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The concentration of free calcium ions in capillary blood from neonates on a routine basis using the ICA 1
Insights
This study measured free calcium ion (cCa2+) and pH levels in 200 infants and 50 adults using a new electrode system. Results show normal physiological ranges for these parameters in both healthy infants and adults.
Area of Science:
- Clinical Chemistry
- Neonatal Physiology
- Pediatric Medicine
Background:
- Accurate measurement of free calcium ions (cCa2+) and pH is crucial for assessing physiological status, especially in neonates.
- Previous methods for blood gas and electrolyte analysis have limitations in accuracy and sample volume.
- A new semi-automatic electrode system offers potential for improved measurement in small sample volumes.
Purpose of the Study:
- To evaluate the performance of a new semi-automatic electrode system (ICA 1 Radiometer) for measuring cCa2+ and pH.
- To establish reference ranges for cCa2+ and pH in full-term infants and healthy adults using capillary blood.
- To assess potential biases associated with hematocrit levels and anticoagulant use in the new system.
Main Methods:
- Analyzed 110 microliter capillary whole blood samples from 200 full-term infants (5-130 h old) and 50 healthy adults (18-60 years old).
- Utilized a new semi-automatic electrode system (ICA 1 Radiometer, Copenhagen) for simultaneous measurement of cCa2+ and pH.
- Investigated potential biases related to hematocrit and heparinized capillaries through controlled experiments with serum pools.
Main Results:
- The electrode system showed no significant bias for erythrocyte effect at hematocrit < 0.60, but a 1-5% negative bias at 0.60-0.80.
- Anticoagulant in heparinized capillaries introduced a bias of < +/- 1% for cCa2+ within the 0.86-2.02 mmol/l range.
- Established reference ranges: Infants (5-48h): cCa2+ 1.27 ± 0.098 mmol/l, pH 7.42 ± 0.07. Adults: cCa2+ 1.28 ± 0.07 mmol/l, pH 7.42 ± 0.03.
Conclusions:
- The ICA 1 Radiometer system provides reliable measurements of cCa2+ and pH in capillary blood within specific hematocrit ranges.
- The study established normative data for cCa2+ and pH in full-term infants and healthy adults.
- The findings support the use of this system for clinical assessment in neonatal and adult populations, with awareness of potential hematocrit-related biases.
Abstract:
The concentration of free calcium ions (cCa2+), and pH was measured in 200 full-term infants aged 5-130 h and in 50 healthy adults aged 18-60 years with a new semi-automatic electrode system (ICA 1 Radiometer, Copenhagen) in 110 microliter capillary whole blood. The blood was obtained anaerobically by heel puncture of the infants and from the earlobe of the adults. No bias was found for the erythrocyte effect on the liquid junction potential with a haematocrit below 0.60 but for a haematocrit between 0.60 and 0.80 there was an increasing negative bias of 1-5% for this instrument. The special heparinized glass capillaries (Radiometer, Copenhagen) used for blood sampling were studied in serum pools at different levels of cCa2+ and the anticoagulant used was shown to give a bias of less than +/- 1% on the measurement of cCa2+ in the range 0.86-2.02 mmol/l. In full-term infants aged 5-48 h cCa2+ was 1.27 +/- 0.098 mmol/l (+/- 2 SD) and pH 7.42 +/- 0.07 (+/- 2 SD). In infants aged 49-96 h, cCa2+ was 1.334 +/- 0.136 mmol/l (+/- 2 SD) and pH 7.42 +/- 0.07 (+/- 2 SD). In infants, aged 97-130 h cCa2+ was 1.383 +/- 0.140 mmol/l (+/- 2 SD) and pH 7.40 +/- 0.076 (+/- 2 SD). In capillary blood from healthy adults, aged 18-60 years cCa2+ was 1.28 +/- 0.07 mmol/l (+/- 2 SD) and pH 7.42 +/- 0.03 (+/- 2 SD).(ABSTRACT TRUNCATED AT 250 WORDS)