Chapter 13: Diagnostic tests
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13.2 Central venous access devices: taking a blood sample for vacuum sampling
Essential equipment
- Personal protective equipment
- Sterile dressing pack
- Extra 10 mL blood bottle without heparin
- Vacuum system container holder (shell)
- Vacuum system adapter
- Clean tray or receiver
- Trolley
- Appropriate vacuumed blood bottles or needleless injection cap (as necessary)
Medicinal products
- 10 mL syringe containing 0.9% sodium chloride
- Flushing solution as per policy
- 10 mL syringe
- 2% chlorhexidine in 70% alcohol swab
Pre‐procedure
ActionRationale
- 1.
Introduce yourself to the patient, explain and discuss the procedure with them, and gain their consent to proceed. Check forms to ascertain sample bottles required and check patient's identity.
Procedure
- 2.Wash hands with bactericidal soap and water or alcohol‐based handrub and allow to dry.To reduce the risk of cross‐infection (NHS England and NHSI [155], C).
- 3.Prepare a tray or trolley and take it to the bedside. Clean hands as above. Open sterile pack and prepare equipment.
- 4.If intravenous fluid infusion is in progress, switch it off.To prevent spillage of fluid following disconnection. E
- 5.Where required, disconnect the administration set from the catheter and cover the end of the set with a sterile cap.To reduce the risk of contaminating the end of the administration set. E
- 6.Clean hands with an alcohol‐based handrub.
- 7.Put on non‐sterile gloves.To prevent possible contamination of the practitioner (NHS England and NHSI [155], C).
- 8.Clean hub or needle‐free cap thoroughly with a 2% chlorhexidine in 70% alcohol swab for at least 15 seconds and allow to dry before accessing the system.To enable the disinfection process to be completed (Loveday et al. [128], R).
- 9.Connect the vacuum container holder and adapter to the needleless injection cap and release the lumen clamp.To maintain a closed system and prevent contamination of the practitioner or air entry. E
- 10.Attach the extra sample bottle; fill and discard.To remove blood, heparin, drugs and intravenous fluids from the ‘dead space’ of the catheter. Samples from this dead space are likely to cause inaccuracies in blood tests. Using a spare bottle keeps the system closed (WHO [257], C).
- 11.Attach the required sample bottles in the correct order of draw (see Table 13.4) for the requested specimens.To obtain the sample. It is not necessary to clamp the catheter when changing collection bottles, as the system is not open. E
- 12.Re‐clamp the lumen/catheter and detach the vacuum container holder.To prevent blood loss or air embolism. E
- 13.Flush with 10 mL 0.9% sodium chloride, using the push–pause method (i.e. 1 mL at a time).
- 14.Reconnect the administration set, unclamp the catheter and recommence infusion or attach a new needle‐free injection cap. Release the clamp and flush the catheter through the injection cap using the push–pause method and finishing with the positive pressure technique.
- 15.Ensure that the blood samples have been placed in the correct containers and invert as necessary (see Table 13.4) to prevent clotting.
- 16.Label the samples with the patient's name, number, date of birth, etc. at the patient's side and send them to the laboratory with the appropriate forms.
Post‐procedure
- 17.Remove gloves and discard waste, making sure it is placed in the correct containers (e.g. sharps into a designated receptacle).To ensure correct clinical waste management and to reduce the risk of cross‐infection (DH [48], C).
- 18.Document the procedure in the patient's records.