Systemic Heparin Anticoagulation Research Articles

Regional citrate versus systemic heparin anticoagulation for continuous renal replacement in critically ill patients

We determined the effect of regional citrate versus systemic heparin anticoagulation for continuous renal replacement therapy in critically ill subjects suffering from acute renal failure who were not at high risk for hemorrhagic complications. Between April 1999 and June 2002, 30 critically ill subjects requiring continuous renal replacement therapy and using 79 hemofilters were randomly assigned to receive regional citrate or systemic heparin anticoagulation. The median hemofilter survival time was 124.5 hours (95% CI 95.3 to 157.4) in the citrate group, which was significantly longer than the 38.3 hours (95% CI 24.8 to 61.9) in the heparin group (P < 0.001). Increasing illness severity score, male gender, and decreasing antithrombin-III levels were independent predictors of an increased relative hazard of hemofilter failure. After adjustment for illness severity, antithrombin-III levels increased significantly more over the period of study in the citrate as compared to the heparin group (P= 0.038). Moreover, after adjustment for antithrombin-III levels and illness severity score, the relative risk of hemorrhage with citrate anticoagulation was significantly lower than that with heparin (relative risk of 0.14; 95% CI 0.02 to 0.96, P= 0.05). Compared with systemic heparin anticoagulation, regional citrate anticoagulation significantly increases hemofilter survival time, and significantly decreases bleeding risk in critically ill patients suffering from acute renal failure and requiring continuous renal replacement therapy.

Is regional citrate superior to systemic heparin anticoagulation for continuous renal replacement therapy? A prospective observational study in an adult regional critical care system

Purpose Continuous renal replacement therapy (CRRT) is commonly used in the care of critically ill patients although the optimal means of anticoagulation is not well defined. We report our regional CRRT protocol that was developed using the principles of quality improvement and compare the effect of regional citrate with systemic heparin anticoagulation on filter life span. Materials and Methods Prospective observational cohort study in a Canadian adult regional critical care system. A standardized protocol for CRRT has been implemented at all adult intensive care units in the Calgary Health Region since August 1999. All patients with acute renal failure treated with CRRT during October 1, 2002, to September 30, 2003, were identified and followed up prospectively until hospital discharge or death. Results Eighty-seven patients with acute renal failure requiring CRRT were identified, 54 were initially treated with citrate, 29 with heparin, and 4 with saline flushes. Citrate and heparin were used in 212 (66%) and 97 (30%) of filters for 8776 and 2651 hours of CRRT, respectively. Overall median (interquartile range) filter life span with citrate was significantly greater than heparin (40 [14-72] vs 20 [5-44] hours, P < .001). The median time to spontaneous filter failure was significantly greater with citrate compared with heparin (>72 vs 33 hours, P < .001). Citrate anticoagulation resulted in greater completion of scheduled filter life span (59% vs 10%, P > .001). Citrate anticoagulation was well tolerated with no patient requiring elective discontinuation for hypernatremia, metabolic alkalosis, or hypocalcemia. Conclusions Regional citrate anticoagulation was associated with prolonged filter survival and increased completion of scheduled filter life span compared with heparin. These data support small studies suggesting that citrate is a superior anticoagulant for CRRT and suggest the need for a future definitive randomized controlled trial.

Endovascular treatment for symptomatic carotid artery dissection

A 64-year-old man presented with a two-hour history of acute onset right hemiparesis. A computed tomography of the head showed no pathologic findings, and a carotid duplex scan revealed a left carotid artery dissection, as evidenced by double lumens originating from the proximal common carotid artery (A). The patient was treated with systemic heparin anticoagulation. However, he continued to experience worsening of neurologic symptoms 3 days later. As a result, endovascular intervention for the carotid dissection was performed. A carotid angiogram confirmed that carotid dissection originated from the proximal left common carotid artery orifice (B [Cover]). Moreover, the dissecting false lumen extended distally into the internal carotid artery (arrow, B [Cover]). A 0.035-in guidewire (Boston Scientific) was placed in the true lumen in the common carotid artery, which was followed by the placement of a 10 50-mm Wallgraft (Boston Scientific) at the common carotid artery origin, which successfully excluded the dissection entry point. Completion angiogram showed complete obliteration of the false lumen with restoration of the carotid artery circulation (C). The patient had a complete resolution of his neurologic symptoms. Follow-up carotid duplex scan at 16 months showed normal carotid artery anatomy without residual dissection.

