Pressure ulcer development in patients treated for acute ischaemic stroke.

OBJECTIVE: The aim of this study was to determine the incidence of pressure ulcers (PUs) in patients treated for acute ischaemic stroke (AIS) and to evaluate comorbid/confounding factors. METHOD: The study included patients treated for AIS who were divided into three treatment groups: those receiving intravenous tissue plasminogen activator therapy (tPA); patients receiving mechanical thrombectomy (MT); and those receiving both tPA and MT. PUs were classified according to the international classification system and factors that may influence their development were investigated. RESULTS: A total of 242 patients were included in this study. The incidence of PUs in patients treated for AIS was 7.4%. Most PUs were located on the sacrum (3.7%), followed by the gluteus (3.3%) and trochanter (2.9%). With regards to PU classification: 29% were stage I; 34% were stage II; and the remainder were stage III. Age was not a significant factor in the development of PUs (p=0.172). Patients in the tPA group had a lower PU incidence (2.3%) than patients in the tPA+MT group (15.7%) and MT group (12.1%) (p=0.001). Patients with PUs had a longer period of hospitalisation (18.5±11.92 days) than patients without a PU (8.0±8.52 days) (p=0.000). National Institute of Health Stroke Scale (NIHSS) scores at admission were higher in patients with PUs than in patients without a PU (14.33±4.38 versus 11.08±5.68, respectively; p=0.010). The difference in presence of comorbidities between patients with and without PUs (p=0.922) and between treatment groups (p=0.677) were not statistically significant. The incidence of PUs was higher in patients requiring intensive care, but this difference was not statistically significant (p=0.089). CONCLUSION: In this study, patients treated for AIS with high NIHSS scores at admission and/or receiving MT were at higher risk for PUs, and so particular attention should be given to these patients in order to prevent PU development.

Factors influencing the efficacy of recombinant tissue plasminogen activator: Implications for ischemic stroke treatment.

Intravenous thrombolysis with a recombinant tissue plasminogen activator (rt-PA) is the first-line treatment of acute ischemic stroke. However, successful recanalization is relatively low and the underlying processes are not completely understood. The goal was to provide insights into clinically important factors potentially limiting rt-PA efficacy such as clot size, rt-PA concentration, clot age and also rt-PA in combination with heparin anticoagulant. We established a static in vitro thrombolytic model based on red blood cell (RBC) dominant clots prepared using spontaneous clotting from the blood of healthy donors. Thrombolysis was determined by clot mass loss and by RBC release. The rt-PA became increasingly less efficient for clots larger than 50 µl at a clinically relevant concentration of 1.3 mg/l. A tenfold decrease or increase in concentration induced only a 2-fold decrease or increase in clot degradation. Clot age did not affect rt-PA-induced thrombolysis but 2-hours-old clots were degraded more readily due to higher activity of spontaneous thrombolysis, as compared to 5-hours-old clots. Finally, heparin (50 and 100 IU/ml) did not influence the rt-PA-induced thrombolysis. Our study provided in vitro evidence for a clot size threshold: clots larger than 50 µl are hard to degrade by rt-PA. Increasing rt-PA concentration provided limited thrombolytic efficacy improvement, whereas heparin addition had no effect. However, the higher susceptibility of younger clots to thrombolysis may prompt a shortened time from the onset of stroke to rt-PA treatment.

Bacterial Aggregation in Cerebral Spinal Fluid: The Extent it Occurs and the Clinical Ramifications.

