Conference Report Published by CareFusion Center for Safety and Clinical Excellence
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- Bu səhifədəki naviqasiya:
- Averted infusion programming errors
- Process and practice improvements
- Table 2. Examples of SJCHS 2006 Heparin CQI Data Date Profile Initial Dose Final Dose Multiple of
- Highest-Risk Averted Overdoses * ( n=33) Patient Care Type Smart Pumps
- Table 1. Averted Overdoses: Risk for Harm/Patient Care Types 4
- New lot evaluation of aPTT reagents— UC Davis Health System protocol
- Variation among laboratories
- Figure 2: Differences between new and existing reagent lots Example of pooled plasma spiked with varying concentrations of argatroban. The two lines represent existing-lot
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Risk score reduction Before implementation of the smart infu- sion system, a failure mode and effects analy- sis (FMEA) demonstrated a risk score of 210 for IV administration of heparin. This risk score was driven predominantly by a lack of a second check of the pump setting by nurses before starting the infusion. FMEA after implementing the smart infusion sys- tem resulted in a risk score of 56, a 4-fold reduction achieved primarily by improved detection of heparin infusion programming errors 2
Averted infusion programming errors An in-depth analysis of CQI data from a nine-month period showed that 245 infu- sion system alerts resulted in a programming change or canceled infusion representing averted errors 4 . Of these, 166 averted over- doses were felt to represent the greatest 21
Executive Summary Conference Report 9th Invited Conference: Improving Heparin Safety potential for harm. Heparin represented 23 (14%) of 166 potentially harmful overdoses 4 . Further analysis using the IV Medication Harm Index 5 demonstrated that heparin accounted for a significant number of averted overdoses with the highest potential for harm. The IV Medication Harm Index is an ana- lytic tool that characterizes the magnitude of potential harm based on three sub-scales: 1) drug risk and magn itude of overdose; 2) level of care and patient acuity and 3) detectability of adverse event. It has a range of values of 3.5 to 14.0. 5 In our analysis, heparin accounted for 42% of those overdoses with risk scores equal to or greater than 11.0 on the IV Medication Harm Index 4 . Most patients who would have received these overdoses were treated in non- ICU medical/surgical nursing units 4 .
Wireless network connectivity of smart infusion devices allows the opportunity to evaluate aggregated data from the system and identify medication-use processes that need improvement. Analysis of heparin data in 2004 demonstrated a need to assess and redesign SJCHS weight-based heparin proto- cols 2
• Multiple IV heparin concentrations were standardized to 50 units/mL • Three time-consuming steps in dose cal- culation were eliminated • Infusion rate calculations by nurse or phar- macist were eliminated by implementing dose-based pump programming in units/ Kg/hr
• Extensive computer-based re-education of nurses and pharmacists was conducted Additional analysis in 2006 demonstrated continued problems with pump program- ming for bolus dosing of heparin infusions (Table 2). To correct these problems, bolus parameters were defined in the infusion-sys- tem’s software drug library and additional nurse and pharmacist education was imple- mented using case scenarios in computer- based learning modules. Recent SJCHS medication-use data indi- cate that more than 75% of parenteral anti- coagulant use is low molecular weight hepa- rins (LMWH); unfractionated heparin (UFH) is administered to a minority of patients who require anticoagulation. Although UFH use is declining, it is unlikely that it will be totally replaced by other anticoagulants in the near future. LMWH may be a safer alternative to UFH in those patients who are appropriate candidates for its use. Summary Smart infusion systems provide actionable data that can be used to improve medica- tion use processes for many IV-administered drugs, including heparin. Although heparin is administered in both intensive care unit (ICU) and non-ICU settings, patients who receive the drug outside of the ICU may be at greater risk for harm, because the level of monitoring for adverse events is less intense in these set- tings. Wireless network communication with infusion devices significantly improves the efficiency and timeliness of process inter- ventions based on CQI data collected by the devices.
