Review of: Van Dyk N, Cloyd D, Rea T, et al: "The effect of pulse oximetry on emergency medical technician decision making." Prehospital Emergency Care. 8(4):417-419, 2004.
The authors of this study tried to answer the question of whether or not adding pulse oximetry to the EMT-Basic scope of practice would have an effect on whether ALS should respond to the scene. The authors provided education on how to obtain pulse oximetry, with the understanding that 97 to 100% was normal. The authors also said that 93 to 96% was also probably normal except in the presence signs or symptoms of respiratory distress and less than 93% indicated a serious condition and supplemental oxygen was indicated and less than 90% represented severe hypoxia.
This tiered system routinely had BLS arrive four to five minutes before ALS and may have had BLS only respond, depending on the dispatch information. BLS previously had the authority to cancel or summon ALS if it had not been simultaneously dispatched. The EMTs were asked to indicate if and how the pulse oximetry reading influenced their decision to either cancel or summon ALS.
Of the 302 patients encountered during the study, EMTs stated that oximetry influenced their decision for 35 (12%) patients. Of these 35 patients, the EMTs requested ALS for 11 (31%), canceled ALS for 8 (23%), and didn't request ALS for 16 (46%) of influenced patients.
The authors concluded that the addition of pulse oximetry improved the efficiency of the EMS system by more appropriately matching response level to patient condition. They subsequently added pulse oximetry to the scope of practice for all of their EMT-Basics.
This is a very important study, as it attempted to critically analyze what for many EMS programs is already a standard scope of practice skill. The decision to cancel or call for ALS in a tiered response system has many ramifications, from cost effectiveness to improving patient care.
The primary limitation of this study is that it is based on self reported data by the EMTs making the decisions. The authors recognize that it would have had greater value had the EMTs been asked their decision prior to obtaining pulse oximetry, but they felt that this would have delayed patient care. I would suggest that such a study could be designed without delaying care and would provide even more valuable information.
Another limitation of the study was the lack of a third party evaluation of each of the influenced patient encounters to determine whether the decision was appropriate. This would help to better hone the role of pulse oximetry in making such decisions.
I applaud the authors for this study and call for more research that would examine not only the cases in more detail but any other possible influences on the decision, such as type of call, years of experience by the EMT-Basic, location and time of day.