Mathematical analysis of isovolemic hemodilution indicates that it can decrease the need for allogeneic blood transfusion

BACKGROUND: The implementation of acute isovolemic hemodilution prior to surgical blood loss is a strategy used in an attempt to diminish the need for or obviate allogeneic transfusion and to avert the potential, attendant complications. Studies examining the efficacy of this technique have produced conflicting results. STUDY DESIGN AND METHODS: The present mathematical analysis was undertaken to resolve these conflicts by determining the efficacy of hemodilution and examining the influence of the variables affecting the outcome. Efficacy was defined as the volume of additional blood loss permitted and the volume and number of units of allogeneic blood saved from transfusion. A mathematical analysis evaluated the impact of circulating blood volume and initial and target hematocrits on the efficacy of isovolemic hemodilution. It was assumed that 1) hemodilution was completed before surgical blood loss; 2) transfusion of removed blood was begun when the target hematocrit was reached and lost surgical blood was replaced at a rate that maintained the target hematocrit; 3) allogeneic transfusion was begun after all autologous blood drawn was transfused; 4) normovolemia was maintained; and 5) a unit of allogeneic blood contains 175 mL of red cells. RESULTS: The analysis showed that isovolemic hemodilution can result in substantial additional allowable surgical blood loss that can diminish the need for or obviate allogeneic transfusion of red cells. Larger circulating blood volume, higher initial hematocrits, and lower target hematocrits increase the efficacy of hemodilution. Removal and isovolemic replacement of 1 to 2 units of blood provide minimal potential savings, as does hemodilution to a circulating (target) hematocrit of 30 percent. The extension of hemodilution to a hematocrit of (or below) 20 percent allows a disproportionately greater surgical blood loss and diminishes the need for allogeneic transfusion. It allows, for example, an additional 4.5 L of surgical blood loss, which represents a savings of 4 units of allogeneic blood when a patient with an initial blood volume of 5.0 L and a hematocrit of 45 percent undergoes isovolemic hemodilution to a hematocrit of 15 percent. CONCLUSION: Isovolemic hemodilution can diminish or in some circumstances eliminate the need for allogeneic transfusion.     

Design and synergistic effect of nano-sized epoxy-NiCo2O4 nanocomposites for anticorrosion applications

In the present work, we evaluated the corrosion inhibition properties of a ligand and mixed metal oxide nanocomposite. The ligand and mixed nickel–cobalt complex were synthesized using 1-naphthoic acid and aminoguanidine with the formulae [C₁₁H₇O₂(CN₄H₅)(CN₄H₆)]·H₂O and {Ni–Co[(CH₅N₄)₂(C₁₁H₇O₂)₂]}·H₂O, respectively. After their synthesis, physicochemical techniques such as CHNS analysis, infrared and UV-visible spectroscopy, thermal analysis, and X-ray diffraction (XRD) were employed to characterize both the synthesized ligand and nickel–cobalt complex. The metal oxide prepared from the decomposition of the metal complex was also characterized using several techniques to confirm its bonding and structure. In addition, the corrosion inhibition efficiency of the epoxy-ligand and epoxy-NiCo₂O₄ nanocomposite on mild steel (MS) in 3 M hydrochloric acid (HCl), 1.5 M sulfuric acid (H₂SO₄), and 0.5 M phosphoric acid (H₃PO₄) solution was examined and compared using weight loss measurements, Tafel plots, isotherms and electrochemical impedance spectroscopy (EIS). The results from the electrochemical studies disclosed that the epoxy coating of mixed metal oxides with 0.8 ppm concentration yielded excellent corrosion protection. The SEM images of mild steel and mild steel coated with epoxy-ligand/epoxy-NiCo₂O₄ in HCl confirmed the anti-corrosive behavior of the synthesized compounds. Hence, the as-prepared material can be a next-generation tool for sustainable anti-corrosive coatings.

This study reports the synthesis of nano-sized epoxy-NiCo₂O₄ nanocomposites and their anti-corrosive efficiency to attain sustainable development.