title: Subcutaneous perfusion and oxygen during acute severe isovolemic hemodilution in healthy volunteers.
abstract: OBJECTIVE
  Acute severe isovolemic anemia (to a hemoglobin [Hb] concentration of 50 g/L) does not decrease subcutaneous wound tissue oxygen tension (PsqO(2)).
  
  
  METHODS
  University hospital operating room and inpatient general clinical research center ward.
  
  
  METHODS
  Twenty-five healthy, paid volunteers.
  
  
  METHODS
  Subcutaneous oxygen tension and subcutaneous temperature (Tsq) were measured continuously during isovolemic hemodilution to an Hb level of 50 g/L. In 14 volunteers (initially well-perfused), "normal" perfusion (Tsq >34.4 degrees C) was achieved by hydration and systemic warming prior to starting isovolemic hemodilution, while in 11 volunteers (perfusion not controlled [PNC]), no attempt was made to control perfusion prior to hemodilution.
  
  
  METHODS
  Measurements of PsqO(2), Tsq, and relative subcutaneous blood flow (flow index).
  
  
  RESULTS
  While PsqO(2), Tsq, and flow index were significantly lower in PNC vs well-perfused subjects at baseline, there was no significant difference between them at the Hb of 50 g/L (nadir). Subcutaneous PO(2) did not decrease significantly in either group. Arterial PO(2) was not different between the groups, and did not change significantly over time; Tsq and flow index increased significantly from baseline to nadir Hb in both groups.
  
  
  CONCLUSIONS
  The level of PsqO(2) was maintained at baseline levels during hemodilution to Hb 50 g/L in healthy volunteers, whether they were initially well-perfused or mildly underperfused peripherally. Given the significant increase in Tsq and flow index, this resulted from a compensatory increase in subcutaneous blood flow sufficient to maintain oxygen delivery. Wound healing depends to a large extent on tissue oxygen delivery, and these data suggest that even severe anemia by itself would not be sufficient to impair wound healing. Thus, transfusion of autologous packed red blood cells solely to improve healing in surgical patients with no other indication for transfusion is not supported by these results.
authors: Department of Anesthesia and Perioperative Care, University of California, Box 0648, 521 Parnassus Ave, San Francisco, CA 94143-0648, USA. hhopf@itsa.ucsf.edu
authors: H W
authors: HW
authors: Hopf
authors: M
authors: M
authors: Viele
authors: J J
authors: JJ
authors: Watson
authors: J
authors: J
authors: Feiner
authors: R
authors: R
authors: Weiskopf
authors: T K
authors: TK
authors: Hunt
authors: M
authors: M
authors: Noorani
authors: H
authors: H
authors: Yeap
authors: R
authors: R
authors: Ho
authors: P
authors: P
authors: Toy
mesh_terms: D000208:Acute Disease; D000328:Adult; D000740:Anemia / Q000378:metabolism; D005260:Female; D006438:Hemodilution; D006801:Humans; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010477:Perfusion; D012720:Severity of Illness Index; D012867:Skin
chemical_list: D010100:Oxygen