Evaluation of an improved sampling method for blood gas analysis from indwelling arterial catheters

Embolic complications of indwelling arterial lines are well documented. We evaluated a method of blood sampling from indwelling arterial lines that minimizes blood loss and eliminates the embolic risks associated with retrograde flushing. The values for PaO2, PaCO2, and pH obtained by the conventional sampling technique were compared to those obtained by a technique termed the "three drop" method. Thirty-five paired samples were obtained from patients in the pediatric ICU. Meaningful statistical and clinical correlations were observed for PaO2 (r = .97, p less than 10(-6], PaCO2 (r = .97, p less than 10(-6], and pH (r = .98, p less than 10(-6]. Evaluation for the slope of the regression line for each pair of variables was also significant (p less than 10(-6]. The means for each variable were also assessed. Only the PaCO2 values were different (t = 2.49, p less than .002). As the absolute value was 2 torr, we feel that there is no clinical significance to this finding. These data confirm that the three drop technique of sampling for arterial blood gas analysis is reliable. It also removes the risks of retrograde flushing and minimizes blood loss.