Bacteria can form aggregates in synovial fluid that are resistant to antibiotics, but the ability to form aggregates in cerebral spinal fluid (CSF) is poorly defined. Consequently, the aims of this study were to assess the propensity of four bacterial species to form aggregates in CSF under various conditions. To achieve these aims, bacteria were added to CSF in microwell plates and small flasks at static and different dynamic conditions with the aid of an incubating shaker. The aggregates that formed were assessed for antibiotic resistance and the ability of tissue plasminogen activator (TPA) to disrupt these aggregates and reduce the number of bacteria present when used with antibiotics. The results of this study show that under dynamic conditions all four bacteria species formed aggregates that were resistant to high concentrations of antibiotics. Yet with static conditions, no bacteria formed aggregates and when the CSF volume was increased, only Staphylococcus aureus formed aggregates. Interestingly, the aggregates that formed were easily dispersed by TPA and significant (p < 0.005) decreases in colony-forming units were seen when a combination of TPA and antibiotics were compared to antibiotics alone. These findings have clinical significance in that they show bacterial aggregation does not habitually occur in central nervous system infections, but rather occurs under specific conditions. Furthermore, the use of TPA combined with antibiotics may be advantageous in recalcitrant central nervous system infections and this provides a pathophysiological explanation for an unusual finding in the CLEAR III clinical trial.

Acute ischemic stroke with a diagnosis of Marfan syndrome: A report of 3 cases in multifaceted settings.

RATIONALE: Marfan syndrome (MFS), which is a dominantly inherited connective tissue disease resulting from a mutation in the FBN1 gene, exhibits variable manifestations affecting the cardiovascular, musculoskeletal, ophthalmologic, and pulmonary systems. Notably, neurologic deficiency, which involves ischemic or hemorrhagic stroke, is a rare but severe manifestation. The safety of rt-PA treatment for ischemic stroke caused by MFS is still under discussion. PATIENT CONCERNS: In the current report, we discuss 3 atypical MFS cases presented as acute ischemic stroke, compared to those exhibiting cardiovascular and musculoskeletal abnormalities. DIAGNOSES: Three patients were diagnosed with acute ischemic stroke accompanied by MFS based on clinical manifestations, imaging examinations, and genetic testings. INTERVENTIONS: The first case underwent intravenous thrombolytic therapy with rt-PA, the second case received antiplatelet therapy, and the third case received anticoagulant therapy and perfusion therapy. OUTCOMES: The neurologic deficiency of all three patients showed improvement upon discharge, and there were no symptoms of recurrence observed during the follow-up period. LESSONS SUBSECTIONS: MFS is a rare etiology in young people with embolic stroke of undetermined source. Physicians should take MFS into consideration when they observe the characteristic symptoms during a consultation. The potential pathogenesis of ischemic stroke secondary to MFS may include cardio-embolism, arterial dissection, and hypoperfusion. Although intravenous thrombolysis is a promising therapy to treat acute ischemic stroke, further examinations should be conducted to rule out contraindications in patients with a suspicion of MFS.

Improved outcome with individualised antifibrinolytic therapy: what is the evidence?

Viscoelastic haemostatic testing (VHT) has been used to determine hyperfibrinolysis and hypofibrinolysis. When modified by addition of tissue plasminogen activator (tPA), VHT has been suggested to assess responses to antifibrinolytic therapy and to estimate the concentration of tranexamic acid in patients undergoing cardiac surgery. Despite some evidence that tPA-modified VHT might allow individualisation of antifibrinolytic therapy, further studies are warranted to prove its clinical benefit for postsurgical bleeding, transfusion of blood products, and thromboembolic events.

Cerebral autoregulation: A reliable predictor of prognosis in patients receiving intravenous thrombolysis.

AIMS: To investigate the characteristics of dynamic cerebral autoregulation (dCA) after intravenous thrombolysis (IVT) and assess the relationship between dCA and prognosis. METHODS: Patients with unilateral acute ischemic stroke receiving IVT were prospectively enrolled; those who did not were selected as controls. All patients underwent dCA measurements, by quantifying the phase difference (PD) and gain, at 1-3 and 7-10 days after stroke onset. Simultaneously, two dCA-based nomogram models were established to verify the predictive value of dCA for patients with mild-to-moderate stroke. RESULTS: Finally, 202 patients who received IVT and 238 who did not were included. IVT was positively correlated with higher PD on days 1-3 and 7-10 after stroke onset. PD values in both sides at 1-3 days after stroke onset and in the affected side at 7-10 days after onset were independent predictors of unfavorable outcomes in patients who received IVT. Additionally, in patients with mild-to-moderate stroke who received IVT, the dCA-based nomogram models significantly improved the risk predictive ability for 3-month unfavorable outcomes. CONCLUSION: IVT has a positive effect on dCA in patients with acute stroke; furthermore, dCA may be useful to predict the prognosis of patients with IVT.

