Patients who are undergoing substantial posterior spinal reconstruction are chosen as the study population because (1) the need for transfusion is highly predictable; (2) all have endotracheal tubes to allow for controlled ventilation and control of inspired gases; (3) the availability of stored non-leukoreduced autologous packed red blood cells (prbcs) will enable comparison of effects of autologous blood containing elevated concentrations of pro-inflammatory cytokines and lyso-phosphatidyl choline with that of autologous red cells without elevated concentrations of pro-inflammatory cytokines (salvaged cells); (4) all have arterial catheters allowing for frequent sampling of arterial blood for blood gas determinations; (5) all have central venous catheters to guide fluid therapy and ensure the absence of fluid overload, thus eliminating an important confounder in assessing alterations of lung function after transfusion. For those not having autologous blood, it will be possible to compare the effects of blood containing elevated concentrations of pro-inflammatory cytokines and lyso-phosphatidyl choline normally associated with blood storage with that of autologous red cells without elevated concentrations of pro-inflammatory cytokines (salvaged cells).