Performance evaluation of a new pulse oximeter during mild hypothermic cardiopulmonary bypass

Newly developed pulse oximeters (POs) are designed to display accurate Spo₂ during motion and hypoperfusion. We compared the performance of a new PO, the Masimo SET Radical (M), with a conventional PO, the Nihon Kohden AY-900P (N), during hypothermic cardiopulmonary bypass. Eighteen patients were studied prospectively. PO failure was defined as failure to show no Spo₂ value or show incorrect Spo₂ values for longer than 3 min continuously. PO failure occurred in 4 and 14 patients with M and N, respectively (P = 0.0022). All 4 patients in whom PO failure developed with M were among the 14 patients with N. No Spo₂ was provided for 4% ± 12% of the duration of aorta cross-clamping with M and 36% ± 39% with N (P = 0.002). Skin temperature and mean arterial blood pressure when PO failure started to occur and ended were similar between M and N. PO failure easily developed in patients with preoperative diuretic therapy or with intraoperative hyperlactatemia in N, but not in M. M was able to display accurate Spo₂ values significantly more frequently and longer than N during mild hypothermic cardiopulmonary bypass with nonpulsatile flow, suggesting that M is more useful for monitoring Spo₂ during hypoperfusion.