Patency Assessment

Common language facilitates communication between professional and organisations, the translation of evidence into clinical practice, data sharing, and research. CNSA, eviQ and eviQ Education are leading vascular access management and education in cancer care in Australia utilizing common, contemporary terminology (Table 1).

Table 1: CVAD terminology

It is essential to maintain the patency of Peripheral Intravenous Cannulas (PIVCs) and Central Venous Access Devices (CVADs) in order to administer medications and fluids, take blood specimens, prevent preventable removal and preserve a patient’s veins for future use. Assessment of patency or device functionality is an essential element of regular device assessment and the early detection of potential complications, for example occlusion, infiltration and extravasation (1). In cancer care, confirming patency of PIVCs and CVADs prior to use is essential due to potential tissue damage related to extravasated or infiltrated chemotherapy agents (2), irritants and vesicants, for example certain antibiotics, parenteral nutrition or computerised tomography (CT) contrast (3).

This question will discuss four practice components for both PIVCs and CVADs including:

1. Patency Assessment Components
2. Patency Assessment Tool
3. Frequency of Patency Assessment
4. Pressure monitoring of intravenous administration lines

Patency assessment of peripheral intravenous cannulas (PIVCs) and Central Venous Access Devices (CVADs) for paediatric and adult patients with cancer should include:

1. Patency Assessment Components:

CNSA recommends patency is assessed and confirmed by the easy aspiration ability of frank blood return and easy injection ability of fluids for CVADs (3-5) and PIVCs (1,6).

Refer to Section 1 for details of the current evidence and expert consensus statements.

2. Patency Assessment Tool:

CNSA recommends patency is assessed and documented using a standardised, validated tool, for example, the Catheter Injection and Aspiration Scheme (CINAS) (4) for CVADs, iDECIDED (7) for PIVCs.

Refer to Section 2 for details of the current evidence and expert consensus statements.

3. Patency Assessment Frequency:

CNSA recommends patency assessment is completed:

1. Inpatients - at least once per shift for inpatients (8)
2. Prior to all medication administration including blood products, parenteral nutrition, antibiotics, electrolytes, intravenous iron
3. Prior to all chemotherapy administration (4,9)
4. Prior to use for Interventional Radiological investigations (3)
5. Unused lumens of a multi-lumen CVAD - once per shift for inpatients and at each outpatient or home visit
6. Outpatient, ambulatory or home visit – during access at each visit (8)

Patency assessment, interventions and outcomes should be documented once per shift for inpatients and at each visit for outpatient, ambulatory or home visit (1).

Refer to Section 3 for details of the current evidence and expert consensus statements.

4. Pressure monitoring of intravenous administration lines

CNSA recommends if pressure monitoring is a feature of the intravenous pump and is used in a clinical setting for example in paediatrics, then:

1. Value changes of greater than 8.8% from the baseline indicate a near future catheter occlusion and should be investigated and further action taken (10), for example to exclude kinks in intravenous tubing or the catheter under the dressing, drug precipitants due to poor flushing between incompatible medications
2. It should be used as part of patency assessment to prevent catheter occlusion (10)
3. Within the home setting, any changes in pressure monitoring values should be promptly reported to the appropriate healthcare service.

Refer to Section 4 for details of the current evidence and expert consensus statements.

1.1 Summary of Evidence

Patency Assessment Components

Studies investigating patency and the prevention of occlusions (a Cochrane Review (11), prospective cross sectional (4), international expert consensus statement ³ and retrospective comparative study (5)) have identified two key components of patency assessment including the ability to:

• Easily aspirate frank blood return from a device; and
• Easily inject fluids into the device

It is essential both components are achieved (3-5,11).

One prospective observational study in adults identified that patency can be confirmed by the ability to flush a Totally Implanted Venous Access Device with 0.9% sodium chloride (9).

Technique

One study identified in a Cochrane review (11) described patency assessment (post thrombolytic administration for example urokinase or alteplase) by attaching a sterile, empty 10 mL syringe and attempting to withdraw 3 mL of blood and then flushing with 0.9% sodium chloride.

1.2 Type of Education Practice Recommendation

CNSA recommends patency assessment is confirmed by easy aspiration of frank blood and easy injection of fluids for Central Venous Access Devices (CVADs) (3-5) and Peripheral Intravenous Catheters (PIVCs) (1,6) for paediatric and adult patients with cancer.

