Ann Thorac Surg 2005;80:2220
© 2005 The Society of Thoracic Surgeons
Original article: Cardiovascular
Invited commentary
Gerald Weinstein, MD
New Mexico Cardiovascular Associates, 5455 Remington Rd, Las Cruces, NM 88011
(Email: gswmd{at}aol.com).
Acute renal failure after cardiac surgery remains a persistent problem in cardiac surgery (ie, a problem that is of increasing importance as patients come to surgery older and sicker).
This study by Ranucci and colleagues [1] addresses the limits of hemodilution during cardiopulmonary bypass. Recognizing that extreme hemodilution is an independent risk factor for postoperative renal failure, they demonstrated that it is not hemodilution alone, but oxygen delivery that is the critical variable. They were able to establish a lower limit for oxygen delivery at a critical value of 272 mL/min/m2. Because oxygen delivery is dependent on both hematocrit and pump flow, increasing the pump flow may compensate for decreased hematocrit (less than 26%). Hematocrits less than 22% were treated with packed red cell transfusion.
This article is of tremendous practical importance in reducing the risk of cardiopulmonary bypass. The equation for oxygen delivery (DO2) may be easily inserted into a programmable calculator. Alternatively a series of tables or nomograms may be produced to facilitate adjusting pump flow to provide adequate oxygen delivery during cardiopulmonary bypass. Keeping oxygen delivery above the 272 mL/min/m2 by considering hematocrit and pump flow should help surgeons reduce the incidence of postoperative renal failure.
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References
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- Ranucci M, Romitti F, Isgrò G, et al. Oxygen delivery during cardiopulmonary bypass and acute renal failure after coronary operations Ann Thorac Surg 2005;80:2213-2220.[Abstract/Free Full Text]
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