Bubbles in samples for blood gas determinations. A potential source of error

Area of Science:

• Clinical Chemistry
• Medical Device Technology
• Analytical Chemistry

Background:

• Accurate blood gas analysis is critical for patient diagnosis and management.
• Gas bubbles in blood collection devices are a known, yet often underestimated, source of analytical error.
• Existing literature lacks comprehensive quantification of bubble-induced errors in common collection devices.

Purpose of the Study:

• To investigate the impact of small gas bubbles on blood gas sample accuracy.
• To derive and substantiate mathematical relationships describing the potential error magnitude.
• To establish a threshold for bubble size that poses a significant risk to sample integrity.

Main Methods:

• Theoretical derivation of error magnitudes based on bubble volume and gas partial pressures.
• Simulation of bubble-induced changes in measured blood gas parameters (e.g., pO2, pCO2).
• Validation of derived relationships against established principles of gas diffusion and fluid dynamics.

Main Results:

• Gas bubbles with a relative volume of 0.5% to 1% or greater can introduce significant errors in blood gas measurements.
• The magnitude of error is directly related to the bubble's relative volume and the concentration gradients of respiratory gases.
• Derived equations provide a quantitative assessment of potential measurement inaccuracies.

Conclusions:

• The presence of small gas bubbles is a critical factor to control in blood gas sample collection.
• Adherence to bubble-free sampling techniques is essential for reliable blood gas analysis.
• The study provides a framework for understanding and mitigating bubble-related errors in clinical practice.