Paradigm shift in blood management for surgery in metastatic spine diseases

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Surgical management is one of the major treatment modalities in metastatic spine diseases, the other two being radiotherapy and chemotherapy. Surgery for such diseases is potentially complex, often requiring complex reconstruction resulting in prolonged operative times, leading to significant blood loss, writes Naresh Kumar.

In a recent meta-analysis, we found that the pooled estimate of the blood loss occurring during spinal tumour surgeries was 2,180ml (95% confidence interval; 1,805–2,554ml). However, the studies included in meta-analysis did not classify the data based on type of tumour, type of surgery and quantum of surgery. Hence, we conducted a retrospective analysis of our database which included 259 patients undergoing spinal tumour surgeries between 2005 and 2014. The analysis revealed that type of tumour, type of surgical approach and level of decompression were significant predictors of intraoperative blood loss and therefore, we need to take into account these factors when we evaluate the amount of blood loss during spinal tumour surgery.

Currently, allogeneic blood transfusion is the gold standard for blood replenishment at most centres worldwide, placing an enormous burden on the limited and precious blood bank resources. Although allogenic blood transfusion has become safer with better testing, there remain deleterious effects such as immune system compromise or transfusion-related acute lung injury from its exposure. As a consequence, there has been an increase in the length of intensive care unit and hospital stays resulting in higher treatment costs. Furthermore, allogenic transfusion may be associated with a worse prognosis, including all-cause mortality and cancer-related mortality. The logical solution to reduce these problems will be finding methods either to reduce intraoperative blood loss or to replenish the lost blood without taking recourse to allogenic transfusion.

In order to reduce intraoperative blood loss, a number of measures are applied preoperatively and intraoperatively. These involve assessment and correction of coagulopathy, preoperative embolisation, antifibrinolytic drugs like Tranexamic acid, prevention of hypothermia, intra-operative ligation of feeding vessels, bipolar electrocautery, and haemostatic agents like Gelfoam or thrombin (Floseal, Baxter).

Among the above methods, preoperative embolisation has been shown to be a reasonably effective method in reducing intraoperative blood loss. Several studies investigated upon renal and thyroid cancer primaries have demonstrated that the patients who received embolisation had less intraoperative blood loss compared with those who did not. However, if the primary cancer of haematological origin, embolisation does not seem to work as the predominant blood supply arises from a fine capillary network within the tumour, not from large segmental feeder vessels and hence they are not responsive to embolisation. We analysed the data on preoperative embolisation in patients undergoing spine tumour surgery and showed that embolisation was most effective in surgery for primary spine tumours and less so for metastatic spine tumour surgery.

Using Tranexamic acid is also shown to be an economical and effective method for reducing blood loss in spinal surgery. It has been demonstrated that patients who received Tranexamic acid had significant reduction of blood loss and required less blood transfusion than patients who received placebo.

Modern minimally invasive surgical approaches are recently-evolved techniques and have shown to be effective in minimising blood loss. Like in degenerative spinal conditions, the advent of minimally invasive surgery for metastatic spine disease has definitely brought clear-cut reduction in intraoperative blood loss and lesser wound problems.

In cases where there is an excessive bleeding despite using the above-mentioned measures, the ideal method would be to salvage the lost blood during surgery and reinfuse it. Intraoperative cell salvage has emerged as a practical blood replenishment strategy in major spine surgeries such as for scoliosis and in trauma surgeries. Using cell salvage, the lost red blood cells during surgery can be salvaged and returned to the patient instead of being discarded. However, the biggest barrier has been proving the safety of salvaged blood for reinsfusion, especially in cancer surgery, and allaying fears of reinfusing tumour cells to the patient via salvaged blood.

Evidence has, however, accumulated supporting the use of cell salvage in different surgical disciplines, such as gynaecological, hepatobiliary, gastrointestinal, urological and lung cancer surgery.1 Some studies have illustrated that the blood which passed through cell salvage and another additional filter, namely a leucocyte depletion filter, was devoid of tumour cells and hence safe for reinfusion. Some other studies suggested that intraoperatively salvaged blood can be a simple and cost effective method for replacement of allogenic blood transfusion. Nevertheless, there remain many controversies among orthopaedic and spine surgeons worldwide on the use of intraoperative cell salvage in surgery for metastatic spine disease, and there has been no evidence in the literature supporting its use in such surgeries.1

My colleagues and I conducted a large non-reinfusion study including 50 consecutive patients to evaluate the safety of cell salvage-leucocyte depletion filter-processed blood since October 2011. Our study showed that after passing through both cell salvage and a leucocyte depletion filter, no viable tumour cells could be detected in the samples using cell block technique.2 The study of samples from a subset of these patients using a flowcytometry technique also demonstrated that the number of tumour cells in the filtered salvaged blood, if any, was significantly lower than amount of circulating tumour cells in the patients’ blood.3 Our findings support the notion that intraoperatively salvaged blood could be used safely and effectively as an alternative to allogenic blood transfusion during spinal tumour surgery. The validation of the safety and efficacy of salvaged blood in metastatic spine tumour surgery is mandated through clinical trials.


References

  1. Kumar N, Chen Y, Zaw AS, et al. Lancet Oncol. 2014; 15(1): e33–41.
  2. Kumar N, Ahmed Q, Lee VK, et al. Ann Surg Oncol. 2014; 21(7): 2436–2443.
  3. Kumar N, Lam R, Zaw AS, et al. Ann Surg Oncol. 2014; 21(13):4330-5.

 

Naresh Kumar is an orthopaedic surgeon at the National University Health System, Singapore