Clinical Evaluation of a Positive Pressure Device to Prevent

CLINICAL JOURNAL OF ONCOLOGY NURSING • VOLUME 5, NUMBER 6 • CLINICAL EVALUATION OF A POSITIVE PRESSURE DEVICE 261

FEATURE ARTICLE

Clinical Evaluation of a Positive PressureDevice to Prevent Central Venous Catheter

Occlusion: Results of a Pilot Study

Submitted January 19, 2001. Accepted forpublication April 15, 2001. ICU Medical, Inc.provided CLC2000TM devices to PennsylvaniaHospital at no cost for the pilot study. (Men-tion of specific products and opinions relatedto those products do not indicate or implyendorsement by the Clinical Journal of On-cology Nursing or the Oncology Nursing So-ciety.

One of the complications related to central venous cathetersis occlusion secondary to thrombus formation within or sur-rounding the catheter lumen. Historically, methods to pre-vent these occlusions have included vigorous flushing, co-ordinated flushing-clamping techniques, and antithromboticprophylaxis using low-dose warfarin or low molecular weightheparin. Positive displacement devices recently have becomeavailable that prevent retrograde blood flow and conse-quently reduce the risk of thrombus formation in the catheterlumen. Maintaining catheter patency results in fewer treat-ment delays and diagnostic procedures, decreased use ofthrombolytics, lower costs, and increased patient satisfac-tion. A trial of a positive displacement device was conductedon an inpatient oncology unit to determine its effectivenessin preventing catheter occlusions. The easy-to-use deviceeffectively reduced the number of occlusions and resulted insignificant cost savings when compared to thrombolytictherapy.

Margaret A. Rummel, RN, MHA, OCN®, Patrick J. Donnelly, RN, MS, CCRN,and Cathy C. Fortenbaugh, RN, MSN, AOCN®

T he presence of acentral venous cath-eter (CVC) is a

known risk factor for throm-bus formation. Catheter-related thrombus (CRT) maybe intraluminal or extra-luminal and can cause partialor total catheter occlusion.CVC occlusions impair IVfluid and medication admin-istration, blood sampling,and blood product adminis-tration. Possible complica-tions of CRT formation in-clude septicemia, superiorvena cava syndrome, venousthrombosis, and pulmonaryembolism (Bona, 1999;Smith, 1998).

The incidence of CRT re-portedly ranges from 20%–55%; however, varying defi-nitions of “occlusion” areused in the literature, and nostandardized method for determining the de-gree of occlusion exists (Cobos, Dixon, &Keung, 1998; Lowell & Bothe, 1995; Whit-man, 1996). In a prospective study, DeCiccoet al. (1997) found that 63 of 95 patients(66%) without symptoms of CVC occlusionhad evidence of catheter thrombus forma-tion when venograms were performed. Al-though CRT is diagnosed in many patientswith CVCs, many more may be asymptom-atic yet have CRT.

Pathogenesis ofThrombus Formation

Several factors appear to predispose pa-tients to CRT. Catheter characteristics arebelieved to play a major role; polyethylene,polyvinyl chloride, and teflon catheters areassociated with a higher incidence of CRTthan silicone catheters. Double-lumen cath-eters are more prone to CRT than single

lumen, and prolonged ind-welling times also are factorsin CRT development. Pa-tients with solid tumors,hypercoagulable states, coex-isting infection, mechanicalfactors (e.g., mediastinal tu-mors), and those receivinginfuscate with a low ph orhigh osmolarity are at risk forCRT (Bona, 1999; Hadaway,1998; Raad et al., 1994).Catheters that are inad-equately maintained (e.g.,not flushed or inadequatelyflushed after use, not regu-larly flushed when not in use)are prone to thrombus forma-tion and occlusion.

Another risk factor asso-ciated with CRT is negativedisplacement of blood thatbackflows into the catheterlumen when an infusion de-vice, such as a syringe, is

262 NOVEMBER/DECEMBER 2001 • VOLUME 5, NUMBER 6 • CLINICAL JOURNAL OF ONCOLOGY NURSING

removed from an injection port attached tothe CVC. This retrograde blood flow intothe catheter lumen may result in stasis ofblood in the catheter and subsequent intralu-minal thrombus formation (see Figure 1).

