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Hematocrit During the Cardiopulmonary Bypass: Impact on Clinical Outcome During
Ascending Aortic Surgery
Department of Anesthesia1
Department of Cardiothoracic and Vascular Surgery2 The University of Texas Medical School at Houston
Memorial Hermann Heart & Vascular Institute
SF Zhou MD1, AL. Estrera MD2, T Pawelek MD1, C Ignacio MD1, S Panthayi MD1, MD; K Shebaclo BS1, H Safi MD2, R Sheinbaum MD1
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Introduction
Blood transfusions worsen clinical outcomes in aortic surgery.
Hemodilutional anemia increases organ ischemia risk.
We show the lowest hematocrit (Hct) that reduces transfusion and prevents hemodilution associated complications.
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Methods
We reviewed 399 cases of Ascending Aortic (Aneurysm or Type A dissection) repair with deep hypothermic circulatory arrest (DHCA).
Demographics and surgical characteristics (except age) were similar between groups.
Patient ages were 17-89 and are grouped by Hct <16%, <18%, 19%-20%, 21%-22%, > 23% at temperature < 20C, 20-28C, 28-32C, 32-34C, 34-35C during CPB.
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Methods
Databases were established by collecting medical information through patient medical records and 2010 ICD-9-CM Volume 1 Diagnosis Codes, including complications of surgical and medical care, not elsewhere classified 996-999 and diseases of the specific system or organ.
The data analysis was by mean ( standard deviation) for continuous variables and by frequency (percentage) for qualitative variables. Two-sample t-test or Chi-Square test was used to compare groups with P-value of less than 0.05 considered significant.
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Results
Changes in outcome were suggested at Hct <16% versus >16% at <20C during DHCA and also for Hct <18% versus>18% at temperature 20-28 C.
Risk of ARF and postoperative tracheotomy increased with Hct < 16 (Table 2).
Chance of discharge home improved with higher Hct at all temperatures (Table 3). Mortality decreased at Hct 21-22% at 20-34C and increased at Hct <16% during DHCA (Table 4).
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Results
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Results
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Conclusion
Patient temperature affects oxygen demand, blood viscosity, oxygen carrying capacity and delivery.
Hct value is a transfusion trigger and should change with body temperature during aortic surgery.
Hct 21-22% appears favorable for CPB at 20-34C. Hct <16% during DHCA increases mortality. Hct <18% during rewarming (20-32C) increases
postoperative ARF risk.