Brain oxygen and metabolism is dependent on the rate of low-flow cardiopulmonary bypass following circulatory arrest in newborn piglets

Peter Pastuszko, Huiping Liu, Alberto Mendoza-Paredes, Steven E. Schultz, Scott D. Markowitz, William J. Greeley, David F. Wilson, Anna Pastuszko

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16 Scopus citations


Objective: To determine the optimum rate of low-flow hypothermic cardiopulmonary bypass (LF), following circulatory arrest (DHCA) on brain oxygenation (bO2), extracellular dopamine (DA), phosphorylation of select neuroregulatory proteins responsible for neuronal injury, and survival following ischemic brain injury: CREB, Erk1/2, Akt, Bcl-2, and Bax. Methods: The piglets were placed on cardiopulmonary bypass (CPB) and cooled to 18 °C. They were then subjected to 30 min of DHCA followed by 1 h of LF at 20, 50, or 80 ml/(kg/min), rewarmed, separated from CPB, and maintained for 2 h. The bO2 was measured by quenching of phosphorescence; DA by microdialysis; phosphorylation of CREB, ERK1/2, Akt, Bcl-2, and Bax by Western blots. The results are means ± SD for seven experiments. Results: Pre-bypass bO2 was 47.4 ± 4.2 mmHg and decreased to 1.9 ± 0.8 mmHg during DHCA. At the end of LF at 20, 50, and 80 ml/(kg/min), bO2 was 11.8 ± 1.6, 26 ± 1.8, and 33.9 ± 2.6 mmHg, respectively. The DA increased 510-fold relative to control (p < 0.001) by 15 min of LF-20 with maximum increase occurring at 45 min. With LF-50, increase in DA was not statistically significant and no increase was observed when LF-80 was used. Bcl-2 immunoreactivity increased after LF-50 and LF-80 (140 ± 14.5%, p < 0.05 and 202 ± 34%, p < 0.05, respectively). Neither flow increased Bax immunoreactivity. The ratio of Bcl-2/Bax, pCREB, pAkt, pErk increased significantly with increasing the flow rate of LF. Conclusions: The protective effect of LF following DHCA on brain metabolism is dependent on the flow rate. Flow-dependent increase in pCREB, pErk1/2, pAkt, increase in Bcl-2/Bax, and decrease in DA indicated that to minimize DHCA-dependent neuronal injury, LF flow should be above 50 ml/(kg/min).

Original languageEnglish
Pages (from-to)900-906
Number of pages7
JournalEuropean Journal of Cardio-thoracic Surgery
Issue number5
StatePublished - May 2007


  • Brain injury
  • Cardiopulmonary bypass
  • Circulatory arrest
  • Newborn
  • Oxygen


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