Clinical evaluation of a multiparameter intra-arterial blood-gas sensor.

OBJECTIVE

To evaluate the in vivo performance of a continuous, intra-arterial, multiparameter blood-gas sensor containing a thermocouple, miniaturized polarographic oxygen electrode, as well as fiberoptic pH and pCO2 sensors.

DESIGN

Prospective, multicenter study comparing pH, PaCO2, and PaO2 measurements from the intraarterial sensor with those obtained from a conventional, laboratory blood-gas monitor.

SETTING

Intensive care units in three academic medical centers.

PATIENTS

Adult ICU patients (n = 26) with a clinical need for a radial artery catheter and frequent monitoring of arterial blood gases for > or = 3 days.

INTERVENTIONS

All patients had the multiparameter intra-arterial sensor placed through a 20-gauge catheter into the radial artery. Every 4 h, or more frequently if clinically indicated, a blood-gas sample was withdrawn from the radial artery catheter and sent to the laboratory for analysis using a conventional laboratory blood-gas analyzer. Immediately prior to withdrawal of the arterial blood, values for pH, PaCO2, and PaO2 from the multiparameter intra-arterial sensor were recorded.

MEASUREMENTS AND MAIN RESULTS

The multiparameter sensor was placed into 26 patients. In 7 of the patients, premature discontinuation of monitoring was necessary because of dampening of the pressure tracing, difficulty in withdrawing blood from the arterial catheter, or bending of the extra-arterial fiberoptic channel owing to the cable being inadequately secured (mean monitoring time in these 7 patients: 40.6 +/- 25.7 h). In the other 19 patients, monitoring was continued until no longer clinically indicated. In these patients, a total of 341 data sets was collected, with the average length of monitoring being 69.9 +/- 37.9 h (range 22.0 to 57.9 h). Comparison of the sensor values with those from the blood-gas analyzer showed bias and precision values of 0.006 and 0.026 for arterial pH - 1.19% and 12.54% for PaO2, and 1.28 mmHg and 2.48 mmHg for PaCO2, respectively. No complications were associated with the intra-arterial sensor.

CONCLUSIONS

Clinical performance of this intra-arterial, multiparameter blood-gas sensor demonstrated stability, consistency, and accuracy comparable to laboratory blood-gas analyzers. The present multiparameter, intravascular blood-gas sensor, when inserted in the radial artery, can provide stable and accurate monitoring of pH, PaCO2, and PaO2 over clinically relevant periods of as long as 6 days in the critical care setting.