Resource Document: Evidence Supporting Current Practice in Timing Assessment

Abstract

Current practice is an important component of evidence-based practice. This resource provides a discussion of timing practice and assessment guidelines and a detailed description of the impact of physiological and nonphysiological factors on the efficacy of intra-aortic balloon pump (IABP) therapy. Conventional Timing AssessmentTiming assessment is the process of determining if the timing settings are correct relative to the cardiac cycle. Conventional timing dictates that all actions of the IABP occur in diastole, so inflation should occur at the dicrotic notch and deflation before the next systolic ejection. To assess timing, set the IABP at 1:2 assist to allow comparison of assisted and unassisted beats. Figure 1 shows the assessment points.To assess inflation, draw a line (circled 1 on the figure) from visible dicrotic notch to dicrotic notch. The inflation point or V between systole and augmentation should be on or slightly above the line. If the V is too far above the line (more than 3 boxes on the electrocardiographic [ECG] paper), inflation timing is too early. If the dicrotic notch is visible between systole and the augmentation waveform, inflation is too late. In addition, the augmentation pressure should be greater than the systolic pressure.Deflation timing is assessed by identifying the assisted diastole, that is, the diastolic pressure after inflation of the balloon, and comparing it with the unassisted diastole (circled 2 on Figure 1), the native diastolic pressure of the patient. The assisted diastole should be lower than the patient's diastolic pressure. Finally, draw a line from the systolic pressure to the next systolic pressure (circled 3 on Figure 1). The assisted systole, the pressure after assisted diastole, should be lower than the patient's native systole. This finding indicates that the decrease in aortic pressure at end diastole reduced systolic pressure work on the next systolic beat.If the assisted systolic pressure is not lower than the native systolic pressure, deflation is too early (Figure 2A). This situation may occur even when deflation produces a decrease in end-diastolic pressure, but if it occurs well before the next systolic ejection, the left ventricle does not benefit from that pressure

Optical Fibre Pressure Sensors in Medical Applications

“…Wu et al [ 143 ] (2013) developed an optical sensor and used it in conjunction with a fractional flow reserve (FFR) technique in a swine model. In the last two years (2014–2015), the amount of research in this field has rapidly increased [ 144 – 148 ]. In 2014, Rodriguez et al [ 149 , 150 ] used an OFPS (OPP-M, Opsens) for simultaneous pressure and volume measurement.…”