CVVHD in Pediatrics Multiorgan Dysfunction Syndrome: Bicarbonate-Based Solutions are Feasible and Safe

OBJECTIVE: To describe continuous veno-venous hemodiafiltration (CVVHD) procedure in a pediatric critical care unit using bicarbonate-based solution. PATIENTS AND METHODS: From 06-2001 to 08-2002, nine patients were treated by CVVHD, age range 1,7–16 yrs, body weight 9,3–45 kg. Indications criteria: oligoanuria and hypevolemia, hemodynamic instability and impossibility of peritoneal dialysis. The patients' primary diseases were: policystic kidney disease (1/9), SLE (1/9), liver disease (6/9), mediastinal germ cells tumos (1/9). All patients were on mechanical ventilation and on vasopressos support. Pancytopenia was diagnosed in 9/9, and hepatic dysfunction in 8/9 pts. The CVVHD prescription was: blood flow rate: 2–4 ml/min, dialisate and replacement flow rate: 2000 ml/1,73m2/h. Systemic heparin anticoagulation could not be used, and citrate regional anticoagulation (4% trissodium citrate) was used in a patient with normal hepatic function. The duration of procedures was 4–72 hours, and the total time range of CVVHD was 28 hours to 19 days. The solution was prepared in our hospital pharmacy. Prisma system (GAMBRO) and poliacrylonitrile M-60 hemofilter was used in all patients. RESULTS: CVVHD was effective to control fluid balance and metabolic derangements. Anaphylactoid reaction was observed in one patient. Six patients died of causes other than renal failure (sepsis in 5/6 pts, hepatic failure in 1/6 pts). Three patients are alive, two with normal renal function. CONCLUSION: CVVHD with bicarbonate-based solutions is feasible and safe and allow metabolic and fluid control in critically ill pediatric patients.

Current management of acute symptomatic deep vein thrombosis.

Venous thromboembolism is a common and potentially fatal disease. If properly used, anticoagulation therapy is effective in preventing recurrence of venous thromboembolism and in improving survival. Symptomatic patients with an objective diagnosis of acute deep vein thrombosis (DVT) or pulmonary embolism (PE) should receive immediate systemic heparin anticoagulation at dosages sufficient to rapidly prolong the activated partial thromboplastin time into the laboratory-specific therapeutic range; this range corresponds to a plasma heparin concentration of 0.2 to 0.4 IU/ml (as measured by protamine sulfate titration), or 0.3 to 0.7 anti-Xa IU/ml. An oral vitamin K antagonist (e.g. warfarin) should be started within 24 hours after starting heparin; the starting dose should be the estimated patient-specific daily dose with no loading dose. Heparin and warfarin anticoagulation should be overlapped for at least 4 to 5 days and until the international normalized ratio (INR) is within the therapeutic range (2.0 to 3.0) on 2 measurements made at least 24 hours apart. The duration of warfarin anticoagulation should be individualized based on the respective risks of venous thromboembolism recurrence and anticoagulant-related bleeding. In general, warfarin should be continued for at least 3 months, and longer for patients with recurrent or idiopathic venous thromboembolism, malignant neoplasm, neurologic disease with extremity paresis, obesity, or laboratory evidence of a lupus anticoagulant/anticardiolipin antibody, homozygous carrier or combined heterozygous carrier for the factor V R506Q (Leiden) and prothrombin G20210A mutations, and possibly deficiency of either antithrombin, protein C, or protein S. Low molecular weight heparin (LMWH) is effective and well tolerated as acute therapy for patients with DVT or stable PE, and does not require laboratory monitoring or dose adjustment. Outpatient LMWH therapy is also well tolerated and cost effective for most patients with DVT, and possibly for selected patients with PE.

