Factors Affecting Blood Loss In Liver Surgery For Colorectal Metastases

Introduction Peri-operative blood loss and blood transfusions are associated with poorer short- and long-term outcomes in patients undergoing hepatectomy. Various techniques are utilised to decrease blood loss though these may also cause an Ischaemia-Reperfusion Injury (IRI). The aim of this thesis was to identify factors which predispose to intra-operative bleeding during liver surgery and to identify methods to decrease blood loss without increasing the likelihood of post-operative liver dysfunction Methods In order to address the aim of this thesis, several studies are performed: 1. A systematic review examining non-surgical methods to decrease blood loss. Primary outcome measures included peri-operative blood loss and transfusion requirements. The secondary outcome measure was occurrence of IRI. The review was performed according to the PRISMA guidelines for systematic reviews. 2. A retrospective database analysed the association between blood transfusion and survival. . Uni- and multivariate analysis were performed. 3. A pilot single blinded, randomised control trial (RCT) was undertaken comparing the Pringle manoeuvre (standard) versus Portal Vein clamping. Results 1. Seventeen studies were included in the systematic review. In 8 studies (n=894) pharmacological methods and in another 9 studies (n=679) anaesthetic methods to decrease blood loss were investigated. In 3 trials potential benefits of anti-fibrinolytics were demonstrated. Six anaesthetic trials demonstrated potential roles for low central venous pressure, acute normovolaemic haemodilution, autologous blood donation techniques and choice of inhalational anaesthetic agent employed. 2. Six hundred and ninety patients were included in this study. Median follow-up was 33 months. Sixty-four (9.3%) patients required a peri-operative RBCT. Red cell transfusion was a predictor for decreased OS (median 41 vs 49 months, p=0.04). However, on multivariate regression analyses pre-operative chemotherapy, post-operative complications and Clinical Risk Score (CRS) were independently associated with reduced overall survival, though RBCT was not. There was no association between RBCT and recurrence free survival ( median 15 vs 17 months, p=0.28) 3. The main findings of the RCT were that it was technically feasible to perform isolated portal vein clamping in patients and to recruit patients into the trial. However, a larger RCT will be needed to obtain definitive evidence on the role of PVC in hepatic resections in the future Conclusions There is potential for use of non-surgical techniques to decrease peri-operative bleeding in liver surgery. RBCT is not independently associated with poorer survival although it may be a surrogate marker for more advanced disease. The RCT confirms that isolated portal vein clamping is technically feasible and it was possible to recruit into the trial; a multi-centre RCT is required to assess the role of isolated portal vein clamping surgery for colorectal liver metastases.