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Quantifying the minimum discard sample required for accurate arterial blood gases
B A Preusser1, J Lash, K S Stone
1College of Nursing, Ohio State University, Columbus.
Nursing Research
|September 1, 1989
Summary
A 2-cc discard volume is sufficient to ensure accurate arterial blood gas (ABG) sampling from indwelling arterial catheters. This finding helps optimize sample collection procedures for reliable patient monitoring.
Area of Science:
- Medical Diagnostics
- Clinical Pathology
- Critical Care Medicine
Background:
- Accurate arterial blood gas (ABG) analysis is crucial for patient management, especially in critical care settings.
- Indwelling arterial catheters are commonly used for continuous monitoring and blood sampling.
- Heparinized saline flushes used in catheters can dilute subsequent blood samples, potentially affecting ABG results.
Purpose of the Study:
- To determine the minimum discard volume necessary to eliminate heparinized saline contamination from arterial catheters.
- To establish optimal protocols for obtaining accurate arterial blood gas (ABG) samples from indwelling catheters.
Main Methods:
- Controlled laboratory study adjusting pH, PO2, and PCO2 to known values.
- Systematic withdrawal of discard samples ranging from 0 to 5 cubic centimeters (cc) in 0.5-cc increments.
- Collection of 319 arterial blood gas (ABG) specimens across 29 sets of 11 consecutive samples over 20 minutes.
Main Results:
- A discard volume of 2 cubic centimeters (cc) was found to be sufficient to ensure accurate blood gas analysis.
- This volume effectively removed heparinized normal saline from an arterial catheter with a 1-cc dead space volume.
Conclusions:
- A 2-cc discard volume is recommended for routine arterial blood gas (ABG) sampling from indwelling arterial catheters.
- Implementing this discard volume can improve the reliability of ABG results and inform clinical decision-making.
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