Prevention of Catheter-Related Thrombus

Although much has been written aboutmanaging catheter occlusions, prevention ofCRT has received less attention. Methodsused in clinical practice to help preventthrombus formation include several untestedmethods, such as vigorous flushing with 10–20 ml of normal saline, coordinated flush-ing/clamping techniques, and the pulsatileflow technique (Camp-Sorrell, 1996; Doyle& Nale, 1999; Krzywda, 1999). The goal ofthese approaches is to clear the catheter andprevent negative displacement of blood.However, forward flushing while withdraw-ing a saline-filled syringe works best with aneedle attached to the syringe and is verydifficult when leur-lock devices are used.Leur-lock and other needleless devices arebeing used increasingly to reduce needle-stick injuries among healthcare workers.

Prophylactic low-dose warfarin also hasbeen used to reduce CRT. At one institution,the rate of CRT was 11% for patients whoreceived warfarin compared to 21% in pa-tients who were not anticoagulated (Carr &Rabinowitz, 2000). In a study of patients with

hematological malignancies, 5 out of 108(5%) patients who received low-dose war-farin (1 mg/day) developed CRT at a medianof day 72 from the time of insertion. Fifteenof 115 patients (13%) not anticoagulated de-veloped CRT at a median of day 16 (Borakset al., 1998). Another study of patients withhematologic and solid tumors found thatthrombotic events, mainly CRT, occurred in10 out of 55 patients (18%), including 7 whoreceived low-dose warfarin. Bleeding oc-curred in three patients, all on warfarin(Ratcliffe, Broadfoot, Davidson, Kelly, &Greaves, 1999). The effectiveness of low mo-lecular weight heparin in preventing CRTwas evaluated in a group of patients with im-planted ports. Thirty-one of 145 patients(21%) developed CRT, and the incidence ofCRT was higher in patients with peripherallyimplanted ports compared to those with cen-trally implanted ports (Tesselaar, Ouwerkerk,Rosendaal, & Osanto, 2001).

All of the various CRT prevention mea-sures described above require nursing time,incur supply, and medication costs; some(e.g., anticoagulation) require patient adher-ence to medication regimens and placepatients at risk for bleeding or other compli-cations.

Positive Pressure Devices A CVC device that creates positive pres-

sure and prevents backflow of blood into thecatheter may be useful in preventing intralu-

minal or extraluminal thrombus formation(Macklin, 2000). Positive displacement refersto the volume of infuscate that exits the cath-eter lumen when an infusion device, such asa syringe, is removed from the injection port(see Figure 2). Eliminating blood in the CVClumen prevents the stasis of blood in the cath-eter and may help to prevent CRT. Twobrands of positive pressure devices are mar-keted in the United States: CLC2000TM (ICUMedical, Inc., San Clemente, CA) and B-DPosiflowTM IV Access System (BectonDickinson, Franklin Lakes, NJ).

Pilot StudyThe staff on the inpatient oncology unit at

Pennsylvania Hospital, part of the Universityof Pennsylvania Health System, conducted apilot study to evaluate the CLC2000 device.The T-shaped positive pressure device con-tains an O-ring that positively displaces bloodwhenever a syringe or IV tubing is discon-nected (see Figure 3). This design feature alsonegates the need for heparin flushes; themanufacturer recommends flushing with nor-mal saline only (ICU Medical, 2001). It islatex-free, lipid and blood compatible, andcan be used with central, peripheral, and ar-terial lines (ICU Medical). The device is de-signed to be used as a component of aneedless system; if a needle is used, eitherintentionally or inadvertently, the O-ringmechanism will begin to leak. The devicethen needs to be changed at once because itspositive displacement ability now is lost.

