The reliability of vital signs in estimating pain severity among adult patients treated by paramedics.

The aim of this study was to examine the strength of correlation between initial pain severity score and systolic blood pressure, heart rate and respiratory rates among adults reporting pain in the prehospital setting as a means of validating the presence and severity of pain. A retrospective cohort study was conducted including all adults with a Glasgow Coma Score >12 assessed by paramedics in a metropolitan area over a 7 day period in 2005. Pain was self-scored by patients using a 0-10 numeric rating scale (NRS). Of the patients transported, 1766/3357 (53%) reported pain, and an NRS score was recorded for 1286. Median age was 57 years, 51% were women, and median initial NRS was six. Mean heart rate was 85 (95% CI 84 to 86), mean systolic blood pressure was 139 mmHg (95% CI 138 to 141) and mean respiratory rate was 18 (95% CI 18 to 18). There was no significant correlation between NRS and heart rate (r=0.002, p=0.61, 95% CI -0.007 to +0.011) or blood pressure (r=-0.0007, p=0.81, 95% CI -0.007 to +0.005), although this was statistically significant for initial pain score and respiratory rate (r 0.058, p=0.001, 95% CI 0.024 to 0.093). A lack of any meaningful correlation between pain scores and changes in vital signs in this population demonstrates that these signs cannot be used to validate the severity of pain reported by adult patients.