Pulse oximeter changes with sentinel lymph node biopsy in breast cancer

Hypothesis: The changes reported with pulse oximetry after the injection of isosulfan blue for sentinel lymph node identification in patients with breast cancer are consistent and predictable. Design: Retrospective study. Setting: University hospital. Patients and Methods: The complete anesthesia records of 92 patients who underwent sentinel lymph node biopsy with intraparenchymal injection of isosulfan blue were reviewed. The study extended from January 1999 to February 2000. The operations were all performed after the patient received general anesthesia. We injected 5 mL of isosulfan blue into the breast tissue surrounding the tumor. The data reviewed included preinjection pulse oximeter saturation readings and postinjection values continuing until the readings returned to baseline levels in the postanesthesia care unit. Main Outcome Measures: Changes in oxygen saturation readings with the pulse oximeter before and after injection of isosulfan blue. Results: Isosulfan blue injection interfered with pulse oximeter measurements for a substantial time-as much as 195 minutes. The mean time to the maximum change in the pulse oximeter reading was 35 minutes. The median decrease in oxygen saturation was 5%. The maximum decrease in the pulse oximeter reading was 11%. Conclusions: Although the changes in pulse oximeter readings can be substantial, their course appears to be predictable, and therefore in most otherwise healthy patients with normal pulmonary function, invasive monitoring is not necessary.