The Journal of Thoracic and Cardiovascular Surgery
Volume 133, Issue 1 , Pages 29-36, January 2007

Hemodilutional anemia impairs neurologic outcome after cardiopulmonary bypass in a piglet model

  • Takashi Miura, MD

      Affiliations

    • Department of Cardiovascular Surgery, Heart Institute of Japan
    • Corresponding Author InformationAddress for reprints: Takashi Miura, MD, Department of Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women’s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
    • ,
  • Takahiko Sakamoto, MD

      Affiliations

    • Department of Cardiovascular Surgery, Heart Institute of Japan
    • ,
  • Makio Kobayashi, MD

      Affiliations

    • Department of Pathology, Tokyo Women’s Medical University, Tokyo, Japan.
    • ,
  • Toshiharu Shin’oka, MD

      Affiliations

    • Department of Cardiovascular Surgery, Heart Institute of Japan
    • ,
  • Hiromi Kurosawa, MD

      Affiliations

    • Department of Cardiovascular Surgery, Heart Institute of Japan

Received 1 January 2006; received in revised form 12 August 2006; accepted 28 August 2006.

Objectives

The effect of hemodilution on neurologic outcome after cardiopulmonary bypass remains unclear. We studied the influences of hematocrit on cerebral oxygenation and neuropathologic outcome in a piglet model.

Methods

Eleven piglets (9.3 ± 1.1 kg) were randomized into 2 groups. Five piglets (group H) received a total blood prime resulting in a high hematocrit (33.0% ± 2.3%), and 6 piglets (group L) received a crystalloid prime resulting in a low hematocrit (14.0% ± 3.2%). Both groups underwent 90 minutes of moderate hypothermic cardiopulmonary bypass (28°C) with alpha-stat strategy. Cerebral oxygenation was monitored by near-infrared spectroscopy. Group L received a blood transfusion immediately after cardiopulmonary bypass to reach the postoperative target hematocrit of 30%. The brain was fixed in situ 6 hours after weaning from cardiopulmonary bypass, and a histologic score for neurologic injury was assessed.

Results

There were no significant differences in arterial blood gas analyses throughout the experiment between the groups. Mean arterial pressure, mixed venous oxygen saturation, and heart rate were significantly higher in group H compared with group L during hypothermia. Oxyhemoglobin and total hemoglobin signals detected by near-infrared spectroscopy were significantly lower in group L (analysis of variance, P < .0001), although the tissue oxygenation index was not different during cardiopulmonary bypass. Group L showed a poorer histologic score compared with group H (P = .0071).

Conclusions

Excessive hemodilution, such as a hematocrit of less than 15%, may be associated with a high incidence of neurologic injury. Further studies are required to determine the safety limits of hematocrit during pediatric cardiopulmonary bypass.

CTSNet classification: 19, 25

Abbreviations and Acronyms: CPB, cardiopulmonary bypass, CytO2, oxidized cytochrome a, a3, HbO2, oxygenated hemoglobin, HbT, total hemoglobin, HHb, deoxygenated hemoglobin, NIRS, near-infrared spectroscopy, TOI, tissue oxygenation index

 

PII: S0022-5223(06)01599-6

doi:10.1016/j.jtcvs.2006.08.048

The Journal of Thoracic and Cardiovascular Surgery
Volume 133, Issue 1 , Pages 29-36, January 2007

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