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Blood Gases

Item Value
Approval req'd? No
Available Stat? Yes
Test code
Parnassus (NCPL) NGAS
Mount Zion ORBG
Test group Blood Gases
Performed by Neonatal Clinical Physiology Laboratory and Mt. Zion Chemistry
In House Availability Test available 24 hours per day 7 days per week
Method
NCPL Radiometer ABL 800
Mt Zion Gem Premier 3500
Collection Instructions 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.

Deliver samples immediately to lab for testing. Send samples via pneumatic tube to NCPL (station #916) at Parnassus. Hand deliver samples to Mount Zion Lab, B bldg, second floor.
Container type Plastic blood gas syringe containing 100 U of dry heparin
Amount to Collect 3 mL blood
Sample type Heparinized whole blood (Blood gas syringe only)
Preferred volume 3 mL blood
Min. Volume 1 mL blood
UCSF Rejection Criteria Samples submitted > 30 min. after collection. Samples with needle attached, containing large bubbles, unlabeled, mislabeled, clotted or of insufficient volume for testing.
Units mmHg, mmol/L, %
Normal range
Analyte Ages Arterial Venous
pH All 7.35-7.45 7.31-7.41
pCO2 < 1 year 27-41 mmHg 41-51 mmHg
pCO2 ≥ 1 year 32-48 mmHg 41-51 mmHg
pO2 < 30 days 80-100 mmHg 35-40 mmHg
pO2 ≥ 30 days 83-108 mmHg 35-40 mmHg
HCO3- All 22-27 mmol/L
Base Excess (BE) All -2 to 2
Oxygen saturation (SaO2) All 95-99%
Critical value Arterial:
pH < 7.20 > 7.55
pCO2 < 25 mmHg > 65 mmHg
Neonatal pO2 < 40 mmHg > 100 mmHg
> 18 year old pO2 < 40 mmHg


Venous:
pH < 7.20
pCO2 > 75 mm Hg


Cord Blood*:
pH < 7.0
Base excess < -10


* Only called to ICN
Synonyms pH; pCO2; pO2; O2 Saturation; O2 Sat; Base excess; A-a gradient; HCO3-; ABG; BG; BE; oxygen; carbon dioxide; bicarbonate
Stability 10 min.
Turn around times 15 min
Additional information Blood gas testing at UCSF is performed in the 15th floor Neonatal Clinical Physiology Laboratory (NCPL, x31755, M1577).

Blood gas testing at Mt. Zion is performed in the UCSF Clinical Laboratory at Mount Zion.

Blood gas offered at the two labs are slightly different:

Parnassus (NCPL) NGAS Blood gas + Hgb
Mount Zion ORBG Blood gas alone


All reported values are corrected to 37C unless otherwise specified.

Results beyond the linear range of the instrument will be reported as < or > the extreme of the linear range.

Samples containing small bubbles may be run at the laboratory's discretion. If analyzed, a comment will be added to the result regarding the presence of bubbles in the sample.
Last Updated 3/15/2013 12:03:58 PM
Entry Number 128
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