Comparison of Accuracy and Signal Consistency of Two Reusable Pulse Oximeter Probes in Critically Ill Children

Abstract

BACKGROUND: To control costs, our institution changed from disposable (DP) to reusable pulse oximeter probes (RP). Anecdotal experience suggested that RPs are not as reliable as DPs. We compared the accuracy and signal consistency of 2 Nellcor RPs in critically ill children, with a subsequent comparison to DPs historical data. We hypothesized no difference in accuracy, a lesser signal consistency in one RP over the other, and that both RPs would be less accurate in blacks than whites. MATERIALS & METHODS: Children with indwelling arterial catheters and continuous pulse oximetry were prospectively enrolled. Nellcor Oxiband® (OB) and Dura-Y® (DY) RPs were placed on the same extremity alternating between adhesive and Velcro®-wrap attachment devices. Two CO-oximetry measured saturations (S_aO2) were obtained for each subject. Oxygen saturation by pulse oximetry (S_pO2) and heart rate were continuously monitored for 12 hours, and data were exported to provide a graphic display of each alarm-limit and desaturation event. Number of artifactual events was determined by examining the pulse amplitude signal during each event. A Wilcoxon signed rank test assessed significance of the difference. Bias ± precision evaluated accuracy of both probes relative to S_aO2, and a paired Student's t test compared probes within different ranges of S_aO2. Repeated measures ANOVA compared probe accuracy with respect to race. RESULTS: 100 arterial blood gas samples were obtained from 50 patients, 15 of whom were black. At S_aO2s≥80%, both probes performed similarly with a bias ± precision of 1.41 (2.59) for OB and 1.15 (2.58) for DY (p = 0.311). At S_aO2S < 80% S_aO2, bias precision for OB was 1.36 (5.19) and for DY 4.11 (3.51), p = 0.313. Both probes were less precise at S_aO2 < 80% compared to higher ranges. No significant difference in bias according to race (p = 0.549) was determined. Signal consistency data were obtained from 27 subjects, and no difference was found between probes (p = 0.194). CONCLUSIONS: OB and DY RPs demonstrated accuracy similar to each other and to historical data for DPs when S_aO2 was ≥ 80%. Signal consistency was similar. Contrary to previous studies, no difference in accuracy between black and white subjects was found. RPs are reliable in critically ill children and represent potential for substantial cost savings.