Invasive blood pressure (IBP) monitoring could be of benefit for certain prehospital patient groups such as trauma and cardiac arrest patients. However, there are disadvantages with using conventional IBP devices. These include time to prepare the transducer kit and flush system as well as the addition of long tubing connected to the patient. It has been suggested to simplify the IBP equipment by replacing the continuous flush system with a syringe and a short stopcock.

In this study, blood pressures measured by a standard IBP (sIBP) transducer kit with continuous flush was compared to a transducer kit connected to a simplified and minimized flush system IBP (mIBP) using only a syringe.

A mechanical, experimental model was used to create arterial pressure pulsations. Measurements were made simultaneously using a sIBP and mIBP device, respectively. This was repeated four times using different mean arterial pressure (MAP): 40, 70, 110, and 140mm Hg. For each series, 16 measurements were taken during 20 minutes. Data were analyzed using Bland-Altman plots. Measurement error greater than five percent was regarded as clinically significant.

Mean bias and standard deviation (SD) for systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP was -3.05 (SD = 2.07), 0.2 (SD = 0.48), and -0.3 (SD = 0.55) mmHg, respectively. Bland-Altman plots revealed that the bias and SD for systolic pressures was mainly due to an increased under-estimation of pressures in lower ranges. All MAP and 98.4% of diastolic pressure measurements had an error of less than five percent. Systolic pressures in the MAP 40 series all had an error of greater than five percent. All other systolic pressures had an error of less than five percent.

Thus, IBP with the mIBP flush system provides accurate measurement of MAP and DBP in a wide range of physiological pressures. For SBP, there was a tendency to under-estimate pressures, with larger error in lower pressures. Implementation of a simplified flush system could allow further development and potentially simplify the use of IBP for prehospital critical care teams.

KarlssonJ, LindeJ, SvensenC, GellerforsM. Prehospital Invasive Arterial Pressure: Use of a Minimized Flush System. Prehosp Disaster Med. 2018;33(5):490–494.