Activity and dosage of alteplase dilution for clearing occlusions of venous-access devices

Efficacy of alteplase 1 versus 2 mg dose in restoring haemodialysis catheter function (Alte-dose 2): A randomized double-blind controlled study

AIM

Data about the optimal alteplase dose required to treat haemodialysis catheter occlusion (HDC) are scarce. The purpose of the clinical trial was to examine the effectiveness of alteplase 2 mg as compared with 1 mg in restoring HDC function.

METHODS

A double-blind, randomized, controlled clinical trial was conducted in a single-centre in southwestern Ontario, Canada. Rate of clot resolution, catheter replacements, catheter stripping, and mean catheter survival time were assessed using Kaplan-Meier, Cox-proportional hazard and clustered logic regression analyses.

RESULTS

On a sample of 48 haemodialysis patients who provided 252 catheter occlusion events, the rate of clot resolution at the catheter site in the 2 mg group was 85.7% as opposed to 84.9% in the 1 mg group. There were only six catheter removals and 10 catheter stripping events. Cox regression analysis revealed no difference between the two groups in the hazard of occlusion on the primary 48 observations after the initial alteplase management (P = 0.267; hazard ratio = 0.72; 95% confidence interval 0.40-1.3). Correlated logistic regression on all 252 observations indicated no difference in the rate of post alteplase clot resolution (P = 0.336; odds ratio = 2.4, 95% confidence interval 0.399-14.6) between the two groups.

CONCLUSION

Alteplase 1 mg is as effective as 2 mg in restoring HDC malfunction and may result in cost reduction in haemodialysis units.

Efficacy of Low-Dose Alteplase for Treatment of Hemodialysis Catheter Occlusions

Background

Traditionally, alteplase 2 mg/lumen doses have been used to treat central venous catheter (CVC) occlusions. On January 20, 2004, our hemodialysis (HD) unit implemented a new protocol to utilize alteplase 1 mg/lumen doses for catheter occlusion.

Objectives

The objectives were to 1) assess the efficacy of low-dose alteplase in restoring HD catheter patency; 2) determine the duration of CVC patency as determined by need for further alteplase doses, or radiological or surgical line interventions; and 3) evaluate the financial implications of the new protocol.

Methods

The study was a prospective, open-label trial of 50 consecutive HD patients with permanent, tunnelled CVC lines. A treatment course consisted of 1 or 2 doses of alteplase instilled for 60 minutes then aspirated or as an overnight (48–72 hour) dwell until the next HD. The patient's first alteplase dose following implementation of the new protocol was evaluated. Patients were followed for two months to record need for further alteplase treatment courses, and four months to document radiological or surgical line interventions. The primary outcome was to assess successful restoration of catheter patency defined as the ability of alteplase to restore or maintain HD blood flow rate at or above 300 mL/minute. A financial analysis compared alteplase costs for 11 months prior to and after implementation of the new protocol.

Results

Alteplase 1 mg/lumen doses restored catheter patency in 72% of HD patients with one dose, increasing to 83% with a second dose. Sixty-two percent of patients required a subsequent alteplase course with a median time to next treatment of 14 days and a median of 2 courses/patient. Radiological interventions were ordered in 38% of patients resulting in 8 lines replacements and 7 line strippings. Financial savings with the new low-dose protocol were ~CDN$22,000.

Conclusion

Low dose alteplase 1 mg/lumen successfully treated occlusion of permanent hemodialysis catheters, with a resulting cost reduction.

Twenty-five Years of Advances in Vascular Access: Bridging Research to Clinical Practice

Vascular access has become a key component for a multitude of IV therapies, including parenteral nutrition. Access of the central venous system has been long recognized for its associated complications of infection, thrombosis, and occlusion. Over the past 25 years, clinical practice based on research and innovation has attempted to decrease complication rates and therefore improve the safety of vascular access. This article highlights the research and its influence on catheter care procedures, technology, and education that has led to advances in vascular access. An improved understanding of the pathophysiology associated with catheter-related complications and an ongoing evaluation of new treatment modalities has provided clinicians today with new options for improved patient care and the ability to preserve vascular access options for patients.