Changes and significance of the fibrinolytic system following two pulmonary thromboembolisms in a rabbit model.

In this study, we examined the changes in the fibrinolytic system in a rabbit model of two acute pulmonary thromboembolisms (PTE). Fourteen healthy adult New Zealand white rabbits were divided into three groups: the single PTE group (five rabbits), the double PTE group (five rabbits), and the control group (four rabbits). A rabbit model of acute pulmonary embolism was established, and immunohistochemistry and polymerase chain reaction (PCR) were performed on tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) in plasma, and pulmonary embolism tissue. Plasma results: 1) t-PA levels: one hour following the initial modeling, the levels of t-PA in the modeling groups were significantly lower than those in the control group (P<0.05). In addition, the t-PA levels in the double PTE group were found to be lower after the modeling, as compared to the pre-modeling period (P<0.05). One hour after the second modeling, the double PTE group had lower t-PA levels compared to the control group (P<0.05). However, t-PA rebounded two hours after modeling in the double PTE group. One week after the second modeling, the double PTE group had higher t-PA levels compared to the other two groups (P<0.05). 2) PAI-1 results: one hour after the initial modeling, PAI-1 levels in the two modeling groups were lower compared to the pre-modeling period and control groups (P<0.05). Two hours following modeling, PAI-1 levels in both modeling groups were lower compared to the control group (P<0.05). PAI-1 levels were lower in the double PTE group one and two hours after the second modeling compared to the other two groups and pre-modeling period (P<0.05). 3) The immunohistochemistry results: the expression of PAI-1 decreased in the two modeling groups, while t-PA expression increased compared to the control group. 4) PCR results: t-PA mRNA expression did not differ among the three groups. The PAI-1 mRNA expression was lower in the two PTE groups compared to the control group. We conclude that in the early stages of PTE, the local fibrinolytic activity of the thrombus is increased, which is favorable for thrombolysis. However, as the thrombus persists, the activity of the fibrinolytic system is inhibited, contributing to the development of chronic thromboembolic pulmonary hypertension.

Use of recombinant tissue plasminogen activator (rTPA) for treatment of fibrin in the anterior chamber of the horse.

BACKGROUND: Recombinant intracameral tissue plasminogen activator (rTPA) administration can aid clearance of fibrin from the anterior chamber. MATERIALS AND METHODS: In this retrospective multicentre case series, the effect of intracameral rTPA administration to treat fibrin in the anterior chamber resulting from trauma or inflammatory ocular disease was evaluated. Clinical data from 30 treatments in 29 horses were obtained from medical records from 2003 to 2022. Association between time from onset of clinical signs and time for rTPA treatment to effect was studied with regression analysis. RESULTS: Twenty-seven horses (93.1%) had no previous history of ophthalmic disease; one had an iridic cyst, and another had equine recurrent uveitis. The majority of cases were related to trauma (79.3%). Median time from the onset of clinical signs to treatment was 12 h (IQR = 4-48 h). rTPA (72% 20 µg; 24% 25 µg; 3.3% 40 µg) was administered once in all but one eye, which was treated twice. Resolution of fibrin was seen in 96.9% (29/30) of treatments. Fibrin accumulation recurred in one case but resolved 14 days after the second treatment. Complications were seen in four treatments (13.3%): moderate pain for 24 h, intracameral debris and mild intracameral haemorrhage in a horse that received 40 µg of tissue plasminogen activator. Recurrence of fibrin accumulation was absent in 96.7% of cases. Median time to effect was 20 min (IQR = 10-45 min). Time for rTPA treatment to effect was not associated with time from fibrin formation (R2 = 0.09; p = 0.11). CONCLUSION: Intracameral rTPA treatment can be considered at 20-25 µg in 0.1 mL solution to aid resolution of fibrin accumulation.