Prior to initiating the pilot study, the nurs-ing staff gathered data on the oncologyunit’s catheter occlusion rate. Staff membersthen conducted a research utilization projectthat resulted in the development of an evi-dence-based policy and procedure forthrombolytic instillation to restore patencyin occluded CVC catheters. The nurses de-veloping the policy noted that littleevidence-based information existed in theliterature addressing CRT prevention and,therefore, designed the pilot study to assessa positive displacement device.

The CLC2000 positive displacement de-vice was used on all patients with a CVC onthe 42-bed inpatient oncology unit. Approxi-mately 10 inpatients per day were entered intothe six-week study, for a total of 420 catheterlumens. Seven hundred positive displacementdevices were used during the study period.The control group consisted of approximately500 outpatients with catheter lumens who re-ceived usual care and had conventionalinjection caps on their CVCs; the positive dis-placement device was not used in thesepatients. The number in the outpatient groupfluctuated slightly during the study period

FIGURE 1. MECHANISMS INVOLVED IN NEGATIVE AND POSITIVE DISPLACEMENT OF BLOOD IN CATH-ETER LUMENS

Note. Copyright ICU Medical, Inc., 2001. Reprinted with permission.


because a few of these patients were trans-ferred to the oncology unit for chemotherapyor did not have conventional injection caps inplace because they were receiving continu-ous infusion chemotherapy. The majority ofpatients had double-lumen peripherally in-serted central catheters and single- ordouble-lumen implanted ports. The devicealso was evaluated in patients with double-lumen tunneled catheters and triple-lumenapheresis catheters. Patients received fluids,blood products, chemotherapy, antibiotics,opioids, and other IV medications via CVCs.In addition, CVCs were used for blood sam-pling. The manufacturer recommends thatCLC2000 be changed every 24 hours or perinstitutional protocol (ICU Medical, 2001),and they were changed weekly when routine

CVC dressing changes were performed forthose patients whose hospital stays exceededone week. The conventional injection capsused on the outpatient group were changed atweekly intervals.

Nurses were educated on the use of thedevice by a representative of the manufac-turer and followed the procedures for usingthe CLC2000 as outlined in Figures 4 and5. “Catheter occlusion” was defined as im-pairment or inability to infuse fluids or med-ications or withdraw blood or fluid from theCVC.

During the six-week study period, onepatient on the inpatient unit who did nothave the device in place (by inadvertentomission) developed a fibrin sheath requir-ing declotting with tissue plasminogen

activator (t-PA). Eleven outpatients, who re-ceived care at home, in the clinic, or in bothsettings, experienced CVC occlusions andrequired t-PA instillation.

The total cost of 700 CLC2000 devices is$2,065 (costing $2.95 each). Conventionalinjection caps cost approximately $1.60each. The approximate cost of t-PA instilla-tion at Pennsylvania Hospital is $300. Forpatients with double-lumen CVCs, the costto restore patency of the CVC is $600 be-cause both lumens require t-PA instillation.The costs associated with this pilot study arepresented in the inset below.

Outpatient study costs amounted to ap-proximately $7,100, and inpatient study costswere approximately $2,665, representing acost difference of $4,435. Theoretically, if allof the outpatients had the device in place andCVC occlusion was avoided in this group, apotential savings of $5,892.90 could result($6,300 for t-PA instillation minus $407.10for CLC2000 devices, changed weekly, for23 patients). Further cost savings possiblycould have been achieved if the inpatient withthe inadvertently placed conventional injec-tion cap had a positive displacement devicein place. The cost to declot this patient’s CRTwas included in the inpatient cost analysis;the objective of this pilot study was to exam-ine and compare inpatient and outpatientcosts of caps and CRT declotting during thesix-week study period.