1. Communication with D.W. Bates, M.D., M.Sc. of Brigham & Women’s Hospital in Boston, October 2001. 2. Williams CK, Maddox RR. Implementation of an i.v. safety system. Am J Health-Syst Pharm 2005: 62:530-6. 3. Maddox RR, Williams CK, Oglesby H, et al. Clinical expe- rience with patient-controlled analgesia using con- tinuous respiratory monitoring and a smart infusion system. Am J Health-Syst Pharm 2006; 63:157-64. 4. Williams CK, Maddox RR, Heape E, et al. Application of the iv medication harm index to assess the nature of harm averted by “smart” infusion safety systems. J Patient Saf 2006; 2:132-9. 5. Sullivan J. IV medication harm index: results of a national consensus conference. In: Schneider PJ, ed. Infusion safety: addressing harm with high-risk drug administration. Hosp Health Netw 2004; 78(5suppl):29- 31. Retrieved September 9, 2005 from: www.cardi- nalhealth.com/clinicalcenter/materials/conferences/ index.asp. Table 2. Examples of SJCHS 2006 Heparin CQI Data Date Profile Initial Dose Final Dose Multiple of Max Limit Times Intended Dose 1/4/06
Adult Critical Care 80 units/kg/hr 18 units/kg/hr 2 4.4 1/12/06 Adult Critical Care 80 units/kg/hr 18 units/kg/hr 2 4.4
2/1/06 Adult Med Surg 80 units/kg/hr 18 units/kg/hr 2 4.4
3/26/06 Adult Med Surg 80 units/kg/hr 12 units/kg/hr 2 6.7
Highest-Risk Averted Overdoses * ( n=33) Patient Care Type Smart Pumps (n=426) Total Averted Overdoses (n=166) Total (n=33) Propofols (n=10) Heparin (n=14) ICU Critical Care 332 (78%) 140 (84.3%) 16 (48.5%) 10 (100%) 1 (7%) Non-ICU
67 (22%) 26 (15.7%) 17 (51.5%) — 13 (93%) * Averted overdoses with scores ≥ on the IV Medication Harm Index16 (drug risk overdose range, level of care /acuity and detectability). © 2006 Lippincott Williams & Wilkins
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PROCEEDINGS
• National Patient Safety Goal Requirement 3E requires hospitals to reduce the likelihood of patient harm associated with the use of anticoagulation therapy. • Unfractionated heparin (UFH) therapy is usually monitored with a clot-based test, activated partial prothrombin time (aPTT). • A laboratory can change aPTT reagents every 12 to 16 months, depending on its manufactur- er-determined stability, and the new therapeutic range may need to be determined using the new reagent lot. • The aPTT result can be affected by variations among testing devices and reagents, patient physiology and pathophysiology, concurrent medications, improper blood collection and plasma preparation and delay in centrifuging or testing a sample. • Test results vary among POC devices and typically do not match laboratory aPTT results because of differences in sample type, clot detection method and sample-reagent incubation period. • Sharing knowledge about the potential shortcomings of aPTT testing to monitor UFH therapy and the possible need to change the therapeutic range can help reduce the likelihood of harm and improve the care of patients receiving anticoagulation therapy. Heparin Safety and the Coagulation Laboratory Robert Gosselin, CLS, Coagulation Specialist, Coagulation Laboratory, University of California Davis Medical Center, Sacramento, CA In 2008, the Joint Commission’s new National Patient Safety Goals included Requirement 3E: Reduce the likelihood of patient harm associated with the use of anti- coagulation therapy 1 . This applies to patients receiving either oral or intravenous (IV) anti- coagulation therapy. The most frequently used IV anticoagulant is heparin. Safe and effective heparin use requires fre- quent monitoring to ensure that drug levels are maintained within a narrow therapeutic window. Unfractionated heparin (UFH) thera- py is usually monitored with a clot-based test, activated partial prothrombin time (aPTT). Other clot-based tests such as thrombin time are infrequently used but can be useful in situations such as patients with lupus who have elevated baseline aPTT levels. Other approaches are to measure levels of heparin or anti-Xa activity. Heparin levels are most commonly measured by chromogenic meth- ods, although protamine titration is still used. Activated clotting time (ACT) is widely used outside the clinical laboratory setting. In this manuscript, the laboratory’s role in monitoring continuous infusion UFH using aPTT testing and some of the associated problems will be discussed.
