Thrombotic Microangiopathy and Renal Failure Exacerbated by ε-Aminocaproic Acid

A 3-year follow-up of a patient with acute renal failure caused by thrombotic microangiopathy related to antiphospholipid syndrome: case report

Background Microvascular manifestations of antiphospholipid antibody syndrome in the kidneys include acute renal failure, thrombotic microangiopathy and hypertension. Therapy has been largely empiric. Case report A 49-year-old Chinese man presented with anuric acute renal failure without abundant proteinuria and heavy haematuria, but markedly low levels of urinary sodium, potassium and chlorine upon admission. On day 1 of hospitalization, his thrombocytopenia, anaemia and renal failure showed rapid progression. The presence of lupus anticoagulant and vascular ischaemia of the small vessels in renal arteriography were also observed. Anticoagulants, continuous renal replacement therapy, glucocorticoids and six sessions of plasma exchange were started. After the fourth plasma exchange (on day 20), his urine output increased and began to normalize. On day 25, haemodialysis was stopped and his general condition gradually improved. A renal biopsy was subsequently performed, and the histopathological diagnosis was thrombotic microangiopathy due to antiphospholipid antibody syndrome. A further 3-year follow-up showed that his haemoglobin level, platelet count and serum creatinine were within the normal range, with stable blood pressure. Conclusion Treatment modalities such as anticoagulation, immunosuppression and plasma exchange are likely to be necessary when severe acute renal failure combined with thrombotic microangiopathy present in nephropathy of antiphospholipid antibody syndrome.

Adverse drug events associated with disorders of coagulation

Disorders of coagulation are common adverse drug events encountered in critically ill patients and present a serious concern for intensive care unit (ICU) clinicians. Dosing strategies for medications used in the ICU are typically developed for use in noncritically ill patients and, therefore, do not account for the altered pharmacokinetic and pharmacodynamic properties encountered in the critically ill as well as the increased potential for drug-drug interactions, given the far greater number of medications ordered. This substantially increases the risk for coagulation-related adverse reactions, such as a bleeding or prothrombotic events. Although many medications used in the ICU have the potential to cause coagulation disorders, the exact incidence will vary based on the specific medication, dose, concomitant drug therapy, ICU setting, and patient-specific comorbidities. Clinicians must strongly consider these factors when evaluating the risk/benefit ratio for a particular therapy. This review surveys recent literature documenting the risk for adverse drug reactions specific to bleeding and/or clotting with commonly used medications in the ICU.

Preliminary experience with epsilon aminocaproic acid for treatment of intractable upper tract hematuria in children with hematological disorders

PURPOSE

Gross, intractable hematuria is rare in children. Although the role of epsilon aminocaproic acid in the management of refractory hematuria is well established in the adult population, few data exist about its use in children for this indication. We present our initial experience with epsilon aminocaproic acid for the treatment of intractable hematuria after more conservative measures failed, and propose an algorithm for administration of epsilon aminocaproic acid in children.

MATERIALS AND METHODS

We reviewed the charts of all patients treated with epsilon aminocaproic acid for intractable gross hematuria at our institution during a period of 36 months. All patients underwent hematological evaluation and any underlying bleeding dyscrasias were addressed. All patients also underwent renal and bladder ultrasound, retrograde pyelogram and ureteroscopy. Demographic information, medical and surgical histories, and epsilon aminocaproic acid dosing and outcomes were recorded.

RESULTS

Three boys and 1 girl 11 to 17 years old were treated with epsilon aminocaproic acid. Three patients had sickle trait (1 with nutcracker phenomenon) and 1 had hemophilia A. Three patients required packed red blood cell transfusions to maintain hematocrit. Three renal angiograms were performed, all of which were nondiagnostic. Duration of hematuria ranged from 1 to 52 weeks before administration of epsilon aminocaproic acid. Endoscopic evaluation demonstrated hematuria localized to 1 ureteral orifice in all 4 patients. All patients received 100 mg/kg epsilon aminocaproic acid orally every 6 hours, which uniformly led to cessation of hematuria.