Enzymatic Stability of Alteplase Solution for Injection: Effect of Various Methods of Thawing Frozen Solutions

Objective

To modify and evaluate an established chromogenic assay protocol for measuring plasminogen activator inhibitor type-1 (PAI-1) activity to measure tissue plasminogen activator (tPA) activity and compare the enzymatic activity of alteplase as a function of the conditions under which it is thawed.

Methods

A 50 mg vial of alteplase was reconstituted with sterile water to make a 1 mg/mL stock solution (nominal concentration). Plastic syringes were loaded with 0.5 mL of alteplase stock solution and stored at -20°C. After 8 days, samples were thawed by 3 methods - via body temperature (37°C), room temperature (20°C), or in a refrigerator (2°C). Thaw times were recorded. The thawed solutions, along with a freshly prepared alteplase solution, were assayed using the modified protocol of the Spectrolyse PAI-1 kit to determine residual tPA enzyme activity.

Results

Validation of the modified protocol for the Spectrolyse PAI-1 kit used to measure tPA activity produced a linear response with coefficients of determination (R2) of greater than 0.9977 when assayed on 2 separate days, which corresponded to an enzymatic activity accuracy between 98.3% and 108.3%. The average percent residual tPA enzyme activity of samples from each group compared to the freshly prepared solution was 106%, 98.7%, and 91.5% for samples thawed at body temperature, room temperature, and refrigerated, respectively.

Conclusion

Modifications to the standard procedure for the Spectrolyse PAI-1 kit allows for accurate determination of tPA activity in aqueous based reconstituted solutions of alteplase. Under thawed conditions, alteplase retained greater than 91% enzyme activity as compared to a freshly prepared control.

Use of Alteplase for Clearing Peritoneal Dialysis Catheter Occlusion

Background

Peritoneal dialysis (PD) catheter complications account for 20% of all transfers from PD to hemodialysis. One complication is outflow obstruction caused by fibrin deposits within the lumen of the catheter. Alteplase is frequently used to clear fibrin deposits in PD catheters that are refractory to other therapies. However, the literature basis for this practice is unclear.

Method

A review of the literature was conducted to determine the evidence existing for alteplase use in PD catheter occlusion due to fibrin. A literature search of MEDLINE (1967-present) was conducted using the search terms "alteplase", "peritoneal dialysis catheter", "occlusion", "fibrin", and "tissue plasminogen activator". Referenced citations were also searched for pertinent material. All data concerning the use of alteplase for peritoneal dialysis catheter occlusion were included in this review. The search resulted in 1 open-label pilot study, 3 case series, and 2 case reports of alteplase use in declotting occluded PD catheters.

Results

Based on the data, alteplase therapy cleared the occlusion of PD catheters in the majority of cases. In those that were unsuccessful, other surgically correctable and mechanical causes were identified in most cases.

Conclusion

Alteplase appears to be an intriguing alternative to the surgical removal of the PD catheter in patients with catheter occlusion due to fibrin. Although not inexpensive, it appears safe and may decrease the need for surgical correction of occluded catheters.

Intraluminal Volume Dose Alteplase for the Clearance of Occluded Peripherally Inserted Central Catheter Lines at a Long-Term Acute Care Hospital: Efficacy and Economic Impact

PURPOSE

To evaluate the efficacy and economic impact of a maximum of 2 doses of intraluminal volume 1 mg/1 mL dose alteplase for the clearance of occluded peripherally inserted central catheter (PICC) lines at a long-term acute care hospital (LTACH).

METHODS

Open-label, nonrandomized quasi-experimental trial taking place over a 3-month period from December 2013 to March 2014. Patients had a standing order of either standard (2 mg/2 mL) or intraluminal volume (1 mg/1 mL) dose alteplase entered for any potential occlusions. The primary efficacy outcome was restored line patency after a maximum of 2 doses of alteplase. Secondary efficacy outcomes included restored patency after 1 dose of alteplase, reocclusion rate, mean time to reocclusion, and mean number of occlusions per patient.

