Prospective study of preoperative autologous blood donation for patients with high risk of allogeneic blood transfusion in lumbar fusion surgery: a study protocol of a randomised controlled trial.

INTRODUCTION: Preoperative autologous blood donation (PABD) can be used to reduce the exposure of allogeneic blood transfusion in patients undergoing elective surgery. Better blood management to avoid anaemia and reduce allogeneic blood transfusion after spine surgery become increasingly important with development of enhanced recovery after surgery. We present here the design of a randomised controlled trial with three groups to verify the clinical effectiveness of PABD in patients at high risk of transfusion for lumbar fusion surgery and explore the optimal timing of autologous blood donation. METHOD AND ANALYSIS: Patients (age 18-70 years) who will receive lumbar fusion surgery for degenerative disease with haemoglobin over 110 g/L and 'high risk' of allogeneic blood transfusion are eligible, unless they refuse participation or are diagnosed with malignant metastases, infection, cardiovascular and cerebrovascular diseases, haematological disorders or relevant drug history and critical illnesses. A total of 1200 patients will be recruited and randomised into three groups. Patients in group A will not receive PABD and be regarded as control group. PABD will be performed for patients in groups B and C. Blood donation will be finished at 1 week (±3 day) before surgery in group B and 2 weeks (±3 day) before surgery in group C. Primary outcome measures will include haemoglobin decline, incidence and amount of allogeneic blood transfusion. Secondary outcome measures will include days of hospitalisation after surgery, haematocrit level and incidence of complications. This study is a single-centre and open-label randomised controlled trial. The sample size is calculated with reference to the retrospective data and previous studies. ETHICS AND DISSEMINATION: This trial has been approved by the Peking University Third Hospital Medical Science Research Ethic Committee (no: 2020-262-02). Results of the trial will be submitted for publication in a peer-reviewed journal and as conference presentations. TRIAL REGISTRATION NUMBER: ChiCTR2000039824, preresults.

The use of CT Hounsfield unit values to identify the undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases.

PURPOSES: Our purpose was to use computed tomography (CT) Hounsfield unit (HU) values to identify the undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases. METHODS: A total of 334 patients with lumbar degenerative diseases were retrospectively reviewed and divided into two groups according to the degree of lumbar degenerative changes in preoperative lumbar CT images. Patients who had at least three vertebrae with severe degeneration at L1-L4 were placed in the degenerative group, and others were placed in the control group. HU value of trabecular bone in middle axial CT image of vertebral body, T-score and bone mineral density (BMD) at L1-L4 and hips were measured. CT HU thresholds for osteoporosis were obtained from control group and then applied to identify undiagnosed spinal osteoporosis. RESULTS: There were 182 patients in the degenerative group and 152 patients in the control group. CT HU value had a positive correlation with T-score and BMD of lumbar spine in both groups (P < 0.001), while the correlation coefficients at L1-L4 were higher in the control group (> 0.7) than in the degenerative group (< 0.7). T-score and BMD of lumbar spine were higher in the degenerative group (P < 0.05), while CT HU value, T-score and BMD of hips had no significant difference between two groups. According to the linear regression equations of vertebral T-score and CT HU value in the control group, the thresholds matching T-score of - 2.5 were 110, 100, 85 and 80HU for L1, L2, L3 and L4, respectively. Defining CT osteoporosis as L1 ≤ 110HU or L2 ≤ 100HU or L3 ≤ 85HU or L4 ≤ 80HU was 88.5% (69/78) specific and 60.8% (45/74) sensitive for distinguishing DXA osteoporosis of lumbar spine in the control group. The rate of undiagnosed spinal osteoporosis was higher in the degenerative group than in the control group according to CT HU thresholds (38.7% vs. 11.5%, P < 0.05). CONCLUSIONS: Degenerative changes in the lumbar spine can increase BMD and T-score provided by lumbar DXA, leading to an underestimation of vertebral osteoporosis. Thresholds for osteoporosis based on CT HU values can be used as a complementary method to identify undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases. These slides can be retrieved under Electronic Supplementary Material.