A COMPARISON OF PULSE OXIMETRY AND RESPIRATORY RATE IN PATIENT SCREENING

Objective: To examine how well respiratory rate correlates with arteri al oxygen saturation status as measured by pulse oximetry, and determi ne whether respiratory rate measurements detect oxygen desaturation re liably. Methods: Respiratory rate (RR) and oxygen saturation (SaO(2)) were measured prospectively on 12 096 consecutive adult emergency depa rtment triage patients at a university medical center. Respiratory rat e was measured by counting ausculated breath sounds for 1 min. Pulse o ximetry was used to measure SaO(2). Measurements were analysed by age (with one group for 18-19 year olds, groups for every 10 yr from age 2 0 to age 60, and groups for every 5 yr for subsequent ages). Pearson c orrelation coefficients were calculated for each age group as well as the weighted average coefficient. Cases having oxygen saturation below 90% were examined to determine how frequently they exhibited increase d RR (increased RRs were defined as any rate in the upper five percent ile by age. Results: Correlation coefficients ranged from 0 . 379 to - 0 . 465 with a weighted mean of -0 . 160. Coefficients for ages IS thr ough 70 years (representing 10 740 patients) all had magnitude <0 . 25 2. Overall, only 33% of subjects with oxygen saturation below 90% exhi bited increased RR. Conclusions: Respiratory rate measurements correla te poorly with oxygen saturation measurements and do not screen reliab ly for desaturation. Patients with low SaO(2) do not usually exhibit i ncreased RR. Similarly, increased RR is unlikely to reflect desaturati on.