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Arterial blood sampling devices influence ionized calcium measurements
S M Koch1, U Mehlhorn, B A McKinley
1Department of Anesthesiology, University of Texas Medical School at Houston 77030-1503, USA.
Critical Care Medicine
|November 1, 1995
Summary
Commercially available arterial blood sampling devices can significantly alter ionized calcium measurements in intensive care unit (ICU) patients. This can lead to incorrect calcium supplementation, impacting patient care.
Area of Science:
- Clinical chemistry
- Critical care medicine
- Medical device evaluation
Background:
- Accurate ionized calcium measurement is crucial for managing critically ill patients.
- Arterial blood sampling is a common method for obtaining these measurements.
- The type of device used for sampling may influence results.
Purpose of the Study:
- To evaluate the impact of various commercial arterial blood sampling devices on ionized calcium levels.
- To identify devices that may cause significant deviations from reference measurements.
Main Methods:
- Prospective study involving 14 intensive care unit (ICU) patients with indwelling arterial catheters.
- Arterial blood samples were collected using 12 different commercial devices.
- Ionized calcium concentrations were compared against a reference test tube (Vacutainer 45).
Main Results:
- Seven of the 12 devices significantly underestimated ionized calcium levels compared to the reference.
- One device significantly overestimated ionized calcium levels.
- No correlation was found between heparin content and measurement accuracy.
Conclusions:
- Commercial arterial blood sampling devices can introduce clinically significant alterations in ionized calcium measurements.
- These inaccuracies may lead to inappropriate calcium therapy in ICU patients.
- Careful selection of arterial blood sampling devices is recommended for accurate ionized calcium monitoring.