Support for Thrombolytic Therapy for Acute Stroke Patients on Direct Oral Anticoagulants: Mortality and Bleeding Complications.

Background: Alteplase (tPA) is the initial treatment for acute ischemic stroke. Current tPA guidelines exclude patients who took direct oral anticoagulants (DOAC) within the prior 48 hours. In this propensity-matched retrospective study we compared acute ischemic stroke patients treated with tPA who had received DOACs within 48 hours of thrombolysis to those not previously treated with DOACs, regarding three outcomes: mortality; intracranial hemorrhage (ICH); and need for acute blood transfusions (as a marker of significant blood loss). Methods: Using the United States cohort of 54 healthcare organizations in the TriNetx database, we identified 8,582 stroke patients treated with tPA on DOACs within 48 hours of thrombolysis and 46,703 stroke patients treated with tPA not on DOACs since January 1, 2012. We performed propensity score matching on demographic information and seven prior clinical diagnostic groups, resulting in a total of 17,164 acute stroke patients evenly matched between groups. We recorded mortality rates, frequency of ICH, and need for blood transfusions for each group over the ensuing 7- and 30-day periods. Results: Patients treated with tPA on DOACs had reduced mortality (3.3% vs 7.3%; risk ratio [RR] 0.456; P < 0.001), fewer ICHs (6.8% vs 10.1%; RR 0.678; P < 0.001), and less risk of major bleeding as measured by frequency of blood transfusions (0.5% vs 1.5%; RR 0.317; p < 0.001) at 7 days post thrombolytic, than the tPA patients not on DOACS. Findings for 30 days post-thrombolytics were similar/statistically significant with lower mortality rate (7.2% vs 13.1%; RR 0.550; P < 0.001), fewer ICHs (7.6% vs 10.8%; RR 0.705; P < 0.001), and fewer blood transfusions (0.9% vs 2.0%; RR 0.448; P < 0.001). Conclusion: Acute ischemic stroke patients treated with tPA who received DOACs within 48 hours of thrombolysis had lower mortality rates, reduced incidence of ICH, and less blood loss than those not on DOACs. Our study suggests that prior use of DOACs should not be a contraindication to thrombolysis for ischemic stroke.

Left ventricular systolic dysfunction predicts clinical prognosis in patients with acute ischemic stroke after intravenous thrombolysis.

BACKGROUND: Although intravenous recombinant tissue plasminogen activator (rt-PA) thrombolysis is the most effective early treatment for acute ischemic stroke (AIS), outcomes vary greatly among patients. Left ventricular systolic dysfunction (LVSD) is prone to distant organ ischemia and may be a predictor for poor prognosis in AIS patients undergoing intravenous thrombolysis (IVT). Our aim was to investigate the predictivity of LVSD diagnosis (as measured by left ventricular ejection fraction (LVEF)) on 90-day clinical outcomes in AIS patients undergoing thrombolysis. METHODS: The current prospective cohort study continuously enrolled 273 AIS patients from the National Stroke Prevention and Treatment Engineering Management Special Database who underwent IVT and completed echocardiography within 24 h of admission between 2021 and 2023. LVSD was examined by evaluation of the echocardiographic LVEF values using Simpson's biplane method of discs in line with international guidelines, and defined as a LVEF value < 50%. Multivariable ordinal logistic regression model was performed to analyze the association between LVEF and functional outcome at 3 months. Restricted cubic spline (RCS) was used to examine the shape of the dose-response association between reduced LVEF and poor functional outcomes. Subgroup analysis was also employed to further verify the reliability and practicability of the results. RESULTS: Baseline data analysis showed LVSD patients had more comorbidities including on multivariate analyses, LVSD (OR 2.78, 95% CI 1.23 to 6.24, P=0.014), pre-existing diabetes mellitus (OR 2.08, 95% CI 1.11 to 3.90, P=0.023) and NIHSS on arrival (OR 1.31, 95% CI 1.21 to 1.49, P<0.001) were independent predictors of poor functional outcomes (mRS ≥ 3) at 3 months. Multivariable-adjusted spline regression indicated a linear dose-response association between LVEF after IVT and poor functional outcomes (p for linearity < 0.001), with the optimal cutoff values of LVEF being 0.48. CONCLUSIONS: Our finding indicated that AIS patients with LVSD after IVT had poorer outcomes, suggesting the need to monitor and optimize LVEF in stroke management.