CNSA recommends for CVADs to:

• use a sterile, empty 10 mL syringe to aspirate 3-5 mLs of blood for adults or twice the volume of the CVAD for paediatric patients
• discard unless it is used for blood cultures
• then flush with 20 mLs 0.9% sodium chloride in a new syringe for adults or double the volume of the CVAD in a new 10 mL syringe for paediatric patients using the appropriate technique

CNSA recommends for PIVCs to:

• aspirate frank blood using a 10 mL syringe and flush with 3 mLs of 0.9% sodium chloride for adult patients and 1-2 mLs as appropriate for paediatric patients using a slow and steady technique (12)

If no blood return is present:

• Do not administer antineoplastic medications (6), vesicants, irritants or medications.
• CVADs: further investigations of the catheter tip and functionality via diagnostic imaging is required before use, as per the Oncology Nurses Society, Access Device Standards (6)
• PIVCs: further assessment is required before use. Consider reinsertion of a new cannula, possibly using ultrasound guidance and/or insertion of a CVAD if peripheral access is not possible and long-term venous access is required

Refer to Flushing and Locking question for more information about current evidence and recommendations.

GRADE: V

Refer to the section on Occlusion Assessment and Management for recommendations related to partial or no blood return, or resistance or no ability to infuse fluids.

2.1 Summary of Evidence

Central Venous Access Devices

A prospective, cross-sectional study evaluated a patency assessment tool, Catheter Injection and Aspiration Scheme (CINAS) which standardised the evaluation of catheter function in regards to injection and aspiration ability (4). This study involved 1 researcher, 111 nurses and 150 patency assessments prior to blood collection from Totally Implanted Venous Access Devices (TIVADs - portacaths). The conclusion was the consistent use of this standardised tool facilitated more ‘rigorous assessment and reporting of catheter function in clinical settings’ (4).

Peripheral Intravenous Catheters (PIVC)

No studies discussed a PIVC patency assessment tool.

2.2 Technique for Assessing Patency - Practice Recommendation

CNSA recommends the consistent use of a standardised, validated tool to assess the patency assessment of Peripheral Intravenous Catheters (PIVC) and Central Venous Access Devices (CVADs) for paediatric and adult patients with cancer.

For example, the Catheter Injection and Aspiration Scheme (CINAS) (4) for CVADs, iDECIDED (7) for PIVCs.

GRADE: V

3.1 Summary of Evidence

Central Venous Access Devices

Studies investigating patency and the prevention of occlusions have identified key times when patency assessment is important including:

Adults:

• Once per inpatient shift and each CVAD access for outpatients in an adult randomised controlled pilot study which performed 698 observations for 26 patients (8)
• Prior to the administration of vesicant chemotherapy in a prospective, cross-sectional study in adults (4)
• Prior to the administration of chemotherapy in a prospective, adult observational study (9)
• Prior to Computerised Tomography (CT) scans - as part of the preliminary view of the entire CVAD system before the CT scan to check for abnormalities. For example, in the case of a Totally Implanted Venous Access Device, a scouting view involved the port body, catheter tip and needle placement as identified in an international expert literature review and consensus statement (3)

Paediatrics:

• Daily for inpatients or every 2–3 days for outpatient in a prospective surveillance study (13)

Peripheral Intravenous Catheters

No studies were identified.

3.2 Practice Recommendation

CNSA recommends the frequency of patency assessment for Peripheral Intravenous Cannulas and Central Venous Access Devices for paediatric and adult patients with cancer to be completed and documented (9):

1. Inpatients - at least once per shift for inpatients (8,14)
2. Prior to all medication administration including blood products, parenteral nutrition, antibiotics, electrolytes, intravenous iron
3. Prior to all chemotherapy administration (4,9)
4. Prior to use for Interventional Radiological investigations (3)
5. Unused lumens of a multi-lumen CVAD - once per shift for inpatients and at each outpatient or home visit
6. Outpatient, ambulatory or home visit patients– during access at each visit (8)

Patency findings should be documented once per shift for inpatients and at each visit for outpatient, ambulatory or home visit (1).

GRADE: V

This is supported by the Infusion Therapy Standards of Practice (1) which states to assess and document for all types of venous access devices prior to intermittent infusions and regularly for continuous infusions.

