Arterial Catheter: Blood Sampling - CE

ALERT

Use of a closed loop blood sampling system is recommended to reduce hospital-acquired anemia.^{undefined#ref2">2}

Remember to route tubes and catheters having different purposes in different, standardized directions (e.g., IV lines routed toward the head; enteric lines toward the feet).³

OVERVIEW

Blood sampling from an arterial catheter is performed to obtain blood specimens for arterial blood gas (ABG) analysis or for other laboratory testing. The catheter should be accessed minimally to decrease the risk of infection.⁶

Before a blood specimen is obtained from an arterial catheter with an open system, a certain amount of fluid, the discard volume, must be withdrawn. The exact amount of discard volume remains undefined and can depend on the test. Coagulation studies may require more discard than other tests. For a reliable coagulation test result, the literature suggests using six times the dead space in the catheter.⁵ Dead space is the space between the insertion site and the access point for blood sampling. A discard volume of two times the dead space removes the priming solution for noncoagulation studies.⁷ The minimum discard volume should be used to avoid hospital-acquired anemia. Closed systems reduce the incidence of hospital-acquired anemia by allowing the replacement of the dead-space volume.

PATIENT AND FAMILY EDUCATION

• Explain the procedure and the equipment to the patient and family.
• Explain the importance of keeping the affected extremity immobile during blood sampling.
• Instruct the patient and family not to pull on the catheter or tubing or disrupt the dressing.
• Instruct the patient to report warmth, redness, pain, or a wet feeling at the insertion site at any time, including after catheter removal.
• Educate the patient and family about central line–associated bloodstream infection (CLABSI) prevention.
• Encourage questions and answer them as they arise.

ASSESSMENT AND PREPARATION

Assessment

1. Perform hand hygiene before patient contact.
2. Introduce yourself to the patient.
3. Verify the correct patient using two identifiers.
4. Assess the patency of the arterial catheter.
5. Assess the patient’s previous laboratory test results.
6. Assess the catheter exit site for signs and symptoms of infection (e.g., erythema, drainage, swelling, pain, tenderness, induration) and catheter migration. Notify the practitioner if signs or symptoms of infection are present.
7. Assess distal portions of the access limb for adequate circulation.
8. Assess the catheter for signs of mechanical damage or leaking. Notify the practitioner and do not use the catheter if signs of damage are present.
9. Assess the integrity of the catheter exit site dressing. Replace a damp, loose, or visibly soiled dressing.

Preparation

1. Position the patient’s extremity so the site can be accessed easily, and the blood sampling port is exposed.
2. Label the tubing at the connection site closest to the patient and at the connection site closest to the source when there are different access sites or several bags.³

   Rationale: Tubing should be labeled to reduce the chance of misconnection, especially in circumstances where multiple IV lines or devices are in use.

3. Review the laboratory directions for the order of the draw, the required volume for each test, and special directions, such as the need to transport certain specimens on ice.

PROCEDURE

Blood Sampling Using a Needleless Sampling Device or a Syringe

1. Perform hand hygiene and don gloves.
2. Verify the correct patient using two identifiers.
3. Explain the procedure to the patient and ensure that he or she agrees to treatment.
4. If obtaining an ABG specimen, open the ABG kit and use the plunger to eliminate excess heparin and air from the syringe.
5. Trace the tubing or catheter from the patient to point of origin (1) before connecting or reconnecting any device or infusion, (2) at any transition (e.g., new setting), and (3) as part of the hand-off process.³
6. Disinfect the needleless connector on the sampling port of the arterial line.
   1. Use vigorous mechanical scrubbing for a minimum of 5 to 60 seconds,¹ according to the organization’s practice, with an appropriate disinfecting agent (e.g., 70% isopropyl alcohol, an iodophor such as povidone-iodine, or greater than 0.5% chlorhexidine in alcohol solution), and allow the solution to dry.¹

      Specific guidelines directing the appropriate technique, disinfectant, or amount of time required to clean various devices have not been determined. ¹ There is moderate quality evidence to support the recommendation to apply mechanical friction for no less than 5 seconds. ¹

   2. If using a disinfecting port protector or cap, remove the protector or cap from the needleless connector. Discard the protector or cap in the appropriate receptacle.

      Rationale: The port protector or cap should never be reused.

      The effective length of time for exposure depends on the product. Consult the manufacturer’s instructions for use.