A novel technique for extensive submacular hemorrhage using high-dose tissue plasminogen activator.

BACKGROUND: Submacular hemorrhage (SMH) is a sight-threatening disorder. Choroidal neovascularization secondary to age-related macular degeneration, polypoidal choroidal vasculopathy, trauma, angioid streaks, and pathological myopia are a few important causes. The conventional treatment of massive SMH is vitrectomy with manual removal of the clot with extensive retinectomy with/without tissue plasminogen activator (tPA). The usual dose of subretinal tPA is 10-25 µg. PURPOSE: To describe a new surgical approach in a case of massive SMH with retinal detachment without retinectomy. SYNOPSIS: In our case of near total hemorrhagic retinal detachment due to subretinal hemorrhage caused by trauma (road traffic accident), the patient presented with a visual acuity of counting fingers. Core vitrectomy was performed and posterior vitreous detachment was induced. The locations for retinotomy to inject and aspirate subretinal blood were selected at the maximum height of retinal elevation near the arcades. Recombinant tPA (10 µg/0.1 ml concentration; 0.3 ml injected in two locations) was injected subretinally with a 23-G soft tip cannula in the superotemporal and inferonasal quadrant causing subretinal bleb formation. Subsequently, the surgeon waited for approximately 20 min on the table for the liquefaction of the clot. The liquefied blood and tPA were drained with a silicone soft tip. Endolaser was performed at the retinotomy site and 1000cs silicone oil was injected. No signs of toxicity such as vitritis, vasculitis, or retinal necrosis were noted. HIGHLIGHTS: Our unique technique of high-dose intraoperative subretinal tPA (60 µg) is safe and helpful in rapid clot lysis and recovery of visual acuity. The patient gained a visual acuity of 20/80 from counting fingers after 1 month of surgery and 20/60 after silicone oil removal. A high dose of tPA aids in the immediate aspiration of blood from a small retinotomy. A 23-G soft tip was used instead of a 41-G subretinal cannula to inject a large quantity of subretinal tPA. VIDEO LINK: https://youtu.be/JzZBDUfa3NA.

Pneumatic displacement with intravitreal tPA injection versus vitrectomy with sub retinal tPA injection in small and medium sub macular hemorrhages- a multicenter comparative study.

PURPOSE: Comparing between the visual outcomes and post operative complications of two surgical treatments for sub macular hemorrhage, pars plana vitrectomy with tissue plasminogen activator (tPA) injection procedure, and pneumatic displacement of submacular hemorrhage with intravitreal tPA injection. METHODS: A retrospective chart review of patients with sub macular hemorrhage (SMH) was performed. Data was collected from 150 patients with sub macular hemorrhage. Patients were followed up from the day of admission and up to a year post surgery. Evaluation included visual acuity, optical coherence tomography (OCT), fundus examination and rates of complications. RESULTS: Pars plana vitrectomy procedure has showed a better visual outcome in small SMH. Comparing complications between the two treatment modalities, no significant difference has been found in the study. CONCLUSIONS: Pars plana vitrectomy and tPA showed a clear advantage with a trend of better visual acuity as well as a significant predictor to better visual acuity for small and medium sub macular hemorrhage.

