Plastic blood gas syringe containing approximately 70 IU dry heparin in a 3 mL syringe or 23 IU in a 1 mL syringe -   or a  capillary tube coated with 70 IU heparin (Radiometer Clinitube).

Arterial puncture:
Due to the risk of arterial damage and subsequent distal ischemia, prior to puncturing an artery the RN assesses the collateral circulation. If the radial artery is to be punctured, then the pulse of the ulnar artery is assessed. If the dorsalis pedis artery is to be accessed then the posterial tibial pulse is assessed and likewise if the posterial tibial approach is used the dorsalis pedis pulse is assessed. The modified Allens's test may be used to assess collateral circulation of the ulnar artery before a radial artery puncture, but it does not always ensure adequate flow. A Doppler ultrasound flow indicator may be used to verify collateral circulation. If the collateral circulation is poor and the RN cannot palpate a pulse then the physician should be notified before proceeding. If for any reason the circulation is compromised to the extremity being assessed for arterial puncture then the physician should be notified prior to proceeding.

1. Palpate the radial artery and identify the site where the pulse is the strongest. Avoid areas with overlying veins to prevent venous admixture.
2. Prepare the patient's skin with an alcohol or 2% chlorhexidine wipe/swab.
3. Place two or three fingers along the course of the artery both to locate its position and direction, and to stabilize it.
4. Penetrate the skin smoothly holding the needle at 30-60 degree angle with the needle bevel up and pointed proximally. The angle of the "butterfly" IV catheter should not exceed 45° for pediatric patients.
5. Re-establish the position and direction of the artery by palpation.
6. Gently and slowly advance the needle or "butterfly", aiming directly for the area of maximum pulsation.
7. When the arterial lumen has been entered, less resistance is felt and blood appears in the syringe above the needle hub.
8. Obtain required amount of arterial blood for test(s).
9. If blood is not obtained on first attempt, withdraw the needle to just below the skin surface and advance needle at same angle but at 1 mm to either side of previous attempt.
10. Place the 2x2 gauze over the site of the puncture then withdraw the needle from the artery. Press firmly at the site for at least five minutes, or until the bleeding stops. Apply bandage or pressure dressing.
11. Expel any air bubble in the syringe with air filter cap placed on specimen syringe.
12. Label sample with patient's name, ID number and DOB.

Venous samples:
1. Avoid excessive venous stasis from prolonged tourniquet application or clenching of the fist prior to sample collection.
2. For central line draws make sure to waste a full red top tube then draw via the blood gas syringe as noted above.
3. Fill syringe completely, remove needle (in peripheral draws), cap sample, expel all bubbles (while holding syringe upright) until blood hits the top of cap.
4. Label sample with patient's name, ID number and DOB.

Capillary Samples:
1. The following are recommended sampling sites: earlobe, finger tip, big toe, heel. The heel and big toe are more suitable for use on neonates and infants.
2. Warm the area or puncture site for 5 to 10 minutes prior to actual sampling. This accelerates flow for blood to be representative of general status of patient.
3. Make a puncture using a lancet or similar device. Do not squeeze the area to avoid tissue juice from mixing into blood sample.
4. Wipe off the first drop of blood. Take the sample from the center of the second drop of blood and hold the capillary at a slightly downward angle for an uninterrupted blood flow. Avoid getting air bubbles in the specimen.
5. Refrain from squeezing or milking the puncture site as this may result in faulty measurements or cause hemolysis of blood sample and cause elevated K+ readings.
6. Apply accompanying caps to both ends of the capillary tube and mix the sample with the heparin immediately after collection to prevent blood from clotting. The manufacturer recommends the use of a mixing wire and magnet for capillary samples.
7. Label sample with patient's name, ID and DOB.

Deliver samples immediately to lab for testing. Samples delivered to the lab > 30 minutes after collection may yield erroneous results.

Reference range adopted from reference range used in the central UCSF hematology laboratory for hematocrit determined from the measurement of MCV and RBC count.

Adult reference ranges adopted from Hematology section spectrophotometry-based hemoglobin assay and verified using 25 male and 25 female volunteers from UCSF Clinical Laboratories.

