A note on the relationship between the isotone assumption of the Abian-Brown fixed point theorem and Abian’s most basic fixed point theorem

In a recent paper Xie et al. (Fixed Point Theory Appl. 2013:192, 2013) gave several extensions and some applications of the Abian-Brown (AB) fixed point theorem. While the AB fixed point theorem and its extensions (as well as other related fixed point theorems) assume that the mapping is isotone, this note shows that for single-valued finite maps this condition relates to the acyclicity of the map, which in turn relates to Abian’s (Nieuw Arch. Wiskd. XVI:184-185, 1968) most basic fixed point theorem for finite sets

Essays in technology gap and process spillovers at the firm level

Ph.DDOCTOR OF PHILOSOPH

The use of the RenalGuard system in cardiac surgery with cardiopulmonary bypass: a first in man prospective, observational, feasibility pilot study

Objectives As proof of concept, this prospective, observational study assessed the feasibility and early clinical outcomes of performing on-pump cardiac surgery with the RenalGuard system. Background Acute kidney injury (AKI) is reported in up to 30% of patients undergoing cardiac surgery and is a recognised independent predictor of both morbidity and mortality. Forced diuresis with the RenalGuard system reduces the incidence of AKI during percutaneous coronary intervention procedures but its use in cardiac surgery has not been explored. Methods Ten consecutive patients who were at risk of developing AKI during cardiac surgery were selected. The RenalGuard system was used to facilitate forced diuresis using weight-adjusted intravenous furosemide while maintaining neutral fluid balance by matched intravenous fluid replacement. This regimen was initiated preoperatively in all patients and continued for 6–12 hours postoperatively. Serum creatinine, electrolytes and need for renal replacement were documented in all patients. Results The RenalGuard system functioned successfully in all patients and facilitated high perioperative urine outputs, even when patients were placed on cardiopulmonary bypass (CPB). There were no incidences of significant (A) electrolyte imbalance, (B) changes in haemoglobin levels or (C) pulmonary oedema. No patients developed AKI within 36 hours of surgery despite one patient developing cardiac tamponade 8 hours postoperatively and one patient developing paralytic ileus. One patient, however, was ‘electively’ haemofiltered on day 2 after developing acute right ventricular failure. The median intensive care stay was 1.5 (1, 5) days. Conclusion The RenalGuard system can be used successfully in patients undergoing cardiac surgery with CPB and may reduce the incidence of AKI in at-risk patients

Early mortality after cardiac transplantation: should we do better?

BACKGROUND: According to International Society for Heart and Lung Transplantation (ISHLT) data, the 30-day survival after heart transplantation has continually improved from 84% (1979-85) to 91% (1996-2001). This has probably been achieved by better donor/recipient selection, along with improved surgical technique and immunosuppressive therapy. On the other hand, the data concerning the early causes of death after cardiac transplantation is incomplete, because in 25% of cases, an unknown cause is listed. This study investigated the incidence and causes of 30-day mortality (determined by postmortem studies) after cardiac transplantation and assessed the possibility of improvements. METHODS: A retrospective study of all patients who underwent heart transplantation at Papworth Hospital from 1979 to June 2001 (n = 879) and who died within 30 days of surgery was carried out. Postmortem examination data were available for all patients. RESULTS: The mean (standard deviation) recipient and donor ages were 46 (12) and 31 (12) years, respectively. Overall, the 30-day mortality was 8.5% (n = 75), 12.1% for the 1979 to 1985 period and 6.9% for the 1996 to 2001 period. The primary causes of death were graft failure (30.7%), acute rejection (22.7%) (1.3% for the 1996-2001 era), sepsis (18.7%) gastrointestinal problems (bowel infarction and pancreatitis; (9.3%), postoperative bleeding (6.7%), and other (12%). CONCLUSIONS: Our 30-day mortality compares favorably with the data from the ISHLT registry, with great improvement in the early mortality. Acute rejection is no longer a major cause of early mortality. Further reduction may be achieved by a better protection of the donor heart against the effects of brainstem death and ischemic injuries. However, the quest to improve early outcome should not be at the expense of needy patients by being overselective

Long-term quality of life postacute kidney injury in cardiac surgery patients.

