Neonatal laboratory blood sampling: comparison of results from arterial catheters with those from an automated capillary device.

PURPOSE

To compare neonatal laboratory results from capillary blood samples drawn using the Tenderfoot automated capillary sampling device with those drawn through arterial catheters.

DESIGN

Prospective, paired comparisons of laboratory results from capillary and arterial blood.

SAMPLE

Twenty-one infants being cared for in an NICU and having indwelling arterial catheters through which a variety of predominantly glucose-containing fluids were being administered.

MAIN OUTCOME VARIABLES

Statistical comparisons of paired capillary and arterial results of pH, PO2, PCO2, lactate, sodium, potassium, ionized calcium, and hematocrit.

RESULTS

No capillary-arterial differences were observed for pH, PCO2, lactate, or sodium. Although capillary results were slightly, but significantly (p < .01), higher for potassium (+0.4 mEq/liter), ionized calcium (+0.47 mg/dl), and hematocrit (+4 percent), these differences fell within acceptable Clinical Laboratories Improvement Act (CLIA) performance criteria. Markedly lower PO2 (-30.2 mmHg) and glucose (-61 mg/dl) values were observed with capillary sampling. With the exception of results for PaO2 and plasma glucose, capillary blood drawn using the Tenderfoot automated device yields laboratory results comparable to those from blood drawn from arterial catheters as assessed by CLIA performance criteria.