Risk Factors Associated With Exclusion of Obese Patients Ischemic Stroke With a History of Smoking From Thrombolysis Therapy.

The objective of this study is to determine risk factors that may contribute to exclusion decision from recombinant tissue plasminogen activator (rtPA) in patients with acute ischemic stroke (AIS) with a combined current or history of smoking and obesity. This study was conducted on data from 5469 patients with AIS collected from a regional stroke registry. Risk factors associated with inclusion or exclusion from rtPA were determined using multivariate logistic regression analysis. The adjusted odds ratios and 95% confidence interval for each risk factor were used to predict the increasing odds of an association of a specific risk factor with exclusion from rtPA. In the adjusted analysis, obese patients with AIS with a history of smoking (current and previous) excluded from rtPA were more likely to present with carotid artery stenosis (OR = 0.069, 95% CI 0.011-0.442), diabetes (OR = 0.604, 95% CI 0.366-0.997), higher total cholesterol (OR = 0.975, 95% CI 0.956-0.995), and history of alcohol use (OR = 0.438, 95% CI 0.232-0.828). Higher NIHSS score (OR = 1.051, 95% CI 1.017-1.086), higher triglycerides (OR = 1.004, 95% CI 1.001-1.006), and higher high-density lipoprotein (OR = 1.028, 95% CI 1.000-1.057) were associated with the inclusion for rtPA. Our findings reveal specific risk factors that contribute to the exclusion of patients with AIS with a combined effect of smoking and obesity from rtPA. These findings suggest the need to develop management strategies to improve the use of rtPA for obese patients with AIS with a history of smoking.

Post-Translational Oxidative Modifications of Hemostasis Proteins: Structure, Function, and Regulation.

Reactive oxygen species (ROS) are constantly generated in a living organism. An imbalance between the amount of generated reactive species in the body and their destruction leads to the development of oxidative stress. Proteins are extremely vulnerable targets for ROS molecules, which can cause oxidative modifications of amino acid residues, thus altering structure and function of intra- and extracellular proteins. The current review considers the effect of oxidation on the structural rearrangements and functional activity of hemostasis proteins: coagulation system proteins such as fibrinogen, prothrombin/thrombin, factor VII/VIIa; anticoagulant proteins - thrombomodulin and protein C; proteins of the fibrinolytic system such as plasminogen, tissue plasminogen activator and plasminogen activator inhibitor-1. Structure and function of the proteins, oxidative modifications, and their detrimental consequences resulting from the induced oxidation or oxidative stress in vivo are described. Possible effects of oxidative modifications of proteins in vitro and in vivo leading to disruption of the coagulation and fibrinolysis processes are summarized and systematized, and the possibility of a compensatory mechanism in maintaining hemostasis under oxidative stress is analyzed.

Spurious Hyperphosphatemia in a Patient with Chronic Kidney Disease - a Rare Case of Alteplase Contamination.

Spurious hyperphosphatemia, a rare occurrence, typically arises from substances in a patient's blood interfering with the colorimetric method for serum phosphate measurement. We present a case of factitious hyperphosphatemia caused by alteplase-contaminated blood samples in an 88-year-old CKD patient on hemodialysis, leading to misleadingly high phosphorus levels. Thorough investigations ruled out other etiologies, highlighting the necessity of stringent adherence to blood collection protocols to prevent sample contamination and avert erroneous laboratory results. This unique cause of hyperphosphatemia should be considered in the differential diagnosis when encountering unexplained elevations in phosphorus levels, particularly in the context of normal blood calcium levels.

Utilization of a Supraglottic Airway Device for Airway Rescue and Tamponade of an Oropharyngeal Hemorrhage After Systemic Thrombolysis for an Acute Ischemic Stroke: A Case Report.