Acute renal failure after cardiac surgery is known to be associated with significant short-term morbidity and mortality. There have as yet been no major reports on long-term quality of life (QOL). This study assessed the impact of acute kidney injury (AKI) and renal replacement therapy (RRT) on long-term survival and QOL after cardiac surgery. The need for long-term RRT is also assessed

Are non-brain stem-dead cardiac donors acceptable donors?

BACKGROUND: The deleterious effects of brainstem death (BSD) on donor cardiac function and endothelial integrity have been documented previously. Domino cardiac donation (heart of a heart-lung recipient transplanted into another recipient) is a way to avoid the effects of brainstem death and may confer both short- and long-term benefits to allograft recipients. METHODS: This study evaluates short- and long-term outcome in heart recipients of BSD donors (cadaveric) as compared with domino hearts explanted from patients who underwent heart-lung transplantation. RESULTS: Patients having undergone cardiac transplantation between April 1989 and August 2001 at Papworth Hospital were included (n = 571). Domino donor hearts were used in 81 (14%) of these cases. The pre-operative transpulmonary gradient was not significantly different between the two groups (p = 0.7). There was no significant difference in 30-day mortality (4.9% for domino vs 8.6% for BSD, p = 0.38) or in actuarial survival (p = 0.72). Ischemic time was significantly longer in the BSD group (p < 0.001). Acute rejection and infection episodes were not significantly different (p = 0.24 vs: 0.08). Relative to the BSD group, the risk (95% confidence interval) of acute rejection in the domino group was 0.89 (0.73 to 1.08). Similarly, the relative risk of infection was 0.78 (0.59 to 1.03). The 5-year actuarial survival rates (95% confidence interval) were 78% (69% to 87%) and 69% (65% to 73%) in the domino and BSD groups respectively. Angiography data at 2 years were available in 50 (62%) and 254 (52%) patients in the domino and BSD groups, respectively. The rates for 2-year freedom from cardiac allograft vasculopathy (CAV) were 96% (91% to 100%) and 93% (90% to 96%), respectively. CONCLUSION: Despite the lack of endothelial cell activation after brainstem death and a shorter ischemic time, the performance of domino donor hearts was similar to that of BSD donor hearts. This may indicate a similar pathology (i.e., endothelial cell activation) in the domino donors

Major adverse cardiac and cerebrovascular event and patients' quality of life after endoscopic vein harvesting as compared with open vein harvest (MAQEH): a pilot study.

This is a prospective, comparative, pilot and follow-up (2-year postoperatively) study in patients undergoing coronary artery bypass graft surgery where the long saphenous vein was harvested either by the endoscopic vein harvest (EVH) technique or open vein harvest (OVH) technique. Quality of life (QOL) and major adverse cardiac and cerebrovascular events (MACCE) were assessed

Assessing the effectiveness of retrograde autologous priming of the cardiopulmonary bypass machine in isolated coronary artery bypass grafts

Introduction Currently, around 35–80% of patients undergoing cardiac surgery in the UK receive a blood transfusion. Retrograde autologous priming (RAP) of the cardiopulmonary bypass circuit has been suggested as a possible strategy to reduce blood transfusion during cardiac surgery. Methods Data from 101 consecutive patients undergoing isolated coronary artery bypass grafts (where RAP was used) were collected prospectively and compared with 92 historic patients prior to RAP use in our centre. Results Baseline characteristics (ie age, preoperative haemoglobin [Hb] etc) were not significantly different between the RAP and non-RAP groups. The mean pump priming volume of 1,013ml in the RAP group was significantly lower (p&lt;0.001) than that of 2,450ml in the non-RAP group. The mean Hb level at initiation of bypass of 9.1g/dl in patients having RAP was significantly higher (p&lt;0.001) than that of 7.7g/dl in those who did not have RAP. There was no significant difference between the RAP and non-RAP groups in transfusion of red cells, platelets and fresh frozen plasma, 30-day mortality, re-exploration rate and predischarge Hb level. The median durations of cardiac intensive care unit stay and in-hospital stay of 1 day (interquartile range [IQR]: 1–2 days) and 5 days (IQR: 4–6 days) in the RAP group were significantly shorter than those of the non-RAP group (2 days [IQR: 1–3 days] and 6 days [IQR: 5–9 days]). Conclusions In the population group studied, RAP did not influence blood transfusion rates but was associated with a reduction in duration of hospital stay. </jats:sec