Regional citrate anticoagulation in continuous venovenous hemofiltration in critically ill patients with a high risk of bleeding

Systemic heparinization is associated with a high rate of bleeding when used to maintain patency of the extracorporeal circuit during continuous renal replacement therapy (CRRT) in critically ill patients. Regional anticoagulation can be achieved with citrate, but previously described techniques are cumbersome and associated with metabolic complications. We designed a simplified system for delivering regional citrate anticoagulation during continuous venovenous hemofiltration (CVVH). We evaluated filter life and hemorrhagic complications in the first 17 consecutive patients who received this therapy at our institution. Blood flow rate was set at 180 ml/min. Ultrafiltration rate was maintained at 2.0 liters/hr and citrate-based replacement fluid (trisodium citrate 13.3 mM, sodium chloride 100 mM, magnesium chloride 0.75 mM, dextrose 0.2%) was infused proximal to the filter to maintain the desired fluid balance. Calcium gluconate was infused through a separate line to maintain a serum-ionized calcium level of 1.0 to 1.1 mM. All patients were critically ill and required mechanical ventilation and vasopressor therapy. Systemic heparin anticoagulation was judged to be contraindicated in all of the patients. A total of 85 filters were used, of which 64 were lost because of clotting, with a mean life span of 29.5 +/- 17.9 hours. The remaining 21 filters were discontinued for other reasons. Control of fluid and electrolyte balance and azotemia was excellent (mean serum creatinine after 48 to 72 hr of treatment was 2.4 +/- 1.2 mg/dl). No bleeding episodes occurred. Two patients, one with septic shock and the other with fulminant hepatic failure, developed evidence for citrate toxicity without a significant alteration in clinical status. Nine patients survived (52.9%). Our simplified technique of regional anticoagulation with citrate is an effective and safe form of anticoagulation for CVVH in critically ill patients with a high risk of bleeding.

Air Travel and Thromboembolic Complications after Percutaneous Nephrolithotomy for Staghorn Stone

Thromboembolic complications after percutaneous surgery for staghorn stone are rare. We report a case of silent deep vein thrombosis (DVT) after long-distance air travel that was complicated by both recurrent pulmonary emboli and paradoxical arterial embolus despite full-dose systemic heparin anticoagulation. Management options for thromboembolic complications in the context of percutaneous renal surgery are discussed, and risk factors predisposing to silent deep vein thrombosis after long-distance air travel are outlined.

Low molecular weight heparin: biochemistry, pharmacology, perioperative prophylaxis regimens, and guidelines for regional anesthetic management.

Low molecular weight heparin: biochemistry, pharmacology, perioperative prophylaxis regimens, and guidelines for regional anesthetic management.

A Scanning Electron Microscopy Study of the Attachment of a Thromboresistive Surface Coating to a Membrane Blood Oxygenator

The need for systemic heparin anticoagulation during extended cardiopulmonary bypass (CPB) remains a serious impediment to clinical CPB support of circulatory and respiratory failures, especially in the newborn. Recent development of thromboresistive substrates which can be used to treat extracorporeal surfaces in contact with blood offers the potential for elimination of systemic blood heparinization. The present paper describes a scanning electron microscopy study of the attachment of one such substrate, tridodecyl- methylammonium chloride (TDMAC), to a novel micro-membrane oxygenator.Figure 1 shows a cross-sectional image of the alternating pattern of microchannel conduits for blood flow through the oxygenator. The micro-channels were fabricated on thin metal sheets with an approximate semi-circular shape (150 + 25 microns in radius). The gas exchange to the blood flow in the channels was accomplished through a micro-porous membrane which was placed across the diametric plane of the channels (1).