CONCLUSIONS

Epsilon aminocaproic acid is useful for the management of gross refractory hematuria when more conservative measures fail. Because of its potential side effects, it should be used cautiously.

Interstitial plasmin activity with epsilon aminocaproic acid: temporal and regional heterogeneity

BACKGROUND

Epsilon aminocaproic acid (EACA) is used in cardiac surgery to modulate plasmin activity (PLact). The present study developed a fluorogenic-microdialysis system to measure in vivo region specific temporal changes in PLact after EACA administration.

METHODS

Pigs (25 to 35 kg) received EACA (75 mg/kg, n = 7) or saline in which microdialysis probes were placed in the liver, myocardium, kidney, and quadricep muscle. The microdialysate contained a plasmin-specific fluorogenic peptide and fluorescence emission, which directly reflected PLact, determined at baseline, 30, 60, 90, and 120 minutes after EACA/vehicle infusion.

RESULTS

Epsilon aminocaproic acid caused significant decreases in liver and quadricep PLact at 60, 90, 120 minutes, and at 30, 60, and 120 minutes, respectively (p < 0.05). In contrast, EACA induced significant biphasic changes in heart and kidney PLact profiles with initial increases followed by decreases at 90 and 120 minutes (p < 0.05). The peak EACA interstitial concentrations for all compartments occurred at 30 minutes after infusion, and were fivefold higher in the renal compartment and fourfold higher in the myocardium, when compared with the liver or muscle (p < 0.05).

CONCLUSIONS

Using a large animal model and in vivo microdialysis measurements of plasmin activity, the unique findings from this study were twofold. First, EACA induced temporally distinct plasmin activity profiles within the plasma and interstitial compartments. Second, EACA caused region-specific changes in plasmin activity profiles. These temporal and regional heterogeneic effects of EACA may have important therapeutic considerations when managing fibrinolysis in the perioperative period.

Temporally and regionally disparate differences in plasmin activity by tranexamic acid

BACKGROUND

A major complication associated with cardiac surgery is excessive and prolonged bleeding in the perioperative period. Improving coagulation by inhibiting fibrinolysis, primarily through inhibition of plasmin activity (PLact) with antifibrinolytics such as tranexamic acid (TXA), has been a pharmacological mainstay in cardiac surgical patients. Despite its almost ubiquitous use, the temporal and regional modulation of PLact profiles by TXA remains unexplored. Accordingly, we developed a fluorogenic-microdialysis system to measure in vivo dynamic changes in PLact after TXA administration in a large animal model.

METHODS

Pigs (25-35 kg) were randomly assigned to receive TXA (30 mg/kg, diluted into 50 mL normal saline; n = 9) or vehicle (50 mL normal saline; n = 7). Microdialysis probes were placed in the liver, myocardium, kidney, and quadriceps muscle compartments. The microdialysate infusion contained a validated plasmin-specific fluorogenic peptide. The fluorescence emission (standard fluorogenic units [SFU]) of the interstitial fluid collected from the microdialysis probes, which directly reflects PLact, was determined at steady-state baseline and 30, 60, 90, and 120 min after TXA/vehicle infusion. Plasma PLact was determined at the same time points using the same fluorogenic substrate approach.

RESULTS

TXA reduced plasma PLact at 30 min after infusion by >110 SFU compared with vehicle values (P < 0.05). Specifically, there was a decrease in liver PLact at 90 and 120 min after TXA infusion of >150 SFU (P < 0.05) and 175 SFU (P < 0.05), respectively. The decrease in liver PLact occurred 60 min after the maximal decrease in plasma PLact. In contrast, kidney, heart, and quadriceps PLact transiently increased followed by an overall decrease at 120 min.

CONCLUSIONS

Using a large animal model and in vivo microdialysis measurements of PLact, the unique findings from this study were 2-fold. First, TXA induced temporally distinct PLact profiles within the plasma and selected interstitial compartments. Second, TXA caused region-specific changes in PLact profiles. These temporal and regional differences in the effects of TXA may have important therapeutic considerations when managing fibrinolysis in the perioperative period.