Skill 18-13

Obtaining an Arterial Blood Sample From an Arterial Catheter

Obtaining an arterial blood sample requires percutaneous puncture of the radial (most common), brachial, or femoral artery. However, an arterial blood sample can also be obtained from an arterial catheter. Arterial catheters are used for hemodynamic monitoring (including measuring arterial pressures, continuous monitoring of blood pressure) and obtaining arterial blood samples without having to perform repeated arterial punctures, such as for blood gas analysis (Burns & Delgado, 2019; Hinkle et al., 2022). A pressure monitoring system (Figure 1) transmits pressures from the intravascular space or cardiac chambers through a catheter and fluid-filled tubing to a pressure transducer, which converts the physiologic signal from the patient to a pressure tracing and digital value. Patency of the system and prevention of backflow of blood through the catheter and tubing is maintained by using a continuous flush solution under pressure (Burns & Delgado, 2019; Morton & Fontaine, 2018).

The procedure below describes obtaining a sample from a closed reservoir system (Figure 2); a closed-loop system should be used when drawing from an existing arterial catheter to reduce health care-acquired anemia and intraluminal contamination and catheter-associated bloodstream infection (CABSI) compared to an open, stopcock system (Gorski et al., 2021).

Delegation Considerations

Obtaining an arterial blood sample from an arterial catheter is not delegated to assistive personnel (AP) or licensed practical/vocational nurses (LPN/LVNs).

Equipment

Arterial blood gas (ABG) kit heparinized (100 to 200 IU) self-filling 10-mL syringe with 22- to 23-gauge, 1-inch needle attached, rubber cap for ABG syringe hub, and ice-filled plastic bag or cup, if ABG is prescribed
Gloves
Goggles or face shield
Additional PPE, as indicated
Vacutainer with blunt cannula for closed reservoir system and appropriate blood collection tubes for prescribed tests
Two additional blood collection tubes, for discard blood volume
Antimicrobial swab, such as chlorhexidine or alcohol, per facility policy
Waterproof protective pad
Passive disinfection caps (based on facility policy) or
Sterile cap for arterial catheter stopcock (based on facility policy)
Appropriate label for specimen, based on facility policy and procedure
Blank labels (2)
Biohazard bag
Bath blanket

Assessment

Review the patient's health record and plan of care for information about their need for an arterial blood sample. Ensure that the necessary computerized laboratory request has been completed. Assess the patient's cardiac status, including heart rate, blood pressure, and auscultation of heart sounds. Also assess the patient's respiratory status, including respiratory rate, excursion, lung sounds, and use of oxygen, if prescribed. Check the patency and functioning of the arterial catheter. Assess the patient's understanding of the need for specimen collection.

Actual or Potential Health Problems and Needs

Many actual or potential health problems or issues may require the use of this skill as part of related interventions. An appropriate health problem or issue may include:

Impaired gas exchange
Impaired cardiac output
Fluid imbalance

Outcome Identification and Planning

The expected outcome to achieve when obtaining an arterial blood sample is that a specimen is obtained without compromise to the patency of the arterial catheter. In addition, the patient experiences minimal discomfort, remains free from infection, and verbalizes an understanding of the rationale for and the steps of the procedure.

