Mechanical ventilation is a well–known trigger for lung inflammation. Research focuses on tidal volume reduction to prevent ventilator-induced lung injury. Mechanical ventilation is usually applied with higher than physiological oxygen fractions. The purpose of this study was to investigate the after effect of oxygen supplementation during a spontaneous ventilation set up, in order to avoid the inflammatory response linked to mechanical ventilation. A prospective randomised study using New Zealand rabbits in a university research laboratory was carried out. Rabbits (n = 20) were randomly assigned to 4 groups (n = 5 each group). Groups 1 and 2 were submitted to 0.5 L/min oxygen supplementation, for 20 or 75 minutes, respectively; groups 3 and 4 were left at room air for 20 or 75 minutes. Ketamine/xylazine was administered for induction and maintenance of anaesthesia. Lungs were obtained for histological examination in light microscopy. All animals survived the complete experiment. Procedure duration did not influence the degree of inflammatory response. The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates. The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure. All animals showed some inflammatory lung response. However, rabbits submitted to oxygen supplementation showed significant more lung inflammation (Odds ratio = 16), characterized by more infiltrates and with higher cell counts; the acute inflammatory response cells was mainly constituted by eosinophils and neutrophils, with a relative proportion of 80 to 20% respectively. This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis. Oxygen supplementation in spontaneous breathing is associated with an increased inflammatory response when compared to breathing normal room air. This inflammatory response was mainly constituted with polymorphonuclear cells (eosinophils and neutrophils). As confirmed in all animals by peripheral blood analyses, the eosinophilic inflammatory response was a local organ event.

The quantitative analysis of pharmaceuticals in biomatrices by liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is often hampered by adduct formation. The use of the molecular ion resulting from solvent adducts for quantification is uncommon, even if formed in high abundance. In this work, we propose the use of a protonated acetonitrile adduct for the quantitative analysis of tranexamic acid (TXA) by LC-MS/MS. The high abundance of the protonated acetonitrile adduct [M + ACN + H]⁺ was found to be independent of source-dependent parameters and mobile phase composition. The results obtained for TXA analysis in clinical samples were comparable for both [M + ACN + H]⁺ and [M + H]⁺, and no statistically significant differences were observed. The relative stability and structure of the [M + ACN + H]⁺ ions were also studied by analyzing probable structures from an energetic point of view and by quantum chemical calculations. These findings, and the studied fragmentation pathways, allowed the definition of an acetimidium structure as the best ion to describe the observed acetonitrile protonated adduct of TXA.

Aims: Tranexamic acid (TXA) stabilizes clot formation by inhibiting fibrin degradation and improves postoperative outcomes. However, rare adverse events (e.g., thrombosis, seizures) warrant dose–risk evaluation. This study examines how perioperative blood loss and transfusion practices affect TXA concentrations during paediatric scoliosis surgery. Methods: Forty‐three patients undergoing scoliosis surgery with TXA were retrospectively analysed. The study assessed the impact of packed red blood cell (PRBC) transfusion on plasma TXA levels and whether maintaining concentrations ≥10 μg/mL correlated with intraoperative blood loss. TXA levels were measured using UHPLC–MS/MS. Results: Median TXA concentration 30 min after the loading dose was 37.8 μg/mL (IQR: 31.4–39.6 μg/mL), decreasing to 10.6 μg/mL (IQR: 9.7–13.5 μg/mL) after transfusion. At surgery end, the mean concentration was 12.9 ± 2.5 μg/mL. Thirty‐one patients maintained TXA levels ≥10 μg/mL, associated with ~80% inhibition of tissue plasminogen activator . Of six patients below this threshold, five had received transfusions. A significant correlation was found between higher intraoperative blood loss and lower TXA levels, consistent with a dilutional effect. In contrast, among patients with TXA ≥ 10 μg/mL, correlation with blood loss was weak (Spearman's ρ = −0.11, p = 0.54). Findings suggest homologous PRBC transfusion reduces plasma TXA through volume expansion. Conclusions: Sustaining TXA concentrations >10 μg/mL is essential for antifibrinolytic efficacy and haemostatic outcomes. The dilutional impact of PRBC transfusion underscores the need for intraoperative dose adjustment. Optimizing TXA dosing requires understanding pharmacokinetics and patient variability.

Despite advances in surgical and blood management techniques, it continues to carry risks of excessive blood loss and transfusion. Tranexamic Acid (TXA), an antifibrinolytic agent, has shown efficacy in reducing these risks across various surgeries. This retrospective cohort study evaluated factors influencing intraoperative blood loss in Adolescent Idiopathic Scoliosis (AIS) surgery, focusing on low-dose TXA administration. This retrospective cohort study included 187 AIS patients undergoing posterior spinal fusion with or without intraoperative TXA. Patients were grouped into non-TXA (116 patients) and TXA (71 patients) cohorts. The TXA group received a 10 mg.kg^-1 intravenous loading dose over 15 minutes, followed by a continuous infusion of 1 mg.kg^-1.h^-1 until skin closure. Outcomes included estimated blood loss, transfusion needs, length of stay, and thromboembolic or neurologic complications. Multivariate regression adjusted intraoperative blood volume loss for potential covariates. Baseline demographic characteristics were similar between groups. However, differences in surgical complexity cannot be excluded and are acknowledged. TXA use was associated with a 39% reduction in estimated intraoperative blood volume loss compared with the non-TXA group. Blood loss correlated significantly with TXA use, sex, ASA status, number of fused levels, curve type, and surgery duration. Low-dose TXA significantly reduced intraoperative blood loss and transfusion requirements during AIS surgery. Greater blood loss was linked to longer procedures and more fused levels, whereas lumbar curve type appeared protective. This study provides insights into AIS outcomes and their associations with predictive factors and TXA use. Level III - retrospective cohort study.