RESULTS

A total of 168 patients were enrolled into the study (intraluminal volume, n = 54; standard, n = 114) and a total of 270 occlusions were recorded; 90 received intraluminal volume dose alteplase and 180 received the standard dose. The primary efficacy endpoint was 93.3% for the intraluminal volume dose group and 94.4% for the standard dose group. Secondary outcomes were similar between groups. The average cost per dose was $123.77 and $60.62 for the standard and intraluminal volume dose alteplase groups, respectively.

CONCLUSION

For the clearance of occluded PICC lines at our LTACH, there was no statistical difference in the efficacy of a maximum of 2 doses of intraluminal volume dose alteplase versus the standard dose. Use of intraluminal volume dose alteplase was found to be significantly more cost-effective.

Pediatric Central Venous Catheter Management: A Review of Current Practice

Due to small vessel size, obtaining stable access in pediatric patients is difficult. In addition, because needle stick pain is a concern for patients with chronic illness, central venous catheters are often utilized to provide intravenous treatment. Catheter occlusion is a common complication in pediatric patients and must be addressed to salvage the catheter and ensure successful therapy. The use of fibrinolytics for occlusion treatment have been successful in pediatric populations.

Alteplase for the treatment of catheter occlusion in pediatric patients

OBJECTIVE

To review the literature pertaining to the efficacy of alteplase for restoration of patency of occluded venous and dialysis catheters in pediatric patients.

DATA SOURCES

A MEDLINE search was conducted and cross-referenced with an EMBASE search through November 2012. Search terms included alteplase, tissue plasminogen activator, and catheter.

STUDY SELECTION AND DATA EXTRACTION

Search results were limited to humans, English language, and ages from neonates to 18 years. Pertinent studies discussing efficacy of alteplase for restoration of occluded venous or dialysis catheter function were included. Case reports, review articles, and studies that specified inclusion of hemophilia patients or more than 75% of children with malignancy were excluded.

DATA SYNTHESIS

Fibrinolytics are the drug class of choice for restoration of patency (defined as the ability to withdraw a blood sample) of thrombus-occluded catheters. The trials used to support Food and Drug Administration approval of alteplase for central venous catheter (CVC) occlusions generally had low pediatric enrollment; however, additional small studies are available that support use of alteplase for this indication in children. Alteplase doses of 0.5-2 mg instilled into the lumen of a CVC with dwell times ranging from 30 to more than 240 minutes plus the potential for repeat dosing were reported. Overall efficacy ranged from approximately 50% to 90%, with greater efficacy generally reported with larger doses and longer dwell times. Alteplase doses of 2-2.5 mg with dwell times of 60-120 minutes were observed in 2 studies of occluded peritoneal or hemodialysis catheters, in which efficacy was reported in 57-100% of cases. Limitations of current studies of alteplase for catheter occlusion in children include small study populations and relative lack of pediatric-specific prospective trials.

CONCLUSIONS

Alteplase appears to show efficacy for treatment of thrombus-related venous catheter occlusion in pediatric patients; however, data regarding its use in occluded dialysis catheters are limited.

Stability of Recombinant Tissue Plasminogen Activator at -30 °C over One Year

Recombinant tissue plasminogen activator (rt-PA) is used to restore patency and avoid inadvertent removal of peripheral and central venous catheters. rt-PA was reconstituted (1 mg/mL) then cryopreserved at −30 °C for 1, 2, 3, 6, 8, and 12 months and, then its stability was determined. After cryopreservation for one and two months, rt-PA kept more than 95% of its activity compared to standard samples, while cryopreservation for three months caused 8% loss of activity. However, after cryopreservation for six months or more, rt-PA retained only 87.5% or less activity compared to standard samples. Therefore, it is recommended that reconstituted rt-PA be cryopreserved at −30 °C for a maximum period of three months.