Implementation

Action	Rationale
1. Check the patient's health record to identify the prescribed laboratory testing.	Checking the prescribed intervention and policy ensures that the proper procedure is initiated.
2. Gather all equipment. Check product expiration dates.	Assembling equipment provides for an organized approach to the task. Use of products that have not expired ensures proper functioning of equipment.
3. Perform hand hygiene and put on PPE, if indicated.	Hand hygiene and PPE prevent the spread of microorganisms. PPE is required based on transmission precautions.
4. Identify the patient.	Identifying the patient ensures the right patient receives the intervention and helps prevent errors.
5. Close the curtains around the bed and close the door to the room, if possible. Explain the procedure to the patient.	This ensures the patient's privacy. Explanation relieves anxiety and facilitates engagement.
6. Assemble equipment on the overbed table or other surface within reach.	Arranging items nearby is convenient, saves time, and avoids unnecessary stretching and twisting of muscles on the part of the nurse.
7. Adjust the bed to a comfortable working height (VHACEOSH, 2016).	Having the bed at the proper height prevents back and muscle strain.
8. Compare the specimen label with the patient identification bracelet. The label should include the patient's name and identification number, the time the specimen was collected, the route of collection, identification of the person obtaining the sample, and any other information required by facility policy. Depending on facility policy, specimen labels may be verified after obtaining blood samples, prior to application to blood sample tubes.	Verifying the patient's identity validates that the correct procedure is being done on the correct patient, and the specimen is accurately labeled.
9. Use blank labels to label the two blood sample collection tubes to be used for the discard blood sample and the discard flush.	Labeling the discard tubes prevents accidental confusion with blood specimen tubes.
10. Assist the patient to a comfortable position that provides easy access to the sampling site. Use the bath blanket to cover any exposed area other than the sampling site. Place a waterproof pad under the site.	Patient positioning and use of a bath blanket provide for comfort and warmth. The waterproof pad protects underlying surfaces.
11. Put on gloves and goggles or a face shield.	Gloves and goggles (or face shield) prevent contact with blood and body fluids.
12. Temporarily silence the arterial pressure monitor alarms.	The integrity of the system is being altered, which will cause the system to sound an alarm. Facility policy may require the alarm be left on.
13. Locate the closed-system reservoir and blood-sampling site. Use an antimicrobial swab to vigorously scrub the sampling site (Figure 2). Allow it to air dry.	Arterial access device administration set entry points, end caps, and needleless connectors must be disinfected prior to each access to reduce the risk for introduction of microorganisms and prevent access device-related infection (Frimpong et al., 2015; Gorski et al., 2021; Harper, 2014; Loveday et al., 2014). Friction is needed to physically remove microorganisms from the top, sides, and threads of the needleless connector or end cap. Allow the antiseptic to dry completely following the manufacturer's directions for use (Gorski et al., 2021).
14. Holding the reservoir upright, grasp the flexures and slowly fill it with blood over a 3- to 5-second period (Figure 2). If you feel resistance, reposition the patient's extremity and check the catheter site for obvious problems (e.g., kinking of the tubing). Then continue with blood withdrawal.	Filling the reservoir pulls the saline from the monitoring line, so the blood sample is not diluted by the fluid in the line.
15. Turn off the shut-off valve to the reservoir by turning the handle perpendicular to the tubing (Figure 2).	This prevents flow of fluid from the reservoir into the blood samples and allows blood from the patient to be drawn through the sampling port.
16. Insert the Vacutainer into the sampling site (see Figure 2). Insert the blood sample tubes into the Vacutainer. If coagulation tests have been prescribed, collect those sample tubes last. After obtaining the final blood sample, grasp the Vacutainer near the sampling site and remove the Vacutainer.	Inserting the Vacutainer or syringe into the sampling port allows blood to be drawn into blood sample tubes. The Vacutainer is a nonvented system, preventing backflow of patient blood. Obtaining coagulation samples last prevents dilution from the flush device.
17. After removal of the Vacutainer, turn the one-way valve to its original position, parallel to the tubing. Push down evenly on the reservoir (see Figure 2) plunger until the flexures lock in place in the fully closed position and all fluid has been reinfused. The fluid should be reinfused over a 3- to 5-second period. Activate the flush release.	Reinfusion of “waste” blood reduces hospital-acquired anemia, intraluminal contamination, and catheter-associated blood stream infection (Gorski et al., 2021). In-line flushing clears the sampling port and flush line to maintain the integrity of the system and prevent clotting and infection.
18. Use an antimicrobial swab to vigorously scrub the sampling site.	Arterial access device administration set entry points, end caps, and needleless connectors must be disinfected prior to each access to reduce the risk for introduction of microorganisms and prevent access device-related infection (Frimpong et al., 2015; Gorski et al., 2021; Harper, 2014; Loveday et al., 2014). Friction is needed to physically remove microorganisms from the top, sides, and threads of the needleless connector or end cap. Allow the antiseptic to dry completely, following the manufacturer's directions for use (Gorski et al., 2021).
19. Remove your gloves and goggles/face shield and perform hand hygiene. Check the monitor for return of the arterial waveform and pressure reading. Reactivate the monitor alarms. Record the date and time the samples were obtained on the labels as well as the required information to identify the person obtaining the samples. If arterial blood gas (ABG) was collected, record the oxygen flow rate (or room air) on the label. Apply the labels to the specimens, according to facility policy. Place them in biohazard bags; place the ABG sample in a bag with ice.	Proper removal of PPE and hand hygiene reduce the risk for infection transmission and contamination of other items. Confirmation of the return of arterial waveform and pressure readings ensures proper functioning and integrity of the system. Reactivating the alarm system ensures proper functioning. Proper labeling prevents error. Recording the oxygen flow rate ensures accurate interpretation of the results of the ABG. Use of a biohazard bag prevents contact with blood and body fluids. Ice maintains the integrity of the sample.
20. Return the patient to a comfortable position. Lower the bed height, if necessary, and adjust the head of the bed to a comfortable position.	Repositioning promotes patient comfort. Lowering the bed promotes patient safety.
21. Remove additional PPE, if used. Perform hand hygiene. Send specimens to the laboratory immediately.	Proper removal of PPE reduces the risk for infection transmission and contamination of other items. Hand hygiene prevents transmission of microorganisms. Specimens must be processed in a timely manner to ensure accuracy.