The pilot study data was shared with nurs-ing leaders at the authors’ institution. Pointsof discussion included the cost of routinelystocking and using the positive displacement

FIGURE 2. CROSS-SECTION OF THE CLC2000TM POSITIVE DISPLACEMENT DEVICE


FIGURE 3. INTERNAL VIEW OF FLUID PATH FOR CLC2000TM POSITIVE DISPLACEMENT DEVICE


Approximate Outpatient Costs for 500Catheter Lumens (Injection Caps,

Declotting Procedures)

Conventional injection caps = $800Outpatients requiring tissue plasminogenactivator (t-PA)• 11 patients with single-lumen central

venous catheters (CVCs) = $3,300• 5 patients with double-lumen

CVCs = $3,000Total outpatient cost = $7,100

Approximate Inpatient Costs for 420Catheter Lumens (Positive Displacement

Devices, Declotting Procedure)

CLC-2000TM = $2,065Inpatients requiring t-PA• 1 patient with double-lumen

CVC = $600Total inpatient cost = $2,665

Cost Comparison

Approximate outpatient costs = $7,100Approximate inpatient costs = $2,665Cost difference = $4,435

264 NOVEMBER/DECEMBER 2001 • VOLUME 5, NUMBER 6 • CLINICAL JOURNAL OF ONCOLOGY NURSING

FIGURE 4. PROCEDURE FOR ATTACHING AND USING THE CLC2000TM FOR CENTRAL, PERIPHERAL,AND ARTERIAL LINES


devices, as well as potential cost savings thatcould be achieved by reducing the numberof fluoroscopic procedures and thrombolyticinstillations and their associated costs interms of nursing time and treatment delays.Anecdotal data from nurses indicated thatthey found the device easy to use and thatthe device was accepted well by patients.

The positive displacement device was ap-proved by the nursing leaders for routine use,and it has been used for the past six monthson all patients on the oncology unit, with noincidents of catheter occlusion occurring. Inaddition, the device now is used hospital-wide on patients with CVCs with theexception of areas in which a CVC is brieflyused, such as the emergency room and daystay unit. The device costs approximately $3;for short infusions, this cost outweighs thelikelihood that an occlusion will occur.

The nursing staff on units in which the de-vice is used received comprehensive initialtraining about using the device, and the in-formation will be reviewed in ongoing skillsfairs for nurses. Policy and procedural infor-mation on using positive displacement de-

vices was added to the institution’s manuals.One possible limitation in implementing

the hospital-wide use of the positive displace-ment device is the potential that agency, perdiem, and newly hired nurses will be unfa-miliar with the device and misuse it.However, if the CVC is clamped or a needleis used with the device and positive displace-ment is negated, then the end result is noworse than having a “regular cap” at the endof the catheter. Another potential limitationis that patients who continue their therapy athome or in physicians’ offices will need toinform their nurses about the device; anotheroption would be to change the device to aconventional injection cap prior to discharge.

Results of this pilot study evaluating theCLC2000 cannot be generalized to other in-stitutions or patient populations. Patientswere not randomized; instead a conveniencesample was used. Future research, perhapsusing patients as their own controls, withrandomized sampling is indicated to furtherevaluate the effectiveness of positive dis-placement devices in reducing CRT inci-dence.

Implications for PracticeBecause CRT is a multifactored phe-

nomenon, not all risk factors for CRT canbe eliminated. Patients with certain riskfactors, such as hypercoagulable states orsolid tumors, are still at risk for develop-ing CRT even if positive displacementdevices are used. However, these devicesappear to prevent negative displacement ofblood into the CVC lumen and, conse-quently, have the potential to reduce CVCocclusion incidence. Potential cost savingsalso may result, especially in institutionsin which heparin flushes are used rou-tinely. Converting to saline flushes reducescosts, and added cost savings may occur ifusing the device results in fewer CVC oc-clusions requiring fluoroscopic evaluationand thrombolytic therapy. The device alsomay play a role in promoting patient satis-faction; patients who are able to completetreatment without interruption and thosewho encounter fewer problems duringtreatment generally are more pleased withtheir care than patients who encounter de-lays and difficulties.

When positive pressure devices are usedto help prevent CRT, nurses who use thesedevices must be knowledgeable about theirproper use and able to educate patients andother colleagues (such as the patient’s home-care nurse) about them. These devices havethe potential to reduce CRT, but only if theyare used properly.

