Ever since a trauma patient billed as normotensive with stable vital signs rolled off the elevator with CPR in progress having "just lost pulses", I've been somewhat skeptical of my prehospital report, including vital signs. This study, at least, supports a position that, barring untruthfulness, EMS providers vital signs are usually not clinically significantly different than vital signs obtained on arrival to the Emergency Department - even if observed techniques for EMS providers weren't perfect.
The first phase study looked at 100 patients arriving in the Emergency Department. BP measurements were obtained within 5 minutes of arrival, and compared to the reported measurement from EMS. There was approximately a 17mmHg +/- spread to the systolic pressures measured by EMS compared to the first BP in the Emergency Department.
The second phase of the study had observers riding with EMS and documenting the technique at which they used to find vital signs - and then having the research assistants performing the same measurement in the field as well. In this phase, EMS providers systolic pressure was only a 10.1mmgHg +/- spread away from the research assistant - despite having ideal technique deficiencies and a terminal digit preference for numbers ending in zero.
The article concludes that EMS providers measurements had poor agreement with subsequent measurements, and that the differences were clinically significant. However, based on the distribution of error in their Bland-Altman plots, I disagree that assessment, as most of the variability occurred throughout a range of inconsequential systolic pressures between 120 and 170. They unfortunately had very few patients with clinically important hypo- or hypertension, so the question really remains unanswered whether EMS measurements at the clinically important extremes are reliable.
I do find it rather entertaining that their methods included a "specially trained research assistant" to measure blood pressure, referred to in the title as an "expert". You can be an "expert" in anything nowadays, apparently.
"Agreement between emergency medical services and expert blood pressure measurements."