Evaluation

The expected outcomes have been met when an arterial specimen has been obtained without compromise to the patency of the arterial catheter, and the patient has experienced minimal discomfort, remained free from infection, and verbalized an understanding of the rationale for and the steps of the procedure.

Documentation

Guidelines

Document any pertinent assessments, the laboratory specimens obtained, the date and time specimens were obtained, and the disposition of the specimens.

Sample Documentation

Developing Clinical Reasoning and Clinical Judgment

Unexpected Situations and Associated Interventions

After obtaining the specimen and reactivating the arterial pressure monitoring system, no waveform is noted: Check the stopcock to make sure that it is open to the patient and recheck all connections and components of the system to ensure proper setup. If necessary, rebalance the transducer or replace the system, as necessary. If problem persists, suspect a clotted catheter tip. Follow facility policy to troubleshoot a potentially clotted arterial catheter and notify the health care team.

Special Considerations

If the patient is receiving oxygen, wait 15 minutes after a change in type or mode of oxygen delivery or rate for specimen collection for ABG analysis (Fischbach et al., 2022). Indicate the amount and type of oxygen therapy the patient is receiving on the laboratory request. Also note the patient's current temperature, most recent hemoglobin level, and current respiratory rate. If the patient is receiving mechanical ventilation, note the fraction of inspired oxygen and tidal volume.
If the patient is not receiving oxygen, indicate that they are breathing room air on the laboratory request for an ABG analysis.

EVIDENCE FOR PRACTICE

Blood Sampling via a Central Venous Access Device

Related Guideline Infusion Nurses Society (INS) Standards of Practice

Gorski, L. A., Hadaway, L., Hagle, M. E., Broadhurst, D., Clare, S., Kleidon, T., Meyer, B. M., Nickel, B., Rowley, S., Sharpe, E., & Alexander, M. Infusion Nurses Society. (2021). Infusion therapy. Standards of practice, 8th edition. Journal of Infusion Nursing, 44(Suppl 1), S1-S224. doi: 10.1097/NAN.0000000000000396.

The Infusion Nurses Society is recognized as the global authority in infusion therapy. The Infusion Nursing Standards of Practice is an evidence-based document, providing guidelines for nurses related to infusion therapy for use in all patient settings and addressing all patient populations. Specific guidance is provided for use of closed-loop systems as these systems return the blood to the patient and reduce blood loss associated with blood sampling.

section name header

Skill 18-13

EVIDENCE FOR PRACTICE