Application of a Single-pulsatile Extracorporeal Life Support System for Extracorporeal Membrane Oxygenation: An experimental study

Kim, Tae Sik; Sun, Kyung; Lee, Kyu Baek; Park, Sung Young; Hwang, Jae Joon; Son, Ho Sung; Kim, Kwang Taik; Kim, Hyoung Mook

Abstract

BACKGROUND: Extracorporeal life support (ECLS) system is a device for respiratory and/or heart failure treatment, and there have been many trials for development and clinical application in the world. Currently, a non-pulsatile blood pump is a standard for ECLS system. Although a pulsatile blood pump is advantageous in physiologic aspects, high pressure generated in the circuits and resultant blood cell trauma remain major concerns which make one reluctant to use a pulsatile blood pump in artificial lung circuits containing a membrane oxygenator. The study was designed to evaluate the hypothesis that placement of a pressure-relieving compliance chamber between a pulsatile pump and a membrane oxygenator might reduce the above mentioned side effects while providing physiologic pulsatile blood flow. MATERIAL AND METHOD: The study was performed in a canine model of oleic acid induced acute lung injury (N=16). The animals were divided into three groups according to the type of pump used and the presence of the compliance chamber. In group 1, a non-pulsatile centrifugal pump was used as a control (n=6). In group 2 (n=4), a single-pulsatile pump was used. In group 3 (n=6), a single-pulsatile pump equipped with a compliance chamber was used. The experimental model was a partial bypass between the right atrium and the aorta at a pump flow of 1.8~2 L/min for 2 hours. The observed parameters were focused on hemodynamic changes, intra-circuit pressure, laboratory studies for blood profile, and the effect on blood cell trauma. RESULT: In hemodynamics, the pulsatile group II & III generated higher arterial pulse pressure (47+/-10 and 41+/-9 mmHg) than the nonpulsatile group I (17+/-7 mmHg, p<0.001). The intra-circuit pressure at membrane oxygenator were 222+/-8 mmHg in group 1, 739+/-35 mmHg in group 2, and 470+/-17 mmHg in group 3 (p<0.001). At 2 hour bypass, arterial oxygen partial pressures were significantly higher in the pulsatile group 2 & 3 than in the non-pulsatile group 1 (77+/-41 mmHg in group 1, 96+/-48 mmHg in group 2, and 97+/-25 mmHg in group 3; p<0.05). The levels of plasma free hemoglobin which was an indicator of blood cell trauma were lowest in group 1, highest in group 2, and significantly decreased in group 3 (55.7+/-43.3, 162.8+/-113.6, 82.5+/-25.1 mg%, respectively; p<0.05). Other laboratory findings for blood profile were not different.
CONCLUSION
The above results imply that the pulsatile blood pump is beneficial in oxygenation while deleterious in the aspects to high pressure generation in the circuits and blood cell trauma. However, when a pressure-relieving compliance chamber is applied between the pulsatile pump and a membrane oxygenator, it can significantly reduce the high circuit pressure and result in low blood cell trauma.