7. Attach a sterile needleless sampling device (Figure 1A) or a sterile syringe (Figure 1B) to the sampling port on the arterial line.
8. Do not force connections and avoid workarounds per the organization’s practice.³

   Rationale: Forced connections or workarounds could indicate that the connection should not be made.

9. Suspend the arterial pressure monitoring alarm.

   Rationale: Suspending the alarm prevents it from sounding when the pressure waveform is lost during the blood draw.

10. Turn the stopcock off to the flush solution (Figure 2) (Figure 3).

    Rationale: The syringe or needleless blood sampling access device is now in direct contact with the blood in the arterial catheter.

11. Obtain the discard blood specimen. Use a discard volume of at least two times the dead space of the catheter.⁷ Use a discard volume of six times the dead space of the catheter when obtaining blood for coagulation studies (particularly activated partial thromboplastin time) from a heparinized arterial line.⁵

    Rationale: Obtaining a discard volume clears the catheter of flush solution to prevent contamination of the blood specimen with fluid.

    1. If using a vacuum tube, attach the sterile sampling device to the needleless connector. Insert a specimen vacuum tube into the sampling device, allowing the device needle to pierce the tube’s rubber cap. Obtain the discard volume and remove the vacuum tube.
    2. If using a sterile syringe, gently aspirate the discard volume.
    3. Dispose of the syringe or the vacuum tube in an appropriate receptacle.
12. Obtain the blood specimens.
    1. If using a sampling device, insert and remove the required specimen vacuum tubes in the laboratory’s recommended order.
    2. If using a sterile syringe
       1. Disinfect the needleless connector using vigorous mechanical scrubbing for a minimum of 5 to 60 seconds,¹ according to the organization’s practice, with an appropriate disinfecting agent (e.g., 70% isopropyl alcohol, an iodophor such as povidone-iodine, or greater than 0.5% chlorhexidine in alcohol solution), and allow the solution to dry.¹

          Specific guidelines directing the appropriate technique, disinfectant, or amount of time required to clean various devices have not been determined. ¹ There is moderate quality evidence to support the recommendation to apply mechanical friction for no less than 5 seconds. ¹

       2. Attach the syringe to the needleless connector.
       3. Gently aspirate to obtain the required blood volume for the test(s).
       4. Attach the syringe to a transfer device. Insert the specimen vacuum tube into the device, allowing the device’s needle to pierce the tube’s rubber top, drawing the required amount of blood into the tube.
       5. Repeat the procedure for any remaining specimens using a new sterile syringe each time.

          Obtain specimens for routine laboratory studies before obtaining specimens for ABG and coagulation studies to minimize the effect of heparin.

          Maintain aseptic technique.

          Aspirate the minimum volume to conserve blood.

          Rationale: The minimum volume of blood should be aspirated because phlebotomy-related anemia is significant in all patient age groups. ²

    3. If obtaining a specimen for ABG analysis, expel any air bubbles from the ABG syringe and cap the syringe with the cap included in the ABG syringe kit.

       Rationale: Expelling air bubbles and capping the syringe helps ensure the accuracy of the ABG results.

13. Turn the stopcock off to the sampling port (Figure 1A) (Figure 1B).
14. Using the fast-flush device, flush the remaining blood in the arterial catheter back into the patient.
15. Turn the stopcock off to the patient.
16. Using the fast-flush device, flush any remaining blood from the sampling port.

    Rationale: Fast-flushing clears blood from the sampling port.

    1. If using a vacuum tube:
       1. Insert a specimen vacuum tube into the sampling device, allowing the device needle to pierce the tube’s rubber cap.
       2. Flush any remaining blood in the sampling port into the vacuum tube.
       3. Remove the discard vacuum tube from the sampling device.
       4. Remove the sampling device.
    2. If using a sterile syringe:
       1. Disinfect the needleless connector using vigorous mechanical scrubbing for a minimum of 5 to 60 seconds,¹ according to the organization’s practice, with an appropriate disinfecting agent (e.g., 70% isopropyl alcohol, an iodophor such as povidone-iodine, or greater than 0.5% chlorhexidine in alcohol solution), and allow the solution to dry.¹

          Specific guidelines directing the appropriate technique, disinfectant, or amount of time required to clean various devices have not been determined. ¹ There is moderate quality evidence to support the recommendation to apply mechanical friction for no less than 5 seconds. ¹

       2. Attach a syringe to the needleless connector.
       3. Flush any remaining blood from the sampling port in the syringe.
    3. Dispose of the syringe or the vacuum tube in an appropriate receptacle.
    4. If using a disinfecting port protector or cap, place the protector or cap on the needleless connector according to the manufacturer’s instructions.

