INFLUENCE OF SENSOR SITE LOCATION ON PULSE OXIMETRY KINETICS IN CHILDREN

A pulse oximeter sensor is used to monitor changes in arterial hemoglo bin oxygen saturation (SpO2) in anesthetized pediatric patients. The a uthors compared the kinetics of desaturation and resaturation measured by sensors placed over central (tongue, cheek) and peripheral (finger , toe) vascular beds in children with congenital heart disease. Desatu ration time was defined as the time which elapsed between the onset of apnea and a 4% decrease in SpO2 from baseline. The desaturation times averaged 24 +/- 12 s, 56 +/- 34 s, and 58 +/- 28 s for the cheek, fin ger, and toe, respectively (n = 40; P < 0.0001 for cheek versus finger or toe). Resaturation time was defined as the interval between the re sumption of ventilation and a 4% increase in SpO2 above the nadir. Res aturation times averaged 12 +/- 8 s for the cheek, 40 +/- 36 s for the finger, and 47 +/- 25 s for the toe (n = 40; P < 0.0001 for cheek ver sus finger or toe). A comparison of the kinetics at two central sensor sites, cheek and tongue, respectively, revealed no significant differ ences in desaturation times (20 +/- 10 s vs 21 +/- 9 s) or resaturatio n times (10 +/- 6 s vs 7 +/- 3 s) (n = 13). The authors conclude that both desaturation and resaturation are detected earlier by centrally p laced sensors.