The Clinical Significance of Patient Specimen Transport Modality: Pneumatic Tube System Impact on Blood Gas Analytes.

INTRODUCTION: A pneumatic tube system (PTS) is a cost-effective, rapid transport modality that utilizes induced pressure changes. We evaluated the clinical importance of 2 transport modalities, human courier and PTS, for blood gas specimens.

METHODS: Following open heart surgery, 35 simultaneous pairs of arterial and venous blood gas specimens were analyzed from 20 subjects. Of each pair, one specimen was transported to the blood gas laboratory via a human courier and the other via a SwissLog PTS. Transport modalities were compared using the Bland-Altman limits of agreement method.

RESULTS: Compared with the walked specimen, the bias for PaO2 was -8.0 mm Hg (95% CI, -40.0 to 24.5 mm Hg); PaCO2 , -0.94 mm Hg (95% CI, -3.76 to 1.86 mm Hg); PvO2 , -0.60 mm Hg (95% CI, -6.90 to 5.70 mm Hg); PvCO2 , -0.58 mm Hg (95% CI, -3.12 to 1.92 mm Hg) for the PTS specimen.

CONCLUSION: The difference in the PO2 and PCO2 of paired (walked vs tubed) arterial and venous blood gas specimens demonstrated a slight bias. PaO2 values demonstrated the greatest bias, however not clinically important. Thus, PTS transport does not impact clinical interpretations of blood gas values.