Harmonic Analysis of Perfusion Pumps

Abstract

The controversy over the use of nonpulsatile versus pulsatile pumps for maintenance of normal organ function during ex vivo perfusion has continued for many years, but resolution has been limited by lack of a congruent mathematical definition of pulsatility. We hypothesized that the waveform frequency and amplitude, as well as the underlying mean distending pressure are all key parameters controlling vascular function. Using discrete Fourier Analysis, our data demonstrate the complexity of the pulmonary arterial pressure waveform in vivo and the failure of commonly available perfusion pumps to mimic in vivo dynamics. In addition, our data show that the key harmonic signatures are intrinsic to the perfusion pumps, are similar for flow and pressure waveforms, and are unchanged by characteristics of the downstream perfusion circuit or perfusate viscosity.

Pressure pulsation in roller pumps: A validated lumped parameter model

“…Pressure oscillations with negative peaks, due to uncontrolled pulsatility, are responsible for blood cell damage [15]. Moreover, the higher harmonic content of the signals is probably responsible for the deleterious effects observed in extracorporeal perfusion [4]. To reduce these effects spurious unwanted pulsations need to be eliminated and this could be pursued by smoothing the compression/release effects during the engaging/disengaging phases.…”

“…Nevertheless, they suffer from several limitations: they normally deliver uncontrolled pulsatile inlet and outlet pressure, which generates high frequency harmonics in pressure signals [4]; a phenomenon known as spallation [5,6] exists, which consists of micro-particles detaching from the tubing inner walls due to cyclic compression by the rollers; blood trauma and microemboli delivered to the patient appears to be more than that encountered with centrifugal pumps [7,8].…”

Inflammatory monocyte response due to altered wall shear stress in an isolated femoral artery model

“…In addition to flow rate, the pulsatility was characterized [22]. The pulsatility is imparted by the roller pump in this study was dependent on the RPM setting.…”

Shear Stress, Energy Losses, and Costs: A Resolved Dilemma of Pulsatile Cardiac Assist Devices

“…Nevertheless, quantifications of lumped models that could be achieved with accuracy according to the Bernoulli's principles of energy losses in vitro remain controversial due to different cardiovascular criteria [37, 38]. …”