Evaluation of finger and forehead pulse oximeters during mild hypothermic cardiopulmonary bypass.

OBJECTIVE: The purpose of this study was to examine and compare the four combination of pulse oximeters (POs) and monitoring sites, the Nihon Kohden BSS-9800 (N), the Masimo SET Radical (M), the Nellcor N550 D-25 (N-D) and the Nellcor N550 Max-Fast (N-MF) in patients with peripheral hypoperfusion. METHODS: About 20 adult patients undergoing cardiac surgery using mild hypothermic cardiopulmonary bypass (CPB) were studied prospectively. PO sensors were applied on fingers in N, M and N-D, while on the forehead in N-MF. RESULTS: PO failure was defined as failure to show no SpO2 value or incorrect SpO2 values. PO failure occurred in 12 patients with N, ten patients with M, four patients with N-D and ten patients with N-MF, respectively (p < 0.05 N-D vs. N, M, N-MF). The duration of PO failure was 19 +/- 30% of aortic cross-clamping with N, 29 +/- 33% with M, 10 +/- 26% with N-D and 43 +/- 57% with N-MF, respectively (p < 0.05 N-D vs. M and N-MF). CONCLUSIONS: The results suggested that N-D is most useful among four combinations of POs and monitoring sites tested in this study for monitoring SpO2 during hypoperfusion. The superiority of N-MF during hypoperfusion was not evident in the present study.

[Intraoperative monitoring of pressure within saline-filled, endotracheal tube cuff in adult patients undergoing CO2 laser laryngomicrosurgery].

In laser laryngomicrosurgery, saline is injected into the endotracheal tube cuff to prevent airway fire. Utilizing regression analyses, we investigated the relation between the saline volume required to obtain optimal intracuff pressure and tracheal diameters in patients undergoing laser laryngomicrosurgery as well as in model tracheas. Although excellent linear correlations were found between the saline volume and the diameter of model tracheas, no significant linear or non-linear correlation was found between the saline volume and the patient's tracheal diameter. In the model tracheas, a rate of rise in the intracuff pressure caused by increments in the injected volume was far steeper when saline was injected into the cuff than when air was injected into the cuff. Addition of only 0.2 ml saline could result in large (> 50 mmHg) increases in the intracuff pressure. Also in patients, addition of 1 ml could result in notable (> 50 mmHg) increases in the intracuff pressure. These results suggest that the saline volume necessary to obtain optimal intracuff pressure is difficult to be predicted from the patient's tracheal diameter, and that slight increases in the saline volume may cause excessive increases in the intracuff pressure. The intracuff pressure should be tightly monitored in patients undergoing laser laryngomicrosurgery.