Does low-dose heparin maintain central venous access device patency?: a comparison of heparin versus saline during a period of heparin shortage

BACKGROUND

A common problem that complicates use of central venous access devices (CVADs) is occlusion by thrombosis. Alteplase, a recombinant tissue plasminogen activator, is used to restore line patency when thrombosis occurs. Heparin flush is commonly used to prevent this complication, but the effectiveness of this practice is unclear. A recent heparin shortage allowed examination of heparin effectiveness in reducing CVAD thrombosis.

METHODS

A retrospective cohort study was performed by querying a pharmacy database for alteplase use for CVAD thrombosis in adult patients during periods when heparin flushes (10 units/mL) were used and when saline flushes were used instead because of a nationwide heparin shortage. The number of patients receiving alteplase, the number of doses administered, and the total amount of alteplase used were compared over 1-month intervals of heparin flush use and 1-month intervals of saline flush use. Patient days and critical care patient days were compared between these time intervals. Peripherally inserted central catheter (PICC) line placements and replacements between time periods of heparin and saline flush were also compared.

RESULTS

Significant increases in the number of patients receiving alteplase (P = .04), the number of alteplase doses administered (P = .04), and total dose of alteplase used (P = .05) occurred during the heparin shortage. No significant differences in patient population were observed. The percentage of PICC line replacements also increased significantly (P < .05) when heparin was not available.

CONCLUSIONS

Heparin flush (10 units/mL) decreases thrombotic occlusions of CVADs, resulting in decreased alteplase use and fewer PICC line replacements.

Efficacy of local instillation of recombinant tissue plasminogen activator for restoring occluded central venous catheters in neonates

OBJECTIVE

To evaluate the efficacy of local instillation of tissue plasminogen activator (tPA) for restoring function to occluded central venous catheters (CVCs) in the neonatal population.

STUDY DESIGN

This was a retrospective review of patients admitted to the neonatal intensive care unit during September 2000 to April 2006 who received instillation of tPA for occluded CVCs.

RESULTS

Among 18 infants who received tPA for occluded CVCs, gestational age at birth was 32.5 weeks, birth weight was 1550 g, and gestational age at tPA administration was 39 weeks, with 4 neonates < or =32 weeks' gestational age at tPA administration; age at tPA use was 39 days (medians reported). Ten of 18 (55%) of CVC occlusions were successfully opened after using tPA. No bleeding complications of tPA were noted, including increased or new-onset intraventricular hemorrhage, overt bleeding, or changes in INR or partial thromboplastin time attributed to tPA use. Three patients (16.5%) had bacteremia within 7 days of tPA administration, and no catheter ruptures occurred.

CONCLUSIONS

Local instillation of tPA was successful in restoring function to occluded CVCs in a significant proportion of neonates, although success rates were lower than that reported in populations of older age. Despite the vulnerability of neonates to the potential complications of tPA, no major complications were detected even among premature infants.

Antithrombotic therapy in neonates and children: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This chapter about antithrombotic therapy in neonates and children is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs, and Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading, see Guyatt et al in this supplement, pages 123S-131S). In this chapter, many recommendations are based on extrapolation of adult data, and the reader is referred to the appropriate chapters relating to guidelines for adult populations. Within this chapter, the majority of recommendations are separate for neonates and children, reflecting the significant differences in epidemiology of thrombosis and safety and efficacy of therapy in these two populations. Among the key recommendations in this chapter are the following: In children with first episode of venous thromboembolism (VTE), we recommend anticoagulant therapy with either unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) [Grade 1B]. Dosing of IV UFH should prolong the activated partial thromboplastin time (aPTT) to a range that corresponds to an anti-factor Xa assay (anti-FXa) level of 0.35 to 0.7 U/mL, whereas LMWH should achieve an anti-FXa level of 0.5 to 1.0 U/mL 4 h after an injection for twice-daily dosing. In neonates with first VTE, we suggest either anticoagulation or supportive care with radiologic monitoring and subsequent anticoagulation if extension of the thrombosis occurs during supportive care (Grade 2C). We recommend against the use of routine systemic thromboprophylaxis for children with central venous lines (Grade 1B). For children with cerebral sinovenous thrombosis (CSVT) without significant intracranial hemorrhage (ICH), we recommend anticoagulation initially with UFH, or LMWH and subsequently with LMWH or vitamin K antagonists (VKAs) for a minimum of 3 months (Grade 1B). For children with non-sickle-cell disease-related acute arterial ischemic stroke (AIS), we recommend UFH or LMWH or aspirin (1 to 5 mg/kg/d) as initial therapy until dissection and embolic causes have been excluded (Grade 1B). For neonates with a first AIS, in the absence of a documented ongoing cardioembolic source, we recommend against anticoagulation or aspirin therapy (Grade 1B).

