Abstract
Background:
During cardiac surgery, CPB machine affecting blood perfusion of all tissues. important marker of blood perfusion is blood lactate. blood lactate in relation to patient morbidity is an indicator for the reliability of blood lactate as a perfusion marker.

Patients and Methods:
In a prospective observational study, 66 patients admitted to Sohag university hospital and Sohag Heart Institute in period between October 2017 and April 2019 for cardiac surgery were enrolled. Immediately after induction of anesthesia, the first sample of arterial blood gas (ABG) was obtained. For measuring of lactate levels, the next samples were obtained just before CPB weaning, the next after 24 hours of staying ICU and the last sample were obtained after 48 hours of staying ICU.

Results:
Blood lactate levels in correlation to ICU length of stay showed both patient groups stayed in the ICU less than 48 hours and more than 48 hours both had significant p-value