       Rationale: Disinfecting port protectors or caps provide passive disinfection and have been associated with decreased infection rates. ¹

       The effective length of time for exposure depends on the product. Consult the manufacturer’s instructions for use.

17. Turn the stopcock off to the sampling port (Figure 1A) (Figure 1B).

    Rationale: Turning the stopcock off to the sampling port opens the system for continuous arterial pressure monitoring.

18. Turn the alarms on and ensure that the waveform returns.
19. In the presence of the patient, label the specimen per the organization’s practice.⁴ For an ABG specimen, record the percentage of oxygen therapy, respiratory rate, ventilator settings, the patient’s temperature, and time the specimen was drawn on the laboratory request form, according to the organization’s practice.
20. Prepare the specimen for transport.
    1. Place the labeled specimen in a biohazard bag.
    2. If the specimen requires ice for transport, place the specimen in a biohazard bag then place the bag with the specimen into a second biohazard bag filled with ice slurry.

       Rationale: Placing the specimen in a separate bag protects the label from being damaged.

21. Immediately transport the specimen to the laboratory.
22. Discard supplies, remove gloves, and perform hand hygiene.
23. Document the procedure in the patient’s record.

Using a Closed Arterial Blood Sampling System

1. Perform hand hygiene and don gloves.
2. Verify the correct patient using two identifiers.
3. Explain the procedure to the patient and ensure that he or she agrees to treatment.
4. If obtaining an ABG specimen, open the ABG kit and use the plunger to eliminate excess heparin and air from the syringe.
5. Trace the tubing or catheter from the patient to point of origin (1) before connecting or reconnecting any device or infusion, (2) at any transition (e.g., new setting), and (3) as part of the hand-off process.³
6. Suspend the arterial pressure monitoring alarm.

   Rationale: Suspending the alarm prevents it from sounding when the pressure waveform is lost during the blood draw.

7. Slowly and gently pull back on the blood withdrawal reservoir plunger until the reservoir is full (Figure 4).

   Rationale: Pulling back on the blood withdrawal reservoir plunger withdraws and stores blood from the patient until it is ready to be reinfused after blood sampling is complete.

8. Close the stopcock by turning the handle perpendicular to the tubing (Figure 5).
9. Attach a needleless cannula to either a sampling device or an ABG syringe (Figure 6) (Figure 7).
10. Disinfect the needleless connector using vigorous mechanical scrubbing for a minimum of 5 to 60 seconds,¹ according to the organization’s practice, with an appropriate disinfecting agent (e.g., 70% isopropyl alcohol, an iodophor such as povidone-iodine, or greater than 0.5% chlorhexidine in alcohol solution), and allow the solution to dry.¹

    Specifc guidelines directing the appropriate technique, disinfectant, or amount of time required to clean various devices have not been determined. ¹ There is moderate quality evidence to support the recommendation to apply mechanical friction for no less than 5 seconds. ¹

11. While holding the base of the blood sampling port, push the needleless cannula (with the attached sampling device or ABG syringe) into the blood sampling port (Figure 8).
12. Insert a specimen vacuum tube into the sampling device, allowing the device needle to pierce the tube’s rubber cap or obtain an ABG specimen via the syringe.

    Obtain specimens for routine laboratory studies before obtaining specimens for ABG and coagulation studies to minimize the effect of heparin.

    Maintain aseptic technique.

    Aspirate the minimum volume to conserve blood.

    Rationale: The minimum volume of blood should be aspirated because phlebotomy-related anemia is significant in all patient age groups. ²

13. After obtaining the blood specimens, hold the base of the blood sampling port and remove the needleless cannula with the attached sampling device or ABG syringe from the sampling port by pulling it straight out (Figure 9).
14. Open the stopcock by turning the handle parallel to the tubing (Figure 5).

    Rationale: Opening the stopcock allows reinfusion of the stored blood specimen.

15. Slowly and smoothly reinfuse the reservoir volume.

    Rationale: Reinfusing the reservoir volume helps reduce the risk of hospital-acquired anemia.

16. Flush the system using the fast-flush device.

    Rationale: Flushing the system promotes the patency of the arterial catheter.

