Changes in transcutaneous oxygen tension during capillary blood-gas sampling

Area of Science:

• Neonatal Medicine
• Respiratory Physiology
• Clinical Diagnostics

Background:

• Transcutaneous oxygen monitoring (ptcO2) is crucial for assessing oxygenation in premature infants.
• Capillary blood gas analysis is a common method for determining arterial oxygen tension (paO2).
• The reliability of capillary blood sampling for oxygen tension measurements in neonates is not fully established.

Purpose of the Study:

• To investigate the fluctuations in transcutaneous oxygen tension (ptcO2) during capillary blood collection from premature infants.
• To determine the impact of capillary blood sampling on oxygenation measurements.
• To assess the suitability of capillary blood for accurate pO2 determination in neonates.

Main Methods:

• Utilized a Radiometer TCM-1 oxygen monitor to track ptcO2.
• Monitored ptcO2 during heel prick capillary blood collection in 30 premature infants with respiratory compromise.
• Compared ptcO2 readings with capillary pO2 values from standard blood-gas analysis.

Main Results:

• Significant and unpredictable ptcO2 fluctuations (increased or decreased) were observed during capillary blood sampling in 125 out of 125 observations.
• Fluctuations exceeded 10 mmHg in 61 observations, with relative changes up to -67%.
• ptcO2 values generally exceeded capillary pO2 values from blood-gas analysis.

Conclusions:

• Capillary blood sampling induces dynamic changes in oxygen tension, leading to unreliable measurements.
• Successive capillary specimens may exhibit different oxygen tensions.
• Capillary blood specimens are not recommended for pO2 determinations in newborns due to potential for inaccurate clinical management.