Comparison of alteplase and heparin in maintaining the patency of paediatric central venous haemodialysis lines: a randomised controlled trial

OBJECTIVES

To determine whether the tissue plasminogen activator, alteplase, is more effective than heparin in preventing blood clots developing in children's haemodialysis central lines between dialysis sessions.

DESIGN

A prospective double-blind, within-patient multiperiod cross-over controlled trial of instilling a "lock" of either heparin 5000 U/ml or alteplase 1 mg/ml into the central lines of two children haemodialysed twice weekly, and seven dialysed thrice weekly, over 10 weeks.

SETTING

A UK paediatric nephrology unit.

MAIN OUTCOME MEASURES

Weight of blood clot aspirated from the line at the start of the next dialysis session.

RESULTS

The odds of a clot forming was 2.4 times greater with heparin than alteplase (95% CI 1.4 to 4.0; p = 0.001), and when present they were 1.9 times heavier (31 vs 15 mg; 95% CI 1.5 to 2.4; p<0.0005). There was no effect of inter-dialytic interval. One child required an alteplase infusion to clear a blocked line following a heparin lock. We subsequently changed our routine locks from heparin to alteplase. Comparing the year before and after that change, the incidence of blocked lines requiring an alteplase or urokinase infusion fell from 2.7 to 1.2 per child (p<0.03), and the need for surgical replacements from 0.7 to nil (p<0.02).

CONCLUSION

Alteplase is significantly more effective than heparin in preventing clot formation in central haemodialysis lines. This reduces morbidity and improves preservation of central venous access. It is more expensive, though relatively economic if packaged into syringes and stored frozen until needed, but reduces the costs of unblocking or replacing clotted lines.

Efficacy and safety of reteplase for central venous catheter occlusion in patients with cancer

PURPOSE

To evaluate the efficacy and safety of reteplase for central venous catheter (CVC) occlusion in patients with cancer.

MATERIALS AND METHODS

An open-label, single-arm, prospective study was conducted. Reteplase (0.4 U) was instilled into each catheter lumen with a dwell time of 30 minutes in patients with cancer with a dysfunctional CVC. If the function of the catheter was not restored in 30 minutes, an additional dwell time of 30 minutes was allowed (a total of 60 minutes possible dwell time for the first dose). A second dose was repeated at 60 minutes after the first dose if catheter function was not restored (a total of 120 minutes for up to two doses). The primary efficacy outcome was the restoration of CVC function.

RESULTS

Of 139 patients who received reteplase, the first-attempt success rate after a 30-minute dwell time was 66.9%. The cumulative success rates at 60, 90, and 120 minutes were 88.5%, 94.7%, and 94.7%, respectively. The variation of patient age, catheter age, CVC occlusion age, CVC type, number of lumen, or occlusion type was not associated with the efficacy of reteplase. There were no treatment-associated adverse events reported during the study period.

CONCLUSION

Reteplase at 0.4-U dosing per catheter lumen is an effective and safe alternative that rapidly restores the patency of occluded CVCs in patients with cancer.

