Optimisation of Radiocephalic Arteriovenous Fistula

Each year, an estimated 5,000-6,000 patients require haemodialysis across United Kingdom (UK). This is only possible with a functional, accessible and permanent arteriovenous fistula (AVF). The current guidelines recommend, radiocephalic AVF (RACVF) to be the primary choice of fistula. Prior to the main objectives of this thesis, a UK wide (clinician based) survey was conducted to ascertain the scope of practice and Functional Maturation (FM) of RCAVF in UK. The survey demonstrated that 40% of surgeons prefer not to create RACVF (due to various factors) despite these current recommendations. In addition, current FM in the UK is around 60%, a finding which corresponds with a systematic review of the literature (comprised of exclusively UK studies). This rate of FM is 12% less than that reported internationally (72%). Therefore, it was hypothesised (null hypothesis) that FM of RCAVF could not be enhanced by optimisation of preoperative evaluation, patient selection (demographics), comorbidities, anatomical factors, operative skills and postoperative care and follow up. A methodological & prospective study, with series of retrospective analytics on n=350 RCAVF over six years from creation to their FM or failure was conducted. The traditional statistical means was also complemented by the first feasibility and applicability study, using artificial intelligence (AI) and deep learning (DL) for pattern recognition, modelling and decision tree in RCAVF stratification and formation. The outcome suggests that the traditional clinical examination for patient selection, should be complemented by the use of preoperative duplex sonography through a multidisciplinary team approach. Patient demographics and comorbidities should not be used as an exclusion criterion for RCAVF formation once the minimum diameter of cephalic vein (>1.8mm) and radial artery (2mm) has been met. Arteriovenous Ratio (AVR) of 0.8 to 1.1 creates minimal alteration in pressure and velocity of RCAVF, limiting early failure. Almost 50% of non-functioning RCAVF through early surveillance could be salvaged by well-designed algorithmic salvage (open & endovascular) techniques. Application of all these outcomes could result in a FM of 80% in clinical practice which is a major improvement on the current rate of 60%. The future role of AI and its implementation with vast dataset could enhance stratification and FM. The findings of cephalic vein and radial artery diameter from this thesis has now influenced "The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI)" and "European society of Vascular Surgery Guidelines". Finally, there is an international study (generated from this thesis) to gather the scope of practice (worldwide) and establish consensus

Blood and blood component transfusion on 30-day mortality and morbidity of infra-renal ruptured abdominal aortic aneurysm

This thesis for the first time in the literature, through a single cohort (n=82), systematic review and meta-aggregation of the data, has identified that the majority (>85%) of ruptured abdominal aortic aneurysm (rAAA) do not present with coagulopathy. In addition, the thesis for the first time, through a retro and prospective cohort study, has demonstrated that the hemostatic resuscitation protocols derived from military and civilian trauma for the correction of coagulopathy with a blood product ratio of one unit of packed red blood cell to one unit of fresh frozen plasma to one pool of platelet (1:1:1), contributes to increased postoperative (30-day) morbidity and mortality, especially thrombotic complications. This was attributed to different baseline demographics, pathophysiology and coagulation status. Through a comparative study, the thesis then confirms that such transfusion practice not only contributes to adverse outcomes, but also has no impact on final coagulation status of rAAAs. In addition, through a retro and prospective cohort study, a novel hematological marker (neutrophil to lymphocyte ratio) (NLR) was identified as an independent predictor of morbidity in rAAAs. This thesis was set on the background of significant research into all factors that could contribute to pathogenesis, inhibition and progression of rAAAs. This thesis concludes that the use of additional blood products (fresh frozen plasma and platelet) in hemostatic resuscitation of ruptured abdominal aortic aneurysms alongside packed red blood cell is not evidence based and a single protocol derived from one cohort (military and civilian trauma) of patients does not apply to another. The use of additional products in ruptured abdominal aortic aneurysms should be tailored to the individual hematological and clinical requirements and not as a part of a set transfusion ratio (1:1:1). This thesis has resulted in a change of practice and has created a platform for further search of the optimal transfusion protocol in this cohort of patients

Feasibility and Short-Term Outcomes of Three-Dimensional Hand-Sewn Esophago-Jejunal Anastomosis in Completely Laparoscopic Total Gastrectomy for Cancer

Laparoscopic total gastrectomy is on the rise. One of the most technically demanding steps of the approach is the construction of esophago-jejunal anastomosis. Several laparoscopic anastomotic techniques have been described, like linear stapler side-to-side or circular stapler end-to-side anastomosis; limited data exist regarding hand-sewn esophago-jejunal anastomosis. The study took place between January 2018 and June 2021. Patients enrolled in this study were adults with proximal gastric or esophago-gastric junction Siewert type III tumors that underwent 3D-assisted laparoscopic total gastrectomy. A hand-sewn esophago-jejunal anastomosis was performed in all cases laparoscopically. Forty consecutive cases were performed during the study period. Median anastomotic suturing time was 55 min, with intra-operative methylene blue leak test being negative in all cases. Median operating time was 240 min, and there were no conversions to open. The anastomotic leak rate and postoperative stricture rate were zero. The 30- and 90-day mortality rates were zero. Laparoscopic manual esophago-jejunal anastomosis utilizing a 3D platform in total gastrectomy for cancer can be performed with excellent outcomes regarding anastomotic leak and stricture rate. This anastomotic approach, although technically challenging, is safe and reproducible, with prominent results that can be disseminated in the surgical community