EMS/ORIGINAL CONTRIBUTION pulse oximetry, prehospital Prehospital Pulse Oximetry: Useful or Misused? From the Department of Emergency Medicine, MetroHealth Medical Center;* Department of Surgery, Case Western Reserve University School of Medicine;t and the City of Cleveland Emergency Medical Services Bureau, Cleveland, OhioJ Received for publication March 26, 1991. Revisions received August 19 and November 9, 1991. Accepted for publication December 4, 1991. Presented at the Society for Academic Emergency Medicine Annual Meeting in Washington, DC, May 1991. Rita K Cydulka, MD, FACEP *t Bruce Shade, EMT-P~ Charles L Emerman, MD, FACEP *t Howard Gersham, MD, PhD *t John Kubincanek, EMT-P~ Study objective: This study evaluated the ability of emergency medical technicians (EMT-As) and emergency medical technicians- paramedics (EMT-Ps)to use pulse oximetry measurements in determin- ing patient oxygen requirements. Design: Prospective case series. Setting: Cleveland emergency medical services (EMS) system. Type of participants: Five hundred thirty-two consecutive patients transported to Cleveland area hospitals by the Cleveland EMS system; no exclusions. Interventions: EMT-Ps and EMT-As predicted patients' supplemen- tal oxygen requirements based on clinical assessment. Pulse oximetry was performed while patients were breathing room air (RA Spo2). Treatment intervention, including oxygen supplementation and medica- tion given, oxygen saturation after intervention, and oxygen saturation on arrival at the hospital, was also recorded. Therapy guided by the patient's initial RASpo 2 was reviewed to determine the appropriate- ness of oxygen therapy. Results: Data were analyzed using the ;(2 test and correlation analy- sis. Eleven percent (59) of patients transported by Cleveland EMS had an initial RASpo 2 of less than 91%. Advanced life support units increased oxygen supplementation on all desaturated patients, whereas basic life support units failed to make appropriate increases in FI0 2 in 20% (two)of desaturated patients (P< .0001). Sixty percent (164)of patients transported by EMT-Ps and 62% (162) of patients transported by EMT-As had an initial RA Spo 2 of 97% or greater. EMT-Ps gave sup- plemental oxygen therapy to all but 7% (11) of these already well-satu- rated patients, and EMT-As gave supplemental oxygen to all but 6% (nine) of these patients. EMT-Ps administered a higher FIo 2 than they had predicted clinically necessary to 2% (four) of patients with an ini- tial RASpo 2 of 97% of greater, whereas EMT-As gave a higher FIo 2 than initially predicted to 16% (25) of such patients (P< .0001). Conclusion: EMT-Ps were more likely to appropriately base oxygen therapy on oximetry measurements than were EMT-As. Both groups failed to decrease supplemental oxygen in patients with high 20/675 ANNALS OF EMERGENCY MEDICINE 21:6 JUNE i992