Development of evidence-based protocols for evaluation and management of dysfunctional vascular access devices in interventional radiology

Assessment and treatment of dysfunctional vascular access devices (VADs) is a mutual responsibility of nurses who use these devices and the interventional radiology (IR) team. Understanding causes of dysfunction, implementing assessment and treatment protocols, and communication between referral areas and the IR team are beneficial to both areas and to the patient. This study describes development of evidence-based protocols, combining research utilization and a quality improvement educational process.

Alteplase versus urokinase for occluded hemodialysis catheters

BACKGROUND

The use of central venous catheters as a source of vascular access in patients undergoing hemodialysis may be complicated by thrombosis. Frequently, thrombolytics are used in an attempt to reestablish blood flow through partially or completely occluded catheters.

OBJECTIVE

To compare the efficacy of alteplase (recombinant tissue plasminogen activator) versus urokinase in reestablishing adequate blood flow through partially or completely occluded vascular catheters.

METHODS

Part 1 of the study prospectively investigated the effect of alteplase in reestablishing adequate blood flow through partially or completely occluded vascular catheters in 30 hemodialysis patients. Part 2 of the trial compared the efficacy of alteplase with that of urokinase in 14 of 30 patients who had also previously received urokinase. A 30-minute push-protocol was used to administer thrombolytics in both parts of the study. The primary endpoint was the proportion of patients with partially or completely occluded catheters achieving post-thrombolytic blood flow of > or =200 mL/min.

RESULTS

Part 1 showed a large proportion of partially or completely occluded catheters achieving post-alteplase blood flows > or =200 mL/min (70/76, 92.1% vs. 34/40, 85%, respectively). In Part 2 of the study, the proportion of partially occluded catheters achieving post-thrombolytic blood flows > or =200 mL/min was not significantly different between the alteplase and urokinase groups, (36/41, 87.8% vs. 21/28, 75%, respectively; p = 0.205). The proportion of completely occluded catheters achieving post-thrombolytic blood flows > or =200 mL/min was significantly better with alteplase compared with urokinase (15/17, 88.2% vs. 6/14, 42.8%, respectively; p =.018).

CONCLUSIONS

Alteplase, administered via the 30-minute push-protocol, is an effective thrombolytic for restoring hemodialysis catheter patency. In our study sample, alteplase was generally more effective than urokinase in restoring blood flow through catheters, especially those that were completely occluded.

Use of tissue plasminogen activator (rt-PA) in young children with cancer and dysfunctional central venous catheters

PURPOSE

To determine the efficacy and safety of low, nonescalating dose tissue plasminogen activator (rt-PA) in restoring the patency of occluded central venous access devices (CVCs) in children with cancer who weigh less than 30 kg.

PATIENTS AND METHODS

A single-center review of the use of rt-PA (0.5 mg indwelling for 30 minutes in the CVC) was conducted in 42 cancer patients with large bore central venous access devices implanted over a 2-year period. All patients weighed less than 30 kg. None had been previously treated with a thrombolytic agent. The efficacy for restoring function to CVCs was measured and correlated with patient age, weight and CVC lumen size. Propensity to rethrombose following an initial occlusion and treatment was also determined.

RESULTS

Of 235 doses of rt-PA administered in a 2-year period, 55 doses administered to 42 patients met the eligibility criteria as outlined. Twenty-nine patients (69%) had function restored with a single dose; 8 patients (19%) required 2 doses, and 5 patients (12%) failed 2 doses; for an overall success rate of 88%. No significant adverse events occurred. Of the 37 cleared CVCs, 14 (38%) reoccluded within 1 month. A higher proportion of patients initially treated with one rt-PA (71%) experienced another CVC dysfunction within 1 month, compared with 29% CVC dysfunction in those requiring >1 dose.