Arterial puncture:
Due to the risk of arterial damage and subsequent distal ischemia, prior to puncturing an artery the RN assesses the collateral circulation. If the radial artery is to be punctured, then the pulse of the ulnar artery is assessed. If the dorsalis pedis artery is to be accessed then the posterial tibial pulse is assessed and likewise if the posterial tibial approach is used the dorsalis pedis pulse is assessed. The modified Allens's test may be used to assess collateral circulation of the ulnar artery before a radial artery puncture, but it does not always ensure adequate flow. A Doppler ultrasound flow indicator may be used to verify collateral circulation. If the collateral circulation is poor and the RN cannot palpate a pulse then the physician should be notified before proceeding. If for any reason the circulation is compromised to the extremity being assessed for arterial puncture then the physician should be notified prior to proceeding.

1. Palpate the radial artery and identify the site where the pulse is the strongest. Avoid areas with overlying veins to prevent venous admixture.
2. Prepare the patient's skin with an alcohol or 2% chlorhexidine wipe/swab.
3. Place two or three fingers along the course of the artery both to locate its position and direction, and to stabilize it.
4. Penetrate the skin smoothly holding the needle at 30-60 degree angle with the needle bevel up and pointed proximally. The angle of the "butterfly" IV catheter should not exceed 45° for pediatric patients.
5. Re-establish the position and direction of the artery by palpation.
6. Gently and slowly advance the needle or "butterfly", aiming directly for the area of maximum pulsation.
7. When the arterial lumen has been entered, less resistance is felt and blood appears in the syringe above the needle hub.
8. Obtain required amount of arterial blood for test(s).
9. If blood is not obtained on first attempt, withdraw the needle to just below the skin surface and advance needle at same angle but at 1 mm to either side of previous attempt.
10. Place the 2x2 gauze over the site of the puncture then withdraw the needle from the artery. Press firmly at the site for at least five minutes, or until the bleeding stops. Apply bandage or pressure dressing.
11. Expel any air bubble in the syringe with air filter cap placed on specimen syringe.
12. Label sample with patient's name, ID number and DOB.

Venous samples:
1. Avoid excessive venous stasis from prolonged tourniquet application or clenching of the fist prior to sample collection.
2. For central line draws make sure to waste a full red top tube then draw via the blood gas syringe as noted above.
3. Fill syringe completely, remove needle (in peripheral draws), cap sample, expel all bubbles (while holding syringe upright) until blood hits the top of cap.
4. Label sample with patient's name, ID number and DOB.

Capillary Samples:
1. The following are recommended sampling sites: earlobe, finger tip, big toe, heel. The heel and big toe are more suitable for use on neonates and infants.
2. Warm the area or puncture site for 5 to 10 minutes prior to actual sampling. This accelerates flow for blood to be representative of general status of patient.
3. Make a puncture using a lancet or similar device. Do not squeeze the area to avoid tissue juice from mixing into blood sample.
4. Wipe off the first drop of blood. Take the sample from the center of the second drop of blood and hold the capillary at a slightly downward angle for an uninterrupted blood flow. Avoid getting air bubbles in the specimen.
5. Refrain from squeezing or milking the puncture site as this may result in faulty measurements or cause hemolysis of blood sample and cause elevated K+ readings.
6. Apply accompanying caps to both ends of the capillary tube and mix the sample with the heparin immediately after collection to prevent blood from clotting. The manufacturer recommends the use of a mixing wire and magnet for capillary samples.
7. Label sample with patient's name, ID and DOB.

Deliver samples immediately to lab for testing. Samples delivered to the lab > 30 minutes after collection may yield erroneous results.

Plastic blood gas syringe containing approximately 70 IU dry heparin in a 3 mL syringe or 23 IU in a 1 mL syringe -   or a  capillary tube coated with 70 IU heparin (Radiometer Clinitube).

Reference range adopted from reference range used in the central UCSF hematology laboratory for hematocrit determined from the measurement of MCV and RBC count.

Adult reference ranges adopted from Hematology section spectrophotometry-based hemoglobin assay and verified using 25 male and 25 female volunteers from UCSF Clinical Laboratories.