The College of American Pathologists (CAP) is one of the organizations that certify clinical laboratories. For UFH monitoring, CAP requires that each laboratory have a docu- mented system for determining and validat- ing an aPTT-based heparin therapeutic range using an appropriate technique 1,2 . The most common approach is to use the method described by Brill-Edwards, et al. to com- pare heparin levels with aPTT values 3 . When chromogenic methods are used, a regression analysis is done between levels of aPTT and heparin. The therapeutic range is determined by drawing intercept lines between 0.3-0.7 units/mL heparin levels and aPTT values (Figure 1). A laboratory can change aPTT reagent every 12 to 16 months, depending on its manufacturer-determined stability. CAP sug- gests that at least 30 UFH patients be tested, with no more than two samples per patient 4 . After concurrent testing of new and existing lots, CAP recommends using the differenc- es between aPTT means and summation of mean differences over past evaluation peri- ods. In either case, if the difference between the aPTT means of the new lot and either the existing lot or cumulative difference is
the change may not be noticed by clinicians. If either difference is >7 seconds, then a new therapeutic range must be determined. To minimize the possibility of having to create a new therapeutic range, a laboratory 23
Executive Summary Conference Report 9th Invited Conference: Improving Heparin Safety can request that a reagent manufacturer sup- ply a new lot with similar heparin responsive- ness. A laboratory could also obtain multiple lots for evaluation and select the lot that more closely matches results for the existing lot. Another option is to save plasma samples from UFH-treated patients throughout the year for future testing. This allows even the smallest laboratory to have enough samples for comparison testing. Any UFH samples that are frozen should be validated, for reasons discussed below. It is not acceptable to deter- mine the therapeutic range using UFH-spiked plasma, because this approach tends to over- estimate the therapeutic range. Pre-analytical variables can affect aPTT results, and mechanisms to ensure proper blood collection and plasma preparation are required. Testing should be performed on unclotted, 3.2% sodium citrate, platelet-poor plasma (<10,000/mm 3 ) within 4 hours of col- lection 5 . For monitoring UFH therapy, the aPTT sample should centrifuged within one hour and tested within four hours of collection 5 .
The citrate tube should be nearly full to avoid an improper citrate:plasma ratio that could falsely increase clotting times. At our institu- tion, before analysis every coagulation sample is rimmed with applicator sticks to check for macroscopic clots. The processing centrifuge is checked daily to assure that platelet-poor plasma is created. For citrated samples to be saved for later testing, the plasma is removed from the primary collection tube and placed into a secondary tube and re-centrifuged. After the second centrifugation, the plasma is then aliquoted into freezer-safe capped vial(s) prior to freezing at -70 o C.
UC Davis Health System protocol At our institution, two to three different lots of aPTT reagent with similar UFH sensitiv- ity are requested from the manufacturer for initial evaluation. The coagulation analyzers are set up to reflex patient testing on new lot aPTT reagents if they meet established crite- ria for evaluation: 1) aPTT within current ther- apeutic range with current lot aPTT reagent, and 2) normal INR. After testing is complete on the new and current lots of reagents, the samples are saved at -70 o C for possible future analysis. Although CAP recommenda- tions allow up to two samples per patient, we prefer to use a patient only once for data analysis. Access to electronic medical records (EMR) allows the staff to review UFH dos- ing to determine whether therapeutic doses have been given. Regression analysis and bias plots are used to determine which new-lot aPTT reagents are preferable. At least 40 UFH- treated patients are evaluated to determine whether a new therapeutic range is warrant- ed. Data are shared with pharmacists to alert them to potential bias areas when transition to a new reagent lot occurs. Establishing rapport between labora- tory staff and the pharmacy staff is prudent. Sharing information facilitates smooth tran- sition if new therapeutic ranges are required and allows the clinical staff to address any issues surrounding the data. New thera- peutic ranges most likely will require a change in dosing orders, so a lead time (one month, at our facility) before new-lot transition would allow new dosing orders to be approved and disseminated for