Emergency Medical Services
Background: The authors sought to determine whether the pulse pressure (systolic-diastolic blood pressure) in the prehospital setting is correlated to stroke severity as measured by the National Institutes of Health Stroke Scale (NIHSS) at hospital arrival by EMS as well as NIHSS at hospital discharge.
Methods: This is an IRB approved prospective observational study performed as part of our quality outcomes database for our county’s EMS system. On scene data including blood pressure values are collected and transmitted in real time. NIHSS at hospital admission and discharge are collected from the receiving hospitals at our monthly QI meetings. Complete data is usually available as reporting of these data are a requirement for the hospitals receiving patients from our EMS agency. The data are then input into our database, and statistical analyses are performed in JMP 12.0 for the mac.
Results: The cohort (n=106) consisted of all patients transported with an ultimate diagnosis of ischemic stroke. The median pulse pressure was 66.5, with an interquartile range (IQR) of 47.75 to 80. The median NIHSS at hospital admission was 9, with an IQR 3.75 to 18. The higher the pulse pressure, the lower the NIHSS (P=0.0345, 95% CI -0.01532 to -0.0054) at hospital arrival. The median NIHSS at hospital discharge was 5, with an IQR of 1-11.75. The higher the pulse pressure, the lower the NIHSS (P=0.0449, 95% CI -0.1727 to -0.0020) at hospital discharge.
Conclusion: An elevated prehospital pulse pressure appears to be significantly associated with a lower NIHSS both at hospital admission and discharge. As this is an observational cohort study, it is not possible to conclude causality. A higher pulse pressure may indeed be protective, and supports not lowering blood pressure unless dangerously elevated.