Accuracy of Laminated Disposable Pulse-Oximeter Sensors

Abstract

BACKGROUND: In our hospital, widespread utilization and clinical importance of arterial oxyhemoglobin saturation monitoring by pulse oximetry (S_pO2) generated a growing cost-center in a time of fiscal restraint. We hypothesized that lamination of a pulse-oximeter sensor and insertion into a disposable, protective shield allowing reusability would not alter sensor response time or relative accuracy. MATERIALS AND METHODS: Six healthy adult men volunteered to be studied during hypoxemia (induced by spontaneous ventilation of a 8-10% oxygen concentration in helium by face mask) to an S_pO2 ≤70%. The S_pO2 was monitored by 2 Nellcor N-200 pulse oximeters with D25II sensors and an Ohmeda 3700 pulse oximeter with the OxyTip sensors. Single de-saturations, repeated twice in 5 subjects, and 2 desaturations, repeated 5 times in 1 subject, were evaluated. After the initial desaturation and recovery, 1 D25II sensor was laminated, inserted into a protective sheath, reattached and followed by repeat desaturation. S_pO2 readings from each oximeter, during both de-saturations sets were compared. Clinical importance was subjectively deter-mined by comparison to published S_pO2 bias data. RESULTS: 907 data sets were collected. In 447 S_pO2 comparisons in 5 individuals (range, 62-100%), 1 lam-inated sensor was 0.8 percentage points lower and one sensor was 1.3 percentage points higher (p < 0.05) than controls compared with prelamination differences. No difference was clinically important. In individual repeated desaturations (range, 52-100%) following lamination, one sensor was 2.9 percentage points and one sensor was 2.6 percentage points higher. During repeat desaturations, differences between the OxyTip and the D2511 control sensor were 1.3 percentage points lower and 1.8 percentage points higher than the initial desaturation (all p<0.001). Response times were not altered. CONCLUSIONS: Lamination and protective shield applied to disposable sensors did not alter S_pO2 measurements or response times to incremental reductions in S_pO2 in a clinically important manner.