the new reagent lots. If the therapeutic range is changed, a concrete transition day and shift must be established and appropriate pharmacy and clinical staff notified. Direct thrombin inhibitors (DTI) are also monitored using the aPTT. Informing clinical staff about the impact of new reagent lots on DTI therapy is strongly recommended, to ensure that they can assess potential issues (Figure 2). Secondly, since aPTT testing is also used in settings such as hemophilia screening or lupus anticoagulation, inform- ing the clinical staff about the performance characteristics of a new aPTT reagent lot would be beneficial. aPTT testing: ancillary issues Many pre-analytical and analytical vari- ables affect the accuracy of aPTT results. Probably the most important variable is the Figure 1: Determination of heparin therapeutic range Heparin therapeutic range comparing chromogenic heparin levels (X axis) to corresponding aPTT values in patients receiving therapeutic UFH. A regression line is drawn, and then intercept lines between 0.3-0.7 units/mL UFH and the aPTT axis. In this example the therapeutic range would be 42-82 seconds. y = 94.14x + 15.673 R 2 = 0.5166 140
120 100
80 60 40 20 0 Anti-Xa activity, U/mL 0 0.1
0.2 0.3
0.4 0.5
0.6 0.7
0.8 0.9
1 1.1
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Analytical variables, e.g., differences between instruments and reagents, may not be evident within a laboratory or consor- tium of laboratories that use like reagents and instruments, but may become apparent when samples are compared to other labo- ratories. While the largest variable is differ- ent reagents, instruments also differ in the endpoint measurement of the test. Different types of activator and the concentration and type of phospholipid in the reagent will yield different results, even if samples are analyzed concurrently on the same instrument 6,7 .
Physiological variations will also affect aPTT results. The aPTT measures the func- tional ability of nine coagulation factors and, to a lesser degree, fibrinogen. Decreased fac- tor levels or activity can increase aPTT, and increased factor levels or activity can decrease aPTT. Especially in UFH monitoring, elevat- ed levels of fibrinogen and factor VIII, both acute-phase reactants, may falsely decrease the aPTT and suggest “heparin resistance” 2,8 .
as thrombolytics, Xigris® and NovoSeven® may also increase or decrease aPTT results. Pathologic states such as antiphospholipid antibody syndrome, vonWillebrand disease, immune causes of factor deficiency, among others, may also affect the aPTT result. Variation among laboratories CAP survey results highlight the prob- lems of aPTT testing for UFH monitoring. CAP requires each clinical laboratory to dem- blood-acquisition (phelebotomy) technique. In healthy individuals, blood is usually drawn from the antecubital fossa using vacutainer- type blood collection tubes without major problems. When drawing blood presents a problem, technique may affect results. The use of small-bore needles (<23 gauge), entry into small veins and increased force in drawing back the syringe plunger may result in lysis of red blood cell (RBC) and the release of phospholipids that may initiate the coagulation process. Cell lysis may not be not readily apparent until the blood is processed in the laboratory. The use of syringes for venipuncture also presents other challenges. Blood is activated by exposure to negatively charged surfaces such as glass or plastic and delays of >60 sec- onds in transferring freshly collected blood into vacutainer tubes containing appro- priate anticoagulants may also effect test results. Other problems include tourniquet time, improper blood-to-anticoagulant ratio, improper anticoagulant uses (different col- ored blue top tubes), improper clearing of indwelling catheters prior to blood collection for testing, improper storage of sample once collected and delays in getting samples to the laboratory. The effects of poorly phle- botomized blood may not become apparent until the sample reaches the laboratory (clot- ted sample) or during the analytical (test- ing) phase (decreased clotting time) or post- analytical phase, when samples are saved for future testing. A properly collected citrated sample must be sent to the laboratory immediately. As noted above, platelet-poor plasma should be processed within one hour of collection 5 . Figure 2: Differences between new and existing reagent lots Example of pooled plasma spiked with varying concentrations of argatroban. The two lines represent existing-lot aPTT reagent (527295) and new-lot aPTT reagent (537224). These spiked samples could be stored at -70 Yüklə 1 Mb. Dostları ilə paylaş:
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