CONCLUSIONS

This article describes the use of rt-PA (0.5 mg, without dose escalation) to lyse CVC-associated thrombi specifically in small children with cancer, a patient population in which it is particularly desirable to minimize the degree of fibrinolysis. One dose of 0.5 mg rt-PA, with an additional dose if necessary, is as safe and effective as previously reported escalating dose regimens for CVC clot lysis. There is no statistically significant correlation of treatment failure with patient age, weight, or catheter lumen size, and no significant propensity for rapid rethrombosis following a single dysfunction and treatment. Patients initially treated with a single dose of rt-PA appear to have more subsequent dysfunctions in the month after treatment, an observation that warrants further study.

Safe and cost effective use of alteplase for the clearance of occluded central venous access devices

PURPOSE

To determine whether cryopreserved solutions of the thrombolytic agent alteplase could be used as a safe, effective, and economically reasonable alternative to urokinase in patients presenting with occluded central venous access devices (CVADs).

MATERIALS AND METHODS

Alteplase has been reported as an efficacious alternative to urokinase for treatment of occluded CVADs. However, the practicality of using alteplase as the thrombolytic of choice for this indication remained conjectural. To make this approach economically feasible, alteplase was diluted to 1 mg/mL and 2.5-mL aliquots were stored at -20 degrees C until use. A need to confirm that the cryopreserving and thawing of the reconstituted solution did not compromise the safety and efficacy reported from prior trials was recognized. A quality assessment initiative was undertaken to concurrently monitor the safety and efficacy of this approach. Patients presenting with occluded CVADs received a sufficient volume of the thawed alteplase solution to fill the occluded catheter(s). Data, including efficacy, adverse reactions, dwell time, and catheter type, were collected over a 5-month period.

RESULTS

One hundred twenty-one patients accounting for 168 attempted clearances were assessable for safety and efficacy. One hundred thirty-six (81%) of the 168 catheter clearance attempts resulted in successful catheter clearance (95% confidence interval, 74% to 86%). No adverse events were reported.

CONCLUSION

Cryopreserved 1-mg/mL aliquots of alteplase are safe and effective in the clearance of occluded CVADs when stored at -20 degrees C for 30 days. The ability to cryopreserve alteplase aliquots makes it an economically reasonable alternative to urokinase in the setting of CVAD occlusion.

Alteplase

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Alteplase use for prevention of central line occlusion in a preterm infant

OBJECTIVE

To report the use of alteplase for catheter clearance in a neonate of 27 weeks' gestation at day 50 of life.

SETTING

Neonatal Intensive Care Unit, Naval Medical Center.

CASE SUMMARY

At day 50 of life, a neonate boy of 27 weeks' gestation had a clotted peripherally inserted central catheter line. He required central access to complete a 28-day course of amphotericin B. An alteplase dose of 0.3 mg/0.3 mL was instilled into the catheter, for an indwelling time of 1 hour. The initial attempt was successful, and the patient was able to finish the course of amphotericin B.

DISCUSSION

When a catheter becomes occluded, the cause must be determined initially; then an appropriate treatment option can be initiated. Hydrochloric acid and ethanol are some of the pharmacologic agents available, with their use dependent on the precipitating cause of the occlusion. Thrombolytic agents, such as streptokinase and urokinase, have also been used in catheter clearance. The potential risk of anaphylactic reactions with streptokinase and the unavailability of urokinase have clinicians searching for other pharmacologic alternatives. Alteplase, a synthetic tissue plasminogen activator, has been shown to be a promising alternative agent. There are various reports of alteplase use in pediatric patients for catheter clearance, with different suggested doses ranging from 0.25 to 2 mg. To minimize the risk of bleeding events, initiation with low doses from the suggested range is recommended.

CONCLUSIONS

Alteplase was shown to be safe and effective for clearance of an occluded central line in a preterm infant.

Recombinant tissue plasminogen activator in the treatment of central venous catheter occlusion in children

Tissue plasminogen activator was used to treat 228 children with 320 central venous catheter (CVC) occlusion events. Patency was restored in 91% of CVCs after 1 to 3 treatments, with no adverse events. Tissue plasminogen activator is effective in restoring patency to occluded CVCs and is a viable alternative to CVC removal or urokinase treatment.

