as the sutured ones. The present study confirmed that temperature-controlled laser soldering of human skin incisions is clinically feasible, and the results obtained were at least equivalent to those of standard suturing.

The effect of tranexamic acid in fibrin sealant on adhesion formation in the rat.

The objective of the research was to determine the effect of the type, dose, and volume of anti-fibrinolytic agents (tranexamic acid, aprotinin) added to fibrin formulations, on adhesion development. Adhesions were induced in 228 male rats by creating apposing parietal and visceral peritoneal defects. Animals were randomized to receive no treatment or a fibrin formulation containing aprotinin or tranexamic acid. Seven days later the incidence of adhesions, and the force and energy required to detach them, were determined. Adhesions developed in 13/13 rats in the control and aprotinin groups. Treatment with fibrin (100 mg/ml tranexamic acid) resulted in adhesions in 4/14 rats (as strips, p < or = 0.0005), 4/10 rats (as spray, p < or = 0.0036), and 12/15 rats (by drip). The reduction of adhesions was dependent on the concentration of tranexamic acid with strip and spray application. Using commercial formulations, tranexamic-acid-containing fibrin (10/15, p = 0.042), but not aprotinin-containing fibrin (13/15), reduced the incidence of side-wall adhesions from 15/15 in controls. Fibrin containing either tranexamic or aprotinin reduced the incidence and severity of adhesions. This effect was greater when tranexamic acid was used and was dependent on the mode of administration, the volume, and to a degree, the concentration of tranexamic acid.

A comparison of the mechanical, kinetic, and biochemical properties of fibrin clots formed with two different fibrin sealants.

The objective of the present study was to compare the mechanical, kinetic, and biochemical properties of fibrin clots produced using EVICEL Fibrin Sealant (Human) and TISSEEL Fibrin Sealant. The stiffness/elasticity and strength of fibrin clots formed with EVICEL and TISSEEL were assessed using applied mechanical force and thromboelastography (TEG). The factor XIII content of the fibrin clots was also evaluated. Mean Young modulus and tensile strength of the fibrin clots produced by EVICEL were significantly higher than those of clots produced by TISSEEL (P < 0.05 for both). The mean time to initial clot formation and mean time to the predefined level of clot formation were numerically shorter for EVICEL compared with TISSEEL. Furthermore, mean maximal amplitude of the clots formed with EVICEL was significantly greater than that for the clots formed with TISSEEL. Mean concentration of factor XIII for the EVICEL fibrinogen samples tested was 9 IU/ml compared with undetectable concentrations of factor XIII for the TISSEEL fibrinogen samples. Fibrin clots formed with EVICEL have a much higher resistance to stretching and tensile strength and are more capable of maintaining their structure against applied force than those formed with TISSEEL. EVICEL also allows more rapid development of fibrin clots than TISSEEL. This superior clot strength and resilience obtained with EVICEL relative to TISSEEL may be due in large part to the presence of factor XIII.

Evaluation of a fibrin preparation containing tranexamic acid (Adhexil) in a rabbit uterine horn model of adhesions with and without bleeding and in a model with two surgical loci.

OBJECTIVE: To compare the efficacy of a fibrin preparation supplemented with tranexamic acid (Adhexil) with that of established devices, and to determine whether its effect is limited to the site of application. DESIGN: Rabbit uterine horns were abraded in nonbleeding and bleeding variants of an established adhesions model. In a separate study, a sidewall excision with approximation of the abraded cecum was added. Animals randomly received Adhexil at both, neither, or either loci. SETTING: Laboratory study. ANIMAL(S): Seventy-two female New Zealand White rabbits (Oryctolagus cuniculus). INTERVENTION(S): Adhexil, Seprafilm or SprayGel and Interceed. MAIN OUTCOME MEASURE(S): The extent of adhesions was evaluated 13 to 16 days after surgery. RESULT(S): Adhexil reduced adhesions (15 +/- 7%; 15 +/- 4%) compared with controls (74 +/- 13%; 78 +/- 9%) in the bleeding and nonbleeding models, respectively. The reductions resulting from the use of Seprafilm (39 +/- 17%; 34 +/- 14%) or SprayGel (61 +/- 18%; 43 +/- 14%) (n = 4) were not statistically significant. In the bleeding model, Interceed (48 +/- 15%) reduced adhesions only modestly. CONCLUSION(S): In the combined uterine and sidewall model, Adhexil reduced selectively the extent and incidence of adhesions. The absolute and relative performance of Adhexil in an established adhesions model and in the presence of bleeding justifies its further investigation.