17. Turn the alarms on and ensure that the waveform returns.
18. In the presence of the patient, label the specimen per the organization’s practice.⁴ For an ABG specimen, record the percentage of oxygen therapy, respiratory rate, ventilator settings, the patient’s temperature, and time the specimen was drawn on the laboratory request form, according to the organization’s practice.
19. Prepare the specimen for transport.
    1. Place the labeled specimen in a biohazard bag.
    2. If the specimen requires ice for transport, place the specimen in a biohazard bag then place the bag with the specimen into a second biohazard bag filled with ice slurry.

       Rationale: Placing the specimen in a separate bag protects the label from being damaged.

20. Immediately transport the specimen to the laboratory.
21. Discard supplies, remove gloves, and perform hand hygiene.
22. Document the procedure in the patient’s record.

MONITORING AND CARE

1. Monitor laboratory results and compare them to the patient’s baseline and trends.

   Reportable condition: Abnormal blood specimen test results

2. Monitor hemoglobin and hematocrit values for anemia if frequent blood sampling is needed.

   Reportable condition: Decrease in hemoglobin or hematocrit levels

3. Assess, treat, and reassess pain.

EXPECTED OUTCOMES

• Adequate blood specimens with minimal blood loss
• No hemolysis of specimens
• No arterial spasm
• Arterial line patency

UNEXPECTED OUTCOMES

• Inadequate blood specimens
• Hemolysis of specimens
• Arterial spasm
• Dilution of specimens, causing inaccurate laboratory results
• Anemia
• Clotting of arterial cannula or catheter

DOCUMENTATION

• Patient and family education
• Date, time, and type of specimens drawn
• Unexpected outcomes and related nursing interventions
• Pain assessment and management

REFERENCES

1. Infusion Nurses Society. (2016). Infusion therapy standards of practice. Standard 34: Needleless connectors. Journal of Infusion Nursing, 39(Suppl. 1), S68-S70. (Level D)
2. Infusion Nurses Society. (2016). Infusion therapy standards of practice. Standard 43: Phlebotomy. Journal of Infusion Nursing, 39(Suppl. 1), S85-S91. (Level D)
3. Joint Commission, The (TJC). (2014). Sentinel event alert 53: Managing risk during transition to new ISO tubing connector standards. Retrieved July 10, 2019, from http://www.jointcommission.org/assets/1/6/SEA_53_Connectors_8_19_14_final.pdf (Level D)
4. Joint Commission, The. (2019). National patient safety goals effective January 2019. Hospital accreditation program. Retrieved July 10, 2019, from https://www.jointcommission.org/assets/1/6/NPSG_Chapter_HAP_Jan2019.pdf (Level D)
5. Laxson, C.J., Titler, M.G. (1994). Drawing coagulation studies from arterial lines: An integrative literature review. American Journal of Critical Care, 3(1),16-24. (classic reference)* (Level C)
6. O’Grady, N.P. and others. (2011). Guidelines for the prevention of intravascular catheter-related infections, 2011. Centers for Disease Control and Prevention. Retrieved July 15, 2019, from https://www.cdc.gov/infectioncontrol/pdf/guidelines/bsi-guidelines-H.pdf (classic reference)* (Level D)
7. Rickard, C.M, and others. (2003). A discard volume of twice the deadspace ensures clinically accurate arterial blood gases and electrolytes and prevents unnecessary blood loss. Critical Care Medicine, 31(6), 1654-1658. (classic reference)* (Level C)

*In these skills, a “classic” reference is a widely cited, standard work of established excellence that significantly affects current practice and may also represent the foundational research for practice.

Adapted from Wiegand, D.L. (Ed.). (2017). AACN procedure manual for high acuity, progressive, and critical care (7th ed.). St. Louis: Elsevier.

AACN Levels of Evidence

• Level A - Meta-analysis of quantitative studies or metasynthesis of qualitative studies with results that consistently support a specific action, intervention, or treatment
• Level B - Well-designed, controlled studies, with results that consistently support a specific action, intervention, or treatment
• Level C - Qualitative studies, descriptive or correlational studies, integrative reviews, systematic reviews, or randomized controlled trials with inconsistent results
• Level D - Peer-reviewed professional organizational standards with clinical studies to support recommendations
• Level E - Multiple case reports, theory-based evidence from expert opinions, or peer-reviewed professional organizational standards without clinical studies to support recommendations
• Level M - Manufacturer's recommendations only