The Annals of Thoracic Surgery, Vol 31, 134-143, Copyright © 1981 by The Society of Thoracic Surgeons
Oxygen transport to tissue under normovolemic moderate and extreme hemodilution during coronary bypass operation
J Niinikoski, V Laaksonen, O Meretoja, J Jalonen and MV Inberg
Oxygen transport to tissue was studied in 12 patients undergoing coronary
bypass operation under normovolemic moderate and extreme hemodilution.
Normovolemic moderate hemodilution (15 ml per kilogram of body weight),
carried out immediately after induction of anesthesia, decreased the mean
hematocrit from 0.43 to 0.33. Simultaneously, the cardiac index and the
left ventricular filling pressure increased slightly but the systemic
oxygen transport was reduced by 20%. The subcutaneous tissue oxygen tension
(PO2) was approximately 40 mm Hg after induction of anesthesia and
underwent a transient increase during moderate hemodilution. During
cardiopulmonary bypass and extreme hemodilution, the mean hematocrit
declined to 0.16. Concurrently, the mean tissue PO2 fell sharply and
reached a minimum of 14 mm Hg at deepest hypothermia. After decannulation
and reinfusion of autologous blood, the PO2 rose to 30 mm Hg. In general,
total-body oxygen consumption changed along with tissue PO2. Blood lactate
concentration underwent a clear increase in the early phase of
extracorporeal circulation and remained rather stationary thereafter. No
perioperative myocardial infarctions were encountered, and each patient
made an uneventful recovery.