Lab Information Manual

Laboratory:

Clinical Biochemistry

Test Name:

VENOUS BLOOD GAS (VBG) - RURAL; Alternate name: Blood Gas, Venous (Rural Sites)

Test Code: VGAS

Clinical Information:

Venous blood gas (VBG) testing is used as a less-invasive alternative to arterial blood gases (ABG), when the clinical question does not include the patient’s oxygenation status. The key physiological parameters included in a VBG panel are:

· pH

· pCO₂

· TCO₂

· Base Excess (Calculated)

· Lactate

Oxygen parameters (i.e., pO₂) are not reported on VBG specimens collected at rural sites as evacuated blood tubes are used, and this may contaminate the sample with oxygen. In addition, VBG pO₂ differs significantly from ABG pO₂, and does accurately reflect the patient’s oxygenation status.

Test Indications: Venous blood gas testing is intended for critically ill patients and is most informative to rule-out hypercapnia and acid-base disturbances in the following clinical scenarios:

· Code Blue

· Toxic ingestion or overdose

· Major Trauma

· Missed dialysis, acute renal failure

· Sepsis (only if 2+ SIRS criteria met)

· Metabolic emergencies such as DKA, HHS, hypoglycemia

If trending lactate, the first lactate may be done with a VBG panel or on a laboratory chemistry analyzer. At sites with a chemistry laboratory analyzer, all subsequent testing should be performed on the laboratory analyzer.

Venous blood gas testing requested on ambulatory outpatients are not to be collected, except if ordered by a Medical Geneticist for a pediatric patient. ALL OTHER OUTPATIENT REQUESTS WILL BE CANCELLED.

Recommendations: Emergency & in-patients only

Collection Devices:

Preferred Device:

1 - Li Heparin, NO GEL 4.0 mL Tube(s) - Full Tube Collection

Li Heparin, NO GEL 4.0 mL Tube(s) - Full Tube Collection
Manufacturer: BD (Becton Dickinson)

Catalogue #: 367884

Preferred Device #2: 1 - Blood Gas Syringe, Heparinized – AT LEAST HALF FULL

BUTTERFLY DEVICES SHOULD BE AVOIDED FOR VBG COLLECTIONS. If a butterfly device is used for difficult venous access, please adhere to the following:

1) Use a 21G needle

2) Use a male adapter directly into the blood collection tube (NO SYRINGES)

3) Flush tubing of all air by discarding at least 2 mL of blood, or collecting the VBG sample after another blood collection tube.

Specimen Required:

Do not leave tourniquet on for more than 1 minute, as this will falsely elevate lactate.

Test within 10 minutes of collection for most accurate results.

After 10 minutes: TCO2 will not be reported

Between 10-30 minutes: Results may be inaccurate due to delayed analysis

After 30 minutes: Multiple analytes will be inaccurate & sample is to be rejected for testing

Referral:

Shared Health laboratories outside the WRHA & Brandon

Requisition:

_SH Hospital Biochemistry Hematology Non Winnipeg Brandon (R250-10-91)

Reference Values:

See individual test listings for complete information

Method of Analysis: i-STAT System 1, CG4+ cartridge

Availability:

Daily