Blood Gases
To view the entire topic, please sign in or purchase a subscription.
Nursing Central is the award-winning, complete mobile solution for nurses and students. Look up information on diseases, tests, and procedures; then consult the database with 5,000+ drugs or refer to 65,000+ dictionary terms. Explore these free sample topics:
-- The first section of this topic is shown below --
Synonym/Acronym:
Arterial blood gases (ABGs), venous blood gases, capillary blood gases, cord blood gases.
Rationale
To assess oxygenation and acid-base balance.
Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.
Normal Findings
Method: Selective electrodes for pH, Pco2, and Po2.
| Blood Gas Value (pH) | Arterial | Venous | Capillary | ||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Scalp | — | — | 7.25–7.35 | ||||||||||||||||||||||||||||||||||||||
| Birth, cord, full term | 7.11–7.36 | 7.25–7.45 | 7.32–7.49 | ||||||||||||||||||||||||||||||||||||||
| Adult/child | 7.35–7.45 | 7.32–7.43 | 7.35–7.45 | ||||||||||||||||||||||||||||||||||||||
| Note: SI units (conversion factor × 1). | |||||||||||||||||||||||||||||||||||||||||
| Pco2 | Arterial | SI Units (Conventional Units × 0.133) | Venous | SI Units (Conventional Units × 0.133) | Capillary | SI Units (Conventional Units × 0.133) |
|---|---|---|---|---|---|---|
| Scalp | — | — | — | — | 40–50 mm Hg | 5.3–6.6 kPa |
| Birth, cord, full term | 32–66 mm Hg | 4.3–8.8 kPa | 27–49 mm Hg | 3.6–6.5 kPa | — | — |
| Newborn–adult | 35–45 mm Hg | 4.7–6 kPa | 41–51 mm Hg | 5.4–6.8 kPa | 26–41 mm Hg | 3.5–5.4 kPa |
| Po2 | Arterial | SI Units (Conventional Units × 0.133) | Venous | SI Units (Conventional Units × 0.133) | Capillary | SI Units (Conventional Units × 0.133) |
|---|---|---|---|---|---|---|
| Scalp | — | — | — | — | 20–30 mm Hg | 2.7–4 kPa |
| Birth, cord, full term | 8–24 mm Hg | 1.1–3.2 kPa | 17–41 mm Hg | 2.3–5.4 kPa | — | — |
| 0–1 hr | 33–85 mm Hg | 4.4–11.3 kPa | — | — | — | — |
| Greater than 1 hr–adult | 80–95 mm Hg | 10.6–12.6 kPa | 20–49 mm Hg | 2.7–6.5 kPa | 80–95 mm Hg | 10.6–12.6 kPa |
| HCO3- | Arterial Conventional and SI Units | Venous Conventional and SI Units | Capillary Conventional and SI Units |
|---|---|---|---|
| Birth, cord, full term | 17–24 mmol/L | 17–24 mmol/L | — |
| 2 mo–2 yr | 16–23 mmol/L | 24–28 mmol/L | 18–23 mmol/L |
| Adult | 22–26 mmol/L | 24–28 mmol/L | 18–23 mmol/L |
| O2 Sat | Arterial | Venous | Capillary | ||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Birth, cord, full term | 40%–90% | 40%–70% | — | ||||||||||||||||||||||||||||||||||||||
| Adult/child | 95%–99% | 70%–75% | 95%–98% | ||||||||||||||||||||||||||||||||||||||
| Values may be at the lower end of the normal range in older adults. | |||||||||||||||||||||||||||||||||||||||||
| Oxygen Content: Arterial | Oxygen Content: Venous |
| 6.6–9.7 mmol/L | 4.9–7.1 mmol/L |
| Tco2 | Arterial Conventional and SI Units mmol/L | Venous Conventional and SI Units mmol/L |
|---|---|---|
| Birth, cord, full term | 13–22 mmol/L | 14–22 mmol/L |
| Adult/child | 22–29 mmol/L | 25–30 mmol/L |
| Base Excess Arterial | Conventional and SI Units |
|---|---|
| Birth, cord, full term | (–10) – (–2) mmol/L |
| Adult/child | (–2) – (+3) mmol/L |
Critical Findings and Potential Interventions
Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.
Consideration may be given to verification of critical findings before action is taken. Policies vary among facilities and may include requesting recollection and retesting by the laboratory.
| Arterial Blood Gas Parameter | Less Than | Greater Than | |
|---|---|---|---|
| Adult/child | pH | 7.2 | 7.6 |
| Adult/child | HCO3- | 10 mmol/L | 40 mmol/L |
| Adult/child | Pco2 | 20 mm Hg (SI: 2.7 kPa) | 67 mm Hg (SI: 8.9 kPa) |
| Adult/child | Po2 | 45 mm Hg (SI: 6 kPa) | |
| Newborns | Po2 | 37 mm Hg (SI: 4.9 kPa) | 92 mm Hg (SI: 12.2 kPa) |
-- To view the remaining sections of this topic, please sign in or purchase a subscription --