SummaryA common complication related to CVCs

is intraluminal thrombus formation and sub-sequent occlusion. Although variousmeasures to reduce or prevent CRT havebeen used historically, few have been evalu-ated scientifically. The findings of this pilotstudy suggest that the use of a positive dis-placement device may reduce CRTincidence and CRT-related costs. However,more research is needed in these areas.

Author Contact: Margaret A. Rummel,RN, MHA, OCN®, can be reached at 817Yardley, PA 19067 or at [email protected]

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Boraks, P., Seale, J., Price, J., Bass, G., Ethell, M.,Keeling, D., Mahendra, P., & Marcus, R.(1998). Prevention of central venous catheter


associated thrombosis using minidose warfarinin patients with haematolgical malignancies.British Journal of Haematology, 101, 483–486.

Camp-Sorrell, D. (1996). Access device guide-lines: Recommendations for nursing practiceand education. Pittsburgh: Oncology NursingPress.

Carr, K., & Rabinowitz, I. (2000). Physician com-pliance with warfarin prophylaxis for centralvenous catheters in patients with solid tumors.Journal of Clinical Oncology, 18, 3665–3667.

Cobos, E., Dixon, S., & Keung, Y.K. (1998). Pre-vention and management of central venouscatheter thrombosis. Current Opinions in He-matology, 5, 355–359.

DeCicco, M., Matovic, M., Balestreri, L., Pana-rello, G., Fantin, D., Morassut, S., & Testa, V.(1997). Central venous thrombosis: An earlyand frequent complication in cancer patientsbearing long-term silastic catheter: A prospec-tive study. Thrombosis Research, 86, 101–113.

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Hadaway, L.C. (1998). Major thrombotic andnonthrombotic complications. Loss of pa-tency. Journal of Intravenous Nursing,21(Supp. 6), S143–S160.

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Krzywda, E.A. (1999). Predisposing factors, pre-vention, and management of central venouscatheter occlusions. Journal of IntravenousNursing, 22(Supp. 6), S11–S17.

Lowell, J.A., & Bothe, A. (1995). Central venouscatheter related thrombosis. Surgical Oncol-ogy Clinics of North America, 4, 479–492.

Macklin, D. (2000). Safety, ease of use are hall-marks of new venous access devices. Advancefor Nurses: Greater Philadelphia-Tri-StateMetro Area, 12(13), 33.

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Ratcliffe, M., Broadfoot, C., Davidson, M., Kelly,K.F., & Greaves, M. (1999). Thrombosis,markers of thrombotic risk, indwelling centralvenous catheters and antithrombotic prophy-laxis using low-dose warfarin in subjects withmalignant disease. Clinical and LaboratoryHaematology, 21, 353–357.

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Tesselaar, M.E.T., Ouwerkerk, J., Rosendaal, S.,& Osanto, S. (2001). Prophylaxis with lowmolecular weight heparin reduces the risk forcatheter-related venous thrombosis in cancerpatients in centrally, but not in peripherally,inserted central venous catheters [Abstract].Proceedings of the 37th Annual Meeting of theAmerican Society of Clinical Oncology, 20,Abstract No. 1584.

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Rapid RecapClinical Evaluation of a Positive Pressure Device to PreventCentral Venous Catheter Occlusion: Results of a Pilot Study

• Retrograde blood flow into a central venous catheter (CVC) can become athrombus and partially or totally occlude the catheter.

• Risk factors for catheter-related thrombus formation include the presenceof a solid tumor, hypercoagulable states, rigid and dual lumen catheters,prolonged dwell times, coexisting infection, and acidic infuscates.

• Positive displacement devices prevent retrograde blood flow into CVCs.• When evaluating a new device, factors to consider include efficacy, ease

of use, cost, and acceptability to patients and nurses.• Patient and staff education and orientation to a new device are key to suc-

cessfully implementing a practice change.

FIGURE 5. PROCEDURES FOR DRAWING BLOOD FROM CENTRAL VENOUS CATHETERS WITH

CLC2000TM DEVICES IN PLACE


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Clinical Evaluation of a Positive Pressure Device to Prevent