Epidemiology and Outcomes of Abdominal Aortic Aneurysms in New Zealand: A 15-Year Experience at a Regional Hospital.

INTRODUCTION: Abdominal aortic aneurysms (AAA) account for approximately 400 deaths per year in New Zealand (NZ). Waikato Hospital caters to a diverse population comprising a high proportion of the indigenous Maori ethnic group considered to be at higher risk of mortality and morbidity. Despite these population factors, there is no screening program for AAA. The aim of this study was to further define the epidemiology and outcomes of AAA repairs in NZ to investigate the utility of implementing a population-specific screening program. METHODS: A retrospective study of all AAA repairs at Waikato Hospital between July 1996 and November 2010 was performed comparing long-term outcomes between Europeans and Maori considering acuity of presentation, age, gender, and type of repair. Perioperative and overall mortality data were obtained to generate Kaplan-Meier survival curves. RESULTS: 1,036 AAA repairs were performed. Maori presented younger (69.1 vs. 74.5, P < 0.001), had lower male predominance (1.6:1 vs. 3.5:1, P < 0.001), less elective repairs (44% vs. 67%, P < 0.001), and more ruptured AAA (RAAA) (40% vs. 21%, P < 0.001) despite the overall incidence of RAAA decreasing from 26% to 7.8% (P = 0.01). Maori had a lower postoperative 10-year survival compared to Europeans (17.4% vs. 36.5%, P < 0.001). There was an initial survival benefit for endoluminal over open repair but this converged at 4.9 years post repair. CONCLUSIONS: This study highlights the epidemiological trends and survival outcomes of AAA management in Maori and Europeans over 15 years. It provides further evidence supporting the consideration of a population-specific screening program in future.

Does diathermy smoke contaminate processed salvaged blood in cardiac surgery?

INTRODUCTION: A cell salvage device is used in cardiac surgery with the aim of reducing allogeneic blood transfusion. Suction of blood from the operating field used for the device is often accompanied by diathermy smoke. There is limited published research to know if this blood is then contaminated with clinically significant levels of harmful chemicals from this smoke. Postoperative cardiac surgery patients are already physiologically vulnerable, making the optimization of salvaged blood worth considering. METHODS: Ten patients who had cardiac surgery using a cell salvage device from a single institution had samples taken from the processed blood just prior to transfusion. Samples were tested for carbon monoxide (CO), cyanide and benzene. Results were compared to preoperative co-oximetry results and normal adult laboratory reference ranges. Demographic data about the patients was collected, including the type of operation, gender, age, body mass index, smoking status and amount of salvaged blood collected and processed. RESULTS: Primary surgery was coronary artery bypass grafting (CABG) in three patients, mitral valve repair or replacement in three patients and one each of aortic valve replacement (AVR)/CABG, AVR/plication of the aorta, CABG/external wrapping of the aorta and valve-sparing root replacement. None were smokers. Neither the blood CO level prior to surgery nor in the processed salvaged blood was above the normal limit of 2% for non-smokers. There was no processed blood benzene found. Cyanide levels in the processed blood ranged from 1.8 to 44.1 µmol/l (where <8 µmol/l is considered within the normal adult laboratory limit). CONCLUSION: Despite the obvious limitations of the current study, it shows that cyanide levels can be found many times the normal level in processed salvaged blood. Whilst the total dose of cyanide is small, the potential impact may be clinically significant due to cyanide's effect on mitochondrial metabolism in the heart and brain.