Recovery of red blood cell mass following orthognathic surgery.

The rates of recovery of red blood cell mass after surgery were compared in three groups of orthognathic surgery patients: 12 patients not receiving transfusions during Le Fort I osteotomy, 10 patients receiving transfusions during Le Fort I osteotomy, and 25 patients undergoing bilateral sagittal split osteotomy. Patients in these groups lost a mean of 421, 455, and 191 mL of blood, respectively, during surgery. Both groups of patients undergoing Le Fort I osteotomy donated a unit of blood prior to surgery, while the patients undergoing bilateral sagittal split osteotomy did not. A control group consisted of 77 presurgical orthognathic patients who donated a unit of blood (450 mL) a mean of 11 days prior to surgery. Among the control group, 38 had recovered red blood cell mass prior to surgery. The patients undergoing Le Fort I osteotomy recovered red blood cell mass after surgery more quickly than did the patients undergoing bilateral sagittal split osteotomy, despite having lost twice as much blood. This unexpected finding can be attributed to the need to lose sufficient red blood cell mass to stimulate the erythropoietic system. The patients undergoing Le Fort I osteotomy experienced two challenges to the system, predonation of blood and greater blood loss during surgery, resulting in a great enough decrease in red blood cell mass to stimulate the release of erythropoietin. Patients undergoing bilateral sagittal split osteotomy did not exceed this threshold. None of the differences among the groups were statistically significant, possibly because of the few number of subjects.