A 39-year-old man presented for mechanical thrombectomy after receiving systemic tissue plasminogen activator (tPA) for a basilar artery occlusion. The anesthesiology team was initially unable to intubate the patient due to oropharyngeal bleeding and a large epiglottis. Two-handed, 2-provider mask ventilation with an oral airway proved difficult. The team successfully placed a supraglottic airway (SGA) through which an oral endotracheal tube (ETT) was advanced over a fiberoptic bronchoscope into the trachea. The SGA remained overnight with the cuff inflated to tamponade the bleeding. The ETT was exchanged over an airway exchange catheter on postoperative day 1 without further airway complications.

What does cognitive screening reveal about early cognitive performance following endovascular clot retrieval and intravenous thrombolysis in acute ischaemic stroke?

Background Little is known regarding cognitive outcomes following treatment with endovascular clot retrieval (ECR) and intravenous tissue plasminogen activator (t-PA). We aimed to determine if there were any differences on a measure of cognitive screening between patients treated with ECR, t-PA, and those who were managed conservatively. Methods The medical records of ischaemic stroke patients admitted to Monash Medical Centre between January 2019 and December 2019 were retrospectively reviewed. Information extracted from medical records included age, sex, National Institutes of Health Stroke Scale at presentation, location of occlusion, treatment type, medical history, and cognitive screening performance measured by the Montreal Cognitive Assessment (MoCA). Results Eighty-two patients met the inclusion criteria (mean age = 66.5 ± 13.9; 49 male, 33 female). Patients treated with ECR performed significantly better on the MoCA (n = 36, 24.1 ± 4.3) compared to those who were managed conservatively (n = 26, 20.7 ± 5.5). Performance for patients treated with t-PA (n = 20, 23.9 ± 3.5) fell between the ECR and conservative management groups, but they did not significantly differ from either. Conclusion Our retrospective chart review found that ischaemic stroke patients treated with ECR appear to perform better on cognitive screening compared to patients who are managed conservatively. We also found that patients treated with ECR and t-PA appear to have similar cognitive screening performances in the acute stages following ischaemic stroke, although this finding is likely to have been impacted by group differences in stroke characteristics and may reflect the possibility that the ECR group performed better than expected based on their stroke severity.

Point-of-care testing for tranexamic acid efficacy: a proof-of-concept study in cardiac surgical patients.

BACKGROUND: Low-dose tranexamic acid (TXA) has been recently recommended for cardiopulmonary bypass (CPB) to reduce associated complications. Although point-of-care laboratory tests for TXA concentrations are unavailable, a novel TPA-test on the ClotPro® system can measure TXA-induced inhibition of fibrinolysis. We evaluated the performance of the TPA-test in vitro and in patients undergoing surgery requiring CPB. METHODS: Blood samples were obtained from six volunteers for in vitro evaluation of tissue plasminogen activator (tPA)-triggered fibrinolysis and the effects of TXA. This was followed by an observational study in 20 cardiac surgery patients to assess clinical effects of TXA on the TPA-test. RESULTS: Hyperfibrinolysis induced by tPA was inhibited by TXA ≥2 mg L-1 in a concentration-dependent manner, and was completely inhibited at TXA ≥10 mg L-1. In patients undergoing CPB, antifibrinolytic effect was detectable on TPA-test parameters after a 0.1 g bolus of TXA at the end of CPB, and complete inhibition of fibrinolysis was obtained with TXA ≥0.5 g. The antifibrinolytic effects of 1 g TXA on TPA-test parameters were gradually attenuated over 18 h after surgery. However, the fibrinolytic inhibition continued in four patients with estimated glomerular filtration rate (eGFR) ≤30 ml min-1 1.73 m-2. The eGFR had strong correlations with TPA-test parameters at 18 h after surgery (r=0.86-0.92; P<0.0001). CONCLUSIONS: The TPA-test is sensitive to low concentrations of TXA and serves as a practical monitoring tool for postoperative fibrinolytic activity in cardiac surgery patients. This test might be particularly useful in patients with severe renal impairment.