4.1 Summary of Evidence

One prospective, pilot trial of 10 paediatric patients undergoing stem cell transplants and 113 pressure monitoring events in 7-9.6 Fr, tunnelled Centrally Inserted Central Catheters concluded turbulent or increased catheter resistance greater than 8.8% ‘was strongly associated with the subsequent development of acute catheter occlusion within 10 days’ (10).

4.2 Practice Recommendation

CNSA recommends if pressure monitoring is a feature of the intravenous pump and is used in a clinical setting for example in paediatrics, then:

1. Value changes of greater than 8.8% from the baseline indicate a near future catheter occlusion and should be investigated and further action taken (10), for example to exclude kinks in intravenous tubing or the catheter under the dressing, drug precipitants due to poor flushing between incompatible medications
2. It should be used as part of patency assessment to prevent catheter occlusion (10)
3. Within the home setting, any changes in pressure monitoring values should be promptly reported to the appropriate healthcare service.

GRADE: IV

1. Gorski L, Hadaway L, Hagle ME, McGoldrick M, Orr M, Doellman D. Infusion therapy: standards of practice. Journal of Infusion Nursing. 2016;39(1S):S1-S159.

2. Mason TM, Ferrall SM, Boyington AR, Reich RR. Central Venous Access Devices: An Investigation of Oncology Nurses' Troubleshooting Techniques. Clin J Oncol Nurs. 2014;18(4):421-5.

3. Bonciarelli G, Batacchi S, Biffi R, Buononato M, Damascelli B, Ghibaudo F, et al. GAVeCeLT consensus statement on the correct use of totally implantable venous access devices for diagnostic radiology procedures. J. 2011;12(4):292-305.

4. Goossens GA, De Waele Y, Jérôme M, Fieuws S, Janssens C, Stas M, et al. Diagnostic accuracy of the Catheter Injection and Aspiration (CINAS) classification for assessing the function of totally implantable venous access devices. Supportive Care in Cancer. 2016(July 26th).

5. Zottele Bomfim GA, Wolosker N, Yazbek G, Bernardi CV, Valentim LA, De Castro TM, et al. Comparative study of valved and nonvalved fully implantable catheters inserted via ultrasound-guided puncture for chemotherapy. Ann Vasc Surg. 2014;28(2):351-7.

6. Cope DG, Elledge CM, Thompson Mackey H, Moran AB, Rogers MA, Schulmeister L, et al. Access Device Standards of Practice for Oncology Nursing. Society ON, editor. Pittsburgh, Pennsylvania: Oncology Nurses Society.; 2017.

7. Ray-Barruel G, Cooke M, Chopra V, Mitchell M, Rickard CM. The I-DECIDED clinical decision-making tool for peripheral intravenous catheter assessment and safe removal: a clinimetric evaluation. BMJ Open. 2020;10(1):e035239.

8. Klein J, Jepsen A, Patterson A, Reich RR, Mason TM. Heparin Versus Normal Saline: Flushing Effectiveness in Managing Central Venous Catheters in Patients Undergoing Blood and Marrow Transplantation. Clin J Oncol Nurs. 2018;22(2):199-202.

9. Voog E, Campion L, du Rusquec P, Bourgeois H, Domont J, Denis F, et al. Totally implantable venous access ports: a prospective long-term study of early and late complications in adult patients with cancer. Support Care Cancer. 2018;26(1):81-9.

10. Wolf J, Tang L, Rubnitz JE, Brennan RC, Shook DR, Stokes DC, et al. Monitoring Central Venous Catheter Resistance to Predict Imminent Occlusion: A Prospective Pilot Study. PLoS ONE. 2015;10(8):e0135904.

11. van Miert C, Hill R, Jones L. Interventions for restoring patency of occluded central venous catheter lumens. Cochrane Database Syst Rev. 2012(4).

12. Piper R, Carr PJ, Kelsey LJ, Bulmer AC, Keogh S, Doyle BJ. The mechanistic causes of peripheral intravenous catheter failure based on a parametric computational study. Scientific reports. 2018;8(1):1-12.

13. Cesaro S, Cavaliere M, Pegoraro A, Gamba P, Zadra N, Tridello G. A comprehensive approach to the prevention of central venous catheter complications: results of 10-year prospective surveillance in pediatric hematology-oncology patients. Ann Hematol. 2016;95(5):817-25.

14.Australian Commission on Safety and Quality in Health Care. Consultation Draft Peripheral Venous Accerss Clincial Care Standard. Sydney: Australian Commission on Safety and Quality in Health Care; 2019.