In vivo assessment of a new method of pulsatile perfusion based on a centrifugal pump.

The aim of this study was to assess platelet dysfunction and damage to organs after extracorporeal circulation using a pump based on a new method that adds a pulsatile flow to the continuous flow provided by a centrifugal pump. The continuous component of the total flow (2-3 L/min) is created by a Bio-Pump centrifugal pump, while the pulsatile component is created by the pulsating of an inner membrane pneumatically controlled by an intra-aortic counterpulsation balloon console (systolic volume of 37.5 mL in an asynchronous way with a frequency of 60 bpm). Six pigs were subjected to a partial cardiopulmonary bypass lasting 180 min and were sacrificed 60 min after extracorporeal circulation was suspended. The hematological study included the measurement of hematocrit, hemoglobin, leukocytes, and platelet function. The new pump did not significantly alter either platelet count or platelet function. In contrast, hematocrit and hemoglobin were significantly reduced during extracorporeal circulation (approximately 5% P = 0.011, and 2 g/dL P = 0.01, respectively). The leukocyte count during extracorporeal circulation showed a tendency to decrease, but this was not significant. In general, the short-term use of the new pump (4 h) did not cause any serious morphological damage to the heart, lung, kidney, or liver. The results suggest that the hemodynamic performance of the new pump is similar to a conventional centrifugal pump and could therefore be appropriate for use in extracorporeal circulation.

A new method of providing pulsatile flow in a centrifugal pump: assessment of pulsatility using a mock circulatory system.

Previous studies have demonstrated the potential advantages of pulsatile flow as compared with continuous flow. However, to date, physiologic pumps have been technically complex and their application has therefore remained in the experimental field. We have developed a new type of centrifugal pump, which can provide pulsatile as well as continuous flow. The inner wall of a centrifugal pump is pulsed by means of a flexible membrane, which can be accurately controlled by means of either a hydraulic or pneumatic driver. The aim of this study was to assess the hydraulic behavior of the new pump in terms of surplus hemodynamic energy (SHE). We conducted experiments using a mock circulatory system including a membrane oxygenator. No differences were found in the pressure-flow characteristics between the new pump and a conventional centrifugal pump, suggesting that the inclusion of the flexible membrane does not alter hydraulic performance. The value of SHE rose when systolic volume was increased. However, SHE dropped when the percentage of ejection time was reduced and also when the continuous flow (programmed by the centrifugal console) increased. Mean flow matched well with the continuous flow set by the centrifugal console, that is, the pulsatile component of the flow was exclusively controlled by the pulsatile console, and was therefore independent of the continuous flow programmed by the centrifugal console. The pulsatility of the new pump was approximately 25% of that created with a truly pulsatile pump.

Injury in organs after cardiopulmonary bypass: a comparative experimental morphological study between a centrifugal and a new pulsatile pump.

The aim of this investigation was to assess organ injury provoked by a new pulsatile pump for cardiopulmonary bypass (CPB) with respect to a conventional centrifugal pump. Eight pigs in the pulsatile group (PG) and five in the centrifugal group (CG) underwent a partial CPB lasting 180 min. The animals were sacrificed 180 min after CPB was suspended, and a morphological study of fragments of ventricular wall, liver, lung, and kidney was performed. In CG, centrilobular hepatic necrosis was observed accompanied by sinusoidal dilatation and congestion, multiple focuses of myocardial ischemia, and minor to moderate pulmonary interstitial edema. In PG, diffuse centrilobular sinusoidal congestion in the liver, congestion and capillary dilatation of low intensity in the ventricular wall, and nonsignificant pulmonary interstitial septal edema was observed. In the kidney, both groups showed degenerative changes of the tubular cells and nonsignificant tubular dilatation. These results suggest a better peripheral circulation in the pulsatile group.