Recombinant tissue plasminogen activator (alteplase) for restoration of flow in occluded central venous access devices: a double-blind placebo-controlled trial--the Cardiovascular Thrombolytic to Open Occluded Lines (COOL) efficacy trial

PURPOSE

Central venous access devices (CVADs) are a mainstay of current medical therapy but often become occluded by thrombus. Tissue plasminogen activator (alteplase), at a dose of 2 mg per 2 mL, has been shown to be effective in restoring flow to catheters proven by radiographic contrast injection to be occluded by thrombus. The purpose of this double-blind placebo-controlled multicenter trial was to determine the efficacy of alteplase in occluded catheters without earlier contrast injections or radiographic examinations.

MATERIALS AND METHODS

Patients were eligible for inclusion if blood could not be withdrawn from their catheter after a period of normal function of at least 48 hours. Single or multiple catheters, peripherally inserted central catheters, catheters with valves, and implanted ports were eligible; catheters used for hemodialysis were not included. Patients were randomly assigned to one of two groups. In one group, patients received a first dose of 2 mg alteplase followed, if needed, by a second dose of 2 mg alteplase and a third dose of placebo. The other group received placebo first followed by one 2-mg dose of alteplase and then a second, if needed. Each dose was allowed to dwell for 2 hours and ability to withdraw blood from the catheter was reassessed. The endpoint was restoration of the ability to withdraw and infuse through the catheter. One hundred forty-nine patients were randomized: 74 received placebo first, 75 received alteplase first.

RESULTS

After the first 2-hour treatment, function was restored to 74% in the alteplase arm and 17% in the placebo arm (P <.0001 compared to placebo). After one or two treatments, function was restored in 90% of patients. There were no serious study-drug-related adverse events, no intracranial hemorrhage, no major hemorrhage, and no embolic events.

CONCLUSION

Infusion of alteplase appeared to be safe and effective in restoring flow to occluded catheters without need for pretreatment radiographic evaluation.

Techniques in dosing for thrombolysis of occluded central venous catheters

Dosing of thrombolytic agents for restoration of flow to thrombotically occluded central venous catheters has been empiric. The lowest effective dose of any agent is not known. Given that none of the dosing regimens in current use has ever been found to be toxic, this is probably not a major clinical problem as long as the regimen is highly effective. Thrombolytic regimens differ in the type of drug, dose of drug, method of administration (injection versus prolonged infusion), and duration of administration. All of these variables are important in determining the efficacy, and possibly the toxicity, of a regimen. Active research is being conducted to determine the most effective ways of using the expanding number of thrombolytic medications that are now, or soon may be, on the market.

Alternatives to Urokinase for the Management of Central Venous Catheter Occlusion

The nationwide shortage of urokinase that began in late 1998 forced the medical community to find suitable alternatives to this agent for the management of various thrombotic processes. A high-use indication for urokinase in our institution is the management of occluded central venous catheters. A comprehensive search of the medical, pharmacy, and nursing literature produced limited but useful information on various alternative agents, including streptokinase, alteplase, hydrochloric acid, ethanol, and sodium hydroxide. This article reviews the available literature on each of these agents.

Alteplase (t-PA) Bolus: Occluded Catheters

Off-Label Drug Uses

ThisHospital Pharmacy feature is extracted from Off-Label DrugFacts, a quarterly publication available from Facts and Comparisons. Off-Label DrugFacts is a practitioner-oriented resource for information about specific FDA-unapproved drug uses. This new guide to the literature will enable the health care professional/clinician to quickly identify published studies on off-label uses and to determine if a specific use is rational in a patient care scenario. The most relevant data are provided in tabular form so that the reader can easily identify the scope of information available. A summary of the data—including, background, study design, patient population, dosage information, therapy duration, results, safety, and therapeutic considerations—precedes each table of published studies. Finally, references direct the reader to the full literature for more comprehensive information prior to patient care decisions.